Endpoint detection during polishing using integrated differential intensity

Patent metadata

Field	Value
Publication number	US-9248544-B2
Application number	US-201213552317-A
Country	US
Kind code	B2
Filing date	Jul 18, 2012
Priority date	Jul 18, 2012
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A method of controlling a polishing operation includes polishing a substrate, during polishing obtaining a sequence over time of measured spectra from the substrate with an in-situ optical monitoring system, for each measured spectrum from the sequence of measured spectra determining a difference between the measured spectrum and an immediate previous spectrum from the sequence, accumulating the difference for each measured spectrum to generate a total difference, comparing the total difference to a threshold, and detecting a polishing endpoint based on the comparison of the total difference to the threshold.

First claim

What is claimed is:

1. A method of controlling a polishing operation, comprising:
polishing a substrate;
during polishing, obtaining a sequence over time of measured spectra from the substrate with an in-situ optical monitoring system;
for each measured spectrum from the sequence of measured spectra, determining a difference between the measured spectrum and an immediate previous spectrum from the sequence;
accumulating the difference for each measured spectrum to generate a total difference;
comparing the total difference to a threshold; and
detecting a polishing endpoint based on the comparison of the total difference to the threshold.

2. The method of claim 1 , wherein obtaining the sequence comprises scanning a sensor of the optical monitoring system across the substrate.

3. The method of claim 2 , wherein obtaining the sequence comprises generating one measured spectrum per scan of the sensor across the substrate.

4. The method of claim 3 , wherein polishing the substrate comprises rotating a platen that supports the sensor, and one measured spectrum is generated per rotation of the platen.

5. The method of claim 3 , wherein the in-situ monitoring system generates a plurality of raw spectra per scan of the sensor across the substrate.

6. The method of claim 5 , wherein generating the one measured spectrum per scan comprises combining at least some of the plurality of raw spectra.

7. The method of claim 6 , wherein combining at least some of the plurality of raw spectra comprises averaging the at least some of the plurality of raw spectra.

8. The method of claim 5 , wherein generating the one measured spectrum per scan comprises selecting a raw spectrum from at least some of the plurality of raw spectra.

9. The method of claim 1 , wherein determining the difference comprises calculating a sum of squared differences between the measured spectrum and the immediate previous spectrum.

10. The method of claim 1 , wherein determining the difference comprises calculating a sum of absolute differences between the measured spectrum and the immediate previous spectrum.

11. The method of claim 1 , wherein obtaining the sequence of measured spectra comprises directing a beam of light onto the substrate and measuring a spectrum of a reflection of the beam.

12. The method of claim 1 , wherein accumulating the difference comprising summing the difference.

13. The method of claim 1 , wherein detecting the polishing endpoint comprises halting polishing if the total difference exceeds the threshold.

14. The method of claim 1 , wherein the total difference is calculated for each measured spectrum to generate a sequence of total differences, and wherein detecting the polishing endpoint includes fitting a function to the sequence of total differences and determining a time at which the function equals the threshold.

15. A method of controlling a polishing operation, comprising:
polishing a substrate;
during polishing, for each zone of a plurality of zones on a substrate, obtaining a sequence over time of measured spectra from the substrate with an in-situ optical monitoring system;
for each measured spectrum from the sequence of measured spectra for each zone, determining a difference between the measured spectrum and an immediate previous spectrum from the sequence;
for each measured spectrum from the sequence of measured spectra for each zone, accumulating the difference to generate a sequence of total differences;
for each zone fitting a function to the sequence of total differences for the zone to generate a plurality of functions; and
adjusting a polishing parameter based on the plurality of functions to provide more uniform polishing.

Assignees

• Zhang Jimin
• Lee Harry Q
• Wang Zhihong
• Tu Wen-Chiang
• Applied Materials Inc

Inventors

• Zhang Jimin
• Lee Harry Q
• Wang Zhihong
• Tu Wen-Chiang

Classifications

• H10P74/238

  comprising acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection or in-situ thickness measurement · CPC title

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• B24B37/105

  the workpieces or work carriers being actively moved by a drive, e.g. in a combined rotary and translatory movement · CPC title

• B24B49/12

  involving optical means · CPC title

• B24B37/042

  operating processes therefor · CPC title