JPS63118643A - Scanning electron microscope or similar device for attaining crystal azimuth distribution image - Google Patents

Abstract

PURPOSE:To check plural azimuth distribution images of crystal particles in a short period by making an electron beam incident on each picture element point on a sample surface while switching the angle of incidence and moving the sample surface to obtain a detection signal and comparing it with a reference value. CONSTITUTION:An electron beam 1 is deflected by coils 2 and 3 to obtain an electron beam 1', and this electron beam is projected to a sample 4. The angle formed between the electron beam 1' and the X direction is defined as an azimuth angle phi, and that between the electron beam 1 and the sample surface 4 is defined as an inclination angle theta. Three kinds of desired specific crystal azimuth (phia, thetaa, phib, thetab, phic, thetac) are set, and the electron beam 1' is projected to each picture element on the sample surface 4 while auccessively switched to these crystal azimuthal angles. The sample surface 4 is moved in X and Y directions and is scanned. The reflected electron beam from the sample surface 4 is detected by a detector 5, and the detection value is compared with the reference value to display distribution images of crystal particles having one azimuth and another on a CRT 14. Since the angle of incidence of the electric beam is automatically switched and the sample is moved two-dimensionally, distribution images of crystal particles are detected in a wide range with a high precision at a short period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a scanning electron microscope or similar apparatus that uses a scanning electron microscope or the like to obtain a distribution image of crystal orientation in a sample.

[Prior Art] The distribution of crystal grains having a plurality of orientations in a sample is determined and displayed using a scanning electron microscope, an X-ray microanalyzer, or the like. For example, JP-A-61-25
In the conventional apparatus described in 'O43, the incident angle of the electron beam on the sample is set to an angle that causes channeling between the electron beam and a specific crystal plane in the crystal, and the electron beam is two-dimensionally incident on the sample surface. The detection signal obtained by this scanning is stored in the first screen information storage area of the image storage device, and then the incident angle of the electron beam is adjusted to match other specific crystal planes in the crystal and the electron beam. The electron beam is scanned two-dimensionally by setting an angle that causes channeling, and the detection signal obtained by this scanning is stored in the second screen storage area of the image storage device, and the images of the first and second screens are stored. By superimposing and developing information on a single screen, the distribution of crystal grains having a plurality of specific crystal orientations can be displayed in a differentiated manner based on differences in color tone, etc.

[Problems to be Solved by the Invention] However, in the conventional apparatus described above, the sample surface is scanned by electron beam scanning, so when trying to obtain a crystal orientation distribution image over a wide area, the deflection of the electron beam The aberration becomes large, and the angle of incidence of the electron beam on the sample cannot be maintained at a predetermined value with high precision. Therefore, in the conventional apparatus, it is not possible to accurately obtain a crystal orientation distribution image over a wide area.

In order to solve this problem, after setting the incident angle of the electron beam on the sample to the first angle as described above and mechanically moving the sample in two dimensions, the incident angle of the electron beam on the sample It is also possible to set the angle to a second angle and mechanically move the sample two-dimensionally again, but since mechanically moving the sample takes time, the distribution image of crystal grains with multiple types of orientations may be considered. cannot be displayed in a short period of time.

The present invention solves these conventional problems and provides a scanning electron microscope or similar device for obtaining a crystal orientation distribution image that can accurately display the distribution of crystal grains having multiple orientations over a wide area in a short period of time. is intended to provide.

[Means for Solving the Problems 1] Therefore, the present invention provides a scanning electron microscope or similar device that irradiates a sample with an electron beam and displays an image based on the detection of a signal obtained by the interaction between the electron beam and the sample. ° in the apparatus, each pixel point (X) on the sample surface.

y) means for automatically switching the incident angle of the electron beam to make the electron beam incident at a plurality of set angles, a means for moving the sample two-dimensionally, and a means for moving the sample two-dimensionally; A means for discriminating and acquiring the value of a detection signal obtained when an electron beam is incident on a sample at an incident angle and comparing each with a plurality of preset reference values; A two-dimensional distribution of crystal grains having one of a plurality of orientations based on an information signal indicating whether or not a detected signal and a reference value match, and the other of the orientations. The present invention is characterized by comprising means for displaying a two-dimensional distribution of crystal grains having .

[Example] Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention, in which 1 indicates an electron beam focused by a focusing lens system not shown;
2 is the first stage deflection coil, 3 is the second stage deflection coil, 4
is a sample, 5 is a backscattered electron detector, 6 is a deflection signal generation circuit,
7X and 7Y are motors for moving the sample 4 in the X and Y directions; 8 is a drive circuit that sends signals to drive the motors 7X and 7Y; 9 is an amplifier; 10 is an AD converter; 11 is a pass line; 12 is a CPU, 13 is a storage device, 14 is a color CRT, and 15 is an operator console.

In the above-mentioned configuration, now consider a plane containing the electron beam 1' deflected by the coil 2.3 and the optical axis C, and the angle formed by the line created by the intersection of this plane and the sample with the X direction is defined as the direction angle φ.
, when the angle formed by the sample surface and the incident electron beam is expressed as the inclination angle θ, select, for example, three specific crystal orientations whose distribution is to be determined, and apply the electron beam to each of the three crystal orientations. The direction angle φ and the inclination angle θ necessary for causing channeling are input using the input device 15. The selection of this specific crystal surrounding is achieved by sequentially fixedly irradiating three appropriate points on the sample with an electron beam, scanning the incident angle of the electron beam on the sample, and applying three types of channeling acids to the CRT. display,
This is done by indicating the extreme point of this channeling acid with a light pen or cursor and transmitting this instruction to CI U12. Each angle input with this light ben etc. (
φa, θa), (φb, θb), (φC0θ, c)
Then, upon receiving such an instruction, the CPU 12 adjusts the deflection coil 2°3 necessary to realize the three types of angles.
The amount of deflection is calculated, and the signal value corresponding to this amount of deflection is set as CP.
It is held in the internal storage device of U12. In addition, the backscattered electron detection signal values obtained when the electron beam channels the crystals in the three types of orientations are obtained in advance by sampling the luminance signal values at each of the pole points using a light vane, and these values are calculated in advance. Reference values La, Lb, L corresponding to each of the values of
c is input using the input device 15. CPU 12 also maintains these values in internal storage.

Therefore, when the input device 15 is used to command the start of measurement, C
The PU 12 controls the drive circuit 8 to move the sample 4 so that the upper left corner of the sample 4 is placed on the optical axis C. CPU1
First, the deflection signal held in the internal storage device is sequentially sent to the deflection signal generation circuit 6 so that the electron beam is sequentially incident on the first pixel point (xi, yl) at the three angles mentioned above. As a result, the electron beam has a direction angle φ and an inclination angle θ sequentially (φa, θa), (φb, θb), (φC2θC
), it is deflected by the coils 2 and 3 and enters the pixel point (xl, yl). As a result, anti! Detection signal 1a from 8 electron detector 5 for three types of incident angles
11, I bll and I C11 are obtained. After these detection signals are converted into digital signals, they are temporarily stored in the storage device 13. CPU12 detects signal value 1
a11, I bll, and I C11 are read out and compared with reference values La, Lb, and LC, respectively. That is, it is determined whether the difference between Iall and 1-a is within a predetermined tolerance range, and if it is within the range, the storage device 13 determines that this pixel is a pixel in which a crystal having the first type orientation exists. The image information is stored in the first image information storage area within the image information storage area. 1b11, Ic11
A similar comparative judgment is also made for .

After the CPU 12 completes the signal collection at the first pixel point and the comparison and determination work described above, it sends a control signal to the drive circuit 8 to move the sample 4 by one pixel, and moves the sample 4 by one pixel, and moves the sample 4 by one pixel to move the sample 4 to the next point (x2,
The electron beam is also sequentially incident on yl) at three different angles. The detection signal 1a21゜I b21 , I obtained at that time
c21 is compared with la, lb, and lc to make a determination, and the determination results are stored in the first .c21 of the storage device 13. Second. Third
Image information storage #A is stored at the memory address corresponding to the pirate pixel (X2, yl). In this way, the CPU 12 makes the electron beam incident on each pixel (Xi, yj) at three different angles, and generates the detection signals Iaij,
Ib1j and Ic1j are compared with La, lb, and lc, respectively, and irradiation of each point in a predetermined two-dimensional area on the sample 4 with the electron beam is completed. As a result, in the first image information storage area of the storage device 13, 1'' is stored in pixels that are crystals in the first type of orientation, and II O11 is stored in pixels that are not crystals in the first type of orientation. Similarly, pixels in which crystals of the second type and third type orientation exist are similarly stored as 111 IT in the second and third image information storage areas.
The input device 15 allows the first. Second. When instructed to display pixels in which crystals of type 3 orientation are present in red, yellow, and green, the CPU 12 reads out the image signal stored in the storage device 13 and uses this read information. Based on this, pixels in which crystals exist in each direction are displayed on the CRT 14 in different colors. As a result, a crystal grain distribution image as shown in FIG. 2, for example, is displayed on the CRT 14. In Figure 2, the diagonal line is the area where the crystals of the first orientation are distributed, which is shown in red, the area where the crystals with the second orientation are present, which is shown in yellow, is the area where the diagonal line is shown with the dotted line. represents a region where crystals of the third type of orientation exist, which are displayed in green. In this way, by mechanically moving the sample 4 only once two-dimensionally, the distribution of crystal grains in a plurality of specific orientations can be displayed with high precision in a short time.

The embodiment described above is only one embodiment of the present invention, and modifications can be made.

For example, in the embodiment described above, the first. 2nd, 3rd
The sample was mechanically moved one pixel each time the electron beam was incident on the sample at an angle of 1. Second. The sample may be moved mechanically to move to the next area after two-dimensionally scanning the thumbtack in this area by deflecting the electron beam with the electron beam set at the third angle. .

Also, 1st. Second. The generation of the deflection signal according to the third angle of incidence may be performed as follows. That is, the polar point displayed on the CRT screen is indicated with a light ben or a cursor, and based on this instruction, the deflection signal value corresponding to the indicated point is held in the sample and hold circuit, and this held signal value is Latch after converting to digital signal,
A deflection signal may be generated by cyclically extracting a plurality of signals latched in this manner.

Also, each time each point is irradiated with an electron beam, Ia and Ib.

lc and l-a, l-b, lc are compared, but the values of Ia, Ib, and Ic at each scanning point are stored in the image information storage area, and these image information for one screen are stored. After the information is acquired, a comparison and determination process may be performed.

Further, in the above-described embodiment, the electron beam is incident on each pixel point at three different angles, but two or more angles may be used.

Further, in the above-described embodiment, a reflected electron detection signal is used as a detection signal, but a crystal orientation distribution image can also be displayed based on an absorbed electron detection signal or the like.

Furthermore, in the above-described embodiment, the distribution of crystal grains having different orientations is displayed in a differentiated manner on a single screen, but it is possible to display the distribution of crystal grains in each orientation on a different screen. You can also do it.

[Effect of the invention] As is clear from the above explanation, the present invention has the following effects:
The incident angle of the electron beam is automatically switched to each pixel point (x, y) on the sample surface, and the electron beam is made incident at a plurality of set angles, and the sample is moved two-dimensionally, The value of the detection signal obtained when the electron beam is incident on the sample at the plurality of incident angles is discriminated and obtained and compared with a plurality of preset reference values, and the comparison means calculates the value obtained for each pixel point. According to the present invention, the distribution of crystal grains having a specific orientation is displayed by reddening the information signal indicating whether the detector No. 1 and the reference value match or not. It is only necessary to perform two-dimensional and original movement once for the entire display area, and a highly accurate crystal grain distribution image over a wide area can be obtained in a short time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of display of crystal orientation distribution by RT. 1: Electron beam 2.3: 0iii direction coil 4: Sample 5: Backscattered electron detector 6: Deflection signal generation circuit 7X, 7Y: Motor 7

Claims (1)

[Claims] In a scanning electron microscope or similar device that irradiates a sample with an electron beam and displays an image based on the detection of a signal obtained by the interaction between the electron beam and the sample, each pixel point (x, y) on the sample surface is means for automatically switching the incident angle of the electron beam and making the electron beam incident at a plurality of set angles, and means for moving the sample two-dimensionally;
means for discriminating and acquiring the values of detection signals obtained when the electron beam is incident on the sample at the plurality of incident angles and comparing them with a plurality of preset reference values; A two-dimensional distribution of crystal grains having one of a plurality of orientations based on an information signal indicating whether or not a detection signal obtained for a reference value matches a reference value; A scanning electron microscope or similar device for obtaining a crystal orientation distribution image, comprising means for displaying a two-dimensional distribution of crystal grains having the other orientation.