IP Library › Granted Patent US 12678914
Granted Patent B2
US 12678914 · App. 17/858,000 · Granted Jul 14, 2026

Acoustic window in pad polishing and backing layer for chemical mechanical polishing

Inventors: Nicholas A. Wiswell (Sunnyvale, CA); Benjamin Cherian (San Jose, CA); Thomas H. Osterheld (Mountain View, CA); Jason Garcheung Fung (Santa Clara, CA)
Assignee: Applied Materials, Inc.
B24B37/205B24B37/013B24B37/22B24B37/24B24B49/003B24B49/10
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Quick Facts
Patent No.
US 12678914
App. No.
17/858,000
Granted
Jul 14, 2026
Kind
B2
Abstract

Disclosed herein is a polishing pad includes a polishing layer, a backing layer, and an acoustic window extending through the backing layer and the polishing layer, wherein an upper surface of the acoustic window is coplanar with a polishing surface of the polishing layer and a chemical mechanical polishing apparatus including a platen; a polishing pad supported on the platen; a carrier head to hold a substrate against the polishing pad; a motor to generate relative motion between the platen and the carrier head so as to polish an overlying layer of the substrate; an in-situ acoustic monitoring system comprising an acoustic sensor coupled to the acoustic window to receive acoustic signals from the substrate; and a controller configured to detect a polishing transition point based on received acoustic signals from the in-situ acoustic monitoring system.

Claims (27)

1 . A polishing pad comprising:

a polishing layer;

a backing layer; and

an acoustic window of solid material extending through the backing layer and the polishing layer, wherein the acoustic window is in direct contact with the backing layer and the polishing layer, the acoustic window has a first acoustic attenuation coefficient that is lower than a second acoustic attenuation coefficient of the backing layer, the polishing layer, or both, an upper surface of the acoustic window is coplanar with a polishing surface of the polishing layer, and a lower surface of the acoustic window is coplanar with a bottom surface of the backing layer.

2 . The polishing pad of claim 1 , where the polishing layer is porous and the acoustic window is non-porous.

3 . The polishing pad of claim 2 , wherein the acoustic window comprises a first matrix material including a first polymer and a second polymer and the polishing layer comprises a second matrix material having pores, the second matrix material including the first polymer and the second polymer in a different percentage contribution than the first matrix material so as to provide the same compressibility.

4 . The polishing pad of claim 3 , wherein the backing layer comprises a third matrix material including the first polymer and the second polymer, the third matrix material including the first polymer and the second polymer in a different percentage contribution than the second matrix material such that the backing layer is more compressible than the polishing layer.

5 . The polishing pad of claim 1 , wherein the polishing layer comprises a matrix material with liquid filled pores.

6 . The polishing pad of claim 1 , wherein the acoustic window is non-porous.

7 . The polishing pad of claim 1 , wherein the acoustic window comprises a matrix material with liquid filled pores.

8 . The polishing pad of claim 7 , wherein the polishing layer comprises a matrix material with air filled pores.

9 . The polishing pad of claim 1 , wherein the acoustic window and the polishing layer are secured by an interface of intermingled polymer.

10 . The polishing pad of claim 9 , wherein the acoustic window and the backing layer are secured by another interface of intermingled polymer.

11 . The polishing pad of claim 1 , wherein the acoustic window has the same compressibility as the polishing layer.

12 . The polishing pad of claim 1 , wherein the backing layer is more compressible than the polishing layer.

13 . The polishing pad of claim 1 , wherein the acoustic window has a diameter less than or equal to a diameter of an acoustic sensor contacting the acoustic window.

14 . The polishing pad of claim 1 , wherein the acoustic window is opaque.

15 . A chemical mechanical polishing apparatus, comprising:

a platen;

a polishing pad according to claim 1 supported on the platen;

a carrier head to hold a substrate against the polishing pad;

a motor to generate relative motion between the platen and the carrier head so as to polish an overlying layer of the substrate;

an in-situ acoustic monitoring system comprising an acoustic sensor having a flat upper-most surface secured to a flat lower-most surface of the acoustic window to receive acoustic signals from the substrate, and the lower surface of the acoustic window is coplanar with a bottom surface of the backing layer; and

a controller configured to detect a polishing transition point based on received acoustic signals from the in-situ acoustic monitoring system.

16 . The apparatus of claim 15 , wherein the controller is configured to change a polishing parameter based on detection of the polishing transition point.

17 . The apparatus of claim 15 , wherein the controller is configured to halt polishing in response to detection of the polishing transition point.

18 . The apparatus of claim 15 , wherein the flat upper-most surface of the acoustic sensor is directly contacted to the flat lower-most surface of the acoustic window.