POLISHING PAD FOR EDDY CURRENT MONITORING

• US 20080003936A1
• Filed: 08/21/2007
• Published: 01/03/2008
• Est. Priority Date: 05/19/2000
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Birang, Manoocher, Swedek, Boguslaw
• Application Number:
  US11/842,829
• Publication Number:
  US 20080003936A1
• Time in Patent Office: Days
• US Class Current: 451/527
• 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 49/02 according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent B24B49/12 takes precedence
• CPC Class Codes: B24B 49/105 using eddy currents
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: G01B 7/105 for measuring thickness of coating

Abstract

A sensor for monitoring a conductive film in a substrate during chemical mechanical polishing generates an alternating magnetic field that impinges a substrate and induces eddy currents. The sensor can have a core, a first coil wound around a first portion of the core and a second coil wound around a second portion of the core. The sensor can be positioned on a side of the polishing surface opposite the substrate. The sensor can detect a phase difference between a drive signal and a measured signal.

Claims

1. A polishing pad, comprising

a unitary polishing layer having a polishing surface and a back surface, the polishing layer having a recess in the back surface extending partially but not entirely through the polishing layer, the recess defining a recessed inner surface and a thinned region of the polishing layer between the recessed inner surface and the polishing surface;

and

a backing layer secured to and abutting the back surface of the polishing layer, the backing layer including an aperture therethrough aligned with the recess.

2. The polishing pad of claim 1, wherein the polishing layer is a foamed material.

3. The polishing pad of claim 2, wherein the foamed material is polyurethane.

4. The polishing pad of claim 1, wherein the polishing layer is formed of a cast material with hollow microspheres.

5. The polishing pad of claim 4, wherein the cast material is polyurethane.

6. The polishing pad of claim 1, wherein a top surface of the thinned region is coplanar with a portion of the polishing surface surrounding the top surface of the thinned region.

7. The polishing pad of claim 1, wherein the thinned region is connected to the polishing layer such that a portion of a top surface of the thinned region is constrained from moving vertically relative to a portion of the polishing surface surrounding the thinned region.

8. The polishing pad of claim 1, wherein the aperture has the same width as the recess.

9. The polishing pad of claim 1, further comprising a plurality of grooves formed in the polishing surface.

10. The polishing pad of claim 1, wherein the polishing layer is harder than the backing layer.