APPARATUS FOR DETECTION OF THIN FILMS DURING CHEMICAL/MECHANICAL POLISHING PLANARIZATION

• US 20080060758A1
• Filed: 10/24/2007
• Published: 03/13/2008
• Est. Priority Date: 12/28/1992
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Tang, Wallace
• Granted Patent: US 7,582,183 B2
• Time in Patent Office: Days
• US Class Current: 156/345.13
• 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 49/12 involving optical means
• CPC Class Codes: G01B 11/0683 measurement during deposition or removal of the layer
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32

Abstract

A technique and apparatus is disclosed for the optical monitoring and measurement of a thin film (or small region on a surface) undergoing thickness and other changes while it is rotating. An optical signal is routed from the monitored area through the axis of rotation and decoupled from the monitored rotating area. The signal can then be analyzed to determine an endpoint to the planarization process. The invention utilizes interferometric and spectrophotometric optical measurement techniques for the in situ, real-time endpoint control of chemical-mechanical polishing planarization in the fabrication of semiconductor or various optical devices. The apparatus utilizes a bifurcated fiber optic cable to monitor changes on the surface of the thin film.

Claims

1. An apparatus for chemical mechanical polishing of a wafer, comprising:

a platen to support a polishing pad having a polishing surface;

a chuck to hold the wafer against the polishing surface;

a motor coupled to the platen to move the platen to generate relative motion between the polishing surface and the wafer; and

an endpoint detector, comprising

a light source positioned and operable to generate a light beam that is directed through the polishing pad to the wafer and produce, from the light beam that is directed through the polishing pad, a light beam reflected from the wafer, and

a receiver positioned and operable to receive the light beam reflected from the wafer directed through the polishing pad, wherein the endpoint detector is operable to determine, based on the light beam reflected from the wafer, when an end point is reached.

2. The apparatus of claim 1, wherein the light source is a laser source and the light beam is a laser beam.

3. The apparatus of claim 2, wherein the laser beam has a wavelength of 632.8 nanometers.

4. The apparatus of claim 1, wherein the receiver comprises a spectrophotometer.

5. The apparatus of claim 1, further comprising a fiber optic cable situated to convey light from the light source to the wafer.

6. The apparatus of claim 1, further comprising a fiber optic cable situated to convey light reflected from the wafer to the receiver.

7. The apparatus of claim 1, wherein the light source is operable to illuminate the wafer at timed intervals.