JP2000057984A - Scanning electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning electron microscope capable of reducing labor for searching an analysis point. SOLUTION: This scanning electron microscope 100 has an electron gun 10 for emitting an electron beam 11, a scanning means 40 for making the electron beam 11 scan on a sample 30, a signal detecting means 60 for detecting electrons emitted from a scanning point at the time of scanning of the electron beam 11 on the sample 30, a first signal processing means 70 for generating an image signal S70 based on an output signal S60 of the signal detecting means 60, a picture image display device 80 for displaying a sample image based on the image signal S70, and a coordinate setting means 50 for setting a coordinate value of an analysis point on the sample 30. The scanning means 40 makes the electron beam 11 move from the starting point fixed beforehand to the analysis point set by the coordinate setting means 50 and scan the analysis point. The electron beam 11 may be made to scan on an imaging surface 30A of a solid imaging element by supposing the sample 30 as the solid imaging element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for analyzing a sample such as a semiconductor device or a solid-state imaging device by irradiating the sample with an electron beam.
The present invention relates to a scanning electron microscope used for analysis and the like.

[0002]

2. Description of the Related Art The invention relating to a scanning electron microscope is disclosed in Japanese Patent Application Laid-Open Nos. 53-43469 and 56-41663. Japanese Patent Application Laid-Open No. 56-41663 discloses that a sample is obtained by irradiating a charged particle beam onto a sample through the lens while controlling the intensity of a focusing lens of a scanning electron microscope in a stepwise manner. Detecting the video signal, differentiating the video signal by a differentiating mechanism, detecting the right focus position based on the differential signal from the differentiating mechanism, and performing focusing on the sample, first with a predetermined step width. A first focus position search is performed by changing the intensity of the focusing lens. Based on the focus position search information, a first focus position search is performed from a start position closer to a right focus position than a start position of the first focus position search. The second focus position search is performed by changing the intensity of the focusing lens with a step width smaller than the step width, and the same operation is sequentially performed until the required number of times. It is disclosed that detects a positive focal point position by repeating.

In a scanning electron microscope, a sample (analyte) having a size of about 5 μm square or less is mounted on a chip having a size of about 0.3 to 1 cm square, and a sample image is sometimes enlarged and displayed on an image display device. Alternatively, an analysis section of about 5 μm square or less on a chip of about 0.3 to 1 cm square may be enlarged, and the sample image may be enlarged and displayed on an image display device. The operator searches for the analysis object or the analysis section by manually operating various control units of the scanning electron microscope while looking at the display screen of the image display device. FIG. 4 is an explanatory diagram illustrating a scanning method of a conventional scanning electron microscope. When the analyte 5 is attached to the sample 130, and the electron beam is moved to the position of the analyte 5, the electron beam is moved from the left end to the right end or from the right end to the left end starting from the starting point set on the sample 130. And scan it. Reference numeral 2 is a range projected on the image display device.

[0004]

In this scanning electron microscope, while the operator monitors the display screen of the image display device and repeats the scanning from one end to the other until the analyte is displayed on the display screen, the scanning electron microscope is used. Searching takes time and effort. Further, the magnification of the scanning electron microscope is 500 to 100.
It may be about 0 times, and it takes time to search for the analysis object or the analysis section at this magnification. As an example,
It may take about 20 minutes to find one analyte. An object of the present invention is to provide a scanning electron microscope capable of reducing the trouble of searching for an analysis point corresponding to an analysis object or an analysis section.

[0005]

A scanning electron microscope according to the present invention comprises an electron gun for emitting an electron beam, scanning means for scanning the electron beam on a sample, and a scanning means for scanning the electron beam on the sample. Signal detecting means for detecting electrons emitted from the scanning point, first signal processing means for generating a video signal based on an output signal of the signal detecting means, and displaying a sample image based on the video signal An image display device, and coordinate setting means for setting a coordinate value of an analysis point on the sample, wherein the scanning means is configured to scan the electronic data from a predetermined starting point to the analysis point set by the coordinate setting means. By moving the line, the analysis location is scanned.

In the scanning electron microscope of the present invention, preferably,
The coordinate setting means sets a coordinate value of the analysis location by a coordinate value of rectangular coordinates, and sets an origin of the rectangular coordinates as the starting point. In the scanning electron microscope of the present invention, more preferably,
The sample is a solid-state imaging device, and the imaging surface of the solid-state imaging device is scanned.The vertical axis of the rectangular coordinates is parallel to the vertical scanning direction of the solid-state imaging device, and the horizontal axis of the rectangular coordinates is the solid state. It is parallel to the horizontal scanning direction of the image sensor.

In the scanning electron microscope of the present invention, preferably,
The coordinate setting means allocates a plurality of blocks arranged in a matrix on the sample, and sets a coordinate value of the analysis location by a position of the block. In the scanning electron microscope of the present invention, more preferably, the sample is a solid-state imaging device, and an imaging surface of the solid-state imaging device is scanned, and a vertical direction of the plurality of blocks arranged in a matrix is the solid-state imaging device. The horizontal direction of the plurality of blocks arranged in a matrix is parallel to the horizontal scanning direction of the solid-state imaging device.

[0008] The electron gun emits an electron beam. The scanning means scans the sample with the electron beam. The signal detecting means detects electrons emitted from a scanning point when the electron beam scans the sample. The signal processing means generates a video signal based on the output signal of the signal detection means. The image display device displays a sample image based on the video signal. The coordinate setting means sets a coordinate value of an analysis point on the sample. The scanning unit moves the electron beam from a predetermined starting point to the analysis location set by the coordinate setting unit and scans the analysis location. Electrons emitted from a scanning point when the electron beam scans the analysis location on the sample are detected by the signal detection means. The signal processing unit generates a video signal corresponding to a sample image of an analysis location based on an output signal of the signal detection unit, and the image display device displays a sample image of the analysis location based on the video signal. .

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic block diagram of an example of a scanning electron microscope according to the present invention.

The scanning electron microscope 100 has an electron beam 11
An electron gun 10 for emitting light, scanning means 40 for scanning the electron beam 11 on the sample 30, and signal detection for detecting electrons emitted from a scanning point when the electron beam 11 scans on the sample 30. Means 60 for generating a video signal S70 based on an output signal S60 of the signal detecting means 60;
A signal processing means 70, an image display device 80 such as a cathode ray tube (CRT) for displaying a sample image based on the video signal S70, and a coordinate setting means 50 for setting a coordinate value of an analysis point on the sample 30. Having. The scanning unit 40 moves the electron beam 11 from a predetermined starting point to the analysis location set by the coordinate setting unit 50 and scans the analysis location. The sample 30 is, for example, a solid-state imaging device having photoelectric conversion elements arranged in a matrix corresponding to pixels on an imaging surface 30A. The position of the analysis location is, for example, a location of a pixel corresponding to an abnormal location of the video signal S30 obtained from the solid-state imaging device 30 in which light is applied to the imaging surface 30A.

The scanning electron microscope 100 includes an electron gun 1
A deflection coil 20 for generating a magnetic field for controlling the direction of the electron beam 11 from zero; and a video signal S30 obtained from the solid-state imaging device 30 in which light is uniformly applied to the imaging surface 30A.
Signal processing means 9 for generating pixel data based on
0, determine whether the value of the pixel data is within a normal range corresponding to the light, and detect the position of the pixel when the value of the pixel data is an abnormal value outside the normal range. And a position detecting means 95 for outputting to the coordinate setting means 50. The coordinate setting means 50 stores the coordinate value of the position of the pixel in the internal memory of the coordinate setting means 50 as the coordinate value of the analysis location. Also, the scanning electron microscope 100
A central processing unit (CPU), a ROM, and a RAM (not shown) are provided for performing various processes and calculations.

In the self-scanning solid-state imaging device 30, a video signal S30 is previously extracted from an output terminal of the solid-state imaging device 30 by uniformly irradiating an imaging surface 30A with visible light.
The video signal S30 is input to the second signal processing means 90. The second signal processing unit 90 generates pixel data S90 based on the video signal S30 and outputs the pixel data S90 to the position detection unit 95. Data indicating a normal range corresponding to the visible light is stored in the position detecting means 95 in advance, and it is determined whether or not each of the pixel data S90 is a value in the normal range. If the pixel data S90 is an abnormal value outside the normal range, the position of the pixel corresponding to the pixel data S90 is calculated by calculation, and the coordinate data of the position is output to the coordinate setting means 50 to obtain the coordinates of the analysis location. Store as data.

Next, the solid-state imaging device 30 is set on an irradiation table to which the electron beam 11 is irradiated. The imaging surface 30 </ b> A of the solid-state imaging device 30 is arranged on the irradiation side of the electron beam 11. The scanning unit 40 supplies a current to the deflecting coil 20 based on the coordinate data of the analysis location stored in the coordinate setting unit 50 to generate a line of magnetic force, and moves the scanning point by the electron beam 11 from the starting point to the analysis location. The scanning means 40 supplies a current to the deflecting coil 20 to generate magnetic force lines so that the electron beam 11 scans on the imaging surface 30A. The scanning unit 40 scans an analysis location of the solid-state imaging device 30.

The signal detection means 60 detects electrons emitted from a scanning point when the electron beam 11 scans on the imaging surface 30A, and outputs an output signal S60 indicating the detection result to the first signal processing means 70. . The first signal processing means 70 generates a video signal S70 containing a horizontal synchronization signal and a vertical synchronization signal based on the output signal S60 of the signal detection means 60,
The video signal S70 is output to the image display device 80. The scanning of the electron beam 11 may be synchronized with the horizontal scanning and the vertical scanning of the image display device 80.

FIGS. 2 and 3 are explanatory views illustrating the scanning method of the scanning electron microscope of the present invention. Reference numeral 2 indicates a range displayed on the image display device 80. Scanning electron microscope 1
In the case of 00, since the analysis point which is the position of the analysis object 5 is known in advance and stored in the coordinate setting means 50, the scanning point by the electron beam 11 is moved from the starting point which is the initial setting position to the position of the analysis object 5. It can be moved linearly. As described above, by moving the scanning point from the starting point to the analysis location by the coordinate setting unit 50 and the scanning unit 40, the trouble of searching for the analysis object 5 can be reduced, and the search time for searching for the analysis object 5 can be shortened. be able to.

The coordinate setting means 50 sets the coordinate value of the analysis location by the coordinate value of rectangular coordinates. The Y axis, which is the vertical axis of the rectangular coordinates, is parallel to the vertical scanning direction V of the solid-state imaging device 30, and the X axis, which is the horizontal axis of the rectangular coordinates, is parallel to the horizontal scanning direction H of the solid-state imaging device 30. The origin O of the orthogonal coordinates is the starting point. On the imaging surface 30A, photoelectric conversion elements are arranged in a matrix corresponding to the pixels, and it is easy to associate with the rectangular coordinates. The imaging surface 30A is
When the solid-state imaging device 30 is used for imaging, an optical image of a subject is irradiated and formed. The origin O of the orthogonal coordinates may be set at one corner of the imaging surface 30A so that the coordinate values of the analysis point have the X coordinate value and the Y coordinate value of 0 or more. The solid-state imaging device 30 is formed as a chip. On the imaging surface 30A in FIG. 2, the coordinate values of the analysis location, which is the position of the analysis object 5, are X = 1.5 mm and Y = 1.2 mm.

In the explanatory diagram of FIG. 3, an analysis point which is the position of the object 5 is indicated by the position of the block. The coordinate setting means 50 allocates a plurality of blocks arranged in a matrix on the solid-state imaging device 30, and sets the coordinate value of the analysis location based on the position of the block. The vertical direction of the plurality of blocks arranged in a matrix is parallel to the vertical scanning direction V of the solid-state imaging device 30, and the horizontal direction of the plurality of blocks arranged in the matrix is the horizontal scanning direction H of the solid-state imaging device 30. Parallel. The unit block has a dimension (length) in the X-axis direction of 1 mm and a dimension (length) in the Y-axis direction of 2 mm, which is input to the internal memory of the coordinate setting unit 50 and stored. The starting point is that the coordinate value is X =
0, Y = 0. On the imaging surface 30A in FIG. 3, the analysis object 5 is attached to a block whose coordinate value of the analysis position is X = 9 and Y = 4. By moving the scanning point by the electron beam 11 to the corresponding block of the analysis location by the coordinate setting unit 50 and the scanning unit 40, the trouble of searching for the analysis object 5 can be reduced, and the search time for searching for the analysis object 5 can be shortened. can do. The unit length of the Y axis, which is the vertical axis, is equal to the pitch of the pixel in the vertical scanning direction V, and the unit length of the X axis, which is the horizontal axis, is equal to the pitch of the pixel in the horizontal scanning direction H. There is an advantage that the analysis location can be represented by using the position. By making the size of the plurality of blocks equal to the size of the pixel, there is an advantage that the analysis location can be represented using the position of the pixel.

The scanning electron microscope 100 includes a coordinate setting means 5
With 0, an address search function can be provided, so that the analysis capability can be improved and the absolute number of objects to be analyzed can be increased. In addition, analysis time can be reduced,
Analysis efficiency can be improved. In addition, the number of analysis steps can be reduced by improving the analysis efficiency and the analysis capability.

The first signal processing means 70 and the second signal processing means 90 may be provided integrally. As the image display device 90, a liquid crystal display device may be used. The deflection coil 20 may be configured as a part of the scanning unit 40. Switch means for setting the unit lengths of the vertical axis and the horizontal axis of the orthogonal coordinates may be provided, and each unit length may be arbitrarily set and variable. In this case, the output signal of the switch means is output to the coordinate setting means 50.
Output to The coordinate value of the analysis location may be based on the metric system or may be based on the yard or pound system. Switch means for setting the vertical and horizontal dimensions of the plurality of blocks may be provided so that each dimension can be arbitrarily set and variable. In this case, the output signal of the switch means is output to the coordinate setting means 50. The irradiation table (stage) may be movable, and the solid-state imaging device 30 may be fixed at a predetermined position on the irradiation table, and then the visible light may be irradiated on the imaging surface 30A to obtain the video signal S30. In addition,
The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment.

[0020]

According to the scanning electron microscope of the present invention, the scanning point by the electron beam can be moved from the starting point to the analysis point by the coordinate setting means and the scanning means. Accordingly, it is possible to provide a scanning electron microscope that can reduce the trouble of searching for an analysis point and can reduce the search time for searching for an analysis point.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram illustrating an example of a scanning electron microscope of the present invention.

FIG. 2 is an explanatory view illustrating a scanning method of the scanning electron microscope of the present invention.

FIG. 3 is an explanatory view illustrating a scanning method of the scanning electron microscope of the present invention.

FIG. 4 is an explanatory view illustrating a scanning method of a conventional scanning electron microscope.

[Explanation of symbols]

2 ... A range displayed on the image display device 80 (display range), 5 ... Analyte, 10 ... Electron gun, 11 ... Electron beam, 20
... Deflection coil, 30 ... Solid-state imaging device (sample), 30A ...
Imaging surface, 40: scanning means, 50: coordinate setting means, 60:
Signal detecting means, 70: first signal processing means, 80: image display device, 90: second signal processing means, 95: position detecting means, 100: scanning electron microscope, 130: sample.

Claims (8)

[Claims] An electron gun for emitting an electron beam, scanning means for scanning the electron beam on a sample, and a signal for detecting electrons emitted from a scanning point when the electron beam scans the sample. Detecting means; signal processing means for generating a video signal based on an output signal of the signal detecting means; an image display device for displaying a sample image based on the video signal; and a coordinate value of an analysis point on the sample. A scanning electron microscope, comprising: coordinate setting means for setting, wherein the scanning means moves the electron beam from a predetermined starting point to the analysis location set by the coordinate setting means and scans the analysis location. 2. The scanning electron microscope according to claim 1, wherein said coordinate setting means sets a coordinate value of said analysis point by a coordinate value of rectangular coordinates, and sets an origin of said rectangular coordinates as said starting point. 3. The solid-state imaging device, wherein the sample is scanned over an imaging surface of the solid-state imaging device; a vertical axis of the orthogonal coordinates is parallel to a vertical scanning direction of the solid-state imaging device; 3. The scanning electron microscope according to claim 2, wherein a horizontal axis is parallel to a horizontal scanning direction of the solid-state imaging device. 4. The scanning electron microscope according to claim 2, further comprising switch means for setting unit lengths of the vertical axis and the horizontal axis of said rectangular coordinates. 5. The scanning electron microscope according to claim 1, wherein said coordinate setting means allocates a plurality of blocks arranged in a matrix on said sample, and sets the coordinate value of said analysis point by the position of said block. 6. The solid-state imaging device, wherein the sample is scanned over an imaging surface of the solid-state imaging device, and a vertical direction of the plurality of blocks arranged in a matrix is parallel to a vertical scanning direction of the solid-state imaging device. The scanning electron microscope according to claim 5, wherein a horizontal direction of the plurality of blocks arranged in a matrix is parallel to a horizontal scanning direction of the solid-state imaging device. 7. The scanning electron microscope according to claim 6, wherein each of the plurality of blocks has a size equal to a size of a pixel on the imaging surface. 8. The scanning electron microscope according to claim 5, further comprising switch means for setting the length and width of said plurality of blocks.