Acoustic Emission Monitoring and Endpoint for Chemical Mechanical Polishing

• US 20160256978A1
• Filed: 03/05/2015
• Published: 09/08/2016
• Est. Priority Date: 03/05/2015
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Ishikawa, David Masayuki, Tang, Jianshe, Cherian, Benjamin, Oh, Jeonghoon, Osterheld, Thomas H.
• Granted Patent: US 10,478,937 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 49/003 involving acoustic means

Abstract

A chemical mechanical polishing apparatus includes a platen to support a polishing pad, and an in-situ acoustic emission monitoring system including an acoustic emission sensor supported by the platen, a waveguide configured to extending through at least a portion of the polishing pad, and a processor to receive a signal from the acoustic emission sensor. The in-situ acoustic emission monitoring system is configured to detect acoustic events caused by deformation of the substrate and transmitted through the waveguide, and the processor is configured to determine a polishing endpoint based on the signal.

Claims

1. A chemical mechanical polishing apparatus, comprising:

a platen to support a polishing pad; and

an in-situ acoustic monitoring system to generate a signal, the in-situ acoustic monitoring system including an acoustic emission sensor supported by the platen and a waveguide positioned to couple the acoustic emission sensor to slurry in a groove in the polishing pad.

2. The apparatus of claim 1, comprising the polishing pad, the polishing pad having a polishing layer and a plurality of slurry-transport grooves in a polishing surface of the polishing layer, and wherein the waveguide extends through the polishing pad and into the groove.

3. The apparatus of claim 2, wherein a tip of the waveguide is positioned below the polishing surface.

4. The apparatus of claim 1, wherein the in-situ acoustic monitoring system comprises a plurality of parallel waveguides.

5. The apparatus of claim 1, wherein a position of the waveguide is vertically adjustable.

6. A chemical mechanical polishing apparatus, comprising:

a platen to support a polishing pad; and

an in-situ acoustic monitoring system to generate a signal, the in-situ acoustic monitoring system including an acoustic sensor supported by the platen, a body of polishing pad material that is mechanically decoupled from the polishing pad, and a waveguide that couples the acoustic sensor to the body of polishing pad material.

7. The apparatus of claim 6, comprising the polishing pad, and wherein the polishing pad material is a same material as a polishing layer in the polishing pad.

8. The apparatus of claim 6, comprising the polishing pad, and wherein the body is separated from the polishing pad by a gap.

9. The apparatus of claim 8, further comprising a seal to prevent slurry leakage through the gap.

10. The apparatus of claim 6, comprising a flushing system to direct fluid into a recess below a tip of the waveguide.

11. A chemical mechanical polishing apparatus, comprising:

a platen to support a polishing pad; and

a pad cord support configured to hold a cord of polishing material in an aperture in the polishing pad.

12. The apparatus of claim 11, wherein the pad cord support comprises a feed reel and a take-up reel, and the pad cord support is configured to guide the pad cord from the feed reel to the take-up reel.

13. The apparatus of claim 11, comprising an in-situ acoustic monitoring system to generate a signal, the in-situ acoustic monitoring system including an acoustic sensor supported by the platen, and a waveguide that couples the acoustic sensor to a region below the pad cord.

14. The apparatus of claim 13, comprising a flushing system to direct fluid into a region between the waveguide and the pad cord.

15. The apparatus of claim 13, wherein a tip of the waveguide comprises a slot to receive the pad cord.

16. The apparatus of claim 11, comprising the polishing pad and the pad cord, and wherein the cord is separated from the polishing pad by a gap.

17. A chemical mechanical polishing apparatus, comprising:

a platen to support a polishing pad; and

an in-situ acoustic monitoring system comprising a plurality of acoustic sensors supported by the platen at a plurality of different positions; and

a controller configured to receive signals from the plurality of acoustic sensors and determine a position on the substrate of an acoustic event from the signals.

18. The apparatus of claim 17, wherein the controller is configured to determine a time difference between the acoustic event in the signals, and determining the position based on the time difference.

19. The apparatus of claim 18, wherein the in-situ monitoring system comprises at least three acoustic sensors and the controller is configured to triangulate the position of the acoustic event.

20. The apparatus of claim 18, wherein the acoustic event is represented in the signals by a burst-type emission.

21. The apparatus of claim 17, wherein the controller is configured to determine a radial distance of the event from a center of the substrate.

22. The apparatus of claim 17, wherein the plurality of acoustic sensors are positioned at different radial distances from an axis of rotation of the platen.

23. The apparatus of claim 17, wherein the plurality of acoustic sensors are positioned at different angular positions around an axis of rotation of the platen.