JP6815469B2 - Pattern inspection device and pattern inspection method - Google Patents

Description

The present invention relates to a pattern inspection device and a pattern inspection method. For example, the present invention relates to a pattern inspection technique for inspecting a pattern defect of a sample object used in semiconductor manufacturing, and relates to an inspection device and a method for inspecting a photomask used when manufacturing a semiconductor element or a liquid crystal display (LCD).

In recent years, with the increasing integration and capacity of large-scale integrated circuits (LSIs), the circuit line width required for semiconductor elements has become narrower and narrower. These semiconductor elements use an original image pattern (also referred to as a mask or reticle, hereinafter collectively referred to as a mask) on which a circuit pattern is formed, and the pattern is exposed and transferred onto a wafer by a reduction projection exposure apparatus called a stepper. Manufactured by forming a circuit. Therefore, a pattern drawing apparatus using an electron beam capable of drawing a fine circuit pattern is used for manufacturing a mask for transferring such a fine circuit pattern to a wafer. A pattern circuit may be drawn directly on the wafer using such a pattern drawing device. Alternatively, an attempt is being made to develop a laser beam drawing apparatus that draws using a laser beam in addition to the electron beam.

Further, improvement of the yield is indispensable for manufacturing an LSI, which requires a large manufacturing cost. However, as represented by 1 gigabit class DRAM (random access memory), the patterns constituting the LSI are on the order of submicron to nanometer. One of the major factors for reducing the yield is a pattern defect of a mask used when exposing and transferring an ultrafine pattern on a semiconductor wafer by photolithography technology. In recent years, with the miniaturization of LSI pattern dimensions formed on semiconductor wafers, the dimensions that must be detected as pattern defects have become extremely small. Therefore, it is required to improve the accuracy of the pattern inspection apparatus for inspecting defects of the transfer mask used in LSI manufacturing.

As an inspection method, an optical image obtained by capturing a pattern formed on a sample such as a lithography mask using a magnifying optical system at a predetermined magnification is compared with a design data or an optical image obtained by capturing the same pattern on the sample. There is a known method of inspecting by doing so. For example, as a pattern inspection method, "die to die inspection" in which optical image data obtained by capturing the same pattern in different places on the same mask are compared with each other, or a pattern is used as a mask using CAD data with a pattern design. The drawing data (design pattern data) converted into the device input format for input by the drawing device at the time of drawing is input to the inspection device, a design image (reference image) is generated based on this, and the pattern is imaged. There is a "die to database (die database) inspection" that compares the measured optical image with the measured data. In the inspection method in such an inspection apparatus, the sample is placed on the stage, and the moving of the stage causes the luminous flux to scan the sample to perform the inspection. The sample is irradiated with a luminous flux by a light source and an illumination optical system. The light transmitted or reflected from the sample is imaged on the sensor via the optical system. The image captured by the sensor is sent to the comparison circuit as measurement data. In the comparison circuit, after the images are aligned with each other, the measurement data and the reference data are compared according to an appropriate algorithm, and if they do not match, it is determined that there is a pattern defect.

For semiconductor products with a short product cycle, shortening the manufacturing time is an important item. When a defective mask pattern is exposed and transferred to a wafer, the semiconductor device made from the wafer becomes defective. Therefore, it is important to perform a pattern defect inspection of the mask. Then, the defect found in the defect inspection is corrected by the defect correction device. However, fixing all the defects found will increase the manufacturing time and reduce the product value. As the development of the inspection device progresses, the inspection device determines that there is a pattern defect even if a very small deviation occurs. However, when the mask pattern is transferred onto the wafer by an actual exposure apparatus, it can be used as an integrated circuit as long as it is not caused by a defect such as disconnection or / or short circuit of the circuit on the wafer. Therefore, it is desired to use the mask for exposure transfer while leaving the state of the defect, instead of correcting the defect each time. However, since the inspection device has an optical system configured to detect minute deviations, the resolution for the mask is set higher than that of the exposure device. Therefore, it is difficult to reproduce the pattern image when transferred by the exposure apparatus by the inspection apparatus. Therefore, it is difficult to grasp how the defects found in the inspection device are exposed by the exposure device by using the inspection device.

A dedicated machine that inspects an exposure image that is exposed and transferred by an exposure device from the beginning, rather than an inspection device that can inspect minute deviations, has been disclosed (see, for example, Patent Document 1). It becomes difficult to inspect.

Japanese Unexamined Patent Publication No. 2001-235853

Therefore, the present invention provides an inspection device and a method capable of inspecting an image formed when exposure transfer is performed by an exposure device in an inspection device for inspecting minute defects.

The pattern inspection apparatus of one aspect of the present invention is
A movable stage on which the mask substrate on which the pattern is formed is placed,
A transmission illumination optical system that illuminates the mask substrate with the first inspection light and can change the illumination shape of the first inspection light.
A reflective illumination optical system that has an objective lens and a polarizing element, illuminates the mask substrate with the second inspection light using the objective lens and the polarizing element, and allows the reflected light from the mask substrate to pass through.
A drive mechanism capable of moving the polarizing element from outside the optical path onto the optical path and moving the polarizing element from the optical path to the outside of the optical path.
While the stage is moving, a sensor that receives the transmitted light from the mask substrate illuminated by the first inspection light, and
An imaging optical system that receives transmitted light through an objective lens and forms an image of the received transmitted light on a sensor.
It is placed between the mask substrate and the sensor so that the numerical aperture (NA) at which transmitted light can be incident from the mask substrate to the objective lens can be switched between a high numerical aperture state and a low numerical aperture state. An aperture diaphragm that adjusts the light beam diameter of the transmitted light,
It is characterized by being equipped with.

In addition, it stores information on the focal position of each position on the mask substrate, which is measured by using the reflected light from the mask substrate illuminated with the second inspection light while the polarizing element is moved on the optical path. Storage device and
While the polarizing element is moved out of the optical path and the sensor receives transmitted light corresponding to a low numerical aperture while the stage is moving, it is dynamically transmitted using the focal position information stored in the storage device. Focusing mechanism that focuses light and
It is preferable to further provide.

The pattern inspection method of one aspect of the present invention is
The sensor can receive the transmitted light or reflected light with a high numerical aperture (NA) that can be incident on the objective lens that magnifies the transmitted light or reflected light from the mask substrate on which the pattern is formed. A step of capturing a transmitted light image or a reflected light image of a pattern formed on the mask substrate by using a sensor by scanning on the mask substrate in this state.
A step of inspecting a defect of a pattern by using an optical image of a transmitted light image or a reflected light image of the pattern of the mask substrate captured.
The process of identifying the area where defects were detected as a result of inspection,
The process of switching the numerical aperture from the high numerical aperture state to the low numerical aperture state,
A mask substrate using predetermined illumination light in a state where the sensor can receive light corresponding to a state where the numerical aperture is low and there is no polarizing element on the optical path between the mask substrate and the sensor. The process of capturing a transmitted light image of a pattern formed on a mask substrate using a sensor by scanning such a specified area.
The pattern of the region acquired as a result of the sensor receiving light with a low numerical aperture using a simulation image assuming that the pattern formed on the mask substrate is transferred to the semiconductor substrate using an exposure device. The process of comparing the transmitted light image and the simulation image of
It is characterized by being equipped with.

Further, by scanning the specified area of the mask substrate with a predetermined illumination light, the sensor receives the transmitted light from the mask substrate corresponding to the state where the numerical aperture is low.
When the sensor receives the reflected light with a high numerical aperture, the focal position of each position on the mask substrate is measured using the reflected light.
When the sensor receives the transmitted light from the mask substrate corresponding to the state where the numerical aperture is low, it is preferable that the transmitted light is dynamically focused using the measured focal position information.

Further, it is preferable to confirm at least one of the circuit disconnection and the circuit short circuit by comparing the transmitted light image of the pattern in such a region with the simulation image.

According to the present invention, in an inspection device for inspecting minute defects of a mask substrate, it is possible to inspect an image when a pattern of the mask substrate is exposed and transferred onto a semiconductor substrate or the like by the exposure apparatus. Therefore, unnecessary defect correction can be eliminated. As a result, for example, the time required for manufacturing a semiconductor product can be shortened.

It is a block diagram which shows the structure of the pattern inspection apparatus in Embodiment 1. FIG. FIG. 5 is a conceptual diagram for comparing the numerical aperture of the inspection device and the numerical aperture of the exposure device according to the first embodiment. It is a flowchart which shows the main part process of the inspection method in Embodiment 1. FIG. It is a figure which shows an example of the structure of the optical system in the high NA inspection mode in Embodiment 1. FIG. It is a conceptual diagram for demonstrating the inspection area in Embodiment 1. FIG. It is a figure for demonstrating the filter processing in Embodiment 1. It is a block diagram which shows the internal structure of the low NA inspection circuit in Embodiment 1. FIG. It is a figure which shows an example of the structure of the optical system in the low NA inspection mode in Embodiment 1. FIG. It is a figure which shows an example of the mechanism which changes the illumination shape in Embodiment 1. FIG. It is a figure which shows another example of the mechanism which changes the illumination shape in Embodiment 1. FIG. It is a figure which shows another example of the mechanism which changes the illumination shape in Embodiment 1. FIG.

Embodiment 1.
FIG. 1 is a configuration diagram showing a configuration of a pattern inspection device according to the first embodiment. In FIG. 1, the inspection device 100 for inspecting defects in the pattern formed on the mask substrate 101 includes an optical image acquisition unit 150 and a control system circuit 160 (control unit).

The optical image acquisition unit 150 includes a light source 103, a transmission illumination optical system 170, an illumination shape switching mechanism 171, a movablely arranged XYθ table 102, an objective lens 104, a reflection illumination optical system 172, an aperture diaphragm 180, and an imaging optical system. It has 178, a photodiode array 105 (an example of a sensor), a sensor circuit 106, a stripe pattern memory 123, and a laser length measuring system 122. The mask substrate 101 is placed on the XYθ table 102. The mask substrate 101 includes, for example, a photomask for exposure that transfers a pattern onto a wafer. Further, in this photomask, a pattern composed of a plurality of graphic patterns to be inspected is formed. The mask substrate 101 is arranged on the XYθ table 102, for example, with the pattern forming surface facing downward.

In the control system circuit 160, the control computer 110, which is a computer, transmits the position circuit 107, the comparison circuit 108, the expansion circuit 111, the reference circuit 112, the autoloader control circuit 113, the table control circuit 114, and the autofocus (AF) via the bus 120. ) Control circuit 140, inspection mode switching control circuit 144, low NA inspection circuit 146, magnetic disk device 109, magnetic tape device 115, flexible disk device (FD) 116, CRT 117, pattern monitor 118, and printer 119. .. Further, the sensor circuit 106 is connected to the stripe pattern memory 123, and the stripe pattern memory 123 is connected to the comparison circuit 108. Further, the XYθ table 102 is driven by an X-axis motor, a Y-axis motor, and a θ-axis motor. Further, the reflection illumination optical system 172 includes an objective lens 104 and a polarization beam splitter 174 (polarizing element). The polarization beam splitter 174 is moved in and out of the optical path by the drive mechanism 176.

In the inspection device 100, a high-magnification inspection optical system is configured by a light source 103, an XYθ table 102, a transmission illumination optical system 170, an objective lens 104, a photodiode array 105, and a sensor circuit 106. For example, an inspection optical system having a magnification of 200 to 300 times is configured. Further, the XYθ table 102 is driven by the table control circuit 114 under the control of the control computer 110. It can be moved by a drive system such as a 3-axis (XY-θ) motor that drives in the X, Y, and θ directions. As these X motors, Y motors, and θ motors, for example, linear motors can be used. The XYθ table 102 can be moved in the horizontal direction and the rotational direction by the motor of each axis of the XYθ. Then, the focal position (optical axis direction: Z-axis direction) of the objective lens 104 is dynamically adjusted to the pattern forming surface of the mask substrate 101 by the AF control circuit 140 under the control of the control computer 110. For example, the focal position of the objective lens 104 is adjusted by being moved in the optical axis direction (Z-axis direction) by the piezo element 142. The moving position of the mask substrate 101 arranged on the XYθ table 102 is measured by the laser length measuring system 122 and supplied to the position circuit 107.

Design pattern data (drawing data) that is the basis for pattern formation of the mask substrate 101 is input from the outside of the inspection device 100 and stored in the magnetic disk device 109.

Here, FIG. 1 describes the components necessary for explaining the first embodiment. It goes without saying that the inspection apparatus 100 may usually include other necessary configurations.

FIG. 2 is a conceptual diagram for comparing the numerical aperture of the inspection device and the numerical aperture of the exposure device according to the first embodiment. FIG. 2A shows a part of the optical system of the exposure apparatus. In the exposure apparatus, illumination light (not shown) is illuminated on the mask substrate 300, the transmitted light 301 from the mask substrate 300 is incident on the objective lens 302, and the light 305 passing through the objective lens 302 is connected to the semiconductor substrate 304 (wafer). Image. Although one objective lens 302 is shown in FIG. 2A, it goes without saying that a combination of a plurality of lenses may be used. Here, in the current exposure apparatus, the pattern formed on the mask substrate 300 is reduced to, for example, 1/4 and exposed and transferred to the semiconductor substrate 304. The numerical aperture NAi of the exposure apparatus with respect to the semiconductor substrate 304 at that time is set to, for example, NAi = 1.2. In other words, the numerical aperture NAi (numerical aperture on the image i side) of the objective lens 302 that can pass through the objective lens 302 is set to, for example, NAi = 1.2. In the exposure apparatus, the transmitted light image from the mask substrate 300 is reduced to 1/4, so that the sensitivity of the objective lens 302 to the mask substrate 300 is 1/4. In other words, the numerical aperture NAo (numerical aperture on the object o side) of the objective lens 302 that can be incident when the transmitted light is incident from the mask substrate 300 to the objective lens 302 is 1/4 of NAi, and NAo = 0.3. It becomes. Therefore, in the exposure apparatus, the transmitted light image from the mask substrate 300 having a luminous flux with a numerical aperture of NAo = 0.3 is exposed and transferred to the semiconductor substrate 304.

On the other hand, in the inspection device 100 according to the first embodiment, as shown in FIG. 2B, illumination light (not shown) is illuminated on the mask substrate 101, and the transmitted light 190 from the mask substrate 101 is the objective lens 104. The light 192 incident on the photodiode array 105 (sensor) is imaged. At that time, the numerical aperture NAo (numerical aperture on the object o side) of the objective lens 104 that can be incident when the transmitted light 190 is incident from the mask substrate 101 to the objective lens 104 is set to, for example, NAo = 0.9. Therefore, in the inspection device 100, the photodiode array 105 receives a transmitted light image from the mask substrate 101 having a luminous flux with a numerical aperture of NAo = 0.9. Therefore, in the inspection device 100, the defect is inspected using light having a higher resolution than the light that is exposed and transferred to the semiconductor substrate 304 by the exposure device. By using such high-resolution light, it is possible to perform high-precision inspection capable of detecting minute defects on the order of nanometers, for example. Although only the objective lens 104 is shown in FIG. 2B, a plurality of lenses (not shown) are arranged between the objective lens 104 and the photodiode array 105.

However, as described above, in the inspection device 100, since the photodiode array 105 receives light having a higher resolution than the light that is exposed and transferred to the semiconductor substrate 304 by the exposure device, the pattern is exposed and transferred to the semiconductor substrate 304 by the exposure device. In this case, it is difficult for the inspection device 100 to reproduce the same image as the pattern image formed on the semiconductor substrate 304. Therefore, in the first embodiment, the numerical aperture 180 is arranged to narrow the light beam of the transmitted light from the mask substrate 101 to adjust the light beam diameter of the transmitted light, and the same as the light to be exposed and transferred to the semiconductor substrate 304 by the exposure apparatus. It is possible for the inspection device 100 to generate light having a numerical numerical aperture NAo (numerical aperture on the object o side) (similar resolution).

In addition, in the exposure apparatus, the transmitted light from the mask substrate 300 is transferred to the semiconductor substrate 304, but the reflected light is not used. Therefore, the polarizing element is not arranged on the optical path from the mask substrate 300 to the semiconductor substrate 304. On the other hand, in the inspection device 100, in addition to the inspection using the transmitted light from the mask substrate 101, it is possible to perform the inspection using the reflected light from the mask substrate 101. Therefore, in addition to the inspection light for the transmitted light inspection (the first inspection light or the first illumination light), the inspection light for the reflected light inspection (the second inspection light or the second illumination) Light) is needed. Therefore, in the inspection device 100, a polarizing beam splitter 174 (polarizing element) is arranged on the optical path for illuminating the mask substrate 300 with the inspection light for the reflected light inspection. Therefore, the photodiode array 105 receives the light that has passed through the polarizing beam splitter 174 (polarizing element). As a result, the light received by the photodiode array 105 in the inspection device 100 has a different deflection component from the light formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 in the exposure apparatus. In this respect as well, it is difficult for the inspection device 100 to reproduce the same image as the pattern image formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 by the exposure apparatus. Therefore, in the first embodiment, the polarization beam splitter 174 (polarizing element) is configured to be able to be excluded from the optical path.

Further, the shape of the illumination light may be different between the inspection device 100 and the exposure device. As a result, the light received by the photodiode array 105 in the inspection device 100 has a different illumination shape from the light formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 in the exposure apparatus. In this respect as well, it is difficult for the inspection device 100 to reproduce the same image as the pattern image formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 by the exposure apparatus. Therefore, in the first embodiment, the illumination shape can be changed.

A point of generating light having the same numerical aperture NAo (numerical aperture on the object o side) (similar resolution) as the light to be exposed and transferred to the semiconductor substrate 304 by the above exposure apparatus, the polarizing beam splitter 174 (polarizing element) is placed on the optical path. By implementing the point of excluding from the light and the point of changing the illumination shape to the same shape as that of the exposure device, the inspection device 100 exposes and transfers the pattern of the mask substrate onto the semiconductor substrate or the like by the exposure device. The image of the case can be reproduced. Therefore, in the first embodiment, the same image as the pattern image formed on the semiconductor substrate 304 is reproduced and inspected when the pattern is exposed and transferred to the semiconductor substrate 304 by the high NA inspection mode in which the normal defect inspection is performed and the exposure apparatus. It is configured so that it can be switched between the low NA inspection mode and the low NA inspection mode.

FIG. 3 is a flowchart showing a main process of the inspection method according to the first embodiment. In FIG. 3, the inspection method according to the first embodiment is referred to as a high NA inspection mode setting step (S102), a high NA scanning (scan) step (S104), and an autofocus (AF) data creation step (S105). Image creation step (S106), comparison step (S108), defect region identification step (S110), low NA inspection mode switching step (S112), low NA scanning (scan) step (S120), AF control step. A series of steps (S122), a simulation image input step (S124), and a comparison step (S126) are carried out.

Further, in the low NA inspection mode switching step (S112), as internal steps, a polarizing element evacuation step (S114), an NA squeezing step (S116), and an illumination shape changing step (S118) are carried out.

As the high NA inspection mode setting step (S102), the inspection mode switching control circuit 144 sets each configuration to the high NA inspection mode for performing a normal high NA defect inspection. Specifically, it operates as follows. Upon receiving the control signal from the inspection mode switching control circuit 144, the illumination shape switching mechanism 171 sets the shape of the illumination light (inspection light) to the illumination shape for normal inspection. Further, in the inspection mode switching control circuit 144, the numerical aperture NAo (the numerical aperture on the object o side) of the objective lens 104 that can be incident when the transmitted light 190 is incident from the mask substrate 101 to the objective lens 104 is, for example, NAo = 0. The squeeze value of the numerical aperture 180 is controlled so as to be 9. Further, the inspection mode switching control circuit 144 controls the drive mechanism 176 to arrange the polarization beam splitter 174 on the optical path. If the polarizing beam splitter 174 is located outside the optical path, it is moved onto the optical path. If the polarizing beam splitter 174 is on the optical path, its position may be maintained.

As a high NA scanning step (S104), the numerical aperture (NA) that can be incident from the mask substrate 101 to the objective lens 104 that magnifies the transmitted light or the reflected light from the mask substrate 101 on which the pattern is formed is high. By scanning the mask substrate 101 in a state where the photodiode array 105 (sensor) can receive the transmitted light or the reflected light in the NA state, the pattern formed on the mask substrate 101 by using the photodiode array 105. The transmitted light image or the reflected light image is imaged. Specifically, it operates as follows.

FIG. 4 is a diagram showing an example of the configuration of the optical system in the high NA inspection mode in the first embodiment. In FIG. 4, a laser beam (for example, DUV light) having a wavelength below the ultraviolet region, which is the inspection light, is generated from the light source 103. The generated light is deflected through the polarizing plate 60, and when the transmitted light inspection is performed, the light for the transmission inspection illumination (one of the p wave and the s wave) is passed. Then, the light for transmission inspection illumination (one of the p wave and the s wave) is reflected by the deflection beam splitter 61. On the other hand, when the reflected light inspection is performed, the light for the reflection inspection illumination (the other of the p wave and the s wave) is passed. Then, the light for reflection inspection illumination (the other of the p wave and the s wave) passes through the deflection beam splitter 61. For example, by rotating the polarizing plate 60, the light that passes through can be restricted. This allows you to choose between transmitted light inspection and reflected light inspection.

When the transmitted light inspection is performed, the light for the transmitted inspection illumination (first inspection light) is illuminated on the mask substrate 101 by the transmitted illumination optical system 170. Hereinafter, a specific example will be described based on the example of FIG. In the transmission illumination optical system 170, the light for transmission inspection illumination branched by the deflection beam splitter 61 is reflected by the mirror 63, passes through the lenses 64, 65, 66, and is reflected by the mirror 67. Then, the light reflected by the mirror 67 is formed by the condenser lens 68 on the pattern forming surface of the mask substrate 101 from the back surface side opposite to the pattern forming surface of the mask substrate 101. The transmitted light transmitted through the mask substrate 101 enters the imaging optical system 178 via the objective lens 104 and the polarizing beam splitter 174. Then, the image is formed on the photodiode array 105 (an example of the sensor) by the imaging optical system 178, and is incident on the photodiode array 105 as an optical image. The light that has passed through the polarizing beam splitter 174 is imaged on the photodiode array 105 by the lens 72 through the lenses 69 and 70 and the aperture diaphragm 180 in the imaging optical system 178. As the photodiode array 105, for example, it is preferable to use a TDI (time delay integration) sensor or the like. The photodiode array 105 (sensor) captures an optical image of a pattern formed on the mask substrate 101 while the XYθ table 102 on which the mask substrate 101 is placed is moving.

On the other hand, when the reflected light inspection is performed, the light for the reflection inspection illumination (second inspection light) is illuminated on the mask substrate 101 by the reflection illumination optical system 172. The reflection illumination optical system 172 has an objective lens 104 and a polarization beam splitter 174 (polarization element), and the mask substrate 101 is illuminated with light for reflection inspection illumination by using the objective lens 104 and the polarization beam splitter 174, and the mask substrate is used. The reflected light from 101 is passed through. Hereinafter, a specific example will be described based on the example of FIG. In the reflection illumination optical system 172, the light for reflection inspection illumination that has passed through the deflection beam splitter 61 passes through the lenses 80, 81, 82, and 83 and is reflected by the polarization beam splitter 174. The light reflected by the polarizing beam splitter 174 is incident on the objective lens 104, and is imaged from the pattern forming surface side of the mask substrate 101 to the pattern forming surface of the mask substrate 101 by the objective lens 104. The reflected light reflected from the mask substrate 101 passes through the objective lens 104 and the polarizing beam splitter 174 and is incident on the imaging optical system 178. Then, the image is formed on the photodiode array 105 (an example of the sensor) by the imaging optical system 178, and is incident on the photodiode array 105 as an optical image. The photodiode array 105 (sensor) captures an optical image of a pattern formed on the mask substrate 101 while the XYθ table 102 on which the mask substrate 101 is placed is moving.

At that time, a part of the reflected light is branched by the mirror 73 arranged between the lenses 69 and 70, and the branched light is imaged on the AF sensor 76 by the AF optical system 173. The light receiving surface of the AF sensor 76 is arranged so as to have a confocal relationship with the light receiving surface of the photodiode array 105 with respect to the beam splitter 73. The output signal from the AF sensor 76 is transmitted to the AF control circuit 140. When the photodiode array 105 receives the reflected light in a state where the numerical aperture is high, the AF control circuit 140 measures the focal position of each position on the mask substrate 101 by using the reflected light. Then, the AF control circuit 140 dynamically forms the pattern of the mask substrate 101 by controlling the piezo element 142 and moving the objective lens 104 in the optical axis direction (Z-axis direction) in real time based on the signal. The focal position (optical axis direction: Z-axis direction) of the objective lens 104 is adjusted on the surface. Even when the transmitted light inspection is performed, a part of the reflected illumination is illuminated on the mask substrate 101 for AF by the reflected illumination optical system 172. Then, the reflected light corresponding to a part of the reflected illumination is reflected by the mirror 73 and imaged on the AF sensor 76. As a result, the focal position (optical axis direction: Z-axis direction) of the objective lens 104 can be dynamically adjusted on the pattern forming surface of the mask substrate 101 even in the inspection of only transmission.

The inspection device 100 can perform one or both of the transmitted light scan and the reflected light scan. The reflected light reflected from the mask substrate 101 includes pattern height information that is difficult to obtain with the transmitted light from the mask substrate 101. Therefore, the AF control circuit 140 performs AF control using the reflected light from the mask substrate 101 instead of the transmitted light from the mask substrate 101. When both the transmitted light scan and the reflected light scan are performed, it does not matter which one is performed first.

FIG. 5 is a conceptual diagram for explaining an inspection area according to the first embodiment. As shown in FIG. 5, the inspection area 10 (the entire inspection area) of the mask substrate 101 is virtually divided into a plurality of strip-shaped inspection stripes 20 having a scan width W, for example, in the y direction. Then, the inspection device 100 acquires an image (striped area image) for each inspection stripe 20. For each of the inspection stripes 20, a laser beam is used to capture an image of a graphic pattern arranged in the stripe region in the longitudinal direction (x direction) of the stripe region. In the XYθ table 102, the movement of the x-stage 74 causes the Zθ stage 70 to be moved in the x-direction, and as a result, the photodiode array 105 is relatively continuously moved in the x-direction to acquire an optical image. The photodiode array 105 continuously captures an optical image having a scan width W as shown in FIG. In other words, the photodiode array 105, which is an example of the sensor, captures an optical image of a pattern formed on the mask substrate 101 using inspection light while moving relative to the XYθ table 102. In the first embodiment, after the optical image of one inspection stripe 20 is captured, the optical image of the scan width W is similarly moved to the position of the next inspection stripe 20 in the y direction and this time in the opposite direction. Images are taken continuously. That is, the imaging is repeated in the forward (FWD) -back forward (BWD) directions in the opposite directions on the outward and return paths.

Here, the direction of imaging is not limited to the repetition of forward (FWD) -back forward (BWD). You may take an image from one direction. For example, FWD-FWD may be repeated. Alternatively, BWD-BWD may be repeated.

The image of the pattern formed on the photodiode array 105 is photoelectrically converted by each light receiving element of the photodiode array 105, and further A / D (analog-digital) converted by the sensor circuit 106. Then, the pixel data of the inspection stripe 20 to be measured is stored in the stripe pattern memory 123. When capturing such pixel data (striped region image), the dynamic range of the photodiode array 105 uses, for example, a dynamic range having a maximum gradation when the amount of illumination light is 60% incident. Further, when acquiring the optical image of the inspection stripe 20, the laser length measuring system 122 measures the position of the XYθ table 102. The measured position information is output to the position circuit 107. The position circuit 107 (calculation unit) calculates the position of the mask substrate 101 using the measured position information.

After that, the stripe region image is sent to the comparison circuit 108 together with the data indicating the position of the photomask 101 on the XYθ table 102 output from the position circuit 107. The measurement data (pixel data) is, for example, 8-bit unsigned data, and represents the gradation (light amount) of the brightness of each pixel. The stripe area image output in the comparison circuit 108 is stored in a storage device (not shown).

In the comparison circuit 108, stripes of a predetermined size (for example, the same width as the scan width W) in the x direction so as to cut out the frame image of the target frame area 30 from the stripe area image (optical image) of the inspection stripe 20. The area image is divided. For example, it is divided into a frame image of 512 × 512 pixels. In other words, the stripe area image for each inspection stripe 20 is divided into a plurality of frame images (optical images) with a width similar to the width of the inspection stripe 20, for example, a scan width W. By such processing, a plurality of frame images (optical images) corresponding to the plurality of frame regions 30 are acquired. As described above, for the plurality of frame images, one image (measured image) data to be compared for inspection is generated.

As an autofocus (AF) data creation step (S105), the AF control circuit 140 focuses on the height position of the mask substrate 101 surface used for AF control at the same time as scanning with the reflected light or transmitted light described above. The position information is stored in the magnetic disk device 109. Therefore, in the magnetic disk device 109 (storage device), the reflected light from the mask substrate 101 illuminated with the light through the reflected illumination optical system 172 in a state where the polarization beam splitter 174 (polarizing element) is moved on the optical path. The information on the focal position of each position on the mask substrate 101 measured using the above is stored.

When only scanning the transmitted light is performed in the high NA scanning step (S104) described above, the focal position information depending on the height position of the mask substrate 101 surface may be acquired in advance using the reflected light. .. When scanning the transmitted light in the high NA scanning step (S104) described above, AF control may be performed using the focal position information obtained at that time.

As the reference image creation step (S106), first, the development circuit 111 (an example of the reference image creation unit) develops an image based on the design pattern data that is the basis of the pattern formation of the mask substrate 101 to create a design image. Specifically, the design data is read from the magnetic disk device 109 through the control computer 110, and each graphic pattern in the area of the target frame 30 defined in the read design data is converted into binary or multi-valued image data ( Image development) to create a design image.

Here, the figure defined in the design pattern data is, for example, a basic figure of a rectangle or a triangle, for example, the coordinates (x, y) at the reference position of the figure, the length of the side, the rectangle, the triangle, or the like. Graphic data (vector data) that defines the shape, size, position, etc. of each pattern graphic is stored with information such as a graphic code that serves as an identifier for distinguishing graphic types.

When the information of the design pattern that becomes the graphic data is input to the expansion circuit 111, the data is expanded to the data for each graphic, and the graphic code, the graphic dimension, etc. indicating the graphic shape of the graphic data are interpreted. Then, binary or multi-valued design image data is developed and output as a pattern arranged in a grid having a grid of predetermined quantization dimensions as a unit. In other words, the design data is read, the inspection area is virtually divided into squares with a predetermined dimension as a unit, the occupancy rate of the figure in the design pattern is calculated for each square, and the n-bit occupancy rate data is obtained. Output. For example, it is preferable to set one square as one pixel. Then, when to have a resolution of 1/2 8 ^{(= 1/256)} to 1 pixel, the occupancy rate of the pixel allocated the small area region amount corresponding 1/256 of figures are arranged in a pixel Calculate. Then, a design image of 8-bit occupancy data is created for each pixel. The design image data is output to the reference circuit 112.

The reference circuit 112 (an example of the reference image creating unit) filters the design image to create the reference image.

FIG. 6 is a diagram for explaining the filtering process in the first embodiment. The measurement data as an optical image obtained from the sensor circuit 106 is in a state in which the filter acts due to the resolution characteristics of the objective lens 104, the aperture effect of the photodiode array 105, and the like, in other words, in an analog state in which the image changes continuously. By filtering the reference design image data whose intensity (shade value) is the image data on the design side of the digital value, it can be adjusted to the measurement data. In this way, a reference image to be compared with the frame image (optical image) is created. The created reference image is output to the comparison circuit 108, and the reference image output in the comparison circuit 108 is stored in a storage device (not shown). As a result, the other image (reference image) data to be compared for inspection is generated.

As the comparison step (S108), the comparison circuit 108 inspects the defect of the pattern by using the optical image of the transmitted light image or the reflected light image of the imaged pattern of the mask substrate 101. The comparison circuit 101 (comparison unit) compares the frame image (optical image) with the reference image for each pixel. Specifically, first, the frame image (optical image) to be compared and the reference image to be compared are aligned by a predetermined algorithm. For example, alignment is performed using the method of least squares. Then, the comparison circuit 108 compares the two for each pixel according to a predetermined determination condition, and determines the presence or absence of a defect such as a shape defect. As a determination condition, for example, the presence or absence of a defect is determined by comparing the two for each pixel according to a predetermined algorithm. For example, it is determined whether or not the difference between the pixel values of both images is larger than the determination threshold value, and if it is larger, it is determined to be a defect. Then, the comparison result is output. The comparison result may be output from the magnetic disk device 109, the magnetic tape device 115, the flexible disk device (FD) 116, the CRT 117, the pattern monitor 118, or the printer 119.

FIG. 7 is a block diagram showing an internal configuration of the low NA inspection circuit according to the first embodiment. In FIG. 7, storage devices 50, 52, 59 such as a magnetic disk device, an area identification unit 51, an alignment unit 56, and a comparison unit 58 are arranged in the low NA inspection circuit 146.

As the defect region identification step (S110), the region identification unit 51 inputs inspection result information (for example, coordinate information of the defect position) from the comparison circuit 108, and based on the inspection result information, the region (defect detection region 51) Hereinafter, the defect area) is specified. As the defect region, for example, the frame region 30 including the defect position can be mentioned. However, the region size is not limited to this, and various area sizes can be selected. The information of the identified defective region is stored in the storage device 59.

As the low NA inspection mode switching step (S112), the inspection mode switching control circuit 144 switches the setting of each configuration from the high NA inspection mode described above to the low NA inspection mode for performing low NA defect inspection. As a result, the photodiode array 105 can receive the same or substantially the same image as the pattern image formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 by the exposure apparatus. For that purpose, the following internal steps are carried out.

As the polarizing element retracting step (S114), the inspection mode switching control circuit 144 controls the drive mechanism 176 to move the polarizing beam splitter 174 from the optical path to the outside of the optical path. In this way, the drive mechanism 176 can move the polarizing element from outside the optical path to the outside of the optical path, and can move the polarizing element from the top of the optical path to the outside of the optical path. Further, since the reflected illumination light is not used due to the retracting of the polarization beam splitter 174, the inspection mode switching control circuit 144 passes the polarizing plate 60 so that only the light for transmission inspection illumination (one of the p wave and the s wave) passes through. Rotate.

As the NA squeezing step (S116), the inspection mode switching control circuit 144 switches the numerical aperture NA from the state of the high numerical aperture to the state of the low numerical aperture. Specifically, the numerical aperture NAo (numerical aperture on the object o side) of the objective lens 104 that can be incident when the transmitted light 190 is incident from the mask substrate 101 to the objective lens 104 has the same characteristics as the exposure device. Control. For example, the aperture value of the aperture stop 180 is controlled so that NAo = 0.3. In the first embodiment, since the numerical aperture is changed from the high numerical aperture to the low numerical aperture, the aperture of the aperture diaphragm 180 is narrowed down. In this way, the aperture diaphragm 180 allows the numerical aperture (NA) at which transmitted light can be incident from the mask substrate 101 to the objective lens 104 to be switched between a high numerical aperture state and a low numerical aperture state. Adjust the light beam diameter of the transmitted light and / and the reflected light. In the example of FIG. 4, the aperture diaphragm 180 is arranged between the lenses 70 and 72 in the imaging optical system 178, but is not limited to this. It suffices that the luminous flux of the light incident on the objective lens 104 or the light incident on the photodiode array 105 through the objective lens 104 can be narrowed down and the luminous flux diameter can be adjusted. Therefore, the aperture diaphragm 180 may be arranged between the mask substrate 101 and the photodiode array 105. More preferably, the aperture diaphragm 180 is arranged at the pupil position.

As the illumination shape changing step (S118), the control signal from the inspection mode switching control circuit 144 is received, and the illumination shape switching mechanism 171 uses the shape of the illumination light (inspection light) in the same manner as the illumination shape used in the exposure apparatus. Change to the lighting shape.

In the low NA scanning step (S120), the photodiode array 105 can receive light corresponding to the state where the numerical aperture is low, and the light is between the mask substrate 101 and the photodiode array 105. Transmitted light of a pattern formed on the mask substrate 101 using the photodiode array 105 by scanning the specified defect region of the mask substrate 101 with a predetermined illumination light in the absence of a polarizing element on the optical path. Take an image. Specifically, it operates as follows.

FIG. 8 is a diagram showing an example of the configuration of the optical system in the low NA inspection mode according to the first embodiment. In FIG. 8, the light generated from the light source 103 is deflected through the polarizing plate 60, and only the light for transmission inspection illumination (one of the p wave and the s wave) is passed. Then, the light for transmission inspection illumination (one of the p wave and the s wave) is reflected by the deflection beam splitter 61. The light for transmission inspection illumination (first inspection light) is illuminated on the mask substrate 101 by the transmission illumination optical system 170. At that time, the illumination shape switching mechanism 171 changes the configuration of the transmission illumination optical system 170 to change the illumination shape of the light for transmission inspection illumination (first inspection light). As described above, the transmission illumination optical system 170 is configured so that the illumination shape of the light for transmission inspection illumination (first inspection light) can be changed. In the example of FIG. 8, after the light for transmission inspection illumination reflected by the deflection beam splitter 61 reaches the lens 65, the illumination shape is changed between the lenses 65 and 66. The light for transmission inspection illumination whose illumination shape has been changed is reflected by the mirror 67. Then, the light reflected by the mirror 67 is formed by the condenser lens 68 on the pattern forming surface of the mask substrate 101 from the back surface side opposite to the pattern forming surface of the mask substrate 101. As a result, the mask substrate 101 can be irradiated with light having an illumination shape similar to that used in the exposure apparatus. The transmitted light transmitted through the mask substrate 101 enters the imaging optical system 178 via the objective lens 104. Then, the image is formed on the photodiode array 105 (an example of the sensor) by the imaging optical system 178, and is incident on the photodiode array 105 as an optical image. At that time, since the numerical aperture is limited by the aperture diaphragm 180, an optical image of low NA light is incident on the photodiode array 105. In the example of FIG. 8, the light that has passed through the objective lens 104 passes through the lenses 69 and 70 in the imaging optical system 178, passes through the aperture diaphragm 180, and is imaged on the photodiode array 105 by the lens 72. As described above, the photodiode array 105 receives the transmitted light from the mask substrate 101 illuminated with the light for transmission inspection illumination (first inspection light) while the XYθ table 102 is moving.

On the other hand, as shown in FIG. 8, since the light for the reflection inspection illumination is blocked by the polarizing plate 60, the light for the reflection inspection illumination does not enter the reflection illumination optical system 172. Even if the light for reflection inspection illumination is incident on the reflection illumination optical system 172, the polarization beam splitter 174 (polarizing element) is retracted from the optical path in the reflection illumination optical system 172, so that the light is reflected by the mask substrate 101. It does not illuminate the light for inspection lighting.

As described above, the photodiode array 105 can receive the same or substantially the same image as the pattern image formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 by the photodiode array 105.

The image of the pattern formed on the photodiode array 105 is photoelectrically converted by each light receiving element of the photodiode array 105, and further A / D (analog-digital) converted by the sensor circuit 106. Then, the pixel data of the defect area to be measured is stored in the stripe pattern memory 123. When capturing such pixel data (defect region image), the dynamic range of the photodiode array 105 uses, for example, a dynamic range whose maximum gradation is when the amount of illumination light is 60% incident. Further, when acquiring the optical image of the defect region, the laser length measuring system 122 measures the position of the XYθ table 102. The measured position information is output to the position circuit 107. The position circuit 107 (calculation unit) calculates the position of the mask substrate 101 using the measured position information.

After that, the defect region image is sent to the low NA inspection circuit 146 together with the data indicating the position of the photomask 101 on the XYθ table 102 output from the position circuit 107. The measurement data (defect area image: pixel data) is, for example, 8-bit unsigned data, and represents the gradation (light amount) of the brightness of each pixel. The defect region image output in the low NA inspection circuit 146 is stored in the storage device 52. As a result, one image (measured image) data to be compared for the low NA test is generated.

FIG. 9 is a diagram showing an example of a mechanism for changing the illumination shape according to the first embodiment. In FIG. 9, the illumination shape switching mechanism 171 moves the polarizing element 90 between the lenses 65 and 66. As a result, the configuration of the transmission illumination optical system 170 can be changed, and the transmission illumination optical system 170 can change the illumination shape. When the light for transmission inspection illumination passes through the polarizing element 90, the illumination shape of the light for transmission inspection illumination can be changed to deflection illumination in which the deflection direction is manipulated. By replacing the polarizing element 90 with a diffraction element, the illumination shape may be changed to N-pole illumination such as 2-pole illumination or 4-pole illumination, or ring-shaped illumination. In the example of FIG. 9, the polarizing element 90 is arranged between the lenses 65 and 66, but the present invention is not limited to this. It suffices if the light can be deflected before reaching the mask substrate 101. Therefore, the polarizing element 90 may be arranged on any of the optical paths from the deflection plate 60 to the condenser lens 68.

FIG. 10 is a diagram showing another example of the mechanism for changing the illumination shape in the first embodiment. In FIG. 10, the illumination shape switching mechanism 171 may be moved so as to arrange the diaphragm 91 between the light source 103 and the polarizing plate 60. As a result, the configuration of the transmission illumination optical system 170 can be changed, and the transmission illumination optical system 170 can change the illumination shape. By narrowing down the aperture 91, the illumination shape can be changed to small sigma illumination. In the example of FIG. 10, the diaphragm 91 is arranged between the light source 103 and the polarizing plate 60, but the present invention is not limited to this. The light may be squeezed before reaching the mask substrate 101. Therefore, the diaphragm 91 may be arranged on any of the optical paths from the polarizing plate 60 to the mask substrate 101.

FIG. 11 is a diagram showing another example of the mechanism for changing the illumination shape in the first embodiment. In FIG. 11, the illumination shape switching mechanism 171 may be moved so as to arrange the reduction optical system by the lenses 92 and 93 between the light source 103 and the polarizing plate 60. As a result, the configuration of the transmission illumination optical system 170 can be changed, and the transmission illumination optical system 170 can change the illumination shape. By reducing the light with such a reduction optical system, the illumination shape can be changed to illumination light having a different illumination magnification. In the example of FIG. 11, the reduction optical system by the lenses 92 and 93 is arranged between the light source 103 and the polarizing plate 60, but the present invention is not limited to this. It suffices if the light can be reduced before the light reaches the mask substrate 101. Therefore, the reduction optical system by the lenses 92 and 93 may be arranged on any of the optical paths from the polarizing plate 60 to the condenser lens 68.

The illumination shape switching mechanism 171 may be configured so that one, any two combinations, or all combinations of the mechanisms shown in FIGS. 9, 10 and 11 can be arranged. The necessary optical elements may be arranged according to the specifications of the exposure apparatus.

Here, in the low NA inspection mode, as described above, since the polarization beam splitter 174 is moved from the optical path to the outside of the optical path, the light passing through the reflection illumination optical system 172 is not illuminated on the mask substrate 101. Therefore, the reflected light from the mask substrate 101 cannot be obtained. Therefore, the reflected light from the mask substrate 101 cannot be used for AF control. Therefore, it is configured as follows.

As an AF control step (S122), in the AF control circuit 140 (a part of the focusing mechanism), the photodiode array 105 is low while the XYθ table 102 is moving while the polarization beam splitter 174 is moved out of the optical path. While receiving the transmitted light corresponding to the numerical aperture, the transmitted light is dynamically focused by using the focal position information stored in the magnetic disk device 109. Specifically, the AF control circuit 140 controls the piezo element 142 (a part of the focusing mechanism) based on the already measured focal position information stored in the magnetic disk device 109, and the objective lens 104. By moving the lens in the optical axis direction (Z-axis direction) in real time, the focal position of the objective lens 104 (optical axis direction: Z-axis) is dynamically moved to the pattern forming surface of the mask substrate 101 to follow the progress of the XYθ table 102. Orientation) is adjusted.

As a simulation image input step (S124), the control computer 110 obtains a simulation image corresponding to the pattern image formed on the semiconductor substrate 304 when the pattern is exposed and transferred to the semiconductor substrate 304 by the exposure apparatus from the outside of the inspection apparatus 100. Input and store in the magnetic disk device 109. The simulation image may be created for each frame area 30, for example. Further, it is preferable to input a simulation image for the entire surface of the inspection area 10 of the mask substrate 101 in advance and store it in the magnetic disk device 109. Then, the control computer 110 reads out the simulation image corresponding to the region identified as defective from the magnetic disk device 109 and transmits it to the low NA inspection circuit 146. The low NA inspection circuit 146 inputs a simulation image corresponding to the region identified as defective and stores it in the storage device 50.

As a comparison step (S126), the low numerical aperture inspection circuit 146 uses a simulation image assuming that the pattern formed on the mask substrate 101 is transferred to the semiconductor substrate by using an exposure apparatus, and the numerical aperture is low. The transmitted light image of the pattern of the defect region identified as having a defect acquired as a result of receiving the light in the state of is received by the photodiode array 105 is compared with the simulated image. Specifically, the alignment unit 56 reads out a frame image (transmitted light image of the pattern of the defect region: optical image) to be compared from the storage device 52. Further, the alignment unit 56 reads out a simulation image to be compared from the storage device 50. Then, the alignment unit 56 aligns the frame image to be compared (transmitted light image of the pattern of the defect region: optical image) and the simulation image to be compared by a predetermined algorithm. For example, alignment is performed using the method of least squares. Then, the comparison unit 58 compares the two according to a predetermined determination condition. For example, by comparing the transmitted light image of the pattern of the defect region with the simulation image, it is confirmed whether or not there is at least one of a circuit disconnection and a circuit short circuit in the defect region. Then, the comparison result is output. The comparison result may be output from the magnetic disk device 109, the magnetic tape device 115, the flexible disk device (FD) 116, the CRT 117, the pattern monitor 118, or the printer 119.

As described above, according to the first embodiment, in the inspection device 100 for inspecting minute defects of the mask substrate 101, the image when the pattern of the mask substrate 101 is exposed and transferred onto the semiconductor substrate or the like by the exposure apparatus is inspected. it can. Even if it is determined to be defective by the high NA inspection, it can be determined that the mask substrate 101 can be used if the disconnection of the circuit or the short circuit of the circuit in the defective region cannot be detected. Therefore, unnecessary defect correction can be eliminated. As a result, for example, the time required for manufacturing a semiconductor product can be shortened.

In the above description, what is described as "-circuit", "-part", or "-process" can be configured by a program that can be operated by a computer. Alternatively, it may be implemented not only by a program that becomes software but also by a combination of hardware and software. Alternatively, it may be combined with firmware. When composed of a program, the program is recorded on a recording medium such as a magnetic disk device, a magnetic tape device, an FD, or a ROM (read-only memory). For example, each circuit in the position circuit 107, the comparison circuit 108, the expansion circuit 111, the reference circuit 112, the autoloader control circuit 113, the table control circuit 114, the AF control circuit 140, the inspection mode switching control circuit 144, and the low NA inspection circuit 146. Etc. may be configured by an electric circuit, or may be realized as software that can be processed by a control computer 110 or a computer arranged in each circuit. It may also be realized by a combination of an electric circuit and software. Similarly, the functions of the area identification unit 51, the alignment unit 56, the comparison unit 58, and the like may be composed of an electric circuit, or may be processed by the control computer 110 or a computer arranged in each circuit. It may be realized as software that can be used. It may also be realized by a combination of an electric circuit and software.

The embodiment has been described above with reference to a specific example. However, the present invention is not limited to these specific examples.

In addition, although the description of parts that are not directly necessary for the description of the present invention, such as the device configuration and control method, is omitted, the required device configuration and control method can be appropriately selected and used. For example, the description of the control unit configuration for controlling the inspection device 100 has been omitted, but it goes without saying that the required control unit configuration is appropriately selected and used.

In addition, all pattern inspection devices and pattern inspection methods that include the elements of the present invention and can be appropriately redesigned by those skilled in the art are included in the scope of the present invention.

10 Inspection area 20 Inspection stripe 30 Frame area 50, 52, 59 Storage device 51 Area identification part 56 Alignment part 58 Comparison part 60 Polarizing plate 61 Deflection beam splitter 63 Mirror 64, 65, 66 Lens 67, 73 Mirror 68 Condenser lens 69 , 70, 72, 80, 81, 82, 83 Lens 90 Polarizing element 91 Aperture 92, 93 Lens 100 Inspection device 101 Mask substrate 102 XYθ Table 103 Light source 104 Objective lens 105 Photo diode array 106 Sensor circuit 107 Position circuit 108 Comparison circuit 109 Magnetic disk device 110 Control computer 111 Deployment circuit 112 Reference circuit 113 Autoloader control circuit 114 Table control circuit 115 Magnetic tape device 116 FD
117 CRT
118 Pattern monitor 119 Printer 120 Bus 122 Laser length measurement system 123 Stripe pattern memory 140 AF control circuit 142 Piezo element 144 Inspection mode switching control circuit 146 Low NA inspection circuit 150 Optical image acquisition unit 160 Control system circuit 170 Transmission illumination Optical system 171 Illumination Shape switching mechanism 172 Reflective illumination optical system 174 Deflection beam splitter 176 Drive mechanism 178 Imaging optical system 180 Aperture aperture 190 Transmitted light 192 Light 300 Mask substrate 301 Transmitted light 302 Objective lens 304 Semiconductor substrate 305 Light

Claims (1)

A movable stage on which the mask substrate on which the pattern is formed is placed,
A transmission illumination optical system capable of changing the illumination shape of the first inspection light, which illuminates the mask substrate with the first inspection light,
A reflection illumination optical system having an objective lens and a polarization beam splitter, illuminating the mask substrate with a second inspection light using the objective lens and the polarization beam splitter, and passing the reflected light from the mask substrate. When,
A sensor that receives transmitted light from the mask substrate illuminated by the first inspection light or reflected light from the mask substrate illuminated by the second inspection light while the stage is moving.
An imaging optical system that receives the transmitted light through the objective lens and forms an image of the received transmitted light on the sensor.
It is arranged between the mask substrate and the sensor, and the numerical aperture (NA) at which the transmitted light can be incident from the mask substrate to the objective lens is switched between a high numerical aperture state and a low numerical aperture state. An aperture diaphragm that adjusts the numerical aperture of the transmitted light so that it becomes possible,
When switching the numerical aperture to the low numerical aperture state, the polarization beam splitter is moved from the optical path of the transmitted light from the mask substrate between the mask substrate and the sensor to the outside of the optical path. When the numerical aperture is switched to the high numerical aperture state, the polarization beam splitter is moved from outside the optical path onto the optical path of the transmitted light and the reflected light from the mask substrate between the mask substrate and the sensor. Drive mechanism to make
With
When the number of openings is switched to the state of the low numerical aperture, the transmission illumination optical system changes the illumination shape of the first inspection light to an illumination shape similar to the illumination shape used in the exposure apparatus, and the openings. When the number is switched to the state of the high numerical aperture, the illumination shape of the first inspection light is changed to the illumination shape for inspection.
When the numerical aperture is switched to the low numerical aperture state, the sensor is in a state where the polarizing beam splitter is not on the optical path of the transmitted light from the mask substrate between the mask substrate and the sensor. When the transmitted light is received and the numerical aperture is switched to the high numerical aperture state, the polarizing beam splitter is used to obtain the transmitted light and the reflected light from the mask substrate between the mask substrate and the sensor. A pattern inspection device characterized in that it receives the transmitted light or the reflected light while being on the road.

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