JPH0375548A - Crystal-defect inspecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect the image of the X-ray diffraction of a crystal highly accurately by providing an X-ray source, slits, an X-ray camera, a sampling part, a motor, a computing means and a monitor. CONSTITUTION:An X-ray source 10 projects X rays on a sample. The X rays are reduced into a parallel beam having the minute width through slits 12 and 14. An X-ray camera 30 receives the X rays which have passed through a sample 16 and outputs the electric signal comprising a plurality of horizontal lines. In a sampling part 34, the electric signals of a plurality of specified scanning lines outputted from the camera 30 are converted into the digital signals for every specified number of pixels. A motor 42 moves the sample 16 intermittently for every specified scanning line in the field of view of the camera 30 for every sampling in a plurality of samplings. A computing means (the second memory in the sampling part 34) computes the digital signals obtained by a plurality of samplings in the stationary state for each pixel. The digital signals for each pixel after the movement are computed in correspondence with the position of the sample. The X-ray image of the sample 16 is displayed on a monitor 44 as a clear image by using a plurality of the computed values.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a crystal defect inspection device using X-rays, especially an X-ray
This invention relates to obtaining images using an X-ray camera similar to the line diffraction microscopy method.

[Prior Art] As seen in recent LSIs and VLSIs, the integration and miniaturization of elements are becoming more sophisticated, and the perfection required of semiconductor materials is also becoming more sophisticated. Therefore, how to control lattice defects in semiconductor crystal parts has become a very important issue, and the importance of inspecting semiconductor crystal defects is becoming more and more important. Furthermore, the use of piezoelectric crystals such as quartz and lithium niobate (LiNb 03) has become essential for electronics, and inspection of defects in these crystals has also become very important.

Various methods have been proposed to inspect internal defects in crystals for electronics, but X-ray diffraction microscopy is known as the most basic and highly accurate method. There is.

This X-ray diffraction microscopy method uses an X-ray source 10 as shown in FIG.
The first slit 12 and the second slit 14 convert the X-rays emitted from the X-rays into parallel beams with a minute width and irradiate the sample 16 with the X-rays. X diffracted by sample 16 in the Bragg angle direction
The rays pass through the third slit 18 and enter an X-ray detector, such as a photographic plate 20, at right angles. Here, the sample 16 and the photographic plate 20 synchronously reciprocate in the same direction. Therefore, by repeating this reciprocating motion, X-rays can be accumulated on the photographic plate 20, and a clear diffraction image can be obtained over a wide range of the sample 16.

Note that this reciprocating movement buys exposure time while averaging exposure unevenness due to temporal fluctuations in X-rays, and is unnecessary when the X-ray output is stable.

[Problems to be Solved by the Invention] According to the above-mentioned X-ray diffraction microscopy method, a high-resolution X-ray diffraction image can be obtained, so that the shape of lattice defects in electronic crystals,
You can find out information about the type and location. However, this X-ray diffraction microscopy method often uses a photographic plate, which must be developed and printed.Furthermore, high-resolution photographic plates have low sensitivity in principle, so it takes a long time to obtain test results. The problem was that it took a long time. That is, there is a problem in that it takes a long time of 10 hours or more to obtain a photograph with sufficient resolution.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a crystal defect inspection device that can efficiently and accurately detect X-ray diffraction images of crystals. do.

[Means for Solving the Problems] A crystal defect inspection apparatus according to the present invention includes an X-ray source for irradiating a sample with X-rays, a slit for regulating the X-rays into a parallel beam of minute width, and a slit for irradiating the sample with X-rays. an X-ray camera that receives the passing X-rays and outputs them as electrical signals on multiple horizontal lines;
sampling means for converting electrical signals of a predetermined plurality of scanning lines outputted from the X-ray camera into digital signals for each predetermined number of pixels; A moving means that moves the sample intermittently line by line, and digital signals obtained by sampling multiple times while stationary are integrated for each pixel, and the digital signal for each pixel after movement is correlated with the position of the sample. and a monitor that displays the integration results as an image for each position of the sample, and is capable of displaying the X-ray image of the sample as a clear image on the monitor using the integrated values of multiple times. Features.

[Operation] X-rays emitted from the X-ray source pass through the sample as a narrow parallel beam, but the transmitted X-rays are stopped by a shielding plate and are not irradiated to the X-ray camera. Then, the X-rays diffracted by this sample are incident on an X-ray camera, and this X-ray camera outputs an electrical signal for each scanning line according to the incident X-rays. The electrical signal output from the X-ray camera is sampled as a digital signal for each predetermined number of pixels, and the sample is moved in synchronization with this sampling.

Here, the sample is moved by a predetermined minute amount,
The data before and after the movement overlap for diffracted X-rays from the same position on the sample. In this manner, by performing multiple samplings while stationary and integrating data before and after movement, a clear X-ray image of the sample showing the defect distribution of the sample can be obtained as a predetermined integrated value of multiple times.

[Example] A crystal defect inspection apparatus according to an example of the present invention will be described based on the drawings.

The X-ray source 10 employs a microfocus X-ray tube, for example, with a tube voltage of 60 kV, 2. The kW type is used at 50kV and tube current of about 10mA.

The X-rays emitted from this X-ray source 10 enter the sample 16 through the first slit 12 and the second slit 14. The X-rays reflected in the Bragg angle direction by the sample 16 pass through the third slit 18 and enter an X-ray camera (X-ray vidicon) 30 that is sensitive to X-rays. In this example, the X-ray camera 30 has 512 pixels in the horizontal direction and 512 lines in the vertical direction. and,
The electrical signal from this X-ray camera 30 is transmitted to the image processing device 3.
2 is input.

The image processing section 32 includes a sampling section 34 and a controller section 36. And an X-ray camera 30
The signals output from the sampling section 34 are sequentially written into the memory as digital signals. That is, 512X5 input from the X-ray camera 30
The signals corresponding to the 12 pixels are each stored in a first memory in the sampling section 34 as digital signals.

Then, in response to a freeze command input from the controller 36 at predetermined time intervals, the first
The data currently stored in the memory is sent to the second memory in the sampling section 34.

When manually inputting data, 5 in the X-ray camera 30
Not all of the 12×512 data is necessary; only a few lines corresponding to the incident X-rays or a portion in the scanning line direction is useful depending on the purpose. Therefore, data for preset scanning lines, for example, three lines, is sent from the first memory to the second memory in the sampling section 34.

In this way, the second memory of the sampling section 34 adds and stores three lines of data sent from the first memory, for example, one line of data 512. This operation is performed after a predetermined number of freeze commands, e.g.
It is repeated until the data for each batch is complete. Then, data for five times is supplied, and the second memory integrates the data for each pixel and holds it internally.

When data sampling and addition have been completed a predetermined number of times in this way, the controller 36 controls the movement control unit 38
A movement command is output to the motor controller 40 of.

The motor controller 40 controls the motor 42 based on this command.
By driving the sample 16, the slit 14 and the X
Move in the direction perpendicular to the direction of line incidence.

Due to this movement of the sample 16, two lines of data obtained by the X-ray camera 30 for three lines overlap with the previous data, and only one line is updated.

In this way, similar to the previous case, the data of the freeze command characteristic is acquired five times, and the second
Add and store this in memory.

Since the two lines of duplicate data are signals for the same position on the sample 16, they are sequentially integrated in the corresponding memory positions.

Data is duplicated 5 times due to the freeze command during one stop and 3 times due to movement, so one pixel is
Data for five times will be accumulated. The data of the line for which 15 integrations have been completed is output to an external storage device after the sample 16 has moved by one line and before new integration. Therefore, by sequentially moving the sample 16 one line at a time, an X-ray diffraction image of the entire sample 16 can be obtained as an integrated value.

The X-ray diffraction image of the sample 16 obtained in this way is displayed on the monitor 44 by the output from the controller 36. Additionally, this result is transmitted from the controller 36 to an external storage device 4 such as a floppy disk or hard disk.
6 is also output.

In addition, in the above example, the X-ray camera 30
Information for each line was obtained, and after repeating this process five times, the sample 16 was moved for one line. However, the X-ray source 1 is not limited to this.
0. The number of times can be changed as appropriate depending on the integrity of the sample 16.

Further, the screen displayed on the monitor 44 may be a screen for integrated data or three lines of data sampled from time to time, but it is possible to switch between these screens as appropriate by switching a switch. You may also do so.

In such an embodiment, since the X-ray camera 30 can integrate the image data as a digital signal, the intensity of the X-rays received by the X-ray camera 30 may be quite low. Therefore, the time required to obtain an appropriate image can be significantly reduced.

Furthermore, since the obtained data is stored as digital data, it is possible to correct screen distortions that inevitably occur due to differences in the lattice planes used to obtain the diffraction lines using a predetermined calculation formula. You can also get a screen.

[Effects of the Invention] As explained above, according to the crystal defect inspection apparatus according to the present invention, an X-ray diffraction image can be obtained dry (electronically) using an X-ray camera, and the image can be The time required to obtain the data can be shortened, and the data can also be stored as digital data on a floppy disk or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of a crystal defect inspection apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the structure of a conventional crystal defect inspection apparatus. 10... X-ray sources 12, 14. 18...Slit 16...
- Sample 30 ... X-ray camera 32 ... Image processing section 34 ... Sampling section 36 ... Controller 38 ... Movement control section 40 ... Motor controller 42 ... Motor 44 ... monitor

Claims (1)

[Claims] An X-ray source for irradiating a sample with X-rays, a slit that regulates the X-rays into a narrow parallel beam, and electrical signals of a plurality of scanning lines that receive the X-rays that have passed through the sample. an X-ray camera that outputs as follows; a sampling means that converts electrical signals of a predetermined plurality of scanning lines outputted from the X-ray camera into digital signals for each predetermined number of pixels; A moving means that intermittently moves the sample by a predetermined scanning line in the field of view of an It has an integration means that integrates the digital signal in correspondence with the position of the sample, and a monitor that displays the integration result as an image for each position of the sample, and the X-ray image of the sample is displayed as the integrated value of a predetermined plurality of times. A crystal defect inspection device characterized by displaying on a monitor.