Polishing apparatus

Patent metadata

Field	Value
Publication number	US-2016354894-A1
Application number	US-201615170645-A
Country	US
Kind code	A1
Filing date	Jun 1, 2016
Priority date	Jun 5, 2015
Publication date	Dec 8, 2016
Grant date	—

Abstract

A polishing apparatus capable of measuring a film thickness of a wafer using a plurality of optical sensors, without using an optical-path switching device for optical fibers, is disclosed. The polishing apparatus includes: an illuminating fiber having a plurality of distal ends arranged at different locations in a polishing table; a spectrometer configured to break up reflected light from a wafer in accordance with wavelength and measure an intensity of the reflected light at each of wavelengths; a light-receiving fiber having a plurality of distal ends arranged at the different locations in the polishing table; and a processor configured to generate a spectral waveform indicating a relationship between the intensity and wavelength of the reflected light and determine a film thickness based on the spectral waveform.

First claim

What is claimed is:

1 . A polishing apparatus comprising:
a polishing table for supporting a polishing pad; a polishing head configured to press a wafer against the polishing pad; a light source configured to emit light; an illuminating fiber having a plurality of distal ends arranged at different locations in the polishing table, the illuminating fiber being coupled to the light source to direct the light, emitted by the light source, to a surface of the wafer; a spectrometer configured to break up reflected light from the wafer in accordance with wavelength and measure an intensity of the reflected light at each of wavelengths; a light-receiving fiber having a plurality of distal ends arranged at the different locations in the polishing table, the light-receiving fiber being coupled to the spectrometer to direct the reflected light from the wafer to the spectrometer; and a processor configured to generate a spectral waveform indicating a relationship between the intensity and wavelength of the reflected light and determine a film thickness based on the spectral waveform.

2 . The polishing apparatus according to claim 1 , wherein:
the illuminating fiber includes an illuminating trunk fiber, a first illuminating branch fiber, and a second illuminating branch fiber, the first illuminating branch fiber and the second illuminating branch fiber branching off from the illuminating trunk fiber; and the light-receiving fiber includes a light-receiving trunk fiber, a first light-receiving branch fiber, and a second light-receiving branch fiber, the first light-receiving branch fiber and the second light-receiving branch fiber branching off from the light-receiving trunk fiber.

3 . The polishing apparatus according to claim 1 , wherein the plurality of distal ends of the illuminating fiber and the plurality of distal ends of the light-receiving fiber constitute a first optical sensor and a second optical sensor for directing the light to the wafer and receiving the reflected light from the wafer, and
wherein the second optical sensor is across a center of the polishing table from the first optical sensor.

4 . The polishing apparatus according to claim 1 , further comprising:
a calibration light source configured to emit light having a specified wavelength, the calibration light source being coupled to the spectrometer through a calibration optical fiber.

5 . The polishing apparatus according to claim 1 , wherein the light source includes a first light source and a second light source.

6 . The polishing apparatus according to claim 5 , wherein the first light source and the second light source are configured to emit light in a same wavelength range.

7 . The polishing apparatus according to claim 5 , wherein the first light source and the second light source are configured to emit light in different wavelength ranges.

8 . The polishing apparatus according to claim 1 , wherein the spectrometer includes a first spectrometer and a second spectrometer.

9 . The polishing apparatus according to claim 8 , wherein the first spectrometer and the second spectrometer are configured to measure the intensity of the reflected light at different wavelength ranges.

10 . The polishing apparatus according to claim 1 , wherein the processor is configured to perform a Fourier transform process on the spectral waveform to generate a frequency spectrum indicating a relationship between film thickness and strength of frequency component, determine a peak of the strength of frequency component which is greater than a threshold value, and determine the film thickness corresponding to the peak.

Assignees

• Ebara Corp

Inventors

• Kimba Toshifumi

Classifications

• B24B37/205

  provided with a window for inspecting the surface of the work being lapped · CPC title

• B24B49/12

  involving optical means · CPC title

• B24B37/005 Primary

  Control means for lapping machines or devices · CPC title

• B24B37/11

  Lapping tools · CPC title

• B24B37/013 Primary

  Devices or means for detecting lapping completion · CPC title