Endpoint detection for chemical mechanical polishing based on spectrometry

Patent metadata

Field	Value
Publication number	US-11715672-B2
Application number	US-202117530390-A
Country	US
Kind code	B2
Filing date	Nov 18, 2021
Priority date	Aug 22, 2005
Publication date	Aug 1, 2023
Grant date	Aug 1, 2023

Abstract

A method of detecting a polishing endpoint includes storing a plurality of library spectra, measuring a sequence of spectra from the substrate in-situ during polishing, and for each measured spectrum of the sequence of spectra, finding a best matching library spectrum from the plurality of library spectra to generate a sequence of best matching library spectra. Each library spectrum has a stored associated value representing a degree of progress through a polishing process, and the stored associated value for the best matching library spectrum is determined for each best matching library spectrum to generate a sequence of values representing a progression of polishing of the substrate. The sequence of values is compared to a target value, and a polishing endpoint is triggered when the sequence of values reaches the target value.

First claim

What is claimed is:

1. A method of controlling a chemical mechanical polishing operation, comprising:
storing a plurality of library spectra, each library spectrum of the plurality of library spectra having a stored associated value representing a degree of progress through a polishing process;
polishing a substrate;
measuring a sequence of spectra from the substrate in-situ during polishing;
for each measured spectrum of the sequence of spectra, finding a best matching library spectrum from the plurality of library spectra to generate a sequence of best matching library spectra;
for each best matching library spectrum from the sequence of best matching library spectra, determining the stored associated value for the best matching library spectrum to generate a sequence of values representing a progression of polishing of the substrate;
comparing the sequence of values to a target value; and
triggering a polishing endpoint when the sequence of values reaches the target value.

2. The method of claim 1 , wherein each library spectrum of the plurality of library spectra has a unique associated value.

3. The method of claim 1 , further comprising smoothing the sequence of values to generate a smoothed sequence and comparing comprises comparing the smoothed sequence to the target value.

4. The method of claim 1 , comprising sweeping a detection spot of an in-situ monitoring system across the substrate, measuring a plurality of spectra in each sweep of the detection spot across the substrate.

5. The method of claim 4 , comprising determining a radial zone on the substrate for each spectrum of the plurality of spectra in each sweep, and generating a sequence of values representing a degree of progress through a polishing process for each radial zone.

6. The method of claim 4 , wherein sweeping the detection spot comprises rotating a platen.

7. The method of claim 4 , comprising averaging a subset of the plurality of spectra from a sweep to provide a measured spectrum.

8. The method of claim 1 , wherein the sequence of values provides a trace, and respective stored associated values of the plurality of library spectra are substantially linearly proportional to a number of values at a point in a trace at which respective library spectra occur.

9. The method of claim 1 , wherein the plurality of library spectra are generated by measurement of spectra during polishing of a test substrate.

10. The method of claim 1 , wherein the plurality of library spectra are generated from theory.

11. The method of claim 1 , comprising applying a high-pass filter to each measured spectrum of the sequence of spectra.

Assignees

• Applied Materials Inc

Inventors

• Benvegnu Dominic J
• David Jeffrey Drue
• Swedek Boguslaw A

Classifications

• H10P95/064

  the removal being chemical etching · CPC title

• H10P95/062

  involving a dielectric removal step · CPC title

• H10P72/0604

  Process monitoring, e.g. flow or thickness monitoring · CPC title

• H10P72/0428

  Apparatus for mechanical treatment or grinding or cutting · CPC title

• H10P72/0422

  for wet etching · CPC title