Optical measurement system, optical measurement method, and non-transitory storage medium having measurement program stored thereon

Patent metadata

Field	Value
Publication number	US-11892281-B2
Application number	US-202217655899-A
Country	US
Kind code	B2
Filing date	Mar 22, 2022
Priority date	Mar 23, 2021
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

An optical measurement system includes a light source, a spectroscopic detector, a reference sample, a switching mechanism that switches between a first optical path through which a sample to be measured is irradiated with light from the light source and light produced at the sample is guided to the spectroscopic detector and a second optical path through which the reference sample is irradiated with light from the light source and light produced at the reference sample is guided to the spectroscopic detector, and a processing unit that calculates, by performing correction processing based on change between a first detection result at first time and a second detection result at second time, a measurement value of the sample from a third detection result provided from the spectroscopic detector as a result of irradiation of the sample with light from the light source at third time temporally proximate to the second time.

First claim

What is claimed is:

1. An optical measurement system comprising:
a light source;
a spectroscopic detector;
a reference sample configured to maintain characteristics against variation in temperature;
a switching mechanism, including an optical switch or an optical shutter, that switches between a first optical path through which a sample to be measured is irradiated with light from the light source and light produced at the sample is guided to the spectroscopic detector and a second optical path through which the reference sample is irradiated with light from the light source and light produced at the reference sample is guided to the spectroscopic detector; and
a processor and/or hard-wired logic circuit that calculates, by performing correction processing based on change between a first detection result provided from the spectroscopic detector as a result of irradiation of the reference sample with light from the light source at first time and a second detection result provided from the spectroscopic detector as a result of irradiation of the reference sample with light from the light source at second time, a measurement value of the sample from a third detection result provided from the spectroscopic detector as a result of irradiation of the sample with light from the light source at third time temporally proximate to the second time,
wherein a length of time between the first detection result and the second detection result is substantially larger than a length of time between the second detection result and the third detection result.

2. The optical measurement system according to claim 1 , wherein
the correction processing is based on change of the second detection result with the first detection result being defined as a reference.

3. The optical measurement system according to claim 1 , wherein
the processor and/or hard-wired logic circuit is configured to
calculate a film thickness based on a detection result provided from the spectroscopic detector, and
calculate the measurement value of the sample by reflecting a rate of change from a first film thickness calculated from the first detection result to a second film thickness calculated from the second detection result on a third film thickness calculated from the third detection result.

4. The optical measurement system according to claim 1 , wherein
the processor and/or hard-wired logic circuit is configured to
associate a wavelength with a detection result provided from the spectroscopic detector by referring to wavelength calibration information, and
correct the wavelength calibration information based on a difference between a result of association of the wavelength with the first detection result and a result of association of the wavelength with the second detection result.

5. The optical measurement system according to claim 1 , wherein
a heat-insulating structure is provided around the reference sample.

6. The optical measurement system according to claim 1 , wherein
the reference sample is composed of a material with which temperature dependency is substantially ignorable.

7. The optical measurement system according to claim 1 , wherein
the switching mechanism includes the optical switch provided on an optical path between the light source, and the sample and the reference sample.

8. The optical measurement system according to claim 1 , wherein
the switching mechanism includes the optical shutter that selectively cuts off any one of an optical path from the light source to the sample and an optical path from the light source to the reference sample.

9. An optical measurement method comprising:
measuring irradiation of a reference sample to obtain a first detection result provided from a spectroscopic detector as a result of irradiation of the reference sample with light from a light source at first time, the reference sample being configured to maintain characteristics against variation in temperature;
measuring irradiation of the reference sample to obtain a second detection result provided from the spectroscopic detector as a result of irradiation of the reference sample with light from the light source at second time;
measuring irradiation of a sample to obtain a third detection result provided from the spectroscopic detector as a result of irradiation of the sample with light from the light source at third time temporally proximate to the second time; and
calculating a measurement value of the sample from the third detection result by performing correction processing based on change between the first detection result and the second detection result,
wherein a length of time between the first detection result and the second detection result is substantially larger than a length of time between the second detection result and the third detection result.

10. The optical measurement method according to claim 9 , wherein
the calculating the measurement value of the sample is based on change of the second detection result with the first detection result being defined as a reference.

11. The optical measurement method according to claim 9 , wherein
the calculating the measurement value of the sample comprises reflecting a rate of change from a first film thickness calculated from the first detection result to a second film thickness calculated from the second detection result on a third film thickness calculated from the third detection result.

12. The optical measurement method according to claim 9 , wherein
the calculating the measurement value of the sample comprises
associating a wavelength with a detection result provided from the spectroscopic detector by referring to wavelength calibration information, and
correcting the wavelength calibration information based on a difference between a result of association of the wavelength with the first detection result and a result of association of the wavelength with the second detection result.

13. The optical measurement method according to claim 9 , wherein
the reference sample is composed of a material with which temperature dependency is substantially ignorable.

14. The optical measurement method according to claim 9 , further comprising
switching an optical path between the light source, and the sample and the reference sample.

15. A non-transitory storage medium having a measurement program for measurement of a sample stored thereon, the measurement program causing a computer to perform:
measuring irradiation of a reference sample to obtain a first detection result provided from a spectroscopic detector as a result of irradiation of the reference sample with light from a light source at first time, the reference sample being configured to maintain characteristics against variation in temperature;
measuring irradiation of the reference sample to obtain a second detection result provided from the spectroscopic detector as a result of irradiation of the reference sample with light from the light source at second time;
measuring irradiation of the sample to obtain a third detection result provided from the spectroscopic detector as a result of irradiation of the sample with light from the light source at third time temporally proximate to the second time; and
calculating a measurement value of the sample from the third detection result by performing correction processing based on change between the first detection result and the second detection result,
wherein a length of time between the first detection result and the second detection result is substantially larger than a length of time between the second detection result and the third detection re

Assignees

• Otsuka Denshi Kk

Inventors

• Kawaguchi Shiro
• Nakajima Kazuya
• Takizawa Hayato
• Maeda Goro

Classifications

• G01B11/0625 Primary

  with measurement of absorption or reflection · CPC title

• G01B5/0014

  due to temperature (on machine tools B23Q11/0003) · CPC title

• G01B9/0207

  Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer · CPC title

• G01B11/06 Primary

  for measuring thickness {; e.g. of sheet material (thickness measurement by thermal means G01B21/085)} · CPC title

• G01B11/0675 Primary

  using interferometry · CPC title