Scanning electron microscope and a method for evaluating accuracy of repeated measurement using the same
First Claim
1. A scanning electron microscope comprising:
- an image acquisition unit which scans an electron beam on a sample under specified imaging conditions at each measurement over the number of times of measurement to acquire an enlarged measurement image at high magnification based on an electron signal emitted from the sample;
an image processing unit which acquires an enlarged measurement area image of a local area by using two-dimensional pattern matching with a roughness template image showing a micro-minute shape of a pattern in the local area, from the enlarged measurement image at high magnification acquired at each measurement over the number of times of measurement by the image acquisition unit;
a measurement unit which measures typical dimensions or a shape of the pattern in the enlarged measurement area on the basis of the enlarged measurement area image of the local area, which has been acquired at each measurement over the number of times of measurement by the image processing unit; and
a measurement repeatability evaluation unit which presents, as an evaluation value of the measurement repeatability as a tool, a value associated with the change in dimensions or the change in shape for the number of times of measurement, said dimensions or said shape being measured over the number of times of measurement by the measurement unit.
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Accused Products
Abstract
The present invention relates to a CDSEM (scanning electron microscope) capable of evaluating and presenting the measurement repeatability as a tool with a high degree of accuracy without being influenced by fluctuations in micro-minute shape that tend to increase with the microminiaturization of semiconductor patterns, and to a method for evaluating accuracy of repeated measurement using the scanning electron microscope. There is provided a function whereby when measuring a plurality of times the same part to be measured, by making use of a micro-minute pattern shape such as the roughness included in the pattern, pattern matching with a roughness template image is performed to correct two-dimensional deviation in position of the part to be measured on an enlarged measurement image acquired, and then an enlarged measurement area image is extracted and acquired. This makes it possible to eliminate variation in measurements caused by the micro-minute pattern shape.
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Citations
17 Claims
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1. A scanning electron microscope comprising:
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an image acquisition unit which scans an electron beam on a sample under specified imaging conditions at each measurement over the number of times of measurement to acquire an enlarged measurement image at high magnification based on an electron signal emitted from the sample; an image processing unit which acquires an enlarged measurement area image of a local area by using two-dimensional pattern matching with a roughness template image showing a micro-minute shape of a pattern in the local area, from the enlarged measurement image at high magnification acquired at each measurement over the number of times of measurement by the image acquisition unit; a measurement unit which measures typical dimensions or a shape of the pattern in the enlarged measurement area on the basis of the enlarged measurement area image of the local area, which has been acquired at each measurement over the number of times of measurement by the image processing unit; and a measurement repeatability evaluation unit which presents, as an evaluation value of the measurement repeatability as a tool, a value associated with the change in dimensions or the change in shape for the number of times of measurement, said dimensions or said shape being measured over the number of times of measurement by the measurement unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A scanning electron microscope comprising:
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an image acquisition unit which scans an electron beam on a sample under specified imaging conditions at each measurement over the number of times of measurement to acquire an enlarged measurement image at high magnification based on an electron signal emitted from the sample; an image processing unit which acquires an enlarged measurement area image of a local area by using two-dimensional pattern matching with a roughness template image showing a micro-minute shape of a pattern in the local area, from the enlarged measurement image at high magnification acquired at each measurement over the number of times of measurement by the image acquisition unit; and a measurement unit which measures dimensions or a shape of the pattern in the enlarged measurement area on the basis of the enlarged measurement area image of the local area, which has been acquired at each measurement over the number of times of measurement by the image processing unit. - View Dependent Claims (11, 12)
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13. A method for evaluating measurement repeatability of a scanning electron microscope, said method comprising:
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an image acquisition step of scanning an electron beam on a sample under specified imaging conditions at each measurement over the number of times of measurement to acquire an enlarged measurement image at high magnification based on an electron signal emitted from the sample; an image processing step of acquiring an enlarged measurement area image of a local area by using two-dimensional pattern matching with a roughness template image showing a micro-minute shape of a pattern in the local area, from the enlarged measurement image at high magnification acquired at each measurement over the number of times of measurement by the image acquisition step; a measurement step of measuring dimensions or a shape of the pattern in the enlarged measurement area on the basis of the enlarged measurement area image of the local area, which has been acquired at each measurement over the number of times of measurement by the image processing step; and a measurement repeatability evaluation step of presenting, as an evaluation value of the measurement repeatability as a tool, a value associated with the change in dimensions or the change in shape for the number of times of measurement, said dimensions or said shape being measured over the number of times of measurement by the measurement step. - View Dependent Claims (14, 15, 16, 17)
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Specification