Temperature measurement system and temperature measurement method

Patent metadata

Field	Value
Publication number	US-11668608-B2
Application number	US-202017063816-A
Country	US
Kind code	B2
Filing date	Oct 6, 2020
Priority date	Oct 7, 2019
Publication date	Jun 6, 2023
Grant date	Jun 6, 2023

Abstract

A temperature measurement system configured to measure a temperature of a target object having a first main surface and a second main surface includes a light source unit configured to emit output light penetrating the target object and including a first wavelength range and a second wavelength range; a measurement unit configured to measure a spectrum of reflected light; an optical path length ratio calculator configured to calculate an optical path length ratio between the output light of the first wavelength range and the output light of the second wavelength range; and a temperature calculator configured to calculate the temperature of the target object based on the optical path length ratio and a previously investigated relationship between the temperature of the target object and a refractive index ratio between the output light of the first wavelength range and the output light of the second wavelength range.

First claim

We claim:

1. A temperature measurement system configured to measure a temperature of a measurement target object having a first main surface and a second main surface facing the first main surface, the temperature measurement system comprising:
a light source unit configured to emit output light penetrating the measurement target object and including a first wavelength range and a second wavelength range different form the first wavelength range;
at least one optical element configured to output the output light from the light source unit to the first main surface of the measurement target object and receive reflected light, which is part of the output light reflected from the first main surface and the second main surface;
a measurement unit connected to the at least one optical element and configured to measure a spectrum of the reflected light from the first main surface and the second main surface;
an optical path length ratio calculator configured to calculate, by performing Fourier transform on the spectrum measured by the measurement unit, an optical path length ratio which is a ratio between a first optical path length as an optical path length of the output light of the first wavelength range and a second optical path length as an optical path length of the output light of the second wavelength range; and
a temperature calculator configured to calculate the temperature of the measurement target object based on the optical path length ratio and a previously investigated relationship between the temperature of the measurement target object and a refractive index ratio which is a ratio between a first refractive index as a refractive index of the measurement target object with respect to the output light of the first wavelength range and a second refractive index as a refractive index of the measurement target object with respect to the output light of the second wavelength range.

2. The temperature measurement system of claim 1 ,
wherein the light source unit comprises:
a first light source configured to emit light of the first wavelength range;
a second light source configured to emit light of the second wavelength range; and
a multiplexer configured to propagate the output light obtained by multiplexing the light of the first wavelength range and the light of the second wavelength range.

3. The temperature measurement system of claim 1 ,
wherein the measurement unit comprises:
a first spectrometer configured to measure the spectrum of first reflected light which is the reflected light from the first main surface and the second main surface generated by the output light of the first wavelength range; and
a second spectrometer configured to measure the spectrum of second reflected light which is the reflected light from the first main surface and the second main surface generated by the output light of the second wavelength range.

4. The temperature measurement system of claim 1 ,
wherein the at least one optical element includes multiple optical elements.

5. The temperature measurement system of claim 1 ,
wherein the measurement target object is made of silicon,
the first wavelength range is from 1200 nm to 1300 nm, and
the second wavelength range is from 1500 nm to 1600 nm.

6. The temperature measurement system of claim 1 ,
wherein the at least one optical element is provided in a substrate processing apparatus configured to accommodate the measurement target object therein, and
the measurement target object is at least one of a substrate, a focus ring or an upper electrode.

7. A temperature measurement method of measuring a temperature of a measurement target object having a first main surface and a second main surface facing the first main surface, the temperature measurement method comprising:
irradiating, to the measurement target object, output light penetrating the measurement target object and including a first wavelength range and a second wavelength range different form the first wavelength range;
measuring a spectrum of reflected light, which is part of the output light reflected from the first main surface and the second main surface of the measurement target object;
calculating, by performing Fourier transform on the spectrum, an optical path length ratio which is a ratio between a first optical path length as an optical path length of the output light of the first wavelength range and a second optical path length as an optical path length of the output light of the second wavelength range; and
calculating the temperature of the measurement target object based on the optical path length ratio and a previously investigated relationship between the temperature of the measurement target object and a refractive index ratio which is a ratio between a first refractive index as a refractive index of the measurement target object of the output light of the first wavelength range and a second refractive index as a refractive index of the measurement target object of the output light of the second wavelength range.

Assignees

• Tokyo Electron Ltd

Inventors

• Wu Tong
• Nagai Kenji

Classifications

• G01N2201/1211

  for temperature · CPC title

• G01K11/00 Primary

  Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 · CPC title

• G01J3/427

  Dual wavelengths spectrometry · CPC title

• G01N21/71

  thermally excited · CPC title

• G01J5/0806

  Focusing or collimating elements, e.g. lenses or concave mirrors · CPC title