JPS59201351A - Scan-type electron microscope - Google Patents

Abstract

PURPOSE:To obtain a scanning device suitable for the overall observation of an extremely slender region by making the amplitude ratio of scanning signals in the X direction and the Y direction applied to a scan-type electron microscope proper variable. CONSTITUTION:An X-direction scanning signal and a Y-direction scanning signal are applied to a sample-illuminating electron beam deflection coil 6 on a scan- type electron microscope proper 2 side through amplifiers 4, 5 capable of independently adjusting the amplification degree. For instance, an X-direction scanning signal and Y-direction scanning signal generator 1 is commonly used for the scan-type electron microscope 2 and a CRT display unit 3, and its output signals are applied to the CRT display unit 3 as they are, i.e., with a constant amplitude ratio between both X, Y scanning signals. On the other hand, output signals of the scanning signal generator 1 are applied to the scan-type electron microscope proper side through amplifiers 4, 5 capable of independently adjusting the amplification degree for each of the X-direction and the Y-direction scanning signals.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a scanning device in a scanning electron microscope.

(b) Prior art The conventional scanning electron microscope
Since the scanning area on the screen is set to have the same aspect ratio, the sample surface and the CRT image have a similar relationship. This is natural for normal observation of the sample surface, but for special purposes, it may be advantageous for the aspect ratio of the scanning area to be different between the sample surface and the CRT image. For example, in the case of detecting foreign matter within a plating layer, when attempting to inspect a cross section of a hair plating layer with a thickness of 10 μm over a length of 1 mm, the foreign matter within the plating layer is approximately 0.5 μm thick. 2mm on the image so that this can be visually detected.
, the magnification will be 4000 times. In this case, the length to be observed becomes 4 m on the image, and considering the time required for one observation on the CRT, the inspection becomes extremely inefficient.

(C) Purpose The present invention provides a scanning device for a scanning electron microscope suitable for the entire observation of an extremely long and narrow area as described above.

(D) Structure The present invention has a fixed amplitude ratio of the scanning signals in the X direction and the Y direction applied to the CRT, and a variable amplitude ratio of the scanning signals in the X direction and Y direction applied to the main body of the scanning electron microscope. It has the following characteristics.

Embodiment FIG. 1 shows an embodiment of the present invention. 1 is an X-direction scanning signal generator and a Y-direction scanning signal generator, a main body of a two-digit scanning electron microscope, and 3 is a CRT display device. The scanning signal generator is common to the scanning electron microscope main body 2 and the CR7 display device 3, and its output signal is sent to the CRT display device as is, with the amplitude ratio of both the X and Y scanning signals being constant. applied. On the other hand, the output signal of the scanning signal generator 1 is applied to the main body of the scanning electron microscope via amplifiers 4 and 5, which can independently adjust the amplification degree for each of the scanning signals in the X direction and the Y direction. 4R and 5R are variable resistors that adjust the amplification degree of the amplifiers 3 and 4. Reference numeral 6 denotes an electron beam deflection coil in the main body 2 of the scanning electron microscope, to which the outputs of the amplifiers 3 and 4 are applied. 7 is a sample, secondary electrons etc. emitted from the sample surface upon being irradiated with an electron beam are detected by a detector 8, and the output of the detector is amplified by an amplifier 9 and sent to CR7.
It is applied to the display device 3 as a brightness modulation signal.

In the above configuration, as shown in FIG. The aspect ratio of the screen V of the 7-surface device 3 is constant.

On the other hand, the scanning range of the surface of the sample 7 in the main body 2 of the scanning electron microscope is determined by selecting the ratio of the amplification degrees of the amplifiers 4 and 5 as shown in FIG. The aspect ratio can be freely changed as shown in S2, 83, etc. In this way, the same pattern P on the sample surface corresponds to the scanning ranges E11, 82, and S3.
On the T screen, images are constructed with different vertical and horizontal magnifications, as shown in Figure 2 A, B, and C.

(f) Effect Figure 3A is an image taken by a conventional scanning electron microscope of a cross section of the chromium plating layer on the iron surface, and the vertical and horizontal magnifications are equal to 20.
The thickness of the plating layer on the image at 0x is 0.5 mm (actual thickness 2-
51 t m ), and it is extremely difficult to find an image of a foreign object contained in this 0.5 mm wide image. Therefore, we had no choice but to keep the vertical and horizontal magnifications at 200x and increase only the vertical (Y-direction) magnification to 4000x (on the scanning electron microscope main body side, the amplitude of the Y-direction scanning signal is smaller than the X-direction scanning signal). ), the magnification is 200 times larger in the length direction as shown in Figure 3B, so when observing a cross section of a plating layer with a length and width of 1 mm, image observation from -00 mm is performed at one time (actually, the sample is moved Since the edges of the front and rear images overlap, the area observed at one time is, for example, about 1.40 mm (as shown in the figure), and it is sufficient to move the sample twice, and it is possible to detect foreign particles with a thickness of 0.5 μm in the plating layer. is width 2
This means that it can be detected as an image of mm.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the CRT screen, sample scanning range, and image shape change according to the present invention, and FIG. 3A is a conventional example. FIG. 1B is a diagram of an example of a CRT screen according to the present invention. FIG. ]-...X direction X direction force Y direction scanning signal generator...Scanning electron microscope main body, G...CRT display device, 4...
X-direction scanning signal amplifier, 5...Y-direction scanning signal amplifier. Agent Patent Attorney Hiroshi Hiru

Claims (1)

[Claims] A scanning type characterized in that an X-direction scanning signal and a Y-direction scanning signal are applied to an electron beam deflection coil for sample irradiation on the scanning electron microscope main body side through amplifiers that can independently adjust the amplification degree. electronic microscope.