Substrate polishing metrology using interference signals

• US 8,556,679 B2
• Filed: 01/06/2012
• Issued: 10/15/2013
• Est. Priority Date: 03/28/1995
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Birang, Manoocher, Pyatigorsky, Grigory
• Primary Examiner(s): Wilson, Lee D
• Application Number:
  US13/345,487
• Publication Number:
  US 20120107971A1
• Time in Patent Office: 648 Days
• Field of Search: 451/6, 451/5, 451/28, 451/41, 451/285, 451/287, 451/526, 451/286, 451/288, 451/9, 451/289, 451/10, 156/636.1, 156/626, 438/16
• US Class Current: 451/6
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/205 provided with a window for inspecting the surface of the work being lapped
• CPC Class Codes: B24B 47/12 by mechanical gearing or electric power B24B47/16 takes precedence
• CPC Class Codes: B24B 49/04 involving measurement of the workpiece at the place of grinding during grinding operation
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: B24B 51/00 Arrangements for automatic control of a series of individual steps in grinding a workpiece if applicable to other machine tools, G05B takes precedence
• CPC Class Codes: G01B 11/06 for measuring thickness ; e.g. of sheet material thickness measurement by thermal means G01B21/085
• CPC Class Codes: G01B 11/0683 measurement during deposition or removal of the layer

Abstract

A polishing pad assembly for a chemical mechanical polishing apparatus includes a polishing pad having a polishing surface and a surface opposite the polishing surface for attachment to a platen, and a solid light-transmissive window formed in the polishing pad. The light-transmissive window is more transmissive to light than the polishing pad. The light-transmissive window has a light-diffusing bottom surface.

Claims

1. A method of in-situ optical monitoring of a substrate during chemical mechanical polishing, comprising:

directing a light beam onto the substrate during chemical mechanical polishing;

measuring an intensity of a reflection of the light beam from the substrate and to generate a signal;

passing the signal through a high frequency filter; and

passing the signal through a low frequency filter.

2. The method of claim 1, wherein passing the signal through the high frequency filter generates a first output signal, passing the signal through the low frequency filter generates a second output signal, and the method comprises combining the first output signal and the second output signal to generate a combined output signal.

3. The method of claim 2, comprising determining a first amplitude of the first output signal and determining a second amplitude of the second output signal.

4. The method of claim 3, wherein combining the first output signal and the second output signal comprises calculating a ratio of the first amplitude to the second amplitude.

5. The method of claim 4, further comprising comparing the ratio to a threshold.