JPH03181809A - Appearance shape evaluation device - Google Patents

Abstract

PURPOSE:To automatically count repeated patterns by providing a detecting means for detecting the cycle of the repeated patterns and a counting means for automatically counting the number of repetitions. CONSTITUTION:An electronic beam 2 is irradiated to a sample 4 on a stage 10 through a beam diaphragm 1 and an objective lens 3. A secondary electron 11 projected by repeated patterns on the surface of the sample 4 is, through a detector 5, converted to signal waveforms corresponding to the shape of the patterns and amplified by an amplifier 6. Peak values are present correspond ing to edges of the patterns among the signal waveforms. Only the peak values over a specific value are detected in a comparator 7. Accordingly, the number of repeated patterns is counted. At the same time, the shape of the patterns is scanned on a CRT 9 through an image processor 8 which processes the signal waveforms. When the stage 10 is driven, signal waveforms are generated from the repeated patterns, so that the number of the patterns is counted by the comparator 7 corresponding to an image of the repeated patterns scanned on a screen of the CRT 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique for automatically counting the number of repetitions of a fine repeating pattern.

[Conventional technology]

In conventional counting of repeating patterns, the number of repeating patterns is visually counted from a certain starting point by enlarging the repeating pattern to a size that can be visually counted using an external shape evaluation device such as an electron microscope.

[Problem to be solved by the invention]

In the above-described conventional counting of repeated patterns, as the number of repeated patterns increases, the possibility that the operator will make a counting error increases. In addition, there was no way to check whether the counting was accurate or not, resulting in a lack of accuracy. The method of moving the sample a specific distance by calculating the moving distance from the line width of a repetitive pattern also requires a high-precision stage, and the accuracy becomes worse when the sample is tilted, making it difficult to reach the target observation point. There was a problem with not being able to move.

The present invention has been made in view of these points, and an object thereof is to obtain an appearance shape evaluation device that can recognize repetitive patterns and automatically count the repetitive patterns.

[Means to solve the problem]

In order to achieve such an object, the appearance shape evaluation apparatus according to the present invention is provided with a detection means for detecting the cycle of a repeating pattern and a counting means for automatically counting the number of repetitions.

[Effect]

In the appearance shape evaluation device according to the present invention, a detector converts information from a repeating pattern of a sample into a signal waveform having a repeating period, and a comparator counts signal waveforms having a certain peak value or more to calculate the number of repeating patterns. demand.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an external shape evaluation apparatus according to the present invention, in which an electron beam is used as the image shape observation means.

In FIG. 1, 1 is an electron beam aperture, 2 is an electron beam, 3 is an objective lens, 4 is a sample, 5 is a detector as a detection means, 6 is an amplifier, 7 is a comparator as a counting means, 8 9 is an image processor, 9 is a CRT, 10 is a sample stage, and 11 is a secondary electron.

Moreover, FIGS. 2(a) and 2(b) are an enlarged view of the sample observation surface and a signal waveform diagram. In the figure, 12 is a repeating pattern, 13 is a detected waveform, and 14 is a peak value.

In the apparatus shown in FIG. 1, when an electron beam is used, an electron beam 2 passes through a beam aperture 1 and an objective lens 3 and is irradiated onto the surface of a sample 4 on a stage 10. Although secondary electrons, reflected electrons, absorbed electrons, characteristic X-rays, transmitted electrons, etc. are emitted from the surface of the sample 4, the case of secondary electrons will be described here. Secondary electrons 11 emitted by the repetitive pattern on the surface of the material are converted into a signal waveform 13 corresponding to the pattern shape through a detector 5, and amplified through an amplifier 6. A peak value 14 is seen in the signal waveform corresponding to the pattern edge. The comparator 7 picks up and measures only the peak values equal to or higher than a specific value from among the peak values 14, and counts the number of repeating patterns.

At the same time, the signal waveform is passed through the image processor 8 to the CRT.
The pattern shape is scanned on Q. By driving the stage 10, signal waveforms from the repeating patterns are sequentially generated, and the comparator 7 simultaneously counts the repeating patterns in correspondence with the image of the repeating patterns scanned on the screen of the CRT 9. By displaying the count value of this repeated pattern on the CRT 9, automatic measurement of the repeated pattern on the CRT 9 screen is carried out.

In this embodiment, an electron beam is used as a method for recognizing the external shape, but any probe that can obtain information from the sample surface may be used, such as a laser beam.

〔Effect of the invention〕

As explained above, the present invention automatically counts signal waveforms from a repetitive pattern of a sample that are equal to or higher than a specific peak value. can be automatically counted, and has the effect of improving the counting accuracy of fine patterns compared to visual counting.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an external shape evaluation apparatus according to the present invention, and FIGS. 2(a) and 2(b) are an enlarged view of a sample observation surface and a signal waveform diagram. DESCRIPTION OF SYMBOLS 1... Beam aperture, 2... Electron beam, 3... Objective lens, 4... Sample, 5... Detector, 6...
・Amplifier, 7... Comparator, 8... Image processor, 9.
...CRT, 10...stage, 11...secondary electron, 12...repetitive pattern, 3...signal waveform, 4...peak value. Agent Masuo Oiwa 1 Figure 1; Ji'-4 Koshiburi 2; 4ζJ Ko'・-Mu 3; Murakami L>Shaku°°. 4; Bu〉7°I. 5; Throwing method 4゜6; tI! I=ia! It-. 7: Kujo number 8; 帛4. Marushibaki 9: CRT 10; Stage' 11: 2: Electronics 2 Figure 2

Claims (1)

[Claims] 1. An external shape evaluation device comprising: a detection means for detecting the cycle of a repeating pattern; and a counting means for automatically counting the number of repetitions.