JP2000188077A - Scanning electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To observe defects other than a sample matrix on a scanning transmission image or impurities at high contrast by two-dimensionally scanning a fine probe formed with a convergent lens and an objective lens by accelerating an electron beam with an electrostatic lens, and masking specified electron beams with a moving diaphragm installed on a detector for detecting the intensity of scattered electron beams. SOLUTION: Electron beams are reduced through first to third step lenses 2a-2c for accelerating to a predetermined voltage, first and second convergent lenses 3a, 3b, and an objective front magnetic field lens 4, and a probe on a sample 5 changes an aperture angle with a convergent diaphragm 6. An electron beam diffraction pattern formed after transmitting the sample 5 changes magnification with first and second step projection lenses 8a, 8b, projects to an electron beam detector 9, and is modulated in brightness. First and second step detector diaphragms 12a, 12b in the lower part of the second step projection lens 8b move in about four steps, have many kinds of mask patterns such as an electron beam diffraction pattern or round holes, mask a substrate crystal relating part, and enhance contrast in other part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope capable of imaging a deviation from the crystal orientation of a sample matrix using the symmetry of the intensity distribution of an electron diffraction pattern.

[0002]

2. Description of the Related Art A conventional method for detecting foreign matter in a sample matrix using a scanning electron microscope image is described in, for example, Applied Physics A, Vol. 57 (1993).
Year), pages 385 to 391 or JP-A-52-
16160.

In this method, a scanning transmission image is observed using an electron beam scattered at a high angle, and the electron beam scattered at a high angle has a contrast depending on the type of an atom. The foreign object is detected from the difference in contrast between the image and the foreign object. Analysis of a crystal structure using a conventional scanning electron microscope image shows that when a scanning transmission image is observed using an electron beam scattered at a high angle, an image corresponding to the crystal structure on a one-to-one basis is obtained. Using, 20
It is performed by directly observing the atomic arrangement at a high magnification of 10,000 times or more.

In the detection of a foreign substance in a sample matrix using the above-mentioned conventional scanning electron microscope image, a scanning transmission image is observed, and the presence or absence of a foreign substance is determined from the image contrast. However, even when electron beams scattered at high angles are used, the intensity of the diffracted electron beam from the sample matrix is dominant in the intensity distribution of the electron diffraction pattern, and detection is almost impossible when the amount of foreign matter is minute. It is. In addition, the intensity of the electron beam scattered at a high angle is extremely small, and even if the amount of the foreign matter is not very small, the intensity of the scattered electron beam from the foreign matter is extremely small at a high angle, so that the S / N of the image is poor. , Difficult to detect.

In the above-described conventional crystal structure analysis method using a scanning electron microscope image, since the atomic arrangement is directly observed at a high magnification, a high stability of the apparatus is required, and the electron beam is converted to the atomic arrangement. It is necessary to converge to a small probe smaller than the interval. Such high-precision analysis takes a long time to stabilize the apparatus, so it is inefficient and requires a probe to be formed under precise optical conditions, requiring a high degree of expertise. In the obtained high-magnification image, the observable sample region is at most 50 nm square, and it is impossible to analyze the crystal structure in a wide range of the order of μm.

[0006]

In the conventional scanning transmission electron microscopy, the electron beam that contributes to the contrast of an image is mainly a diffraction electron beam from a sample matrix, and a small amount of foreign matter contained in the sample matrix is detected as a contrast. Difficult to do. In the method of obtaining a scanning transmission image using the electron beam scattered at a high angle, the contrast of the foreign matter can be improved. However, since the number of the electron beam scattered at a high angle is small, the S / N of the image is low. The bad and effective detection sensitivity is not much different from the case using low-angle scattered electrons.

In the conventional crystal structure analysis method using a scanning transmission electron microscope, an atomic arrangement can be directly observed at a high magnification.
In order to set the apparatus conditions and optical conditions for observing an image at a high magnification, very high knowledge and skill were required. Further, since the atomic arrangement can be observed only at a high magnification, the area of the sample that can be analyzed at one time is considerably small.

An object of the present invention is to observe a scanning transmission image with a scanning electron microscope and cut off a diffraction electron beam from a sample matrix in an electron diffraction pattern when detecting a foreign substance.
By selectively detecting the diffracted electron beam from the foreign matter on the low angle side and at a high S / N, the contrast of the foreign matter in the scanning transmission image is improved, and the specific diffracted electron beam is selectively detected. Scanning that enables high-contrast observation of parts and particles having the crystal orientation that you want to observe by detecting the difference in the crystal orientation of the sample matrix from the crystal orientation using the symmetry of the electron diffraction pattern. An object of the present invention is to provide an electron microscope device.

[0009]

To achieve the above object, the present invention provides an electrostatic lens having at least one stage for increasing the energy of an electron beam generated from an electron source, and a sub-nanometer micro probe. One or more stages of a converging lens and an objective lens for forming, a sample holder for holding a sample in the objective lens, and one or more stages of a deflection coil for two-dimensionally scanning the probe on the sample surface; An electron microscope equipped with a detector for detecting the intensity of the electron beam scattered by the sample in synchronization with the scanning of the deflection coil and modulating the intensity of the electron beam to a luminance to obtain a scanning transmission image; At least one mask stop is installed on top of the detector, and these are used to mask a specific diffracted electron beam in an electron diffraction pattern, and a high-level control of foreign objects in a scanning transmission image, such as a substrate, for observation. To be observed in the strike.

Further, specific diffracted electrons are selectively detected by the mask aperture, so that, for example, only particles having a specific crystal orientation in a polycrystalline material can be observed. In addition, the electron beam detector is divided into two parts, the left and right intensity distributions of the electron beam diffraction pattern are detected independently, and these are divided to detect, for example, a deviation from the crystal orientation of the sample matrix in a specific portion as a contrast. I do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for obtaining a scanning transmission image by reducing information of a sample matrix by using a scanning electron microscope and efficiently extracting information other than the sample matrix contained in the sample will be described.

FIG. 1 shows the configuration of a scanning electron microscope. The electron beam generated from the electron beam source 1 is changed from 2a to 2c.
Are accelerated to a predetermined acceleration voltage by the multi-stage electrostatic lenses described above. By setting the acceleration voltage per stage to about 30 kV and changing the voltage applied to the lens of each stage, the final acceleration voltage of the electron beam can be changed. The electron beam accelerated to a predetermined acceleration voltage is reduced by the first-stage converging lens 3a and the second-stage converging lens 3b.

The reduction ratio of the electron beam can be arbitrarily changed by changing the combination of the current excitation of the first-stage convergent lens 3a and the second-stage convergent lens 3b.
Further, the electron beam is reduced by the pre-magnetic field objective lens 4 set to strong excitation, and a probe having a sub-nanometer diameter is finally formed on the sample 5. The opening angle of the probe is changed by the converging stop 6 provided below the second-stage converging lens 3b, and the balance between diffraction aberration and spherical aberration exerted on the probe diameter can be adjusted.

The electron beam transmitted through the sample 5 forms an electron beam diffraction pattern below the sample 5. By changing the current excitation of the first-stage projection lens 8a and the second-stage projection lens 8b installed below the rear magnetic field objective lens 7, the magnification of the electron diffraction pattern is arbitrarily changed and the electron beam detector 9 is controlled. Can be projected. The electron beam detector 9 comprises a disc-shaped scintillator for converting the intensity of the electron beam into light intensity, and a photomultiplier tube for amplifying the intensity of the light and converting it to a current signal. The scintillator and the photomultiplier tube A quartz light guide is installed in between, and a preamplifier 18 is installed after the photomultiplier tube.

[0015] The first lens provided below the second stage projection lens 8b.
The second-stage detector alignment coil 10a and the second-stage detector alignment coil 10b are used for aligning the electron diffraction pattern with the electron beam detector 9. An imaging device 11 is provided below the electron beam detector 9, and a CCD camera or the like that can observe an electron beam diffraction pattern in real time is used. When this imaging device 11 is used, the electron beam detector 9 is removed from the optical axis by a pneumatic drive type driving mechanism installed in the electron beam detector 9. A first-stage detector aperture 12a and a second-stage detector aperture 12b are provided below the second-stage projection lens 8b. These are diaphragms that can be moved in about four steps, and have various types of mask patterns, such as electron diffraction pattern patterns and round holes, and can cope with various changes in the crystal structure and incident direction of the sample matrix. It has become.

The scanning transmission image is obtained by two-dimensionally scanning the probe on the sample 5 by the deflection coil 13 and synchronizing the scanning with the signal from the electron beam detector 9 to modulate the intensity of the signal to the image intensity. At this time, the image intensity is recorded as a digital image file based on the output of the A / D converter 14. Control of all lenses, coils, and detectors in a series of operations is C
The PU 15 performs the operation via the D / A converter 16, and the operator sets conditions through the interface 17.

Next, a method of using an optical system for forming a scanning transmission image and a detector aperture will be described. FIG. 2 shows how the electron beam transmitted through the sample 5 is imaged on the image plane 22 by the post-objective magnetic lens 7. Here, the traveling direction of the transmitted electron beam 19 traveling in parallel to the incident direction of the probe and the diffracted electron beam 20 traveling in a direction different from that is changed by the post-objective magnetic field lens 7. Back focal plane 21
In this case, electron beams traveling in the same direction after passing through the sample converge at one point. That is, on this focal plane 21, an electron beam diffraction pattern in which the electron beam is dispersed depending on the angle diffracted by the sample is formed.

The electron beam that has passed through the back focal plane 21 forms an image plane 22 corresponding to the sample 5 on an one-to-one basis. The image formed on the image plane 22 along with the parallel scanning of the probe moves in parallel in synchronization with the scanning of the probe, and moves to the rear focal plane 21.
Does not move. Therefore, in order to extract information depending on the probe position when observing the scanning transmission image, the focus of the first-stage projection lens 8a is adjusted to the back focal plane 21 and the electron beam formed on the rear focal plane 21 is focused. The diffraction pattern is imaged on the electron beam detector 9. Furthermore, the second stage projection lens 8
By using b to enlarge or reduce the image plane 50 of the first-stage projection lens 8a and projecting it on the electron beam detector 9, the detection angle range of the scanning transmission image can be changed.

The first-stage detector aperture 12a is provided below the second-stage projection lens 8b and functions to mask a specific diffracted electron beam. Since the diffracted electron beam 51 masked by the first-stage detector aperture 12a does not reach the electron beam detector 9 and the unmasked diffracted electron beam 52 reaches, the diffracted electron beam not masked in the obtained scanning transmission image. The information of only the line 52 is selectively reflected.

Next, the characteristics of the electron beam diffraction pattern formed when the electron beam probe is incident on the sample will be described. When an electron beam is incident on the sample in parallel using a transmission electron microscope to form an electron diffraction pattern, a two-dimensional projection of the Fourier-transformed crystal structure viewed from the electron beam incident direction is performed. Observed figure is observed. This figure is a figure in which small spots are regularly arranged.

On the other hand, when the electron beam is converged as shown in FIG.
A figure in which the discs are regularly arranged on the back focal plane 21 with the transmitted electron beam at the center is obtained. What is a spot in the parallel irradiation but becomes a disk in the case of the focused electron beam probe 23 is related to the opening angle 24 of the electron beam probe 23. The aperture angle 24 is the angle between the optical axis and the outer shape of the electron beam virtually converged when the electron beam is converged by the electromagnetic lens. It is adjusted to balance with aberration. When a convergent electron beam is used as described above, the electron beam diffraction pattern has a disk shape, and therefore, it is necessary to prepare a mask pattern of the detector aperture in which the disks are arranged.

Next, a method of determining the mask pattern of the detector aperture will be described. When an electron beam is incident parallel to a certain zone axis of the crystal sample, a figure in which diffraction disks are arranged rotationally symmetrically around the disk corresponding to the transmitted electron beam is formed on the back focal plane.

FIG. 4 shows a crystal having a diamond type structure.
FIG. 4 is a schematic diagram showing an electron beam diffraction pattern formed when electron beam probes having the same opening angle are incident on two different crystal orientations. The rotational symmetry and the distance between the disks are different in each electron beam incident direction. For this reason, it is not possible to cope with one type of aperture mask pattern, so it is necessary to switch and use about four steps of movable apertures or to use a plurality of detector apertures to cope with them. However, the number of mask patterns is not necessarily required depending on the type of the sample. The reason for this is that, for example, in the case of substances having the same crystal structure, the pattern of the electron diffraction pattern is the same, and only the distance between the disks is different. This is because only the length of the crystal unit cell is different.

In this case, the magnification of the electron diffraction pattern may be changed by the second-stage projection lens so that the actual diffraction pattern matches the mask pattern. Also, for example,
The pattern of the electron diffraction pattern in the case of [001] incidence of the face-centered cubic lattice structure and the [0] of the diamond structure shown in FIG.
[01] Since the pattern of the electron beam diffraction pattern at the time of incidence is the same, it is sufficient to adjust only the shift of the disk interval due to the length of the crystal unit cell in the same manner as described above.

Next, the effect of observing the scanning transmission image while masking the electron diffraction pattern will be described. FIG. 5 shows an angle distribution in a direction having a high electron diffraction pattern intensity when a small amount of impurities is present in the crystalline substrate. Here, it is assumed that the crystal structure of the substrate is a diamond structure and the incident direction of the electron beam is [001]. Since the amount of impurities is very small and the electron beam is incident on the zonal axis of the crystalline substrate, the electron diffraction pattern shows the transmission electron beam (000).
And strong diffraction from substrate crystal (220), (440)
Are dominant, and the diffracted electron beam from the impurity is buried in the diffracted electron beam from the substrate as shown in the figure.

Here, by observing the scanning transmission image while masking a portion of the electron beam diffraction pattern relating to the substrate crystal, the contrast of impurities other than the substrate is improved and detection becomes easy. This method is not applicable when the diffraction electron beam from the substrate crystal and the impurity from the impurity overlap, for example, when the lattice constant is the same and the diffraction pattern in the specific electron beam incident direction is the same. It is possible to search for applicable conditions by changing the electron beam incident direction.

Next, the structure of the detector aperture will be described. FIG. 6 is an external view of a detector aperture provided with a pattern for a diffraction pattern mask. The mask pattern is processed on a detector aperture plate 26 made of a metal plate such as molybdenum having a thickness of about 0.3 to 0.1 mm, and an electron beam removing plate 28 for removing transmitted and diffracted electron beams. Is bridge 29
Is fixed on the detector aperture plate 26. The detector diaphragm plate 26 is a thin film, and is fixed to the detector diaphragm base plate 25 by screws 27 to increase the strength as a diaphragm. The detector aperture shown in FIG. 6 is an example of a pattern for masking an electron beam diffraction pattern. About four types of different patterns are arranged, and can be changed manually or by air drive.

FIG. 7 is an example of another mask pattern for the detector aperture. 6, the detector aperture plate 26 is fixed to the detector aperture base plate 25 by screws 27. The detector aperture plate 26 has a round hole 30.
And the slit 31 are processed. The circular hole 30 is a mask pattern for the purpose of allowing only a specific diffracted electron beam to pass therethrough and selectively extracting a portion of the sample that is diffracted in that direction. This is a mask pattern for selectively extracting a direction.

The effect of using the round hole 30 is as follows. If the position of the diffracted electron beam from the portion to be observed on the back focal plane is known, the round hole 30 is adjusted to that position. The contrast of a target portion can be improved. For example, by aligning the round hole 30 with the position of the (111) diffraction electron beam, (11)
1) Only particles having a crystal orientation can be observed. The observation of the specific crystal orientation is also possible using the slit 31.
In this case, for example, both (200) and (−200) diffracted electron beams can be selected simultaneously, so that the image contrast is improved. Next, a method for aligning the electron beam diffraction pattern with the detector aperture and the electron beam detector will be described.

FIG. 8 shows a state in which the electron beam passing through the sample 5 is enlarged by the second stage projection lens 8b and projected on the electron beam detector 9. First, the electron beam detector 9 is removed from the optical axis, and an electron beam diffraction pattern is observed by the imaging device 11. While observing the electron beam diffraction pattern, the first-stage detector aperture 12a is inserted into the optical axis, and the fine adjustment knob is used to align the electron beam diffraction pattern with the mask pattern of the first-stage detector aperture 12a. Next, the electron beam detector 9 is inserted into the optical axis to display a scanning transmission image.

When a low-magnification scanning transmission image is displayed, the scanning transmission image is displayed at the position of the mask pattern. Therefore, the first stage detector alignment coil 10a and the second stage detector alignment coil 10b are used to display the scanning transmission image. Is adjusted so that the scanning transmission image displayed in the image coincides with the center of the image display screen. Thus, the center of the electron beam diffraction pattern coincides with the center of the electron beam detector 9. The first-stage detector alignment coil 10a and the second-stage detector alignment coil 10b are set so that the deflection ratio is set back to 1: 1 so that the electron beam diffraction pattern is parallel on the electron beam detector 9. It is designed to move.

Next, a description will be given of a method of acquiring a scanning transmission image using the electron beam detector divided into two right and left sides and efficiently extracting information on the crystal orientation of the sample. FIG. 9 is a top view (a) and a side view (b) showing the structure of a detector divided into two right and left parts. The detector has a hole at the center for passing an electron beam, a light shielding plate 36 for isolating the left and right detectors is arranged, and components are assembled symmetrically on the left and right sides. The left and right detectors are scintillator 32, light guide 3
3. It comprises a photomultiplier tube 34 and a preamplifier 35.

The signals from the preamplifier 35 are independently collected on the left and right sides and processed by the division circuit 37. The divided signal is supplied to the photomultiplier tube high voltage adjustment and DC voltage addition circuit 3
8 and displayed as a scanning transmission image by the image display device 39.

The user adjusts the photomultiplier tube high voltage adjustment and the DC voltage addition circuit 38 while observing the scanning transmission image displayed on the image display device 39 to adjust the contrast of the observation image.

Next, the advantage of obtaining a scanning transmission image by using the electron beam detector divided into two right and left parts will be described. FIG.
Numeral 0 schematically represents an electron diffraction pattern formed on the electron beam detector 9. When the incident direction of the electron beam coincides with the crystal orientation of the substrate, the left and right diffraction intensities become the same with respect to the transmitted electron beam of (000). On the other hand, when the incident direction of the electron beam does not coincide with the crystal orientation of the substrate, the left and right diffraction intensities are different. Here, if the right and left diffraction intensities are independently detected and divided, the contrast becomes 1 when the crystal orientations match, and 1 or more when they do not match (however, the side with the higher intensity is smaller). Divided by the side). If this is used, information on the deviation from a specific crystal orientation can be imaged.

Next, a method of matching the electron diffraction pattern to the right and left detectors will be described. First, the electron beam detector 9 is removed from the optical axis as in the method described with reference to FIG. Alternatively, in the case of the left-right split type, the current excitation of the second projection lens 8b is adjusted so that the electron beam diffraction pattern passes through the central round hole. In this state, the desired crystal orientation of the electron beam diffraction pattern is adjusted using the imaging device 11. Next, a raster rotation signal is added to the deflection coil to rotate the scanning area on the sample surface. Since the electron beam diffraction pattern is rotated with this operation, the electron beam diffraction pattern is adjusted so that the electron beam diffraction pattern is symmetrical with respect to the electron beam detector 9. Finally, the electron beam detector 9 is returned to the optical axis, the scanning transmission image is observed, and the electron diffraction pattern is aligned with the center of the detector. By adjusting in this manner, information on the deviation from a specific crystal orientation can be imaged as a scanning transmission image.

Next, a description will be given of a method of detecting an electron diffraction pattern using a pattern mask or a left and right division using a multi-channel detector. FIG. 11 is a schematic diagram of the multi-channel type detector 40, and is an example of use in a case where detection is performed in two right and left divisions. Each square in the figure is one channel, and the left and right sides are set to be independently inputted to the division circuit without detecting the center. Similarly, in order to perform a pattern mask of a diffraction pattern, setting is performed so as to detect a specific channel.

FIG. 12 is a diagram showing a method of attaching a mirror and a vacuum flange to which a detector aperture and a detector are attached. Vacuum flange 6 for first and second stage detectors
It is arranged so as to be inserted into the optical axis from the side of 2, and is arranged above the electron beam detector 9. The vacuum flange 62 is vacuum-sealed and disposed on a lower magnetic path portion of the projection lens magnetic path 60 below the projection lens coil 61.

The first-stage detector-aperture drive mechanism 63a is on the atmosphere side via a vacuum seal and drives the detector aperture by external control. First stage detector aperture drive rod 64a
Is for transmitting drive control from the first-stage detector-aperture drive mechanism 63a to the detector-aperture, and a first-stage-detector-aperture base plate 65a is attached to the tip thereof, and the first-stage-detector-aperture is mounted thereon. The plate 66a is fixed with screws.

The first-stage detector aperture drive rod 64a, the first-stage detector aperture base plate 65a and the first-stage detector aperture plate 66a are integrated into a first-stage detector aperture drive mechanism 63a.
The translational movement to the optical axis is performed by the drive control from. This translation is adjusted so that it can be driven stepwise in about four steps, and a plurality of mask patterns formed on the first-stage detector aperture plate 66 can be selected stepwise.

The second-stage detector aperture is a second-stage detector aperture drive mechanism 63b, a second-stage detector aperture drive rod 64b, a second-stage detector aperture base plate 65b, and a second-stage detector aperture plate 66.
The translation drive mechanism and the like are the same as those of the first-stage detector diaphragm, and are vacuum-sealed below the first-stage detector diaphragm and fixed to the vacuum flange 62. A mask pattern different from that of the first-stage detector aperture plate 66a is formed on the second-stage detector aperture plate 66b, so that the second-stage detector aperture can be used alone, as well as the first-stage detector aperture. Various applications are possible by using the combination of the second stage and the second stage detector diaphragm.

FIG. 13 is a view showing a method of mounting the detector and the detector aperture on the vacuum flange and a fine movement mechanism of the detector aperture. The electron beam detector has a preamplifier 3 on the atmosphere side.
5 is provided with a scintillator 32 and a light guide 33 on the vacuum side, and a photomultiplier tube 34 provided by a hermetic vacuum seal. Above it, a detector aperture is arranged. The detector aperture is finely controlled from outside the vacuum through a detector aperture fine movement rod 71 vacuum-sealed by a bellows 70. A detector diaphragm base plate 25 and a detector diaphragm plate 26 are provided at the tip of the detector diaphragm fine movement rod 71.

A detector aperture horizontal fine adjustment knob 72, a detector aperture translation fine adjustment knob 73, and a detector aperture vertical fine adjustment knob 74 are provided on the atmosphere side of the detector aperture.
Can be adjusted to the optical axis. The detector aperture translation fine adjustment knob 73 has a gear 75 and a rotation translation conversion gear 76 installed therein, and converts the rotational movement of the translation fine adjustment knob 73 into translational motion to drive the detector aperture fine adjustment rod 71. ing. Detector aperture translation fine adjustment knob 7
3. The detector aperture vertical fine-adjustment knob 74 is installed in such a manner that the knob is pressed directly against the detector aperture fine-adjustment rod 71.
Move 1 slightly. The detector throttle fine movement rod 71 is always tensioned by the detector throttle fine movement rod retainer 77 having a built-in spring, and the thrust from the detector throttle translation fine movement knob 73 and the detector throttle vertical fine movement knob 74 is controlled. The balance is maintained, and the rod 71 for fine movement of the detector aperture is kept stable.

[0044]

According to the present invention, a detector aperture is provided at the upper stage of an electron beam detector, and the aperture is used to mask a diffracted electron beam from the sample matrix. Defects and impurities can be observed with high contrast. In addition, the use of a round hole or a slit-shaped mask pattern can improve the contrast of particles oriented in a specific crystal orientation. By using left and right detectors and dividing the left and right signals, a shift in crystal orientation from the sample matrix can be imaged as a difference in contrast in a scanning transmission image.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a configuration of a scanning electron microscope apparatus according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing formation of an image plane and a back focal plane by an objective lens.

FIG. 3 is a perspective view showing an electron diffraction pattern formed using an electron beam probe.

FIG. 4 is an explanatory diagram showing a difference in an electron beam diffraction pattern depending on an electron beam incident direction of a crystal having a diamond structure.

FIG. 5 (a) is an intensity distribution diagram of an electron diffraction pattern of a sample containing impurities in a substrate. (B) The enlarged view in the frame of (a).

FIG. 6 is a top view showing a first example of a detector aperture structure.

FIG. 7 is a top view showing a second example of the detector aperture structure.

FIG. 8 is a longitudinal sectional view showing a method for aligning an electron beam diffraction pattern and an electron beam detector by a detector alignment coil.

9A and 9B are a top view and a side view illustrating a configuration of a left-right split electron beam detector.

FIG. 10 is an explanatory diagram showing a difference in intensity distribution of an electron beam diffraction pattern depending on a crystal orientation.

FIG. 11 is a top view showing a method of detecting electron beam intensity by dividing into left and right parts by using a multi-channel electron beam detector.

FIGS. 12A and 12B are a side view and a top view showing a method of attaching a vacuum flange to which a detector aperture is attached and a magnetic body magnetic path.

FIG. 13 is a perspective view showing a method of attaching a detector and a detector aperture to a vacuum flange and a fine movement mechanism of the detector aperture.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron beam source, 2a ... 1st stage electrostatic lens, 2b ... 2nd stage electrostatic lens, 2c ... 3rd stage electrostatic lens, 3a ... 1st stage convergent lens, 3b ... 2nd stage convergent lens, 4 ... Magnetic field lens before objective, 5 ... Sample, 6 ... Convergent aperture, 7 ... Magnetic field lens after objective, 8a ... First stage projection lens, 8b ... Second stage projection lens, 9 ... Electron beam detector, 10a ... First stage Detector alignment coil, 10b: second-stage detector alignment coil, 11: imaging device, 12a: first-stage detector aperture, 12
b: second stage detector aperture, 13: deflection coil, 14: A /
D converter, 15 CPU, 16 D / A converter, 17 interface, 18 preamplifier, 19
... Transmission electron beam, 20 ... Diffraction electron beam, 21 ... Back focal plane, 2
2: image plane, 23: electron beam probe, 24: opening angle, 25
... Detector diaphragm base plate, 26 ... Detector diaphragm plate, 27 ... Screw, 28 ... Electron beam removal plate, 29 ... Bridge, 30 ... Round hole, 31 ... Slit, 32 ... Scintillator, 33 ... Light guide, 34 ... Photomultiplier tube, 35 ... preamplifier, 3
Reference Signs List 6 light-shielding plate, 37 division circuit, 38 photomultiplier tube high voltage adjustment and DC voltage addition circuit, 39 image display device, 40 multi-channel electron beam detector, 50 1
Image plane of the stage projection lens, 51: masked diffraction electron beam, 60: magnetic path of the projection lens, 61: coil of the projection lens,
62: Vacuum flange, 63a: First stage detector aperture drive mechanism, 63b: Second stage aperture drive mechanism, 64a: First stage aperture drive rod, 64b: Second stage aperture drive rod, 65a ... First-stage detector aperture base plate, 65b
… Second stage diaphragm base plate, 66a… first stage diaphragm plate, 66b… second stage diaphragm plate, 70… bellows,
71: Detector aperture fine-adjustment rod, 72: Detector aperture horizontal fine-adjustment knob, 73: Detector aperture translation fine-adjustment knob, 74 ...
Detector aperture vertical fine adjustment knob, 75: gear, 76: gear for rotational / translation conversion, 77: rod holder for fine movement of the detector aperture.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mikio Ichihashi 882 Ma, Hitachinaka-shi, Ibaraki Pref.Measurement Division, Hitachi, Ltd. Within the Measuring Instruments Division of Manufacturing Works (72) Inventor Yuji Sato 882 Ma, Hitachinaka-shi, Ibaraki Pref. F-term in Hitachi Measuring Instruments Division (reference) 5C033 BB01 EE05 EE06 NN03 NP03 SS03 SS04 SS07

Claims (8)

[Claims] An electron beam generated from an electron source is accelerated to a predetermined voltage by one or more electrostatic lenses, and a fine electron beam probe is formed by one or more converging lenses and an objective lens. The probe is two-dimensionally scanned on the sample surface by the deflection coil, the intensity of the electron beam scattered by the sample is detected in synchronization with the scanning of the deflection coil, and the electron beam intensity is modulated into luminance to scan and transmit. 1. A scanning electron microscope, wherein an electron microscope for obtaining an image, which masks a specific electron beam among the electron beams detected by a movable aperture provided on a detector and extracts information other than a sample matrix. 2. A method according to claim 1, wherein the movable stop provided on the detector has a plurality of patterns corresponding to an electron beam diffraction pattern depending on an electron beam incident direction. Scanning electron microscope. 3. A scanning electron microscope according to claim 1, wherein said scanning transmission microscope has a plurality of movable stops provided on said detector. 4. The multi-stage diaphragm according to claim 3, further comprising one or more electromagnetic lenses for changing the magnification of the diffraction pattern so that the diffraction spot coincides with the mask position. Scanning electron microscope. 5. The method according to claim 1, further comprising the step of: moving the electron beam diffraction pattern two-dimensionally so that the center of the electron beam diffraction pattern coincides with the center of the electron beam detector.
A scanning electron microscope comprising a deflection coil having at least two stages. 6. A scanning electron microscope according to claim 1, wherein a multi-channel detector is used as the electron beam detector in acquiring the scanning transmission image. 7. The method according to claim 1, wherein the intensities of the left and right halves of the electron beam diffraction pattern projected on the detector are independently detected based on the center of the electron beam diffraction pattern, and the crystalline sample matrix is obtained. A scanning electron microscope characterized in that a shift in crystal orientation between the two is detected as image contrast. 8. A scanning electron microscope according to claim 1, wherein a computer having an operating system of a graphical user interface is used for controlling the electron microscope and analyzing an image.