JP6584946B2 - Inspection device - Google Patents

Description

  The present invention relates to an inspection apparatus that inspects a defect or the like of a pattern formed on a surface of an inspection target, and more specifically, captures secondary charged particles that change according to the properties of the surface of the inspection target to form image data. The present invention relates to an inspection apparatus that inspects a pattern or the like formed on the surface of an inspection object based on the image data with high throughput.

  The conventional semiconductor inspection apparatus has been an apparatus and technology corresponding to the 100 nm design rule. However, the samples to be inspected are diversified with wafers, exposure masks, EUV masks, NIL (nanoimprint lithography) masks, and substrates, and currently, there is a need for an apparatus and technology corresponding to the design rule for samples of 5 to 30 nm. ing. That is, it is required to deal with generations in which the node of L / S (line / space) or hp (half pitch) in the pattern is 5 to 30 nm. When inspecting such a sample with an inspection apparatus, it is necessary to obtain high resolution.

  Here, the sample is an exposure mask, EUV mask, nanoimprint mask (and template), semiconductor wafer, optical element substrate, optical circuit substrate, or the like. Some of these have a pattern and some have no pattern. Some of them have a pattern and some do not. Patterns with no irregularities are formed with different materials. Those without a pattern include those coated with an oxide film and those not coated with an oxide film.

  In recent years, a primary optical system using a photocathode that generates a primary beam when irradiated with laser light has been developed as a primary optical system of an inspection apparatus. Conventionally, laser light sources that generate laser light are generally those that generate laser light with a Gaussian distribution.

International Publication No. WO2002 / 001596 JP 2007-48686 A Japanese Patent Laid-Open No. 11-132975

  However, when a Gaussian laser beam is irradiated onto the photocathode, a Gaussian primary beam is also generated from the photocathode. When the primary beam of the Gaussian distribution is used, there is a problem that the central portion of the sample inspection region (beam irradiation region) is bright and the end portion is dark, making it difficult to perform a uniform inspection over the entire surface of the sample inspection region. .

  The present invention has been made in view of the above problems, and an object thereof is to provide an inspection apparatus capable of performing a uniform inspection over the entire inspection region of a sample.

  The inspection apparatus of the present invention is an inspection apparatus for inspecting a sample, a stage on which the sample is placed, a primary optical system that irradiates the sample on the stage with a primary beam, and the primary beam A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample; and a secondary optical system that guides the secondary beam to the two-dimensional sensor. The optical system includes a laser light source that generates a Gaussian-distributed laser beam, a homogenizer that converts intensity distribution of the Gaussian-distributed laser beam into a uniformly-distributed laser beam, and the primary laser beam that is irradiated with the uniform-distributed laser beam And a photocathode for generating a beam.

  With this configuration, the Gaussian laser beam generated from the laser light source is converted into a uniform laser beam by the homogenizer and irradiated onto the photocathode. When the photocathode is irradiated with uniformly distributed laser light, a primary beam of uniform distribution is generated from the photocathode. By using a uniformly distributed primary beam, a uniform inspection can be performed over the entire inspection region of the sample.

  In the inspection apparatus of the present invention, the primary optical system includes a beam splitter that divides the laser light whose intensity distribution is converted by the homogenizer, and a beam profiler that measures the intensity distribution of the laser light divided by the beam splitter. , May be provided.

  With this configuration, the laser light whose intensity distribution has been converted by the homogenizer is divided by the beam splitter, and the intensity distribution is measured by the beam profiler. By measuring the intensity distribution with a beam profiler, it can be confirmed whether or not the laser light whose intensity distribution has been converted by the homogenizer has a uniform distribution. Thereby, it can be confirmed whether the laser beam of uniform distribution is irradiated to the photocathode.

  In the inspection apparatus of the present invention, the photocathode may be disposed in a vacuum chamber, and the laser light source and the homogenizer may be disposed outside the vacuum chamber.

  With this configuration, since the laser light source and the homogenizer are disposed outside the vacuum chamber, the position (fine adjustment) of the homogenizer with respect to the laser light generated from the laser light source can be easily performed.

  In the inspection apparatus of the present invention, the primary optical system includes a beam diameter adjusting unit that adjusts a beam diameter of the laser light generated from the laser light source, a focal length adjusting unit that adjusts a focal length of the laser light, May be provided.

  With this configuration, the beam diameter and focal length of the laser light generated from the laser light source can be adjusted appropriately, and a uniformly distributed laser light can be obtained by the homogenizer.

  According to the present invention, a uniform inspection can be performed over the entire inspection region of a sample.

FIG. 3 is an elevational view showing main components of an inspection apparatus according to an embodiment of the present invention, viewed along line AA in FIG. 2. It is the top view of the main components of the inspection apparatus shown in FIG. 1, Comprising: It is the figure seen along line BB of FIG. It is a schematic sectional drawing which shows the other Example of the board | substrate carrying-in apparatus in the test | inspection apparatus of this invention which concerns on one Embodiment. It is sectional drawing which shows the mini-environment apparatus of FIG. 1, Comprising: It is the figure seen along line CC. FIG. 3 is a diagram illustrating the loader housing of FIG. 1, as viewed along line DD in FIG. 2. It is an enlarged view of a wafer rack, [A] is a side view, [B] is a sectional view taken along line EE of [A]. It is a figure which shows the modification of the support method of a main housing. It is a figure which shows the modification of the support method of a main housing. It is the figure which showed the structure of the electron beam inspection apparatus which concerns on one Embodiment of this invention. It is a figure which concerns on one Embodiment of this invention, and is a figure which shows the electron beam inspection apparatus with which this invention was applied. It is a figure which concerns on one Embodiment of this invention, and is a figure which shows an example of a structure in the case of installing the electronic column of a mapping optical type | mold inspection apparatus, and a SEM type | mold inspection apparatus in the same main chamber. It is the figure which showed the structure of the electronic column type | system | group based on one Embodiment of this invention. It is explanatory drawing of the focus adjustment on NA image formation conditions in one Embodiment of this invention. It is explanatory drawing of the focus adjustment on NA image formation conditions in one Embodiment of this invention. It is explanatory drawing of the adjustment method of the incident angle of the primary beam in one Embodiment of this invention. It is a figure concerning one embodiment of the present invention. It is a figure concerning one embodiment of the present invention. It is explanatory drawing of the primary optical system of the test | inspection apparatus in embodiment of this invention. It is explanatory drawing of the primary optical system of the test | inspection apparatus in embodiment of this invention. It is explanatory drawing of the transmittance | permeability and the uniformity of a primary beam with respect to GL output in embodiment of this invention. It is explanatory drawing of rotation of the photocathode in this Embodiment. It is explanatory drawing of the test | inspection apparatus in embodiment of this invention. It is explanatory drawing of the scanning electron microscope with which the inspection apparatus in embodiment of this invention is equipped. It is explanatory drawing of the test | inspection apparatus in embodiment of this invention. It is explanatory drawing of the shift | offset | difference (shift) of the crossover position of the secondary optical system in embodiment of this invention. It is explanatory drawing of the change of the crossover position (distance with a secondary system aperture) of a mirror electron with respect to the change of the voltage of the quadrupole electrode in embodiment of this invention. It is a figure which shows an example of the fine adjustment of the crossover position of the mirror electron in embodiment of this invention. It is a figure which shows an example of the fine adjustment of the crossover position of the mirror electron in embodiment of this invention. It is a figure which shows an example of the fine adjustment of the crossover position of the mirror electron in embodiment of this invention. It is a figure showing composition of an inspection system concerning one embodiment of the present invention. It is a figure explaining the cell period in the case of the cell-cell comparison which concerns on one Embodiment of this invention, and the edge tolerance in the case of die-die comparison. It is a flowchart which shows operation | movement of the test | inspection system which concerns on one Embodiment of this invention. It is a figure which concerns on one Embodiment of this invention, and is a figure for demonstrating the 1st process of a scanning method. It is a figure which concerns on one Embodiment of this invention, and is a figure for demonstrating the 2nd process of a scanning method. It is a figure which concerns on one Embodiment of this invention, and is a figure for demonstrating the 3rd process of a scanning method. It is a figure which concerns on one Embodiment of this invention, and is a figure for demonstrating the 4th process of a scanning method. It is a figure showing an inspection device concerning one embodiment of the present invention. It is the schematic which expands and shows a scanning electron microscope, an energy dispersive X-ray spectrometer, and the sample on a stage in the inspection apparatus shown in FIG. It is a figure for demonstrating operation | movement of the turning means at the time of the material analysis of a defect. It is a figure for demonstrating operation | movement of the tilt means at the time of the material analysis of a defect. It is a figure for demonstrating operation | movement of the deflector at the time of the material analysis of a defect. It is a figure for demonstrating the photocathode divided | segmented into the 1st area | region and the 2nd area | region. It is a figure for demonstrating the area | region where the primary beam generated from the 1st area | region of the photocathode injects on the sample surface, and the area | region where the primary beam generate | occur | produced from the 2nd area | region enters. The first step of the inspection method when the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident are adjacent in the direction of the step operation of the stage apparatus will be described. FIG. The second step of the inspection method when the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident are adjacent in the direction of the step operation of the stage apparatus will be described. FIG. The first step of the inspection method when the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident are adjacent in the direction of the scanning operation of the stage apparatus will be described. FIG. The second step of the inspection method when the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident are adjacent to each other in the scanning operation direction of the stage apparatus will be described. FIG. It is a figure for demonstrating the aspect by which the aperture was arrange | positioned on the photocathode.

  A semiconductor inspection apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The embodiment described below shows an example when the present invention is implemented, and the present invention is not limited to the specific configuration described below. In carrying out the present invention, a specific configuration according to the embodiment may be adopted as appropriate.

  1 and 2A, the main components of the semiconductor inspection apparatus 1 of the present embodiment are shown in an elevational plane and a plane.

  The semiconductor inspection apparatus 1 according to the present embodiment includes a cassette holder 10 that holds a cassette that stores a plurality of wafers, a mini-environment device 20, a main housing 30 that defines a working chamber, and a mini-environment device 20. A loader housing 40 disposed between the main housing 30 and defining two loading chambers; a loader 60 for loading a wafer from the cassette holder 10 onto a stage device 50 disposed in the main housing 30; An electron optical device 70 attached to a vacuum housing, an optical microscope 3000, and a scanning electron microscope (SEM) 3002 are provided and are arranged in a positional relationship as shown in FIGS. 1 and 2A. The semiconductor inspection apparatus 1 further includes a precharge unit 81 disposed in the vacuum main housing 30, a potential application mechanism that applies a potential to the wafer, an electron beam calibration mechanism, and a wafer on the stage apparatus 50. The optical microscope 871 which comprises the alignment control apparatus 87 for performing positioning is provided. The electron optical device 70 includes a lens barrel 71 and a light source tube 7000. The internal structure of the electro-optical device 70 will be described later.

<Cassette holder>
The cassette holder 10 includes a plurality of cassettes c (for example, closed cassettes such as SMIF and FOUP manufactured by Assist) in which a plurality of wafers (for example, 25 wafers) are stored in parallel with each other in the vertical direction. 2 in this embodiment). As this cassette holder, a cassette having a structure suitable for the case where the cassette is transported by a robot or the like and automatically loaded into the cassette holder 10, or an open cassette having a structure suitable for the manual loading is used. Each can be selected and installed. In this embodiment, the cassette holder 10 is of a type in which the cassette c is automatically loaded. For example, the cassette holder 10 includes an elevating table 11 and an elevating mechanism 12 that moves the elevating table 11 up and down. 2A can be automatically set in the state shown by the chain line in FIG. 2A, and after setting, the first conveyance unit 61 in the mini-environment apparatus 20 is automatically rotated to the state shown in the solid line in FIG. Directed to the pivot axis. Further, the lifting table 11 is lowered to the state shown by the chain line in FIG. As described above, the cassette holder used for automatic loading or the cassette holder used for manual loading may be a known structure as appropriate. Description is omitted.

  In another embodiment, as shown in FIG. 2B, a plurality of 300 mm substrates are accommodated in a grooved pocket (not shown) fixed inside the box body 501, and are transported, stored, etc. It is. This substrate transport box 500 is connected to a rectangular tube-shaped box body 501 and a substrate loading / unloading door automatic opening / closing device, and a substrate loading / unloading door 502 capable of opening and closing a side opening of the box body 501 by a machine, A lid 503 that is positioned on the opposite side and covers an opening for attaching and detaching the filters and fan motor, a groove-type pocket (not shown) for holding the substrate W, a ULPA filter 505, a chemical filter 506, And a fan motor 507. In this embodiment, the substrate is loaded and unloaded by the robot-type first transport unit 61 of the loader 60.

  The substrate, that is, the wafer housed in the cassette c is a wafer to be inspected, and such inspection is performed after or during the process of processing the wafer in the semiconductor manufacturing process. Specifically, a substrate that has been subjected to a film forming process, CMP, ion implantation, or the like, that is, a wafer having a wiring pattern formed on the surface, or a wafer on which a wiring pattern has not yet been formed is stored in a cassette. Since a large number of wafers accommodated in the cassette c are arranged side by side in parallel in the vertical direction, the first transfer unit 61 can be held by the first transfer unit 61 and the wafer at an arbitrary position. The arm 612 can be moved up and down.

<Mini-environment device>
1 to 3, a mini-environment device 20 includes a housing 22 that defines a mini-environment space 21 that is controlled in atmosphere, and a gas such as clean air in the mini-environment space 21. A gas circulation device 23 for circulating and controlling the atmosphere, a discharge device 24 for collecting and discharging a part of the air supplied into the mini-environment space 21, and a mini-environment space 21 are provided. And a pre-aligner 25 for roughly positioning a substrate to be inspected, that is, a wafer.

  The housing 22 has a top wall 221, a bottom wall 222, and a peripheral wall 223 that surrounds four sides, and has a structure that blocks the mini-environment space 21 from the outside. In order to control the atmosphere of the mini-environment space, the gas circulation device 23 is attached to the top wall 221 in the mini-environment space 21 as shown in FIG. 3, and gas (air in this embodiment) is installed. And a gas supply unit 231 for flowing clean air in a laminar flow downwardly through one or more gas outlets (not shown), and on the bottom wall 222 in the mini-environment space 21 A recovery duct 232 that is disposed and recovers air that has flowed down toward the bottom; and a conduit 233 that connects the recovery duct 232 and the gas supply unit 231 and returns the recovered air to the gas supply unit 231. ing. In this embodiment, the gas supply unit 231 takes about 20% of the supplied air from the outside of the housing 22 and cleans it. However, the ratio of the gas taken in from the outside can be arbitrarily selected. . The gas supply unit 231 includes a HEPA or ULPA filter having a known structure for producing clean air. The laminar flow of the clean air, that is, the downward flow, that is, the downflow is mainly supplied to flow through the transport surface by the first transport unit 61 disposed in the mini-environment space 21 and is generated by the transport unit. This prevents dust having a risk of adhering to the wafer. Therefore, it is not always necessary that the downflow jet outlet is located close to the top wall as shown in the drawing, and it is sufficient if it is above the transport surface of the transport unit. Moreover, there is no need to flow over the entire mini-environment space. In some cases, cleanliness can be ensured by using ion wind as clean air. Further, a sensor for observing the cleanliness can be provided in the mini-environment space, and the apparatus can be shut down when the cleanliness deteriorates. An entrance / exit 225 is formed in a portion of the peripheral wall 223 of the housing 22 adjacent to the cassette holder 10. A shutter device having a known structure may be provided in the vicinity of the doorway 225 so that the doorway 225 is closed from the mini-environment device side. The laminar flow downflow created near the wafer may be, for example, a flow rate of 0.3 to 0.4 m / sec. The gas supply unit may be provided outside the mini-environment space 21 instead of inside it.

  The discharge device 24 includes a suction duct 241 disposed below the first transfer unit 61 at a position below the wafer transfer surface of the first transfer unit 61, a blower 242 disposed outside the housing 22, And a conduit 243 connecting the suction duct 241 and the blower 242. The discharge device 24 flows down around the first transport unit 61, sucks the gas containing dust that may be generated by the first transport unit 61 through the suction duct 241, and the conduits 243, 244 and It discharges to the outside of the housing 22 through the blower 242. In this case, the air may be discharged into an exhaust pipe (not shown) drawn near the housing 22.

  The pre-aligner 25 disposed in the mini-environment space 21 is formed on an orientation flat formed on the wafer (referred to as a flat portion formed on the outer periphery of a circular wafer, hereinafter referred to as an orientation flat) or on the outer peripheral edge of the wafer. One or more V-shaped notches or notches are detected optically or mechanically to pre-position the rotational position around the wafer axis OO with an accuracy of about ± 1 degree. It is supposed to keep. The pre-aligner 25 constitutes a part of the mechanism for determining the coordinates of the inspection object, and is responsible for the rough positioning of the inspection object. Since the pre-aligner 25 itself may have a known structure, the description of the structure and operation is omitted.

  Although not shown, a recovery duct for a discharge device may be provided below the pre-aligner 25 so that air containing dust discharged from the pre-aligner 25 may be discharged to the outside.

<Main housing>
1 and 2A, a main housing 30 that defines a working chamber 31 includes a housing body 32 that is mounted on a vibration isolating device or vibration isolating device 37 disposed on a base frame 36. It is supported by the mounted housing support device 33. The housing support device 33 includes a frame structure 331 assembled in a rectangular shape. The housing main body 32 is disposed and fixed on the frame structure 331, and is connected to the bottom wall 321 mounted on the frame structure, the top wall 322, the bottom wall 321 and the top wall 322, and surrounds the circumference. 323 to isolate the working chamber 31 from the outside. In this embodiment, the bottom wall 321 is composed of a relatively thick steel plate so as not to be distorted by weighting by equipment such as the stage device 50 placed on the bottom wall 321. Also good. In this embodiment, the housing body 32 and the housing support device 33 are assembled in a rigid structure, and vibration from the floor on which the base frame 36 is installed is transmitted to the rigid structure by the vibration isolator 37. It comes to stop. Of the peripheral wall 323 of the housing body 32, an entrance / exit 325 for taking in and out the wafer is formed in a peripheral wall adjacent to a loader housing described later.

  The vibration isolator 37 may be an active type having an air spring, a magnetic bearing or the like, or a passive type having these. Since any of them may have a known structure, description of its own structure and function is omitted. The working chamber 31 is maintained in a vacuum atmosphere by a known vacuum device (not shown). A control device 2 that controls the operation of the entire apparatus is disposed under the base frame 36.

<Loader housing>
1, 2 </ b> A, and 4, the loader housing 40 includes a housing body 43 that defines a first loading chamber 41 and a second loading chamber 42. The housing main body 43 includes a bottom wall 431, a top wall 432, a peripheral wall 433 that surrounds the four circumferences, and a partition wall 434 that partitions the first loading chamber 41 and the second loading chamber 42. Can be isolated from the outside. The partition wall 434 has an opening, that is, an entrance / exit 435 for exchanging wafers between both loading chambers. In addition, entrances 436 and 437 are formed in a portion of the peripheral wall 433 adjacent to the mini-environment device and the main housing. The housing main body 43 of the loader housing 40 is placed on and supported by the frame structure 331 of the housing support device 33. Therefore, the floor vibration is not transmitted to the loader housing 40. The entrance / exit 436 of the loader housing 40 and the entrance / exit 226 of the housing 22 of the mini-environment device 20 are aligned with each other, and there is a shutter that selectively blocks communication between the mini-environment space 21 and the first loading chamber 41. A device 27 is provided. The shutter device 27 surrounds the doorways 226 and 436 and seals 271 fixed in close contact with the side wall 433, and a door 272 that blocks air flow through the doorway in cooperation with the sealant 271. And a driving device 273 for moving the door. Further, the entrance / exit 437 of the loader housing 40 and the entrance / exit 325 of the housing main body 32 are aligned with each other, and there is a shutter device 45 that selectively blocks the communication between the second loading chamber 42 and the working chamber 31. Is provided. The shutter device 45 surrounds the entrances and exits 437 and 325, closely contacts the side walls 433 and 323, and cooperates with the sealing material 451 and the sealing material 451 that are fixed to the side walls 433 and 323. It has a door 452 for blocking and a driving device 453 for moving the door. Further, the opening formed in the partition wall 434 is provided with a shutter device 46 which is closed by a door 461 and selectively prevents communication between the first and second loading chambers. These shutter devices 27, 45 and 46 are adapted to hermetically seal each chamber when in the closed state. Since these shutter devices may be known ones, detailed description of their structure and operation will be omitted. The support method of the housing 22 of the mini-environment device 20 and the support method of the loader housing are different, and vibrations from the floor are prevented from being transmitted to the loader housing 40 and the main housing 30 via the mini-environment device 20. Therefore, an anti-vibration cushion material may be disposed between the housing 22 and the loader housing 40 so as to airtightly surround the doorway.

  In the first loading chamber 41, a wafer rack 47 is disposed that supports a plurality (two in this embodiment) of wafers in a horizontal state with a vertical separation. As shown in FIG. 5, the wafer rack 47 includes support columns 472 that are fixed upright at four corners of a rectangular substrate 471, and two support portions 473 and 474 are formed on each support column 472. Then, the periphery of the wafer W is placed on and held on the support portion. Then, the tips of arms of first and second transfer units, which will be described later, are brought close to the wafer from between adjacent columns, and the wafer is held by the arm.

The loading chambers 41 and 42 can be controlled in a high vacuum state (the degree of vacuum is 10 ⁻⁵ to 10 ⁻⁶ Pa) by an evacuation apparatus (not shown) having a known structure including a vacuum pump (not shown). It has become. In this case, the first loading chamber 41 can be maintained as a low vacuum chamber in a low vacuum atmosphere, and the second loading chamber 42 can be maintained as a high vacuum chamber in a high vacuum atmosphere to effectively prevent wafer contamination. By adopting such a structure, a wafer which is accommodated in the loading chambers 41 and 42 and to be subsequently inspected for defects can be transferred into the working chamber 31 without delay. By adopting such loading chambers 41 and 42, the throughput of defect inspection is improved, and the degree of vacuum around the electron source that is required to be kept in a high vacuum state is as high as possible. Can be.

  The first and second loading chambers 41 and 42 are connected to a vacuum exhaust pipe and a vent pipe (not shown) for an inert gas (for example, dry pure nitrogen), respectively. Thereby, the atmospheric pressure state in each loading chamber is achieved by an inert gas vent (injecting an inert gas to prevent oxygen gas other than the inert gas from adhering to the surface). Since the apparatus for performing such an inert gas vent itself may have a known structure, a detailed description thereof will be omitted.

<Stage device>
The stage device 50 includes a fixed table 51 disposed on the bottom wall 321 of the main housing 30, a Y table 52 that moves in the Y direction (a direction perpendicular to the paper surface in FIG. 1) on the fixed table, and a Y table. An X table 53 that moves in the X direction (left-right direction in FIG. 1), a rotary table 54 that can rotate on the X table, and a holder 55 that is arranged on the rotary table 54 are provided. The wafer is releasably held on the wafer placement surface 551 of the holder 55. The holder may have a known structure capable of releasably gripping the wafer mechanically or by an electrostatic chuck method. The stage apparatus 50 uses a servo motor, an encoder, and various sensors (not shown) to operate the plurality of tables as described above, thereby causing the wafer held by the holder on the mounting surface 551 to be electro-optically. Positioning can be performed with high accuracy in the X direction, Y direction, and Z direction (vertical direction in FIG. 1) with respect to the electron beam emitted from the apparatus 70, and further in the direction around the vertical axis (θ direction) on the support surface of the wafer. It is like that. For positioning in the Z direction, for example, the position of the mounting surface on the holder may be finely adjusted in the Z direction. In this case, the reference position of the mounting surface is detected by a position measuring device (laser interference distance measuring device using the principle of an interferometer) using a fine-diameter laser, and the position is controlled by a feedback circuit (not shown). Instead, the position of the notch or orientation flat of the wafer is measured to detect the planar position and the rotational position of the wafer with respect to the electron beam, and the rotary table is rotated by a stepping motor capable of controlling a minute angle or the like. Servo motors 521 and 531 for the stage device 50 and encoders 522 and 532 are disposed outside the main housing 30 in order to prevent dust from being generated in the working chamber as much as possible. Note that the stage device 50 may have a known structure used in, for example, a stepper and the like, and a detailed description of the structure and operation will be omitted. Also, since the laser interference distance measuring device may have a known structure, detailed description of the structure and operation is omitted.

  Standardization of signals indicating wafer rotation position and X / Y position obtained during inspection by inputting the rotation position and X / Y position of the wafer with respect to the electron beam in advance to a signal detection system or image processing system described later. Can also be planned. Further, the wafer chuck mechanism provided in the holder is adapted to apply a voltage for chucking the wafer to the electrode of the electrostatic chuck, and has three points (preferably equally spaced in the circumferential direction) on the outer periphery of the wafer. It is designed to press and hold (separated). The wafer chuck mechanism includes two fixed positioning pins and one pressing clamp pin. The clamp pin can realize automatic chucking and automatic release, and constitutes a conduction point for voltage application.

  In this embodiment, the table that moves in the horizontal direction in FIG. 2A is the X table and the table that moves in the vertical direction is the Y table. However, the table that moves in the horizontal direction in FIG. The moving table may be an X table.

<Loader>
The loader 60 includes a robot-type first transfer unit 61 arranged in the housing 22 of the mini-environment device 20 and a robot-type second transfer unit 63 arranged in the second loading chamber 42. I have.

The first transport unit 61 has a multi-node arm 612 that is rotatable about the axis O ₁ -O ₁ with respect to the drive unit 611. As the multi-node arm, an arbitrary structure can be used, but in this embodiment, the multi-node arm has three portions which are rotatably attached to each other. One portion of the arm 612 of the first transport unit 61, that is, the first portion closest to the drive unit 611 is a shaft that can be rotated by a drive mechanism (not shown) having a known structure provided in the drive unit 611. 613 is attached. The arm 612 can be rotated around the axis O ₁ -O ₁ by the shaft 613, and can expand and contract in the radial direction with respect to the axis O ₁ -O ₁ as a whole by relative rotation between the parts. A gripping device 616 for gripping a wafer such as a mechanical chuck or an electrostatic chuck having a known structure is provided at the tip of the third portion farthest from the shaft 613 of the arm 612. The drive unit 611 can be moved in the vertical direction by an elevating mechanism 615 having a known structure.

  The first transfer unit 61 has an arm extending in one direction M1 or M2 of the two cassettes c in which the arm 612 is held by the cassette holder 10, and arms the wafers accommodated in the cassette c. On the top of the arm or gripped by a chuck (not shown) attached to the tip of the arm. Thereafter, the arm contracts (as shown in FIG. 2A), and the arm rotates to a position where it can extend in the direction M3 of the pre-aligner 25 and stops at that position. Then, the arm 612 extends again and the wafer held by the arm 612 is placed on the pre-aligner 25. After receiving the wafer from the pre-aligner 25 in the opposite direction, the arm 612 further rotates and stops at a position (direction M4) where the arm 612 can extend toward the second loading chamber 41, and the wafer in the second loading chamber 41 is stopped. The wafer is delivered to the receiver 47. When the wafer is mechanically gripped, the peripheral edge of the wafer (in the range of about 5 mm from the peripheral edge) is gripped. This is because a device (circuit wiring) is formed on the entire surface of the wafer except for the peripheral portion, and if this portion is gripped, the device is broken or a defect is generated.

  The second transfer unit 63 is basically the same in structure as the first transfer unit 61, and is different only in that the wafer is transferred between the wafer rack 47 and the mounting surface of the stage device 50. Therefore, detailed description is omitted.

  In the loader 60, the first and second transfer units 61 and 63 transfer wafers from the cassette held in the cassette holder 10 onto the stage device 50 arranged in the working chamber 31 and vice versa. The arm of the transfer unit moves up and down while keeping it in a horizontal state, simply taking out the wafer from the cassette and inserting it into the cassette, placing the wafer on the wafer rack and taking it out from the wafer rack, and the wafer. This is only at the time of mounting on the stage device 50 and taking it out from the stage device 50. Therefore, a large wafer, for example, a wafer having a diameter of 30 cm or 45 cm, can be moved smoothly.

<Wafer transfer>
Next, the transfer of the wafer from the cassette c supported by the cassette holder 10 to the stage device 50 disposed in the working chamber 31 will be described in order.

  As described above, the cassette holder 10 has a structure suitable for manually setting a cassette, and has a structure suitable for automatically setting a cassette. In this embodiment, when the cassette c is set on the lifting table 11 of the cassette holder 10, the lifting table 11 is lowered by the lifting mechanism 12 and the cassette c is aligned with the entrance / exit 225.

  When the cassette is aligned with the entrance / exit 225, a cover (not shown) provided in the cassette c is opened, and a cylindrical cover is disposed between the cassette c and the entrance / exit 225 of the mini-environment. The inside of c and the mini environment space 21 is shut off from the outside. Since these structures are publicly known, detailed description of the structure and operation is omitted. When a shutter device that opens and closes the entrance / exit 225 is provided on the mini-environment device 20 side, the shutter device operates to open the entrance / exit 225.

  On the other hand, the arm 612 of the first transport unit 61 is stopped in a state facing in either the direction M1 or M2 (in this description, the direction of M2). One of the wafers stored in the wafer is received. In this embodiment, the vertical position adjustment of the arm 612 and the wafer to be taken out from the cassette c is performed by the vertical movement of the driving unit 611 and the arm 612 of the first transfer unit 61. You may carry out by the up-and-down movement of the raising / lowering table 11, or you may perform both.

When the receipt of the wafer by the arm 612 is completed, the arm 612 is contracted, the shutter device is operated to close the entrance / exit (when there is a shutter device), and then the arm 612 is rotated around the axis O ₁ -O _1. It will be in the state which can expand | extend toward the direction M3. Then, the arm 612 extends, and the wafer placed on the tip or held by the chuck is placed on the pre-aligner 25, and the pre-aligner 25 changes the direction of rotation of the wafer (direction around the central axis perpendicular to the wafer plane). Position within a predetermined range. When the positioning is completed, the first transfer unit 61 receives the wafer from the pre-aligner 25 at the tip of the arm 612 and then contracts the arm 612 so that the arm 612 can be extended in the direction M4. Then, the door 272 of the shutter device 27 moves to open the entrances 226 and 436 and the arm 612 extends to place the wafer on the upper stage side or the lower stage side of the wafer rack 47 in the first loading chamber 41. Note that the opening 435 formed in the partition wall 434 is closed in an airtight state by the door 461 of the shutter device 46 before the shutter device 27 is opened and the wafer is transferred to the wafer rack 47 as described above.

  During the wafer transfer process by the first transfer unit 61, clean air flows in a laminar flow (as a down flow) from the gas supply unit 231 provided on the housing 22 of the mini-environment device 20. Dust is prevented from adhering to the upper surface of the wafer. Part of the air around the transport unit 61 (in this embodiment, air that is mainly dirty with about 20% of the air supplied from the supply unit) is sucked from the suction duct 241 of the discharge device 24 and discharged out of the housing. . The remaining air is recovered via a recovery duct 232 provided at the bottom of the housing 22 and returned to the gas supply unit 231 again.

  When a wafer is loaded on the wafer rack 47 in the first loading chamber 41 of the loader housing 40 by the first transfer unit 61, the shutter device 27 is closed and the loading chamber 41 is sealed. Then, after the inert gas is expelled in the first loading chamber 41 and the air is expelled, the inert gas is also discharged and the inside of the loading chamber 41 is made a vacuum atmosphere. The vacuum atmosphere in the first loading chamber 41 may be a low degree of vacuum. When the degree of vacuum in the loading chamber 41 is obtained to some extent, the shutter device 46 operates to open the doorway 434 that has been sealed by the door 461, the arm 632 of the second transfer unit 63 extends, and the wafer is held by the gripping device at the tip. One wafer is received from the receiver 47 (mounted on the tip or held by a chuck attached to the tip). When the receipt of the wafer is completed, the arm 632 contracts, and the shutter device 46 operates again to close the doorway 435 with the door 461. Note that before the shutter device 46 is opened, the arm 632 can be extended in advance in the direction N1 of the wafer rack 47. In addition, as described above, the doors 437 and 325 are closed by the door 452 of the shutter device 45 before the shutter device 46 is opened, thereby preventing communication between the second loading chamber 42 and the working chamber 31 in an airtight state. The inside of the second loading chamber 42 is evacuated.

When the shutter device 46 closes the entrance / exit 435, the inside of the second loading chamber 42 is evacuated again, and is evacuated at a higher degree of vacuum than in the first loading chamber 41. Meanwhile, the arm 632 of the second transfer unit 63 is rotated to a position where it can extend toward the stage device 50 in the working chamber 31. On the other hand, in the stage apparatus 50 in the working chamber 31, the Y table 52 has an X axis line X ₁ − that passes through the rotation axis O ₂ −O ₂ of the second transport unit 63 with the center line X ₀ -X ₀ of the X table 53. X ₁ and up to approximately match the position, moves upward in FIG. 2A, Further, X table 53 is moved to a position close to the leftmost position in FIG. 2A, waiting in this state. When the second loading chamber 42 becomes substantially the same as the vacuum state of the working chamber 31, the door 452 of the shutter device 45 moves to open the entrances 437 and 325, the arm 632 extends and the tip of the arm 632 holding the wafer is the working. The stage device 50 in the chamber 31 is approached. Then, a wafer is placed on the placement surface 551 of the stage apparatus 50. When the placement of the wafer is completed, the arm 632 contracts and the shutter device 45 closes the entrances 437 and 325.

  The operation until the wafer in the cassette c is transferred onto the stage device 50 has been described above. To return the wafer that has been placed on the stage device 50 and completed processing from the stage device 50 into the cassette c, The reverse operation is performed. Further, in order to place a plurality of wafers on the wafer rack 47, the first transfer unit 61 performs the transfer of the wafers between the wafer rack 47 and the stage apparatus 50 by the second transfer unit 63. Wafers can be transferred between the cassette c and the wafer rack 47, and inspection processing can be performed efficiently.

  Specifically, when the wafer rack 47 of the second transfer unit 63 includes the already processed wafer A and the unprocessed wafer B, (1) First, the unprocessed wafer B is moved to the stage apparatus 50. (2) During this process, the processed wafer A is moved from the stage device 50 to the wafer rack 47 by the arm 632, and the unprocessed wafer C is extracted from the wafer rack 47 by the arm 632, After positioning by the pre-aligner 25, the wafer moves to the wafer rack 47 of the loading chamber 41. In this way, in the wafer rack 47, the processed wafer A can be replaced with the unprocessed wafer C while the wafer B is being processed.

  Further, depending on how to use such an apparatus for performing inspection and evaluation, a plurality of stage apparatuses 50 are placed in parallel, and a plurality of wafers are transferred by moving wafers from one wafer rack 47 to each apparatus. Simultaneous processing is also possible.

  FIG. 6 shows a modification of the main housing support method. In the modification shown in FIG. 6, the housing support device 33a is formed of a thick and rectangular steel plate 331a, and the housing body 32a is placed on the steel plate. Therefore, the bottom wall 321a of the housing body 32a has a thin structure as compared with the bottom wall of the above embodiment. In the modification shown in FIG. 7, the housing body 32b and the loader housing 40b are suspended and supported by the frame structure 336b of the housing support device 33b. Lower ends of the plurality of vertical frames 337b fixed to the frame structure 336b are fixed to four corners of the bottom wall 321b of the housing main body 32b, and the peripheral wall and the top wall are supported by the bottom wall. The vibration isolator 37b is disposed between the frame structure 336b and the base frame 36b. The loader housing 40 is also suspended by a suspension member 49b fixed to the frame structure 336. In the modification shown in FIG. 7 of the housing main body 32b, since it is supported in a suspended manner, the center of gravity of the main housing and the various devices provided therein can be lowered. In the main housing and loader housing support methods including the above-described modifications, vibrations from the floor are not transmitted to the main housing and the loader housing.

  In another variant not shown, only the main housing outside the main housing is supported from below by the housing support device, and the loader housing can be placed on the floor in the same way as the adjacent mini-environment device 20. In yet another modification, not shown, only the housing body of the main housing is supported in a suspended manner on the frame structure, and the loader housing can be placed on the floor in the same manner as the adjacent mini-environment device 20.

According to the above embodiment, the following effects can be obtained.
(A) An overall configuration of a mapping projection type inspection apparatus using an electron beam is obtained, and an inspection object can be processed with high throughput.
(B) Inspecting the inspection object while monitoring the dust in the space by providing a sensor for observing the cleanliness by supplying a clean gas to the inspection object in the mini-environment space to prevent the adhesion of dust. Can do.
(C) Since the loading chamber and the working chamber are integrally supported via the vibration preventing device, it is possible to supply and inspect the inspection target to the stage device 50 without being affected by the external environment.

"Electronic inspection equipment"
FIG. 8 is a diagram showing the configuration of an electron beam inspection apparatus to which the present invention is applied. In the above description, the principle part of the foreign matter inspection method has been mainly described. Here, a foreign substance inspection apparatus applied to execute the above-described foreign substance inspection method will be described. Therefore, all the foreign substance inspection methods described above can be applied to the following foreign substance inspection apparatus.

  The inspection object of the electron beam inspection apparatus is the sample 20. The sample 20 is a silicon wafer, a glass mask, a semiconductor substrate, a semiconductor pattern substrate, a substrate having a metal film, or the like. The electron beam inspection apparatus according to the present embodiment detects the presence of the foreign matter 10 on the surface of the sample 20 made of these substrates. The foreign material 10 is an insulator, a conductive material, a semiconductor material, or a complex thereof. The types of the foreign matter 10 are particles, cleaning residues (organic matter), reaction products on the surface, and the like. The electron beam inspection apparatus may be an SEM system apparatus or a mapping projection apparatus. In this example, the present invention is applied to a mapping projection inspection apparatus.

  The projection type electron beam inspection apparatus forms a primary optical system 40 that generates an electron beam, a sample 20, a stage 30 on which the sample is placed, and an enlarged image of secondary emission electrons or mirror electrons from the sample. Secondary optical system 60 to be detected, a detector 70 for detecting those electrons, an image processing device 90 (image processing system) for processing a signal from the detector 70, an optical microscope 110 for alignment, and a review SEM120. The detector 70 may be included in the secondary optical system 60 in the present invention. Further, the image processing apparatus 90 may be included in the image processing unit of the present invention.

  The primary optical system 40 is configured to generate an electron beam and irradiate the sample 20. The primary optical system 40 includes an electron gun 41, lenses 42 and 45, apertures 43 and 44, an E × B filter 46, lenses 47, 49 and 50, and an aperture 48. An electron beam is generated by the electron gun 41. The lenses 42 and 45 and the apertures 43 and 44 shape the electron beam and control the direction of the electron beam. In the E × B filter 46, the electron beam is affected by the Lorentz force due to the magnetic field and the electric field. The electron beam enters the E × B filter 46 from an oblique direction, is deflected vertically downward, and travels toward the sample 20. The lenses 47, 49, and 50 adjust the landing energy LE by controlling the direction of the electron beam and appropriately decelerating.

  The primary optical system 40 irradiates the sample 20 with an electron beam. As described above, the primary optical system 40 irradiates both the precharge charging electron beam and the imaging electron beam. According to the experimental results, the difference between the precharge landing energy LE1 and the imaging electron beam landing energy LE2 is preferably 5 to 20 eV.

  In this regard, it is assumed that when there is a potential difference between the foreign material 10 and the surrounding area, the precharge landing energy LE1 is irradiated in the negatively charged region. The charge-up voltage varies depending on the value of LE1. This is because the relative ratio of LE1 and LE2 changes (LE2 is the landing energy of the imaging electron beam as described above). When LE1 is large, the charge-up voltage becomes high, whereby a reflection point is formed at a position above the foreign material 10 (position closer to the detector 70). Depending on the position of this reflection point, the trajectory and transmittance of the mirror electrons change. Therefore, an optimum charge-up voltage condition is determined according to the reflection point. On the other hand, if LE1 is too low, the efficiency of forming mirror electrons decreases. The present invention has found that the difference between LE1 and LE2 is preferably 5 to 20 [eV]. The value of LE1 is preferably 0 to 40 [eV], more preferably 5 to 20 [eV].

  In the primary optical system 40 of the mapping projection optical system, the E × B filter 46 is particularly important. The primary electron beam angle can be determined by adjusting the electric field and magnetic field conditions of the E × B filter 46. For example, the condition of the E × B filter 46 can be set so that the primary electron beam and the secondary electron beam are incident on the sample 20 substantially perpendicularly. In order to further increase the sensitivity, for example, it is effective to tilt the incident angle of the primary electron beam with respect to the sample 20. An appropriate inclination angle is 0.05 to 10 degrees, preferably about 0.1 to 3 degrees.

  As described above, by irradiating the foreign material 10 with the electron beam at a predetermined angle θ, the signal from the foreign material 10 can be strengthened. As a result, it is possible to form a condition in which the orbit of the mirror electrons does not deviate from the center of the secondary system optical axis, and therefore it is possible to increase the transmittance of the mirror electrons. Therefore, when the foreign material 10 is charged up and the mirror electrons are guided, the tilted electron beam is very advantageously used.

  The stage 30 is a means for placing the sample 20 and is movable in the xy horizontal direction and the θ direction. Further, the stage 30 may be movable in the z direction as necessary. A sample fixing mechanism such as an electrostatic chuck may be provided on the surface of the stage 30.

  The sample 20 is on the stage 30, and the foreign material 10 is on the sample 20. The primary optical system 40 irradiates the sample surface 21 with an electron beam with landing energy LE-5 to -10 [eV]. The foreign material 10 is charged up, and incident electrons of the primary optical system 40 are bounced back without contacting the foreign material 10. Thereby, the mirror electrons are guided to the detector 70 by the secondary optical system 60. At this time, secondary emission electrons are emitted in a direction extending from the sample surface 21. Therefore, the transmittance of secondary emission electrons is a low value, for example, about 0.5 to 4.0%. On the other hand, since the direction of the mirror electrons is not scattered, the mirror electrons can achieve a high transmittance of almost 100%. The mirror electrons are formed by the foreign material 10. Therefore, only the signal of the foreign material 10 can cause high luminance (a state in which the number of electrons is large). The brightness difference / ratio with the surrounding secondary emission electrons is increased, and high contrast can be obtained.

  Further, as described above, the mirror electron image is magnified at a magnification larger than the optical magnification. The enlargement ratio ranges from 5 to 50 times. Under typical conditions, the magnification is often 20 to 30 times. At this time, foreign matter can be detected even if the pixel size is three times or more the foreign matter size. Therefore, it can be realized at high speed and high throughput.

  For example, when the size of the foreign material 10 is 20 [nm] in diameter, the pixel size may be 60 [nm], 100 [nm], 500 [nm], or the like. As in this example, it is possible to image and inspect a foreign object using a pixel size that is three times or more that of the foreign object. This is a feature that is remarkably superior for increasing the throughput as compared with the SEM method or the like.

  The secondary optical system 60 is a means for guiding the electrons reflected from the sample 20 to the detector 70. The secondary optical system 60 includes lenses 61 and 63, an NA aperture 62, an aligner 64, and a detector 70. The electrons are reflected from the sample 20 and pass through the objective lens 50, the lens 49, the aperture 48, the lens 47 and the E × B filter 46 again. Then, the electrons are guided to the secondary optical system 60. In the secondary optical system 60, electrons are collected through the lens 61, the NA aperture 62, and the lens 63. The electrons are arranged by the aligner 64 and detected by the detector 70.

  The NA aperture 62 has a role of defining the transmittance and aberration of the secondary system. The size and position of the NA aperture 62 are selected so that the difference between the signal from the foreign object 10 (mirror electron etc.) and the signal at the surrounding (normal part) becomes large. Alternatively, the size and position of the NA aperture 62 are selected so that the ratio of the signal from the foreign object 10 to the surrounding signal is increased. Thereby, S / N can be made high.

  For example, it is assumed that the NA aperture 62 can be selected in the range of φ50 to φ3000 [μm]. It is assumed that mirror electrons and secondary emission electrons are mixed in the detected electrons. In order to improve the S / N of the mirror electron image in such a situation, the selection of the aperture size is advantageous. In this case, it is preferable to select the size of the NA aperture 62 so as to reduce the transmittance of secondary emission electrons and maintain the transmittance of mirror electrons.

  For example, when the incident angle of the primary electron beam is 3 °, the reflection angle of the mirror electrons is approximately 3 °. In this case, it is preferable to select a size of the NA aperture 62 that allows the trajectory of mirror electrons to pass. For example, a suitable size is φ250 [μm]. Since it is limited to the NA aperture (diameter φ250 [μm]), the transmittance of secondary emission electrons is lowered. Therefore, the S / N of the mirror electron image can be improved. For example, when the aperture diameter is changed from φ2000 to φ250 [μm], the background gradation (noise level) can be reduced to ½ or less.

  The detector 70 is means for detecting electrons guided by the secondary optical system 60. The detector 70 has a plurality of pixels on its surface. Various two-dimensional sensors can be applied to the detector 70. For example, a CCD (Charge Coupled Device) and a TDI (Time Delay Integration) -CCD may be applied to the detector 70. These are sensors that detect signals after converting electrons to light. Therefore, means such as photoelectric conversion are necessary. Therefore, electrons are converted into light by using photoelectric conversion or scintillator. The image information of light is transmitted to TDI that detects light. In this way, electrons are detected.

  Here, an example in which EB-TDI is applied to the detector 70 will be described. EB-TDI does not require a photoelectric conversion mechanism / light transmission mechanism. Electrons enter the EB-TDI sensor surface directly. Therefore, there is no deterioration in resolution, and a high MTF (Modulation Transfer Function) and contrast can be obtained. Conventionally, detection of the small foreign material 10 has been unstable. On the other hand, when EB-TDI is used, it is possible to increase the S / N of the weak signal of the small foreign material 10. Therefore, higher sensitivity can be obtained. The improvement in S / N reaches 1.2 to 2 times.

  FIG. 9 shows an electron beam inspection apparatus to which the present invention is applied. Here, an example of the overall system configuration will be described.

  In FIG. 9, the foreign matter inspection apparatus includes a sample carrier 190, a mini-environment 180, a load lock 162, a transfer chamber 161, a main chamber 160, an electron beam column system 100, and an image processing apparatus 90. The mini-environment 180 is provided with a transfer robot in the atmosphere, a sample alignment device, a clean air supply mechanism, and the like. The transfer chamber 161 is provided with a transfer robot in vacuum. Since the robot is always placed in the transfer chamber 161 in a vacuum state, it is possible to minimize the generation of particles and the like due to pressure fluctuations.

  The main chamber 160 is provided with a stage 30 that moves in the x direction, the y direction, and the θ (rotation) direction, and an electrostatic chuck is installed on the stage 30. The sample 20 itself is installed on the electrostatic chuck. Or the sample 20 is hold | maintained at an electrostatic chuck in the state installed in the pallet or the jig.

  The main chamber 160 is controlled by the vacuum control system 150 so that a vacuum state is maintained in the chamber. Further, the main chamber 160, the transfer chamber 161, and the load lock 162 are placed on the vibration isolation table 170 so that vibration from the floor is not transmitted.

  In addition, an electronic column 100 is installed in the main chamber 160. The electron column 100 includes columns of the primary optical system 40 and the secondary optical system 60 and a detector 70 that detects secondary emission electrons or mirror electrons from the sample 20. The signal from the detector 70 is sent to the image processing device 90 for processing. Both on-time signal processing and off-time signal processing are possible. On-time signal processing is performed during the inspection. When performing off-time signal processing, only an image is acquired and signal processing is performed later. Data processed by the image processing apparatus 90 is stored in a recording medium such as a hard disk or memory. Moreover, it is possible to display data on the monitor of the console as necessary. The displayed data includes, for example, an inspection area, a foreign matter number map, a foreign matter size distribution / map, a foreign matter classification, a patch image, and the like. In order to perform such signal processing, system software 140 is provided. An electron optical system control power supply 130 is provided to supply power to the electron column system. Further, the main chamber 160 may be provided with the optical microscope 110 and the SEM type inspection device 120.

  FIG. 10 shows an example of the configuration when the electronic column 100 of the mapping optical inspection apparatus and the SEM inspection apparatus 120 are installed in the same main chamber 160. As shown in FIG. 10, it is very advantageous that the mapping optical inspection device and the SEM inspection device 120 are installed in the same chamber 160. The sample 20 is mounted on the same stage 30, and the sample 20 can be observed or inspected by both the mapping method and the SEM method. The usage and advantages of this configuration are as follows.

  First, since the sample 20 is mounted on the same stage 30, when the sample 20 moves between the mapping type electronic column 100 and the SEM type inspection apparatus 120, the coordinate relationship is uniquely obtained. Therefore, when specifying a foreign matter detection location or the like, the two inspection devices can easily specify the same location with high accuracy.

  Assume that the above configuration is not applied. For example, the mapping optical inspection device and the SEM inspection device 120 are configured separately as separate devices. Then, the sample 20 is moved between the separated devices. In this case, since it is necessary to place the sample 20 on different stages 30, it is necessary for the two apparatuses to perform alignment of the sample 20 separately. Further, when the alignment of the sample 20 is performed separately, the specific error at the same position is 5 to 10 [μm]. In particular, in the case of the sample 20 having no pattern, since the position reference cannot be specified, the error is further increased.

  On the other hand, in the present embodiment, as shown in FIG. 10, the sample 20 is placed on the stage 30 of the same chamber 160 in two types of inspection. Even when the stage 30 moves between the mapping-type electronic column 100 and the SEM inspection apparatus 120, the same position can be specified with high accuracy. Therefore, even in the case of the sample 20 without a pattern, the position can be specified with high accuracy. For example, the position can be specified with an accuracy of 1 [μm] or less.

  Such high-precision identification is very advantageous in the following cases. First, the foreign substance inspection of the sample 20 without a pattern is performed by a mapping method. Then, identification and detailed observation (review) of the detected foreign matter 10 are performed by the SEM type inspection apparatus 120. Since an accurate position can be specified, it is possible not only to determine the presence or absence of the foreign material 10 (pseudo detection if there is no foreign material), but also to perform detailed observation of the size and shape of the foreign material 10 at high speed.

  As described above, if the electronic column 100 for foreign matter detection and the SEM inspection device 120 for review are provided separately, it takes a lot of time to identify the foreign matter 10. In the case of a sample having no pattern, the degree of difficulty increases. Such a problem is solved by this embodiment.

  As described above, in the present embodiment, the ultra-fine foreign matter 10 is inspected with high sensitivity using the aperture imaging condition of the foreign matter 10 by the mapping optical method. Further, the mapping optical type electronic column 100 and the SEM type inspection device 120 are mounted in the same chamber 160. Thereby, in particular, the inspection of the ultrafine foreign material 10 of 30 [nm] or less and the determination and classification of the foreign material 10 can be performed very efficiently and at high speed. In addition, this embodiment is applicable also to Embodiment 1-28 mentioned above and embodiment which does not attach | subject the number.

  Next, another example of inspection using both the projection type inspection apparatus and the SEM will be described.

  In the above description, the projection type inspection apparatus detects a foreign object, and the SEM performs a review inspection. However, the present invention is not limited to this. Two inspection devices may be applied to different inspection methods. By combining the characteristics of each inspection apparatus, an effective inspection can be performed. Another inspection method is as follows, for example.

  In this inspection method, the projection type inspection apparatus and the SEM inspect different areas. Furthermore, "cell to cell" inspection is applied to the projection type inspection apparatus, and "die to die" inspection is applied to the SEM, so that high-accuracy inspection can be realized efficiently as a whole. Is done.

  More specifically, the mapping projection inspection apparatus performs “cell-to-cell” inspection on an area having a large number of repeated patterns in the die. Then, the SEM performs “die-to-die” inspection on an area where there are few repetitive patterns. Both of the inspection results are combined to obtain one inspection result. “Die-to-die” is an inspection in which images of two dies obtained sequentially are compared. A “cell to cell” is an inspection that compares images of two cells obtained sequentially, and the cell is a part of the die.

  In the inspection method described above, a high-speed inspection is performed using a mapping projection method in a repetitive pattern portion, while an inspection is performed with an SEM with high accuracy and less pseudo in an area where the repetitive pattern is small. SEM is not suitable for high-speed inspection. However, since the region with few repeating patterns is relatively narrow, the SEM inspection time does not become too long. Therefore, the entire inspection time can be reduced. Thus, this inspection method can make the most of the merit of the two inspection methods and perform a highly accurate inspection in a short inspection time.

  Here, the transport mechanism of the sample 20 will be described with reference to FIG.

  A sample 20 such as a wafer or mask is transferred from the load port into the mini-environment 180, and alignment work is performed therein. The sample 20 is transferred to the load lock 162 by a transfer robot in the atmosphere. The load lock 162 is exhausted from the atmosphere to a vacuum state by a vacuum pump. When the pressure becomes a certain value (about 1 [Pa]) or less, the sample 20 is transferred from the load lock 162 to the main chamber 160 by the transfer robot in vacuum arranged in the transfer chamber 161. Then, the sample 20 is placed on the electrostatic chuck mechanism on the stage 30.

  A sample 20 such as a wafer or mask is transferred from the load port into the mini-environment 180, and alignment work is performed therein. The sample 20 is transferred to the load lock 162 by a transfer robot in the atmosphere. The load lock 162 is exhausted from the atmosphere to a vacuum state by a vacuum pump. When the pressure becomes a certain value (about 1 [Pa]) or less, the sample 20 is transferred from the load lock 162 to the main chamber 160 by the transfer robot in vacuum arranged in the transfer chamber 161. Then, the sample 20 is placed on the electrostatic chuck mechanism on the stage 30.

  FIG. 11 shows the electron column system 100 installed in the main chamber 160 and in the upper part of the main chamber 160. The same components as those in FIG. 8 are denoted by the same reference numerals as those in FIG.

  The sample 20 is placed on a stage 30 that can move in the x, y, z, and θ directions. High precision alignment is performed by the stage 30 and the optical microscope 110. Then, the mapping projection optical system performs foreign matter inspection and pattern defect inspection of the sample 20 using the electron beam. Here, the potential of the sample surface 21 is important. In order to measure the surface potential, a surface potential measuring device capable of measuring in vacuum is attached to the main chamber 160. This surface potential measuring device measures a two-dimensional surface potential distribution on the sample 20. Based on the measurement result, focus control is performed in the secondary optical system 60a that forms an electronic image. A focus map of the two-dimensional position of the sample 20 is produced based on the potential distribution. Using this map, the inspection is performed while changing and controlling the focus during the inspection. As a result, blurring and distortion of the image due to changes in the surface circular potential depending on the location can be reduced, and accurate and stable image acquisition and inspection can be performed.

  Here, the secondary optical system 60 a is configured to be able to measure the detection current of electrons incident on the NA aperture 62 and the detector 70, and further configured to be able to install an EB-CCD at the position of the NA aperture 62. Yes. Such a configuration is very advantageous and efficient. In FIG. 11, the NA aperture 62 and the EB-CCD 65 are installed on an integral holding member 66 having openings 67 and 68. The secondary optical system 60a includes a mechanism that can independently perform the current absorption of the NA aperture 62 and the image acquisition of the EB-CCD 65, respectively. In order to realize this mechanism, the NA aperture 62 and the EB-CCD 65 are installed on an X and Y stage 66 operating in a vacuum. Therefore, the position control and positioning of the NA aperture 62 and the EB-CCD 65 are possible. Since the stage 66 is provided with openings 67 and 68, mirror electrons and secondary emission electrons can pass through the NA aperture 62 or the EB-CCD 65.

  The operation of the secondary optical system 60a having such a configuration will be described. First, the EB-CCD 65 detects the spot shape of the secondary electron beam and its center position. Then, voltage adjustments of the stigmeter, the lenses 61 and 63, and the aligner 64 are performed so that the spot shape is circular and minimized. With respect to this point, conventionally, the spot shape and astigmatism at the position of the NA aperture 62 cannot be directly adjusted. Such direct adjustment is possible in the present embodiment, and astigmatism can be corrected with high accuracy.

  In addition, the center position of the beam spot can be easily detected. Therefore, the position of the NA aperture 62 can be adjusted so that the hole center of the NA aperture 62 is arranged at the beam spot position. In this regard, conventionally, the position of the NA aperture 62 cannot be directly adjusted. In the present embodiment, the position of the NA aperture 62 can be directly adjusted. This enables highly accurate positioning of the NA aperture, reduces the aberration of the electronic image, and improves uniformity. Further, the transmittance uniformity is improved, and an electronic image with high resolution and uniform gradation can be acquired.

  In the inspection of the foreign material 10, it is important to efficiently acquire the mirror signal from the foreign material 10. The position of the NA aperture 62 is very important because it defines the transmittance and aberration of the signal. Secondary emission electrons are emitted from the sample surface in a wide angle range according to the cosine law, and reach a uniformly wide region (for example, φ3 [mm]) at the NA position. Therefore, the secondary emission electrons are insensitive to the position of the NA aperture 62. On the other hand, in the case of mirror electrons, the reflection angle on the sample surface is approximately the same as the incident angle of the primary electron beam. Therefore, the mirror electrons show a small spread and reach the NA aperture 62 with a small beam diameter. For example, the spreading region of mirror electrons is 1/20 or less of the spreading region of secondary electrons. Therefore, the mirror electrons are very sensitive to the position of the NA aperture 62. The spreading region of the mirror electrons at the NA position is usually a region of φ10 to 100 [μm]. Therefore, it is very advantageous and important to obtain the position where the mirror electron intensity is the highest and arrange the center position of the NA aperture 62 at the obtained position.

  In order to realize the installation of the NA aperture 62 at such an appropriate position, in the preferred embodiment, the NA aperture 62 is x, y with an accuracy of about 1 [μm] in the vacuum of the electron column 100. Moved in the direction. The signal intensity is measured while the NA aperture 62 is moved. Then, the position with the highest signal intensity is obtained, and the center of the NA aperture 62 is set at the obtained coordinate position.

  The EB-CCD 65 is very advantageously used for signal intensity measurement. Thereby, two-dimensional information of the beam can be known, and the number of electrons incident on the detector 70 can be obtained, so that quantitative signal strength evaluation can be performed.

  Alternatively, the aperture arrangement may be determined so that the position of the NA aperture 62 and the position of the detection surface of the detector 70 are conjugated, and the condition of the lens 63 between the aperture and the detector is May be set. This configuration is also very advantageous. Thereby, an image of the beam at the position of the NA aperture 62 is formed on the detection surface of the detector 70. Therefore, the beam profile at the position of the NA aperture 62 can be observed using the detector 70.

  The NA size (aperture diameter) of the NA aperture 62 is also important. Since the signal region of the mirror electrons is small as described above, the effective NA size is about 10 to 200 [μm]. Further, the NA size is preferably a size larger by +10 to 100% than the beam diameter.

  In this regard, an electron image is formed by mirror electrons and secondary emission electrons. By setting the aperture size, the ratio of mirror electrons can be further increased. Thereby, the contrast of mirror electrons can be increased, that is, the contrast of the foreign material 10 can be increased.

  More specifically, when the aperture hole is made smaller, the secondary emission electrons decrease in inverse proportion to the aperture area. Therefore, the gradation of the normal part becomes small. However, the mirror signal does not change and the gradation of the foreign material 10 does not change. Therefore, the contrast of the foreign material 10 can be increased by the reduction of the surrounding gradation, and a higher S / N can be obtained.

  Further, an aperture or the like may be configured so that the position of the aperture can be adjusted not only in the x and y directions but also in the z axis direction. This configuration is also advantageous. The aperture is preferably installed at a position where the mirror electrons are most narrowed. Thereby, the aberration of the mirror electrons can be reduced and the secondary emission electrons can be reduced very effectively. Therefore, higher S / N can be obtained.

  As mentioned above, mirror electrons are very sensitive to NA size and shape. Therefore, proper selection of the NA size and shape is very important to obtain a high S / N. Hereinafter, an example of a configuration for selecting such an appropriate NA size and shape will be described. Here, the shape of the aperture (hole) of the NA aperture 62 will also be described.

  Here, the NA aperture 62 is a member (part) having a hole (opening). Generally, the member is sometimes called an aperture, and the hole (opening) is sometimes called an aperture. In the following description related to the aperture, the member is referred to as an NA aperture in order to distinguish the member (part) from its hole. And the hole of a member is called an aperture. The aperture shape generally means the shape of the hole.

  Next, focus adjustment under the NA imaging condition will be described with reference to FIGS. 12 and 13. FIG. 12 is a side view of the state of the crossover point at the aperture of the mirror electrons and the secondary emission electrons. In FIG. 12, the trajectory of mirror electrons is indicated by a broken line, and the trajectory of secondary emission electrons is indicated by a solid line.

  As shown in FIG. 12, the mirror electrons and the secondary emission electrons have a difference in the best focus position (focus value difference: about 0.5 mm, for example). When the focus is changed, the area of secondary emission electrons becomes larger as the focus becomes positive, while the area of mirror electrons becomes longer and narrower at a certain focus point. When the focus is changed to the plus direction at the point, the vertical direction is collapsed and the horizontal direction is extended, and when the focus is changed to the negative direction, the peak is changed so as to be divided into two.

  FIG. 13 shows how the object looks when the focus is changed and a foreign object is imaged. As shown in FIG. 13A, when the focus is in the minus direction, the foreign matter appears black. On the other hand, when the focus is set in the plus direction, the foreign matter appears white. In FIG. 13B, the mirror electrons from the sample surface are indicated by broken lines, and the mirror electrons from the foreign matter (defect) are indicated by solid lines. As shown in FIG. 13B, when the focus is changed from minus to plus, the amount of mirror electrons from foreign matters (defects) that pass through the aperture increases.

  In this embodiment, as shown in FIG. 14, the primary beam is irradiated via E × B. That is, the primary beam is incident on E × B from obliquely above in the Y-axis direction. In this case, the incident angle in the X-axis direction can be adjusted by adjusting the electrode voltage in the X-axis direction of the primary aligner. The incident angle in the Y-axis direction can be adjusted using E × B.

<Modification of Photoelectron Generator in Primary Optical System>
The other example of the photoelectron generator in a primary optical system is shown. FIG. 15 and FIG. 16 are examples when light or laser is guided to the photoelectron surface from a midway position of the primary system by a mirror installed in the column.

  FIG. 15 is an example when the reference voltage of the primary optical system 2000 is a high voltage, for example, 40 kV. At this time, a voltage of V2 = 40 kV is applied to the tube 10071 to which a high voltage is applied in order to form a reference voltage. The inside of the tube 10071 is the same voltage space. Therefore, in this example, DUV light or a UV laser is introduced through a hole provided in a tube 100071 (not shown) using a mirror having a hole through which photoelectrons pass in the center, for example, a triangular mirror 2170, and this triangular mirror 2170 The photoelectron surface 2121 is irradiated after reflection. Then, photoelectrons are generated from the irradiated surface, and the photoelectrons pass through the EX lens 2120 and NA 2125 and the downstream aligner and are irradiated onto the sample surface. At this time, a specified voltage is applied to the photoelectron surface 2121 in order for the generated photoelectrons to form a primary orbit. LE = RTD voltage −V1.

  On the other hand, FIG. 16 shows an example in which the photoelectron surface is irradiated with light or a laser that generates photoelectrons by the triangular mirror 2070 as in the example shown in FIG. 15, and the reference voltage of the primary optical system 2000 is GND. is there. At this time, for example, V2, V4, and V5 are GND, and the vicinity thereof is a reference voltage space. Then, it becomes possible to install a mirror similar to that shown in FIG. At this time, since the amount of generated photoelectrons is determined by the irradiation intensity of light or laser, the irradiation intensity is controlled. For this, the above-described intensity control method is used. At this time, the mirror surface and the entire structure are coated with a conductor or a conductor. The potential is the same as the reference potential. They are the same potential so as not to disturb the space potential. Further, a hole is formed in the center of the optical axis of the mirror so that the primary beam can pass without being affected by the mirror, and the primary beam passes through the hole. A conductor material or a conductor is coated and connected to the reference voltage portion so that the same potential as the reference voltage is provided inside the hole.

  In addition, two methods are shown for the shape of photoelectron generation. This will be described with reference to FIG. One is to use an FA aperture 2010 that defines the beam system before the incidence of the mirror in the column. A beam having a shape of a field aperture (FA) 2010 is formed, and the photocathode is irradiated with the beam to generate photoelectrons having the shape. At this time, the projection size of the field aperture (FA) 2010 is controlled by the lens position upstream of the field aperture (FA) 2010.

<Primary optical system: homogenization by homogenizer>
(Embodiment)
The configuration of the inspection apparatus according to the present embodiment will be described with reference to the drawings. Here, the description will focus on the primary optical system. FIG. 17 is an explanatory diagram showing a primary optical system of the inspection apparatus according to the present embodiment. As shown in FIG. 17, the primary optical system of the inspection apparatus includes a laser light source 1701 that generates a Gaussian laser beam and a photocathode 1702 that generates a primary beam when irradiated with the laser beam. A homogenizer 1703 is provided between the laser light source 1701 and the photocathode 1702 to convert a Gaussian laser beam into a uniform laser beam (intensity distribution conversion). Therefore, in this case, the photocathode 1702 is irradiated with a uniformly distributed laser beam.

  The homogenizer 1703 is an optical element having a function of converting a Gaussian distribution beam into a uniform distribution beam (intensity distribution conversion) and emitting the beam. As the homogenizer 1703 of the present embodiment, a known one can be used. For example, a homogenizer 1703 configured with an aspheric lens or a homogenizer 1703 configured with a diffraction grating element is used. In the case of the aspherical lens homogenizer 1703, a single aspherical lens may be used, or a plurality of aspherical lenses may be used in combination.

  As shown in FIG. 17, the primary optical system includes a beam splitter 1704 that divides the laser light converted into a uniform distribution by the homogenizer 1703, and a beam profiler that measures the intensity distribution of the laser light divided by the beam splitter 1704. 1705. As the beam profiler 1705, for example, a CCD beam profiler can be used.

  Further, the primary optical system includes a mechanical shutter 1706 for controlling on / off of laser light irradiation, a variable attenuator 1707 for adjusting the transmittance (intensity) of the laser light, and a beam of laser light generated from the laser light source 1701. A beam diameter adjustment lens 1708 for adjusting the diameter and an astigmatism correction lens 1709 for adjusting the focal length of the laser light are provided.

  In this case, the photocathode 1702 is disposed inside the vacuum chamber 1710, and the laser light source 1701 and the homogenizer 1703 are disposed outside the vacuum chamber 1710. As shown in FIG. 17, the laser light emitted from the laser light source 1701 is reflected by a mirror 1711, passes through a mechanical shutter 1706, and the intensity is adjusted by a variable attenuator 1707. Thereafter, the beam diameter is adjusted by the beam diameter adjusting lens 1708, the focal length is adjusted by the astigmatism correcting lens 1709, and then incident on the homogenizer 1703.

  The laser light whose intensity distribution is converted from a Gaussian distribution to a uniform distribution by the homogenizer 1703 is reflected by the mirror 1712 and divided into two by the beam splitter 1704. The intensity distribution (beam profile) of one laser beam divided by the beam splitter 1704 is measured by a beam profiler 1705. The other laser beam is reflected by the mirror 1713, guided from the view port 1714 into the vacuum chamber 1710, reflected by the triangular mirror 1715, and then irradiated on the photocathode 1702.

  According to such an inspection apparatus of the present embodiment, the Gaussian laser beam generated from the laser light source 1701 is converted into a uniform laser beam (intensity distribution conversion) by the homogenizer 1703 and irradiated onto the photocathode 1702. Is done. When the uniformly distributed laser light is irradiated onto the photocathode 1702, a primary beam of uniform distribution is generated from the photocathode 1702. By using a uniformly distributed primary beam, a uniform inspection can be performed over the entire inspection region of the sample.

  In the present embodiment, the laser light whose intensity distribution has been converted by the homogenizer 1703 is divided by the beam splitter 1704, and the intensity distribution is measured by the beam profiler 1705. By measuring the intensity distribution with the beam profiler 1705, it is possible to confirm whether or not the laser light whose intensity distribution has been converted by the homogenizer 1703 has a uniform distribution. Thereby, it can be confirmed whether or not the photocathode 1702 is irradiated with a uniformly distributed laser beam.

  In this embodiment mode, since the laser light source 1701 and the homogenizer 1703 are disposed outside the vacuum chamber 1710, the position (fine adjustment) of the homogenizer 1703 with respect to the laser light generated from the laser light source 1701 can be easily adjusted. it can.

  In this embodiment mode, the beam diameter and focal length of the laser light generated from the laser light source 1701 can be adjusted appropriately, and the homogenizer 1703 can obtain laser light with a uniform distribution.

<Primary optical system: homogenization by defocusing, rotating photocathode>
(background)
In recent years, a primary optical system using a photocathode that generates a primary beam when irradiated with laser light has been developed as a primary optical system of an inspection apparatus. Conventionally, laser light sources that generate laser light are generally those that generate laser light with a Gaussian distribution.

(Task)
However, when a Gaussian laser beam is irradiated onto the photocathode, a Gaussian primary beam is also generated from the photocathode. When the primary beam of the Gaussian distribution is used, there is a problem that the central portion of the sample inspection region (beam irradiation region) is bright and the end portion is dark, and it is difficult to perform a uniform inspection in the sample inspection region.

  The present invention has been made in view of the above problems, and an object thereof is to provide an inspection apparatus capable of performing a more uniform inspection in an inspection region of a sample.

(Solution)
The inspection apparatus of the present invention is an inspection apparatus for inspecting a sample, a stage on which the sample is placed, a primary optical system that irradiates the sample on the stage with a primary beam, and the primary beam A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample; and a secondary optical system that guides the secondary beam to the two-dimensional sensor. The optical system includes a laser light source that generates laser light, a photocathode that generates the primary beam when irradiated with the laser light, and the sample that is irradiated with the primary beam at a defocus position shifted from a focus position. As described above, a focus position adjusting means for adjusting the focus position of the primary beam is provided.

  With this configuration, when the photocathode is irradiated with laser light from a laser light source, a primary beam is generated from the photocathode, and the primary beam generated from the photocathode is irradiated to the sample at a defocus position shifted from the focus position. . When the sample is irradiated with the primary beam at the defocus position, the uniformity of the primary beam is improved. By using a uniformly distributed primary beam, a more uniform inspection can be performed in the inspection region of the sample.

  In the inspection apparatus of the present invention, at the defocus position, the primary beam transmittance may be higher than a predetermined reference transmittance, and the primary beam uniformity may be lower than a predetermined reference uniformity rate.

  With this configuration, when the sample is irradiated with the primary beam at the defocus position, the transmittance of the primary beam is higher than a predetermined reference transmittance (for example, 8.0%), and the uniformity ratio of the primary beam is a predetermined reference uniformity ratio. (For example, 2.5%). Thereby, the uniformity of the primary beam is improved, and a more uniform inspection can be performed in the inspection region of the sample. Here, the “uniformity” is a value indicating the degree of variation in the intensity of the primary beam, and the smaller the uniformity ratio, the higher the uniformity.

  In the inspection apparatus of the present invention, the primary optical system includes a rotation mechanism that rotates the photocathode on a plane along the photocathode so that an irradiation position of the laser beam changes on the photocathode. May be.

  With this configuration, the photocathode rotates on a plane along the photocathode, and the irradiation position of the laser light changes on the photocathode. Thereby, it is possible to prevent the laser beam from being continuously irradiated on the same position on the photocathode, so that the emission of the primary beam is stabilized and the lifetime of the photocathode can be extended.

  In the inspection apparatus of the present invention, the rotating mechanism spirals the photocathode on a plane along the photocathode so that the irradiation position of the laser beam draws a spiral trajectory over the entire surface of the photocathode. It may be rotated in a shape.

  With this configuration, the photocathode rotates in a spiral shape on a plane along the photocathode, and the irradiation position of the laser light changes so as to draw a spiral trajectory over the entire surface of the photocathode. Thereby, it is possible to prevent the laser beam from being continuously irradiated on the same position on the photocathode, so that the emission of the primary beam is stabilized and the lifetime of the photocathode can be extended.

(Embodiment)
The configuration of the inspection apparatus according to the present embodiment will be described with reference to the drawings. Here, the description will focus on the primary optical system. FIG. 18 is an explanatory diagram showing a primary optical system of the inspection apparatus according to the present embodiment. As shown in FIG. 18, the primary optical system of the inspection apparatus includes a laser light source 1801 that generates laser light with a Gaussian distribution and a photocathode 1802 that generates a primary beam when irradiated with the laser light.

  In this embodiment mode, the photocathode 1802 is rotatable on a plane along the photocathode 1802. In this case, the primary optical system includes a rotation mechanism 1803 that rotates the photocathode 1802 on a plane along the photocathode 1802 and a rotation control unit 1804 that controls the rotation of the photocathode 1802. The method of rotating the photocathode 1802 will be described in detail later with reference to the drawings.

  As shown in FIG. 18, the primary optical system includes a gun lens (GL) 1805 and an E × B filter 1806. The focal position of the primary beam generated from the photocathode 1802 is adjusted by the gun lens 1805 so that the sample is irradiated with the primary beam at a position shifted from the focus position. The output (magnetic field strength) of the gun lens 1805 is controlled by the GL control unit 1807. The focal position of the primary beam can be adjusted by controlling the output of the gun lens 1805 with the GL control unit 1807. Further, the E × B filter 1806 has a function of changing the traveling direction of the primary beam by the Lorentz force due to the magnetic field and the electric field. The primary beam is incident on the E × B filter 1806 from an oblique direction, deflected vertically downward, and directed toward the sample 1809 on the stage 1808.

  FIG. 19 is an explanatory diagram of the transmittance / uniformity of the primary beam with respect to the output (GL output) of the gun lens 1805. In the present embodiment, the transmittance of the primary beam is higher than a predetermined reference transmittance (for example, 8.0%), and the uniformity ratio of the primary beam is lower than a predetermined reference uniformity ratio (for example, 2.5%). As described above, the focal position of the primary beam is adjusted. The focus position adjusted in this way is referred to as a “defocus position” in the present embodiment.

  In the example of FIG. 19, when the GL output is 830AT or 840AT, it corresponds to the “defocus position”. When the GL output is 850 AT or higher, the transmittance of the primary beam is improved, but the uniformity rate is increased (the uniformity is decreased). On the other hand, when the GL output is 820 or less, the uniformity of the primary beam decreases (the uniformity increases), but the transmittance decreases.

  FIG. 20 is an explanatory diagram of the rotation of the photocathode in the present embodiment. As shown in FIG. 20, in the present embodiment, the photocathode 2001 is circular in a plan view, and the laser light irradiation region 2002 is also circular in a plan view (a circle having a smaller diameter than the photocathode). A rotating mechanism (not shown in FIG. 20) rotates the photocathode 2001 in a spiral shape on a plane along the photocathode 2001. Thereby, the irradiation position 2002 of the laser beam draws a spiral trajectory over the entire surface of the photocathode 2001. For example, the rotation mechanism rotates the photocathode 2001 at a rotation speed of 1 rotation / 10 hours.

  According to such an inspection apparatus of this embodiment, when the photocathode 1802 is irradiated with laser light from the laser light source 1801, a primary beam is generated from the photocathode 1802, and the primary beam generated from the photocathode 1802 is focused. The sample is irradiated at a defocus position shifted from the position. When the sample is irradiated with the primary beam at the defocus position, the uniformity of the primary beam is improved. By using a uniformly distributed primary beam, a more uniform inspection can be performed in the inspection region of the sample.

  In this case, when the sample is irradiated with the primary beam at the defocus position, the transmittance of the primary beam is higher than a predetermined reference transmittance (for example, 8.0%), and the uniformity ratio of the primary beam is a predetermined reference uniformity ratio ( For example, 2.5%). Thereby, the uniformity of the primary beam is improved, and a more uniform inspection can be performed in the inspection region of the sample. The “uniformity” is a value indicating the degree of variation in the intensity of the primary beam. The smaller the uniformity ratio, the higher the uniformity.

  Further, in this embodiment mode, the photocathode 1802 rotates on a plane along the photocathode 1802, and the irradiation position of the laser light changes on the photocathode. Thereby, it is possible to avoid the laser beam from being continuously irradiated on the photocathode, to stabilize the emission of the primary beam and to prolong the lifetime of the photocathode 1802.

  In this case, the irradiation position of the laser beam is changed so that the photocathode 1802 rotates in a spiral shape on a plane along the photocathode 1802 and draws a spiral trajectory over the entire surface of the photocathode 1802. Thereby, it is possible to avoid the laser beam from being continuously irradiated on the photocathode, to stabilize the emission of the primary beam and to prolong the lifetime of the photocathode 1802.

<SEM: deflection correction>
(background)
Conventionally, a mapping projection type inspection apparatus is known. In the projection type inspection apparatus, the sample on the stage can be inspected. As a result of inspection, if a defect such as a foreign object is found in the sample, the sample is transferred from the stage of the inspection apparatus to the stage of a scanning electron microscope (SEM), and an image of the defect (foreign material) of the sample is obtained using the scanning electron microscope. Take a picture. In the scanning electron microscope, a step-and-repeat method is adopted. That is, after moving the stage to the target position, the stage is fixed with a brake (fixed so as not to cause nano-stage swing), and the sample surface is scanned with an electron beam to take an image of the sample. .

(Task)
However, in the conventional scanning electron microscope, it is necessary to fix the stage each time an image of the sample is taken, and thus there is a problem that it takes a long time from image inspection to image acquisition. If a long time is required from the inspection of the sample to the acquisition of the image, the defect of the sample may be deteriorated, and there is a problem that the reproducibility of the defect confirmation by the image is lowered.

  The present invention has been made in view of the above problems, and an inspection apparatus that can take an image of a sample while moving the stage and can acquire an image of the sample in a short time after the inspection of the sample. The purpose is to provide.

(Solution)
The inspection apparatus of the present invention includes a stage on which a sample is placed, a projection type inspection apparatus that inspects the sample on the stage, a scanning electron microscope that captures an image of the sample while moving the stage, The mapping projection type inspection apparatus comprises: a primary optical system that irradiates the sample on the stage with a primary beam; and the sample that is irradiated with the primary beam from the sample. A detector including a two-dimensional sensor that generates an image of the generated secondary beam, and a secondary optical system that guides the secondary beam to the two-dimensional sensor, wherein the scanning electron microscope moves the stage A stage movement control unit for controlling the position, a position fluctuation detection unit for detecting a deviation of the current position of the stage from a target position as a position fluctuation when the stage is moved, and And an electron beam is deflected in a direction to cancel the positional variation for photographing an image, and a, and a deflection control unit for performing deflection control for correcting the deviation of the position of the stage.

  With this configuration, the sample on the stage can be inspected with the projection projection inspection apparatus, and an image of the sample can be taken with the scanning electron microscope. In this case, since the sample image can be taken while moving the stage, the sample image can be acquired in a short time after the sample is inspected. Therefore, alteration of the defect of the sample can be prevented and the reproducibility of the defect confirmation by the photographed image is improved.

  Moreover, if the image of the sample is simply taken while moving the stage, the resolution of the image decreases due to the influence of the stage position fluctuation (deviation from the target position of the stage). By deflecting the electron beam in the canceling direction, the shift of the stage position can be corrected, and a high-resolution image can be acquired.

  The control method of the present invention includes a stage on which a sample is placed, a projection type inspection apparatus that inspects the sample on the stage, a scanning electron microscope that captures an image of the sample while moving the stage, The projection projection type inspection apparatus comprises: a primary optical system for irradiating the sample on the stage with a primary beam; and irradiating the sample with the primary beam. A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample, and a secondary optical system that guides the secondary beam to the two-dimensional sensor, and the control method includes: While moving, the deviation of the current position of the stage from the target position is detected as a position variation, and the electron beam for photographing the image is deflected in a direction to cancel the position variation. Te, it performs deflection control for correcting the deviation of the position of the stage.

  Also by this method, the sample on the stage can be inspected with the projection type inspection apparatus, and an image of the sample can be taken with the scanning electron microscope, as described above. In this case, since the sample image can be taken while moving the stage, the sample image can be acquired in a short time after the sample is inspected. Therefore, alteration of the defect of the sample can be prevented and the reproducibility of the defect confirmation by the photographed image is improved.

  Similarly to the above, if an image of the sample is simply taken while moving the stage, the resolution of the image is lowered due to the influence of the stage position fluctuation (shift from the target position of the stage). Then, the deviation of the stage position can be corrected by deflecting the electron beam in the direction to cancel the position fluctuation, and a high-resolution image can be acquired.

(Embodiment)
The configuration of the inspection apparatus according to the present embodiment will be described with reference to the drawings. FIG. 21 is an explanatory diagram of the inspection apparatus according to the present embodiment. As shown in FIG. 21, the inspection apparatus according to the present embodiment includes a stage 2102 on which a sample 2101 is placed, a projection type inspection apparatus 2103 that inspects a sample 2101 on the stage, and a sample 2101 while moving the stage 2102. A scanning electron microscope (SEM) 2104 for taking the image is provided. In this case, the mapping projection type inspection apparatus 2104 can take an image of the sample 2101 while moving the stage 2102 in the XY directions.

  FIG. 22 is an explanatory diagram of a scanning electron microscope provided in the inspection apparatus. As shown in FIG. 22, the scanning electron microscope includes an electron beam source 2201 that generates an electron beam, a deflection electrode 2202 that deflects the electron beam so as to scan the surface of the sample, and a stage 2204 on which the sample 2203 is placed. A stage movement control unit 2205 that controls the movement of the stage, a position variation detection unit 2206 that detects a position variation when the stage 2204 is moved, and a deflection that performs deflection control to deflect the electron beam in a direction that cancels the position variation. A control unit 2207 is provided.

  The position variation detection unit 2206 has a position sensor function that detects the current position of the stage 2204. In addition, a target position when the stage 2204 is moved from the stage movement control unit 2205 is input to the position variation detection unit 2206. The position fluctuation detection unit 2206 detects a deviation of the current position of the stage 2204 from the target position as a position fluctuation. The deflection control unit 2207 corrects the position shift of the stage 2204 by deflecting the electron beam in a direction that cancels the position variation.

  According to such an inspection apparatus of the present embodiment, the projection projection inspection apparatus 2103 can inspect the sample 2101 on the stage, and the projection projection inspection apparatus 2104 can take an image of the sample 2101. it can. In this case, since the image of the sample 2101 can be taken while moving the stage 2102, the image of the sample 2101 can be acquired in a short time after the inspection of the sample 2101. Therefore, alteration of the defect of the sample 2101 can be prevented and the reproducibility of the defect confirmation by the photographed image is improved.

  Moreover, if the image of the sample 2101 is simply taken while moving the stage 2102, the resolution of the image is reduced due to the influence of the position fluctuation of the stage 2102 (deviation from the target position of the stage 2102). The position of the stage 2102 can be corrected by deflecting the electron beam in a direction that cancels the position variation, and a high-resolution image can be acquired.

<Crossover position adjustment with multipole electrodes>
(background)
By the way, in recent years, development of a primary optical system using a photocathode that generates a primary beam when irradiated with laser light has been advanced as a primary optical system of an inspection apparatus.

(Task)
However, in an inspection apparatus using a photocathode for a primary optical system, if the optical conditions determined by simulation (optical conditions suitable for the camera size) are used, the crossover position of the secondary optical system (secondary beam at the aperture position) There is a problem that the crossover position) may shift.

  The present invention has been made in view of the above problems, and provides an inspection apparatus capable of adjusting the crossover position of the secondary optical system by adjusting the voltage of the multipole electrode of the primary optical system. With the goal.

(Solution)
The inspection apparatus of the present invention is an inspection apparatus for inspecting a sample, a stage on which the sample is placed, a primary optical system that irradiates the sample on the stage with a primary beam, and the primary beam A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample; and a secondary optical system that guides the secondary beam to the two-dimensional sensor. The optical system includes a photocathode that generates the primary beam when irradiated with laser light, and a multipole electrode for adjusting an aspect ratio of an irradiation region of the primary beam, and the secondary optical system includes: An aperture disposed on the optical path of the secondary beam; and a lens that forms an image of the secondary beam that has passed through the aperture on the image plane of the two-dimensional sensor, the multipole element of the primary optical system By adjusting the poles of the voltage crossover position of the secondary beam in the aperture position of the secondary optical system is adjusted.

  With this configuration, by adjusting the voltage of the multipole electrode (for example, quadrupole electrode) in the primary optical system that generates the primary beam on the photocathode, the crossover position of the secondary optical system (the crossing of the secondary beam at the aperture position) is performed. Over position) can be adjusted. Thus, for example, even when the crossover position of the secondary optical system (the crossover position of the secondary beam at the aperture position) is shifted as a result of using the optical conditions determined by the simulation, the primary optical system By adjusting the voltage of the multipole electrode, the crossover position of the secondary optical system can be adjusted.

  In the inspection apparatus of the present invention, the secondary beam is a mirror electron generated from the sample by irradiating the sample with the primary beam, and adjusts the voltage of the multipole electrode of the primary optical system. Thereby, the crossover position of the mirror electrons at the aperture position of the secondary optical system may be adjusted.

  With this configuration, mirror electrons are generated by irradiating the sample with the primary beam, and the sample is inspected using the mirror electrons. In this case, as a result of using the optical conditions determined in the simulation, even if the mirror electron crossover position at the aperture position (the crossover position of the secondary optical system) is shifted, the voltage of the multipole electrode of the primary optical system is changed. By adjusting, the crossover position of the secondary optical system can be adjusted.

  In the inspection apparatus of the present invention, the primary optical system includes an electrostatic lens that adjusts the size of the irradiation region of the primary beam, and the voltage of the multipole electrode is adjusted to adjust the crossover position. When the size of the irradiation region of the primary beam is changed, the size of the irradiation region of the primary beam may be adjusted by the electrostatic lens.

  With this configuration, even when the voltage of the multipole electrode is adjusted to adjust the crossover position and the size of the irradiation region of the primary beam changes to become the target size, the electrostatic lens causes the primary beam to be The size of the irradiation area can be adjusted to a target size.

(Embodiment)
The configuration of the inspection apparatus according to the present embodiment will be described with reference to the drawings. FIG. 23 is an explanatory diagram of the inspection apparatus according to the present embodiment. As shown in FIG. 23, the inspection apparatus includes a lens barrel 2301 of a primary optical system and a lens barrel 2302 of a secondary optical system. The lens barrel 2301 of the primary optical system has a photocathode 2303 that generates a primary beam when irradiated with laser light, an electrostatic lens 2304 that adjusts the size of the irradiation region of the primary beam, and an optical path of the primary beam. Are provided with a primary system aperture 2305 and an aligner electrode 2306, a quadrupole electrode 2307 for adjusting the aspect ratio of the primary beam irradiation area, and an electrode 2308 for changing the irradiation position of the primary beam in the XY direction. It has been. Further, a secondary optical system barrel 2302 includes a TDI camera 2309 as a two-dimensional sensor, a secondary aperture 2310 disposed on the optical path of the secondary beam, and a secondary that has passed through the secondary aperture 2310. A lens 2311 for forming an image of the beam on the image plane of the TDI camera 2309 is provided. For convenience of explanation, the stage on which the sample is placed is not shown in FIG.

  Here, an example in which a quadrupole electrode 2307 is used as a multipole electrode will be described. However, a dipole electrode, an octupole electrode, a twelve pole electrode, or the like can also be used. That is, 2n pole electrodes (n = 1, 2, 4,...) Can be used as the multipole electrodes. Further, as the multipole electrode, an N-pole electrode (N = 12 or more 2n times) can be used.

  Here, with reference to FIG. 24, the shift | offset | difference (shift) of the crossover position of a secondary optical system is demonstrated. As shown in FIG. 24, in the inspection apparatus using the photocathode 2303 for the primary optical system, the crossover position of the secondary optical system (the optical condition suitable for the camera size) determined by the simulation is used. The crossover position of the secondary beam at the aperture position may shift. In the example of FIG. 24, the secondary beam generated from the sample 2402 on the stage 2401 is refracted by the objective lens 2403 and the intermediate lens 2404, then passes through the secondary system aperture 2405, and is refracted by the projection lens 2406 to be TDI. The image is formed on the image plane of the camera 2407. In this case, the crossover position of the secondary optical system is shifted to the TDI camera side (upper side in FIG. 24).

  In the inspection apparatus of this embodiment, the crossover position of the secondary beam at the aperture position of the secondary optical system is adjusted by adjusting the voltage of the quadrupole electrode 2307 of the primary optical system. In this case, the secondary beam is mirror electrons generated from the sample by irradiating the sample with the primary beam. Therefore, in this embodiment, the crossover position of the mirror electrons at the aperture position of the secondary optical system is adjusted by adjusting the voltage of the quadrupole electrode 2307 of the primary optical system.

  Here, terms such as secondary charged particles and mirror electrons will be described. “Secondary charged particles” include secondary emission electrons, mirror electrons, and some or a mixture of photoelectrons. When an electromagnetic wave is irradiated, photoelectrons are generated from the sample surface. When the sample surface is irradiated with charged particles such as an electron beam, “secondary emission electrons” are generated from the sample surface or “mirror electrons” are formed. “Secondary emission electrons” are generated when an electron beam collides with the sample surface. That is, “secondary emission electrons” indicate a part or a mixture of secondary electrons, reflected electrons, and backscattered electrons. Also, what is reflected by the irradiated electron beam in the vicinity of the surface without colliding with the sample surface is called “mirror electron”.

  FIG. 25 is an explanatory diagram of a change in mirror electron crossover position (distance to the secondary system aperture 2310) with respect to a change in voltage of the quadrupole electrode 2307 in this embodiment. As shown in FIG. 25, when the voltage applied to the quadrupole electrode 2307 is changed, the crossover position of mirror electrons (distance from the secondary system aperture 2310) changes. Therefore, by adjusting the voltage of the quadrupole electrode 2307 of the primary optical system, the crossover position of the mirror electrons of the secondary optical system can be adjusted.

  Further, as described above, when the voltage of the quadrupole electrode 2307 is adjusted in order to adjust the crossover position, the size of the irradiation region of the primary beam is changed accordingly. In that case, the size of the irradiation region of the primary beam can be adjusted by adjusting the voltage of the electrostatic lens 2304.

  Furthermore, in this embodiment, it is possible to finely adjust the crossover position of the mirror electrons. The fine adjustment of the mirror electron crossover position is performed after adjusting (roughly adjusting) the mirror electron crossover position of the secondary optical system by adjusting the voltage of the quadrupole electrode 2307 of the primary optical system. Note that fine adjustment of the crossover position of the mirror electrons is not necessarily required.

  26 to 28 are diagrams illustrating an example of fine adjustment of the crossover position of the mirror electrons. In the example of FIG. 26, the crossover position of the mirror electrons can be adjusted to the position of the secondary system aperture 2601 by adjusting the optical conditions of the objective lens. In the examples of FIGS. 27A and 27B, the crossover position of the mirror electrons can be adjusted to the position of the secondary system aperture 2701 by moving the secondary system aperture 2701 in the optical axis direction. In the example of FIG. 28, the crossover position of the mirror electrons can be adjusted to the position of the secondary aperture 2801 by adjusting the focus condition of the objective lens.

  According to such an inspection apparatus of the present embodiment, by adjusting the voltage of the quadrupole electrode 2307 in the primary optical system that generates the primary beam on the photocathode 2303, the crossover position (aperture position) of the secondary optical system is adjusted. The cross-over position of the secondary beam at can be adjusted. Thus, for example, even when the crossover position of the secondary optical system (the crossover position of the secondary beam at the aperture position) is shifted as a result of using the optical conditions determined by the simulation, the primary optical system By adjusting the voltage of the quadrupole electrode 2307, the crossover position of the secondary optical system can be adjusted.

  In this embodiment, mirror electrons are generated by irradiating the sample with the primary beam, and the sample is inspected using the mirror electrons. In this case, even if the mirror electron crossover position at the aperture position (secondary optical system crossover position) is shifted as a result of using the optical conditions determined by the simulation, the voltage of the quadrupole electrode 2307 of the primary optical system is shifted. By adjusting the crossover position of the secondary optical system can be adjusted.

  Further, in this embodiment, even when the voltage of the quadrupole electrode 2307 is adjusted to adjust the crossover position, the size of the irradiation region of the primary beam is changed to be no longer the target size. The size of the irradiation region of the primary beam can be adjusted by the lens 2304 to obtain a target size.

<Re-inspection simulation by software>
(background)
In an inspection system for inspecting defects occurring in a sample, in order to reliably detect true defects and not detect non-defects (pseudo defects), while changing inspection conditions such as detection thresholds It is necessary to repeat the inspection many times and determine the optimum inspection conditions.

(Task)
However, when inspection is repeated, there is a problem that optimization of inspection conditions takes time. In addition, by repeating the inspection, there is a problem that damage is accumulated in the sample or the sample is contaminated.

  Therefore, the present embodiment provides an inspection system that can determine the inspection conditions with a small number of inspections while avoiding damage to the sample and contamination of the sample.

(Solution)
The inspection system according to the present embodiment includes an inspection device and a simulation device. The inspection device irradiates a sample with a primary beam, acquires a secondary beam image using the secondary beam from the sample, and performs the secondary operation. A cell-cell comparison inspection is performed on the beam image to obtain a defect image, and the defect image and the secondary beam image are output. The simulation apparatus determines a cell period in the cell-cell comparison inspection for the secondary beam image. The modified re-inspection simulation is performed and the inspection result is output.

  According to this configuration, a re-inspection simulation for obtaining an optimum cell cycle can be performed without repeating the actual inspection by the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection system according to the present embodiment includes an inspection device and a simulation device. The inspection device irradiates a sample with a primary beam, acquires a secondary beam image using the secondary beam from the sample, and performs the secondary operation. A defect image is obtained by performing a die-to-die comparison inspection on the beam image, and the defect image and the secondary beam image are output, and the simulation apparatus performs an edge tolerance in the die-die comparison inspection on the secondary beam image. A re-inspection simulation is performed and the re-inspection result is output.

  According to this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum edge tolerance without repeating the actual inspection in the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection system according to the present embodiment includes an inspection device and a simulation device. The inspection device irradiates a sample with a primary beam, acquires a secondary beam image using the secondary beam from the sample, and performs the secondary operation. The beam image is filtered by an image processing filter, a defect image is acquired, the defect image and the secondary beam image are output, and the simulation apparatus re-changes the image processing filter for the secondary beam image. Perform inspection simulation and output re-inspection results.

  According to this configuration, a re-inspection simulation for obtaining an optimal image filter can be performed without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection system according to the present embodiment includes an inspection device and a simulation device. The inspection device irradiates a sample with a primary beam, acquires a secondary beam image using the secondary beam from the sample, and performs the secondary operation. A defect image is acquired after shading correction is performed on the beam image, and the defect image and the secondary beam image are output. The simulation apparatus performs a re-inspection simulation with the shading correction value changed on the secondary beam image. The re-inspection result is output.

  According to this configuration, a re-inspection simulation for obtaining an optimum shading correction value can be performed without repeating the actual inspection by the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  In the inspection system, the inspection device detects a defect having a predetermined threshold value or more from the secondary beam image to generate the defect image, and the simulation device further performs a re-inspection simulation with the threshold value changed. And re-inspection results may be output.

  According to this configuration, re-inspection simulation for obtaining an optimum threshold can be performed without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The simulation apparatus according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image with the secondary beam from the sample, performs a cell-cell comparison inspection on the secondary beam image, and generates a defect image. The secondary beam image is acquired from an inspection apparatus that acquires and outputs the defect image and the secondary beam image, and the secondary beam image is subjected to a re-inspection simulation in which a cell cycle in a cell-cell comparison inspection is changed. And output the inspection result.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum cell period without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The simulation apparatus according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image with a secondary beam from the sample, performs a die-to-die comparison inspection on the secondary beam image, and generates a defect image. Re-inspection simulation in which the secondary beam image is acquired from an inspection apparatus that acquires and outputs the defect image and the secondary beam image, and the edge allowable value in the die-to-die comparison inspection is changed for the secondary beam image And output the re-inspection result.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum edge tolerance without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The simulation apparatus according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image with a secondary beam from the sample, filters the secondary beam image with an image processing filter, and then performs a defect processing. The secondary beam image is acquired from an inspection apparatus that acquires an image and outputs the defect image and the secondary beam image, and performs a re-inspection simulation with a changed image processing filter for the secondary beam image, Output inspection results.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum image filter without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The simulation apparatus according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image with a secondary beam from the sample, acquires a defect image after correcting the shading of the secondary beam image. The secondary beam image is acquired from the inspection apparatus that outputs the defect image and the secondary beam image, and a reinspection simulation is performed on the secondary beam image with a shading correction value changed, and a reinspection result is output. To do.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum shading correction value without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection result review program according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image by a secondary beam from the sample, performs a cell-cell comparison inspection on the secondary beam image, and performs a defect. An image is acquired and executed by the simulation apparatus that acquires the secondary beam image from the inspection apparatus that outputs the defect image and the secondary beam image. A simulation processing unit that performs re-inspection simulation in which the cell period in the cell-cell comparison inspection is changed and outputs the inspection result is configured.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum cell period without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection result review program according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image with a secondary beam from the sample, performs a die-to-die comparison inspection on the secondary beam image, and performs defect inspection. An image is acquired and executed by the simulation apparatus that acquires the secondary beam image from the inspection apparatus that outputs the defect image and the secondary beam image. A simulation processing unit that performs a re-inspection simulation in which the edge tolerance in the die-to-die comparison inspection is changed and outputs a re-inspection result is configured.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum edge tolerance without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection result review program according to the present embodiment irradiates a sample with a primary beam, obtains a secondary beam image with a secondary beam from the sample, and filters the secondary beam image with an image processing filter. In the simulation apparatus, the secondary beam is acquired by the simulation apparatus that acquires the secondary beam image from the inspection apparatus that acquires the defect image and outputs the defect image and the secondary beam image. For the image, a re-inspection simulation in which the image processing filter is changed is performed, and a simulation processing unit that outputs a re-inspection result is configured.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum image filter without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

  The inspection result review program according to the present embodiment irradiates a sample with a primary beam, acquires a secondary beam image with a secondary beam from the sample, performs shading correction on the secondary beam image, and then displays a defect image. When the secondary beam image is obtained from the inspection apparatus that acquires and outputs the defect image and the secondary beam image, the simulation apparatus acquires the secondary beam image. A simulation processing unit configured to perform a re-inspection simulation with the correction value changed and output a re-inspection result.

  Also with this configuration, it is possible to perform a re-inspection simulation for obtaining an optimum shading correction value without repeating the actual inspection with the inspection apparatus. Therefore, the time for optimizing the inspection conditions can be shortened, damage to the sample can be reduced, and contamination of the sample can be reduced.

(Embodiment)
FIG. 29 is a diagram showing a configuration of the inspection system of the present embodiment. The inspection system includes an inspection device 100 and a simulation device 200. The inspection apparatus 100 may be any electron beam inspection apparatus according to the above embodiment. The inspection apparatus 100 includes a main housing 30, an electro-optical device 70 installed on the main housing 30, a stage device 50 provided in the main housing 30, and a detector installed on the electro-optical device 70. 761 and an image processing unit 763 connected to the detector 761.

  The electron optical device 70 irradiates the wafer W, which is a sample held on the stage device 50, with a primary beam, which is a surface beam, and thereby guides the secondary beam generated from the wafer W to the detector 761. The detector 761 captures the secondary beam with a two-dimensional sensor (not shown), generates an image of the secondary beam image, and outputs the image to the image processing unit 763.

  As an inspection processing apparatus, the image processing unit 763 applies an image processing filter (an average value (Mean) filter, a Gaussian filter, a median (Median) filter, etc.) to the secondary beam image input from the detector 761. ), And after performing shading correction, inspection is performed by comparison processing such as cell-cell comparison, die-die comparison, die-database comparison, and the like. Specifically, the image processing unit 763 detects a portion exceeding a predetermined threshold in the comparison process as a defect, and generates a defect image. The image processing unit 763 outputs a defect image and an unprocessed image (secondary beam image) used to generate the defect image to the simulation apparatus 200.

  The image processing unit 763 performs inspection according to the set inspection condition parameter. The inspection condition parameters include cell period for cell-cell comparison, edge tolerance value for die-die comparison, threshold for detecting defects, image processing filter, shading correction value, and die-database comparison parameters. , Classification information of defects that are not desired to be detected are included. It should be noted that this defect classification information that is not desired to be detected is obtained as a result of classification by imaging with an SEM after inspection.

  The simulation apparatus 200 includes a simulation processing unit 201, an input unit 202, and a monitor 203. For example, the simulation apparatus 200 includes a general-purpose computer including an input unit, a monitor, an arithmetic processing unit, a memory, a storage device, an input / output port, and the like. Is done. The simulation processing unit 201 is realized by the inspection result review program according to the present embodiment being executed by the arithmetic processing unit. This inspection result review program may be provided to the simulation apparatus 200 through a network, or may be provided to the simulation apparatus 200 by reading out the search result review program stored in the storage medium. The search result review program provided in this way is stored in the storage device of the simulation apparatus 200, and is read out and executed from there to constitute the simulation processing unit 201.

  The simulation processing unit 201 performs a re-inspection simulation on the secondary beam image input from the inspection apparatus 100 while changing the inspection condition parameter, and determines an optimal inspection condition parameter. The inspection condition parameters deflected by the simulation processing unit 201 for re-inspection simulation include a cell period in the case of cell-cell comparison, an edge tolerance value in the case of die-to-die comparison, a threshold value for detecting defects, and image processing. Filters, shading correction values, die-database comparison parameters, defect classification information that should not be detected, and the like are included.

  FIG. 30 is a diagram for explaining a cell period in the case of cell-cell comparison and an edge allowable value in the case of die-to-die comparison. Now, as shown in FIG. 30, a plurality of dies D1 and D2 are formed on the surface of the wafer W. Each die has a cell region C in the center and “A” at the lower left of the cell region. ”Is formed. In the cell region C, a plurality of “F” repeating patterns (cells) are formed.

  The cell period as the inspection condition parameter is a period p of a repetitive pattern in the main scanning direction (downward in the example of FIG. 30) when the inspection apparatus 100 performs inspection by cell-cell comparison. If this period is not correct at the time of cell-cell comparison in the image processing unit 763, the inspection result by the cell-cell comparison cannot be obtained correctly. Therefore, the simulation processing unit 201 performs cell-cell comparison again on the unprocessed image obtained from the inspection apparatus 100 while changing the cell period to obtain an optimal cell period.

  The edge allowable value as the inspection condition is a threshold value for detecting a defect in the edge portion when the inspection apparatus 100 performs inspection by die-to-die comparison. As shown in FIG. 30, in the die-to-die comparison, the difference d is likely to occur at the edge portion of “A” to be compared. Therefore, if it is determined whether or not the edge portion is a defect using the same threshold value as the portion other than the edge portion, a pseudo defect is likely to be generated from the edge portion. Therefore, for the edge portion, a threshold value for detecting as a defect is set larger than that for other portions. A threshold value set large for the edge portion is an edge allowable value. If the edge tolerance is too small, a pseudo defect is detected from the edge, and if the edge tolerance is too large, a true defect generated at the edge cannot be detected. Therefore, the simulation processing unit 201 performs die-to-die comparison again on the unprocessed image obtained from the inspection apparatus 100 while changing the edge allowable value to obtain an optimum edge allowable value.

  Hereinafter, the operation of the inspection system configured as described above will be described. FIG. 31 is a flowchart showing the operation of the inspection system. First, the inspection apparatus 100 performs an inspection, and the image processing unit 763 outputs the inspection result to the simulation apparatus 200 (step S331). At this time, the image processing unit 763 also outputs the unprocessed image (secondary beam image) used to obtain the inspection result and the classification information of the defect not to be detected to the simulation apparatus 200 together with the inspection result. In the simulation apparatus 200, the simulation processing unit 201 reads this inspection result, generates a defect image, and displays it on the monitor 203 (step S332).

  Next, the simulation processing unit 201 changes the inspection condition, executes re-inspection simulation (step S333), and outputs the re-inspection result obtained thereby (step S334). In this re-inspection simulation, as in the inspection in the inspection apparatus 100, the defect in the defect classification information that is not to be detected is not detected. The simulation processing unit 201 reads the reinspection result obtained in step S334, generates a defect image, and outputs the defect image to the monitor 203 (step S335).

  Next, by evaluating the defect image obtained by this re-inspection, it is determined whether the inspection condition is optimal (step S336). If the inspection condition is not optimal (NO in step S336), the process proceeds to step S333. Returning, the inspection condition is changed, and the re-inspection simulation is executed (step S333). When the re-inspection simulation is repeated while changing the inspection condition parameters as described above and the inspection conditions become optimal (YES in step S336), the optimal inspection conditions are used as inspection conditions adopted by the inspection apparatus 100. Determination is made (step S337), and the process is terminated. The simulation processing unit 201 may determine whether the search condition is optimal based on an input from the input unit 202, for example.

  As described above, according to the inspection system of the present embodiment, after the actual inspection is performed by the inspection apparatus 100, the defect image and the unprocessed image output from the inspection apparatus 100 by the simulation apparatus 200 are used. Since the reinspection simulation is performed by the inspection result review software while changing the inspection conditions, the inspection conditions can be optimized with a small number of inspections, and the time for optimizing the inspection conditions can be shortened. In addition, since it is not necessary to repeat the actual number of inspections by the inspection apparatus 100, damage to the sample can be reduced, and contamination of the sample can be reduced.

<Scanning method>
(background)
The inspection method using the primary optical system using the photocathode is the same inspection after pre-charging by repeating scanning operation and step operation (moving laterally by the visual field width) to the inspection area under pre-charge energy conditions. An inspection method in which a scan operation and a step operation are repeatedly performed on a region under an inspection energy condition is conceivable.

(Task)
However, in such an inspection method, when attention is paid to one small area in the inspection area, it takes time to perform the inspection after the precharge is performed. The effect of may be weakened.

  The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a scanning method for an inspection apparatus capable of performing an inspection by effectively using the effect of precharge.

(Solution)
The scanning method of the inspection apparatus according to the present invention includes:
Irradiating the sample with a primary beam under precharge energy conditions while moving the sample in one direction, and continuously precharging the strip-shaped inspection region of the sample;
Irradiating the sample with a primary beam under an inspection condition while moving the sample in a direction opposite to the one direction, and continuously inspecting a strip-shaped inspection region of the sample; and
Moving the sample in a direction perpendicular to the one direction by a visual field width;
Repeat in order.

(Embodiment)
With reference to FIGS. 32A to 32D, a scanning method of the inspection apparatus according to the present embodiment will be described.

  In the scanning method of the present embodiment, first, as shown in FIG. 32A, the primary beam is applied to the sample 20 in a state where a retarding voltage (precharge voltage) that realizes the precharge energy condition is applied to the sample 20. , The stage 30 on which the sample 20 is placed is moved (scanned) at a constant speed (see arrow A1), and pre-charging is continuously performed on the strip-shaped inspection region 211 of the sample 20.

  Next, as shown in FIG. 32B, the sample 20 is irradiated with the primary beam while the retarding voltage (inspection voltage) that realizes the inspection condition is applied to the sample 20, and the sample 20 is mounted. The stage 30 is moved (scanned) in the reverse direction at a constant speed (see arrow A2), and the inspection is continuously performed on the same inspection region 211 of the sample 20.

  Next, as shown in FIG. 32C, after moving the stage 30 sideways (step) by the visual field width (see arrow A3), the sample 20 is irradiated with the primary beam while the precharge voltage is applied to the sample. At the same time, the stage 30 on which the sample 20 is placed is moved (scanned) at a constant speed (see arrow A4), and the precharge is continuously performed on the inspection region 212 adjacent to the previous inspection region 211. .

  Next, as shown in FIG. 32D, the primary beam is irradiated to the sample 20 with the inspection voltage applied to the sample 20, and the stage 30 on which the sample 20 is placed moves in the reverse direction at a constant speed ( (Refer to arrow A5), and the same inspection area 212 of the sample 20 is continuously inspected.

  Thereafter, the steps shown in FIGS. 32C and 32D are alternately repeated, so that precharge and inspection are alternately performed on the entire surface of the sample 20.

  According to the present embodiment as described above, after the precharge is performed by repeating the scan operation and the step operation on the precharge energy condition for the inspection region, the same inspection region is scanned on the inspection energy condition. Compared to the inspection method in which the inspection is performed by repeating the operation and the step operation, when attention is paid to one small region in the inspection region, the time between the precharge and the inspection is performed. Since it becomes shorter, it is possible to carry out the inspection by effectively using the effect of the precharge.

<Electron optical device + SEM + EDX>
(background)
In sample defect inspection, after detecting foreign matter using an electron optical device, a scanning electron microscope (hereinafter sometimes referred to as SEM) is used to reinspect (review) the detected defect and determine authenticity. Then, it is desirable to perform material analysis of true defects using an energy dispersive X-ray spectrometer (hereinafter sometimes referred to as EDX). Here, in the inspection using SEM and EDX, it is necessary to accurately irradiate the electron beam to the defect position detected by the electron optical device.

(Task)
However, in the conventional inspection apparatus, the electron optical device, the SEM, and the EDX are provided in separate vacuum housings, and it is necessary to move the sample between the vacuum housings and align the coordinates between the vacuum housings. In the inspection using EDX, it is difficult to accurately irradiate the defect position detected by the electron optical device with the electron beam. For this reason, the material cannot be determined for particularly thin or small foreign matters.

  The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide an inspection apparatus that can determine the material of thin or small foreign matter on a sample surface.

(Solution)

The inspection apparatus according to the present invention includes:
An inspection device for inspecting a sample,
A stage device for continuously moving a sample placed thereon;
A vacuum housing that houses the stage device;
An electro-optical device provided in the vacuum housing;
A scanning electron microscope and an energy dispersive X-ray spectrometer provided adjacent to each other in the vacuum housing;
With
The electro-optical device includes:
A primary optical system for irradiating the sample on the stage device with a primary beam;
A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample with the primary beam;
A secondary optical system for guiding the secondary beam to the two-dimensional sensor.

  According to the present invention, the electron optical device, the scanning electron microscope, and the energy dispersive X-ray spectrometer are provided in the same vacuum housing, and the sample is moved by the same stage device. It is not necessary to move the sample at this point and to coordinate the vacuum housing. As a result, in inspection using SEM and EDX, it is possible to accurately irradiate the defect position detected by the electron optical device with the electron beam, and even a thin foreign object or a small foreign object can be determined. Can do. The ability to determine the material of thin or small foreign matter enables more accurate identification of the defect generation process and parts, etc., thereby making it possible to improve processes, improve parts and improve equipment, and improve production line yields. To help.

  In the inspection apparatus according to the present invention, the primary optical system may include a laser light source that generates laser light and a photoelectric surface that generates the primary beam when irradiated with the laser light.

  According to such an aspect, since the energy dispersion of electrons emitted from the photocathode is relatively small, an accurate precharge energy condition can be selected independently of the inspection energy condition by changing the retarding voltage. can do. Thereby, the detection sensitivity in the electron optical device is improved, and finer foreign matters can be detected.

  In the inspection apparatus according to the present invention, the scanning electron microscope and the energy dispersive X-ray spectroscopy may be provided in the vacuum housing so that an angle of an optical axis of the scanning electron microscope with respect to the sample on the stage device is adjusted. A turning means for turning the device together with respect to the stage device may be provided.

  According to such an aspect, at the time of reviewing defects by a scanning electron microscope, the optical axis of the scanning electron microscope is directed at a right angle to the sample, and the electron beam is irradiated at a right angle to the sample surface. The pattern can prevent the electron beam from being shaded. On the other hand, during material analysis using an energy dispersive X-ray spectrometer, the electron beam passes through a thin foreign object by tilting the optical axis of the scanning electron microscope with respect to the sample and irradiating the sample surface with the electron beam obliquely. Thus, it is possible to prevent the generation of a signal from other than a thin foreign substance that reaches the inside of the sample.

  In the inspection apparatus according to the present invention, the stage device includes a tilt unit that tilts the sample on the stage device so that an angle of an optical axis of the scanning electron microscope with respect to the sample on the stage device is adjusted. May be provided.

  Even in such an embodiment, in the re-inspection of defects by the scanning electron microscope, the optical axis of the scanning electron microscope is oriented at right angles to the sample, and the sample surface is irradiated with an electron beam at right angles. It is possible to prevent the pattern from being shaded. On the other hand, in material analysis using an energy dispersive X-ray spectrometer, the electron beam passes through a thin foreign object by tilting the optical axis of the scanning electron microscope with respect to the sample and irradiating the sample surface with the electron beam obliquely. Thus, it is possible to prevent the generation of a signal from other than a thin foreign substance that reaches the inside of the sample.

  In the inspection apparatus according to the present invention, the scanning type is arranged between the scanning electron microscope and the stage device so that an angle of an optical axis of the scanning electron microscope with respect to the sample on the stage device is adjusted. A deflector for deflecting the electron beam emitted from the electron microscope may be provided.

  Even in such an embodiment, in the re-inspection of defects by the scanning electron microscope, the optical axis of the scanning electron microscope is oriented at right angles to the sample, and the sample surface is irradiated with an electron beam at right angles. It is possible to prevent the pattern from being shaded. On the other hand, in material analysis using an energy dispersive X-ray spectrometer, the electron beam passes through a thin foreign object by tilting the optical axis of the scanning electron microscope with respect to the sample and irradiating the sample surface with the electron beam obliquely. Thus, it is possible to prevent the generation of a signal from other than a thin foreign substance that reaches the inside of the sample.

  The inspection apparatus according to the present invention includes a cathode power source that applies a cathode voltage to the cathode of the scanning electron microscope, a retarding power source that applies a retarding voltage to the sample on the stage, the scanning electron microscope, and the energy. Setting of the cathode voltage and the retarding voltage that can be imaged by both of the dispersive X-ray spectrometer, and setting of the cathode voltage and the retarding voltage that can only be imaged by the energy dispersive X-ray spectrometer And a mode switching unit for switching between and.

  According to such an aspect, even when a high voltage cannot be applied to the cathode due to the conditions of the scanning electron microscope, the mode switching unit can capture images by both the scanning electron microscope and the energy dispersive X-ray spectrometer. By switching from possible voltage settings to voltage settings that can only be imaged with an energy dispersive X-ray spectrometer, at least X-ray image acquisition with an energy dispersive X-ray spectrometer is continued without stopping the device. can do.

In the inspection apparatus according to the present invention,
The photocathode is in a state divided into at least a first region and a second region,
Different cathode voltages are applied to the first region and the second region,
A laser beam may be irradiated to a boundary between the first region and the second region.

  According to such an aspect, since different cathode voltages are applied to the first region and the second region of the photocathode, the landing energy of the primary beam generated from the first region and the primary beam generated from the second region Are different from each other. That is, primary beams with different energies are simultaneously irradiated onto adjacent regions of the sample. Thereby, inspection under various conditions becomes possible.

  In the inspection apparatus according to the present invention, a voltage is applied to the first region such that the landing energy of the primary beam realizes the inspection energy condition, and the landing energy of the primary beam is applied to the second region in the precharge energy condition. A voltage that realizes the above may be applied.

  According to such an aspect, it is possible to precharge the other while inspecting one of the adjacent regions of the sample.

  In the inspection apparatus according to the present invention, the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident on the sample surface are the step operations of the stage device. Adjacent to the direction.

  In the inspection apparatus according to the present invention, the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident on the sample surface are scanning operations of the stage device. Adjacent to the direction.

  In the inspection apparatus according to the present invention, the cathode power supply reverses the voltage applied to the first region and the voltage applied to the second region in synchronization with the stage device reversing the direction of the scanning operation. May be.

  In the inspection apparatus according to the present invention, an aperture having the same potential as that of the photocathode may be disposed on the photocathode.

  According to such an aspect, a portion of the base of the Gaussian laser beam having a low intensity is cut by the aperture, so that the intensity distribution of the laser beam is made uniform. As a result, a primary beam having a uniform intensity distribution is generated from the photocathode. By using a primary beam having a uniform intensity distribution, noise during defect inspection can be reduced. In addition, since the aperture has the same potential as the photocathode, the influence on the extraction electric field can be reduced.

  In the inspection apparatus according to the present invention, a distance between the photocathode and the aperture may be 0.1 to 2.0 mm.

  According to such an aspect, since the interval is 2.0 mm or less, it is possible to prevent diffraction from occurring between the time when the laser light passes through the aperture and the time when it reaches the photocathode.

  In the inspection apparatus according to the present invention, the aperture may be covered with Cr or C.

  According to such an aspect, since the electron efficiency of Cr or C is low, the electrons generated from the aperture can be reduced, thereby reducing noise during defect inspection.

(Embodiment)
An inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 35 is a diagram illustrating an example of an inspection apparatus according to the present embodiment.

  As shown in FIG. 35, the inspection apparatus 10 includes a stage device 30 on which the sample 20 is continuously moved, a vacuum housing 11 that houses the stage device 30, and an electron optical device provided in the vacuum housing 11. 100 and a scanning electron microscope (SEM) 200 and an energy dispersive X-ray spectrometer (EDX) 300 provided adjacent to each other in the vacuum housing 11.

  Among these, as described above, the electron optical device 100 includes the primary optical system 40 that irradiates the sample 20 on the stage device 30 with the primary beam, and the second generated from the sample 20 by irradiating the sample 20 with the primary beam. The detector 70 includes a two-dimensional sensor 71 that generates an image of the secondary beam, and the secondary optical system 60 that guides the secondary beam to the two-dimensional sensor 70.

  In the present embodiment, the primary optical system 40 includes a laser light source 49 (see FIG. 39) that generates laser light, and a photocathode 2011 that generates a primary beam when irradiated with the laser light. . The relationship LE = RTD−V1 is established between the landing energy LE of the primary beam, the retarding voltage RTD applied to the sample 20, and the cathode voltage V1 applied to the photocathode 2021.

  By the way, as described above, in the defect inspection of the sample 20, after the foreign matter is detected using the electron optical device 10, the detection defect is re-inspected (reviewed) and the authenticity is determined using the SEM 200, and then the EDX 300 is detected. It is desirable to perform material analysis of true defects using Here, in the inspection using the SEM 200 and the EDX 300, it is necessary to irradiate the electron beam accurately to the defect position detected by the electron optical device.

  In the conventional inspection apparatus, the electron optical device, the SEM, and the EDX are provided in separate vacuum housings, and it is necessary to move the sample between the vacuum housings and align the coordinates between the vacuum housings. In the inspection using, it was difficult to accurately irradiate the defect position detected by the electron optical device with the electron beam. For this reason, the material cannot be determined for particularly thin or small foreign matters.

  On the other hand, in the present embodiment, the electron optical device 100, the SEM 200, and the EDX 300 are provided in the same vacuum housing 11, and the sample 20 is moved by the same stage device 30. Therefore, it is not necessary to move the sample between the vacuum housings and to coordinate the coordinates between the vacuum housings. Thereby, in the inspection using the SEM 200 and the EDX 300, it is possible to accurately irradiate the electron beam to the defect position detected by the electron optical device 100, and the material of the thin foreign matter or the small foreign matter is determined. be able to. The ability to determine the material of thin or small foreign matter enables more accurate identification of the defect generation process and parts, etc., thereby making it possible to improve processes, improve parts and improve equipment, and improve production line yields. To help.

  FIG. 34A is a schematic diagram showing the SEM 200 and EDX 300 and the sample 20 on the stage 30 in an enlarged manner.

  As shown in FIG. 34A, in the present embodiment, the SEM 299 and the EDX 300 are combined together in the vacuum housing 11 so that the angle of the optical axis of the SEM 200 with respect to the sample 20 on the stage device 30 is adjusted. A swiveling means 310 is provided for swiveling with respect to.

  When the defect is reviewed by the SEM 200, the swivel unit 310 directs the optical axis of the SEM 200 perpendicular to the sample 30 and irradiates the surface of the sample 30 with an electron beam (see FIG. 34A). Thereby, it can prevent that the shadow of an electron beam arises with the pattern of the sample 30 surface. On the other hand, during the material analysis by the EDX 300, the turning means 310 tilts the optical axis of the EM 200 with respect to the sample and irradiates the electron beam obliquely on the surface of the sample 30 (see FIG. 34B). As a result, it is possible to prevent the electron beam from passing through the thin foreign matter and reaching the inside of the sample 30 and generating a signal from other than the thin foreign matter. Therefore, the material determination of the thin foreign matter can be performed more accurately.

  If the electron beam can be irradiated perpendicularly to the surface of the sample 30 at the time of defect review and can be irradiated obliquely to the surface of the sample 30 at the time of material analysis, the embodiment is limited to a mode in which the turning means 310 is provided in the vacuum housing 11. Not. For example, as shown in FIG. 34C, the stage device 30 includes tilt means 320 that tilts the sample 20 on the stage device 30 so that the angle of the optical axis of the SEM 200 with respect to the sample 20 on the stage device 30 is adjusted. It may be provided. Alternatively, as shown in FIG. 34D, the electron beam emitted from the SEM is deflected between the SEM 200 and the stage apparatus 30 so that the angle of the optical axis of the SEM 200 with respect to the sample 20 on the stage apparatus 30 is adjusted. A deflector 210 may be provided. Even in these aspects, the surface of the sample 30 can be irradiated with an electron beam at a right angle during defect review, and the surface of the sample 30 can be irradiated with an electron beam obliquely during material analysis.

  Returning to FIG. 33, the inspection apparatus 10 according to the present embodiment includes a cathode power source 201 that applies a cathode voltage to the cathode of the SEM 200, a retarding power source 82 that applies a retarding voltage to the sample 20 on the stage 30, and a mode. And a switching unit 202. The mode switching unit 202 can switch between the setting of the cathode voltage and the retarding voltage that can be imaged by both the SEM 200 and the EDX 300, and the setting of the cathode voltage and the retarding voltage that can only be imaged by the EDX 300. .

  As a result, even when a high voltage cannot be applied to the cathode due to the conditions of the SEM 200, the mode switching unit 202 changes from a voltage setting that enables imaging by both the SEM 200 and the EDX 300 to a voltage setting that allows only imaging by the EDX 300. By switching to the above, at least X-ray image capturing by the EDX 300 can be continued without stopping the apparatus.

  Specifically, for example, the EDX 300 can capture an X-ray image of the surface of the sample 20 if the potential of the surface of the sample 20 is 5 kV or less. Therefore, the cathode voltage was set to -5 kV, the retarding voltage was set to 0 V, and imaging was performed by both the SEM 200 and the EDX 300. When the switching unit 202 switches the cathode voltage to −2.5 kV and the retarding voltage to 2.5 V, at least the X-ray image capturing by the EDX 300 can be continued thereafter.

"Primary optical system: Photocathode division"
In the present embodiment, as shown in FIG. 35, the photocathode 2011 of the primary optical system 40 of the electron optical device 100 is divided into at least a first region 2011a and a second region 2011b. The photocathode 2011 may be divided into three or more regions. In the illustrated example, the first region 2011 a has a circular shape and is arranged at the center of the photocathode 2011. On the other hand, the second region 2011b has an annular shape and is disposed so as to surround the first region 2011a.

  Different cathode voltages are applied to the first region 2011a and the second region 2011b from a cathode power source (not shown). Further, as shown in FIG. 35, the laser light generated from the laser light source 49 is applied to the boundary between the first region 2011a and the second region 2011b. Since different cathode voltages are applied to the first region 2011a and the second region 2011b of the photocathode 2011, the landing energy of the primary beam generated from the first region 2011a and the primary beam generated from the second region 2011b are different from each other. It will be a thing. That is, as shown in FIG. 36, adjacent regions 25a and 25b of the sample 20 are simultaneously irradiated with primary beams having different energies. For example, when −4010V is applied to the first region 2011a, −4001V is applied to the second region 2011b, and −4000V is applied to the sample 20, the landing energy of the primary beam generated from the first region 2011a is 10 eV, and the landing energy of the primary beam generated from the second region 2011 b is 1 eV. Thereby, inspection under various conditions becomes possible.

  For example, a voltage such that the landing energy of the primary beam realizes the inspection energy condition is applied to the first region 2011a, and a voltage that realizes the precharge energy condition is applied to the second region 2011b. In this case, the other region 25b can be precharged while inspecting one of the regions 25a and 25b of the sample 20 adjacent to each other.

  With reference to FIG. 37A and FIG. 37B, the 1st example of the test | inspection method of the sample 20 is demonstrated. In the example shown in FIGS. 37A and 37B, the region 25a on which the primary beam generated from the first region 2011a is incident and the region 25b on which the primary beam generated from the second region 2011b is incident on the surface of the sample 20 are the stage device. Adjacent to the direction of 30 step motions.

  In the present embodiment, first, as shown in FIG. 37A, a region 25a where the primary beam generated from the first region 2011a is incident and a region 25b where the primary beam generated from the second region 2011b is incident are the stage device 30. By moving (scanning) the stage 30 on which the sample 20 is placed at a constant speed while irradiating the sample 20 with the primary beam in the direction adjacent to the direction of the step operation (see arrow A1), the sample 20 The pre-charge is continuously performed on the belt-shaped inspection area 212.

  When it moves to the end of the sample 20, as shown in FIG. 37B, the stage 30 is moved (stepped) sideways by half the visual field width (see arrow A2). Next, while irradiating the sample 20 with the primary beam in the same direction as in the previous scan, the stage 30 on which the sample 20 is placed is moved (scanned) at a constant speed in the direction opposite to that in the previous scan (see arrow A3). . As a result, the belt-shaped inspection region 212 precharged at the previous scan is continuously inspected, and the adjacent belt-shaped inspection region 213 is continuously precharged (first). 2 steps).

  Thereafter, when moving to the end of the sample 20, the stage 30 is moved sideways (step) by half of the visual field width, and then the sample 20 is placed while irradiating the sample 20 with the primary beam in the same direction as in the previous scan. The entire surface of the sample 20 is inspected by repeating the process of moving (scanning) the stage 30 at a constant speed in the opposite direction to the previous scan.

  Next, a second example of the inspection method of the sample 20 will be described with reference to FIGS. 38A and 38B. In the example shown in FIGS. 38A and 38B, the region 25a on which the primary beam generated from the first region 2011a is incident and the region 25b on which the primary beam generated from the second region 2011b is incident on the surface of the sample 20 are the stage device. Adjacent to the direction of 30 scan operations.

  In the present embodiment, first, as shown in FIG. 38A, the region 25a where the primary beam generated from the first region 2011a is incident and the region 25b where the primary beam generated from the second region 2011b is incident are the stage device 30. The stage 30 on which the sample 20 is placed is moved (scanned) at a constant speed while irradiating the sample 20 with the primary beam in a direction adjacent to the scanning operation direction (see arrow A1). Accordingly, both precharge and inspection are continuously performed on the strip-shaped inspection region 211 of the sample 20.

  When it moves to the end of the sample 20, as shown in FIG. 38B, the stage 30 is moved (stepped) sideways by the visual field width (see arrow A2). Next, the applied voltage of the first region 2011a and the applied voltage of the second region 2011b on the photocathode 2011 are reversed. That is, a voltage is applied to the first region 2011a so that the landing energy of the primary beam realizes the precharge energy condition, and a voltage is applied to the second region 2011b to realize the inspection energy condition. In this state, the stage 30 on which the sample 20 is placed is moved (scanned) at a constant speed in the opposite direction to the previous scan while irradiating the sample 20 with the primary beam in the same direction as the previous scan (see arrow A3). ). As a result, both precharge and inspection are continuously performed on the strip-shaped inspection region 212 of the sample 20.

  Thereafter, when moving to the end of the sample 20, the stage 30 is moved (stepped) horizontally by the visual field width, and then the applied voltage of the first region 2011a and the applied voltage of the second region 2011b on the photocathode 2011 are reversed, In this state, a process of moving (scanning) the stage 30 on which the sample 20 is placed at a constant speed in the opposite direction to the previous scan while irradiating the sample 20 with the primary beam in the same direction as the previous scan. By repeating, the entire surface of the sample 20 is inspected.

“Primary optical system: Aperture on photocathode”

  In the present embodiment, as shown in FIG. 39, an aperture 2012 having the same potential as the photocathode 2011 is arranged on the photocathode 2011. For example, the diameter of the laser beam is 30 μm to 200 μm, whereas the aperture 2012 has a diameter of 10 μm to 100 μm.

  Since the aperture 2012 is disposed on the photocathode 2011, the laser light generated from the laser light source 49 and reflected by the mirror 2070 passes through the aperture 2012 before being irradiated onto the photocathode 2011. When passing through the aperture 2012, a portion of the base of the Gaussian laser beam having a weak intensity is cut by the aperture 2012, so that the intensity distribution of the laser beam irradiated on the photocathode 2011 is made uniform. As a result, a primary beam having a uniform intensity distribution is generated from the photocathode 2011. By using a primary beam having a uniform intensity distribution, noise during defect inspection can be reduced.

  Since the aperture 2012 has the same potential as the photocathode 2011, the influence on the extraction electric field is small.

  The distance between the photocathode 2011 and the aperture 2012 is preferably 0.1 to 2.0 mm. According to the knowledge of the present inventors, if the distance between the photocathode 2011 and the aperture 2012 is 2.0 mm or less, the laser beam passes through the aperture 2012 and then reaches the photocathode 2011. , It is possible to prevent the intensity distribution from becoming non-uniform due to diffraction.

  In the present embodiment, the aperture 2012 is covered with Cr or C. Since Cr or C has low electron efficiency, electrons generated from the aperture 2012 can be reduced when the laser light passes through the aperture 2012. This stabilizes the primary beam and reduces noise during defect inspection.

  The embodiments of the present invention have been described above by way of example, but the scope of the present invention is not limited to these embodiments, and can be changed or modified according to the purpose within the scope of the claims. is there. Further, each embodiment can be appropriately combined within a range in which processing contents are not contradictory.

  As described above, the inspection apparatus according to the present invention has an effect that uniform inspection can be performed on the entire inspection area of the sample, and is useful as a semiconductor inspection apparatus or the like.

1701 Laser light source 1702 Photocathode 1703 Homogenizer 1704 Beam splitter 1705 Beam profiler 1706 Mechanical shutter 1707 Variable attenuator 1708 Beam diameter adjustment lens 1709 Astigmatism correction lens 1710 Vacuum chamber 1711 Mirror 1712 Mirror 1713 Mirror 1714 Mirror 1714 Mirror port 1714

Claims (16)

An inspection device for inspecting a sample,
A stage on which the sample is placed;
A primary optical system for irradiating the sample on the stage with a primary beam;
A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample with the primary beam;
A secondary optical system for guiding the secondary beam to the two-dimensional sensor;
With
The primary optical system is
A laser light source that generates a Gaussian laser beam;
A homogenizer for converting the intensity distribution of the Gaussian laser beam into a uniform laser beam;
A photocathode that generates the primary beam by being irradiated with the uniformly distributed laser beam;
Equipped with a,
The inspection apparatus , wherein the photocathode is disposed in a vacuum chamber, and the laser light source and the homogenizer are disposed outside the vacuum chamber . The primary optical system is
A beam splitter that splits the laser light whose intensity distribution has been converted by the homogenizer;
A beam profiler for measuring the intensity distribution of the laser beam divided by the beam splitter;
The inspection apparatus according to claim 1, comprising: The primary optical system is
Beam diameter adjusting means for adjusting the beam diameter of the laser light generated from the laser light source;
A focal length adjusting means for adjusting a focal length of the laser beam;
The comprising inspection apparatus according to claim 1 or claim 2. A vacuum housing that houses the stage and is provided with the secondary optical system;
A scanning electron microscope and an energy dispersive X-ray spectrometer provided adjacent to each other in the vacuum housing;
Inspection device according to any one of claims 1 to 3, further comprising a. In the vacuum housing, the scanning electron microscope and the energy dispersive X-ray spectrometer are put together on the stage so that the angle of the optical axis of the scanning electron microscope with respect to the sample on the stage is adjusted. The inspection apparatus according to claim 4 , further comprising a turning means for turning relative to the turning means. The stage is provided with tilting means for tilting the sample on the stage so that the angle of the optical axis of the scanning electron microscope with respect to the sample on the stage is adjusted. The inspection apparatus according to claim 4 . An electron beam emitted from the scanning electron microscope is placed between the scanning electron microscope and the stage so that the angle of the optical axis of the scanning electron microscope with respect to the sample on the stage is adjusted. The inspection apparatus according to claim 4 , further comprising a deflector for deflecting. A cathode power supply for applying a cathode voltage to the cathode of the scanning electron microscope;
A retarding power source for applying a retarding voltage to the sample on the stage;
The cathode voltage and the retarding voltage that can be imaged by both the scanning electron microscope and the energy dispersive X-ray spectrometer, and the cathode voltage that can only be imaged by the energy dispersive X-ray spectrometer. And a mode switching unit for switching the setting of the retarding voltage,
Inspection device according to any one of claims 4 to 7, further comprising a. The photocathode is in a state divided into at least a first region and a second region,
Different cathode voltages are applied to the first region and the second region,
Inspection device according to any one of claims 1 to 8, characterized in that is adapted to the laser light is irradiated to the boundary of the first region and the second region. Before SL in the first region, the landing energy of the primary beam is applied a voltage which realizes the test energy condition, wherein the second region, the voltage such as the landing energy of the primary beam to achieve a pre-charge energy conditions The inspection apparatus according to claim 9 , wherein: is applied. On the sample surface, the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident are adjacent to each other in the direction of the step operation of the stage. The inspection apparatus according to claim 10 . On the sample surface, the region where the primary beam generated from the first region is incident and the region where the primary beam generated from the second region is incident are adjacent to each other in the scanning operation direction of the stage. The inspection apparatus according to claim 10 . The cathode power supply is synchronized to the stage reverses direction scanning operation, according to claim 8, characterized in that reversing the voltage applied voltage applied to the first region and the second region The inspection apparatus according to claim 12 , which cites claim 10, which cites claim 9 . Wherein the photocathode on the inspection apparatus according to any one of claims 1 to 13, characterized in that the aperture of the photoelectric surface and the same potential are disposed. The inspection apparatus according to claim 14 , wherein a distance between the photocathode and the aperture is 0.1 to 2.0 mm. 16. The inspection apparatus according to claim 14 , wherein the aperture is covered with Cr or C.