Chemical mechanical polishing vibration measurement using optical sensor

Patent metadata

Field	Value
Publication number	US-12447579-B2
Application number	US-202217858011-A
Country	US
Kind code	B2
Filing date	Jul 5, 2022
Priority date	Jul 6, 2021
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

A chemical mechanical polishing apparatus includes a platen to support a polishing pad, a carrier head to hold a substrate against a polishing surface of the polishing pad, a motor to generate relative motion between the platen and the carrier head so as to polish an overlying layer on the substrate, an in-situ vibration monitoring system including a light source to emit a light beam and a sensor that receives a reflection of the light beam from a reflective surface of the polishing pad, and a controller configured to detect exposure of an underlying layer due to the polishing of the substrate based on measurements from the sensor of the in-situ pad vibration monitoring system.

First claim

What is claimed is:

1. A chemical mechanical polishing apparatus, comprising:
a platen to support a polishing pad;
a carrier head to hold a substrate against a polishing surface of the polishing pad;
a motor to generate relative motion between the platen and the carrier head so as to polish an overlying layer on the substrate;
an in-situ pad vibration monitoring system including a light source to emit a light beam and a sensor that receives a reflection of the light beam from a reflective surface parallel with a polishing surface of the polishing pad; and
a controller configured to detect exposure of an underlying layer due to the polishing of the substrate based on measurements from the sensor of the in-situ pad vibration monitoring system, the measurements indicative of a vibration of the reflective surface in a direction normal to the polishing surface.

2. The apparatus of claim 1 , comprising the polishing pad, and wherein the reflective surface is recessed from a lower surface of the polishing pad.

3. The apparatus of claim 2 , wherein the polishing pad comprises an insert and an upper surface of the insert is coplanar with an upper surface of the polishing pad, and the reflective surface is housed within the insert.

4. The apparatus of claim 3 , wherein the polishing pad comprises a porous material and the insert comprises a non-porous material.

5. The apparatus of claim 3 , wherein a distance between the upper surface and the reflective surface of the insert is in a range between from 10 mil to 30 mil.

6. The apparatus of claim 3 , wherein the reflective surface of the insert has a width in a range between from 8 mm to 18 mm.

7. The apparatus of claim 3 , wherein the insert comprises a durometer value within 10 Shore of a polishing pad durometer value.

8. The apparatus of claim 3 , wherein the polishing pad has a polishing layer and a plurality of slurry-transport grooves in a polishing surface of the polishing layer, and wherein the insert is positioned in a portion of the polishing pad lacking a slurry-transport groove.

9. The apparatus of claim 1 , wherein the controller is configured to:
perform a frequency domain analysis of the measurements received from the sensor of the in-situ pad vibration monitoring system.

10. The apparatus of claim 2 , wherein the controller is configured to detect a polishing endpoint based on the frequency domain analysis.

11. The apparatus of claim 1 , wherein the controller is configured to, in response to the measurements from the sensor of the in-situ pad vibration monitoring system:
adjust a current pressure of the carrier head; or
adjust a baseline pressure of a subsequent polishing of a new substrate.

12. The apparatus of claim 1 , wherein the sensor is configured to receive the reflected light beam at a sampling frequency of 250 kHz or more.

13. The apparatus of claim 1 , wherein the sensor is configured to receive the reflected light beam at a sampling frequency of 395 kHz.

14. A method, comprising:
generating relative motion between a substrate and a polishing pad of a chemical mechanical polishing apparatus;
generating a light beam, wherein the light beam is reflected from a reflective surface parallel with a polishing surface of the polishing pad;
receiving the reflected light beam with a sensor of the chemical mechanical polishing apparatus; and
determining a polishing endpoint of a substrate supported by the chemical mechanical polishing apparatus based on the reflected light beam, wherein the reflected light beam is indicative of a vibration of the reflective surface in a direction normal to the polishing surface.

15. The method of claim 14 , further comprising determining a frequency domain analysis of the reflected light beam.

16. The method of claim 15 , wherein the determining the polishing endpoint is based on the frequency domain analysis.

17. The method of claim 15 , wherein the determining a frequency domain analysis comprises performing a Fast Fourier Transform (FFT), or a wavelet packet transform (WPT).

18. The method of claim 15 , further comprising:
adjusting a current pressure of a carrier head; or
adjusting a baseline pressure of a subsequent polishing of a new substrate based upon the frequency domain analysis.

Assignees

• Applied Materials Inc

Inventors

• Oh Jeonghoon
• Osterheld Thomas H
• Zuniga Steven M

Classifications

• H10P95/062

  involving a dielectric removal step · CPC title

• H10P52/403

  of conductive or resistive materials · CPC title

• H10P52/402

  of semiconductor materials · CPC title

• 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

• B24B37/042

  operating processes therefor · CPC title