Pattern evaluation system and pattern evaluation method
Provided is a technology for evaluating a property of a pattern formed inside a sample from two-dimensional information of the sample. A pattern evaluation system of the present disclosure includes a computer subsystem that executes a process of evaluating a property of a pattern by reading a program from a memory that stores the program for evaluating the property of the pattern formed inside a sample. The computer subsystem executes a process of acquiring an image of the sample; a process of extracting a signal waveform from the image; a process of calculating a feature amount in a predetermined region of the signal waveform; a process of comparing the feature amount with a reference value of the feature amount; and a process of evaluating the property of the pattern based upon a comparison result in the comparison process.
1. A pattern evaluation system, comprising:
a computer subsystem that executes a process of evaluating a property of a pattern by reading a program from a memory that stores the program for evaluating the property of the pattern formed inside a sample, wherein
the computer subsystem executes:
a process of acquiring an image of the sample;
a process of extracting a signal waveform from the image;
a process of calculating a feature amount in a predetermined region of the signal waveform;
a process of comparing the feature amount with a reference value of the feature amount; and
a process of evaluating the property of the pattern based upon a comparison result in the comparison process,
wherein the reference value is the feature amount of the signal waveform of the pattern in which a plurality of patterns are embedded with respect to a surface of the sample, or the pattern which is formed in a depth direction with respect to the surface of the sample.
2. The pattern evaluation system according to claim 1 , wherein
the feature amount is any one or more of an area, a height, a width, and an inclination in the predetermined region of the signal waveform.
3. The pattern evaluation system according to claim 1 , wherein
the computer subsystem evaluates any one or more of a volume and a density of the pattern as the property of the pattern.
4. The pattern evaluation system according to claim 1 , wherein
the computer subsystem evaluates the property of the pattern based upon a difference between the feature amount and the reference value in the process of evaluating the property of the pattern.
5. The pattern evaluation system according to claim 1 , wherein
the signal waveform is a line profile of a brightness value of the image.
6. The pattern evaluation system according to claim 1 , wherein
the computer subsystem calculates a feature amount of a signal waveform of an ideal pattern by a simulation based upon design data of the ideal pattern, and further executes a process of setting the calculated feature amount as the reference value.
7. The pattern evaluation system according to claim 1 , wherein
the computer subsystem further executes:
a process of respectively extracting signal waveforms from images at a plurality of measurement points of the sample;
a process of calculating a feature amount in a predetermined region for each of the signal waveforms; and
a process of calculating an average value of the plurality of feature amounts, and setting the feature amount closest to the average value as the reference value.
8. The pattern evaluation system according to claim 1 , wherein
the computer subsystem further executes a process of setting the feature amount of the signal waveform at a place where the property of the pattern is known as the reference value.
9. The pattern evaluation system according to claim 1 , wherein
the computer subsystem further executes:
a process of obtaining a plurality of comparison results by comparing the feature amount and the reference value with respect to a plurality of measurement points of the sample; and
a process of specifying a place where the property of the pattern is changed in the sample from the plurality of comparison results.
10. The pattern evaluation system according to claim 1 , wherein
the computer subsystem further executes a process of determining whether the pattern satisfies a manufacturing specification based upon the comparison result between the feature amount and the reference value.
11. A pattern evaluation system according to claim 1 , further comprising
a charged particle beam emission subsystem controlled by the computer subsystem, wherein
the charged particle beam emission subsystem includes:
a charged particle source that irradiates the sample with a charged particle beam;
a deflector that deflects the charged particle beam and scans the sample; and
a detector that detects an emitted particle emitted from the sample by emission of the charged particle beam, and
the computer subsystem further executes a process of generating the image based upon a detection signal of the detector.
12. The pattern evaluation system according to claim 11 , wherein
the sample includes a plurality of the patterns arranged in a depth direction,
the charged particle beam emission subsystem irradiates a region including the plurality of patterns with the charged particle beam by using the charged particle source and the deflector, and detects the emitted particle from the region by using the detector, and
the computer subsystem executes a process of generating the image based upon the detection signal of the detector and a process of evaluating properties of the plurality of patterns.
13. The pattern evaluation system according to claim 11 , wherein
the sample includes a plurality of the patterns arranged in a depth direction,
the computer subsystem further executes:
a process of generating a first image based upon a detection signal obtained by irradiating the sample with the charged particle beam at a first acceleration voltage, and extracting a first signal waveform from the first image;
a process of generating a second image based upon a detection signal obtained by irradiating the sample with the charged particle beam at a second acceleration voltage, and extracting a second signal waveform from the second image; and
a process of acquiring a third signal waveform which is a difference between the first signal waveform and the second signal waveform,
in the process of calculating the feature amount, a feature amount in a predetermined region of the third signal waveform is calculated,
in the comparison process, the feature amount of the third signal waveform is compared with the reference value, and
in the process of evaluating the property of the pattern, the property of the pattern at a predetermined position in the depth direction is evaluated.
14. The pattern evaluation system according to claim 11 , further comprising:
a deposition device that forms a metal film on a surface of the sample.
15. The pattern evaluation system according to claim 11 , wherein
the pattern is a hole pattern provided in the sample, and
the system further includes a filling device that fills the hole pattern with a first material.
16. A pattern evaluation method, comprising:
obtaining an image of a sample in which a pattern is formed;
extracting a signal waveform of the image;
calculating a feature amount in a predetermined region of the signal waveform; and
evaluating a property of the pattern by comparing the feature amount with a reference value of the feature amount,
wherein the reference value is the feature amount of the signal waveform of the pattern in which a plurality of patterns are embedded with respect to a surface of the sample, or the pattern which is formed in a depth direction with respect to the surface of the sample.
17. The pattern evaluation system according to claim 1 , wherein the pattern formed inside the sample is a lower part of the plurality of patterns embedded with respect to a surface of the sample, or a lower part thereof along the depth direction with respect to the surface of the sample, and
the plurality of patterns overlap when seen from a Z axis direction perpendicular to an X axis and a Y axis parallel to the surface of the sample.
18. The pattern evaluation system according to claim 1 , wherein the pattern formed in the depth direction with respect to the surface of the sample is a hole pattern, a protrusion pattern, or a hole pattern filled with a first material.