Workpiece carrier with adjustable pressure zones and barriers

• US 6,390,905 B1
• Filed: 03/31/2000
• Issued: 05/21/2002
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: SpeedFam-Ipec Corporation (Lam Research Corporation)
• Inventors: Schultz, Stephen C., Korovin, Nikolay N., Herb, John D., Farmer, James L.
• Primary Examiner(s): Eley, Timothy V.
• Assistant Examiner(s): NGUYEN, DUNG V
• Application Number:
  US09/540,476
• Time in Patent Office: 781 Days
• Field of Search: 451/285, 451/286, 451/287, 451/288, 451/289, 451/388, 451/398, 451/41
• US Class Current: 451/286
• CPC Class Codes: B24B 37/30 for single side lapping of plane surfaces
• CPC Class Codes: B24B 37/32 Retaining rings
• CPC Class Codes: B24B 49/16 taking regard of the load

Abstract

An apparatus and method are disclosed for planarizing a wafer in a carrier with adjustable pressure zones and adjustable barriers between zones. The carrier has an independently controlled central zone and concentric surrounding zones for distributing the pressure on the backside of a wafer while the wafer is being pressed against an abrasive surface in a chemical-mechanical polishing tool. The pressure zones may be created by mounting an elastic web diaphragm to a carrier housing that has a plurality of recesses. A corresponding plurality of elastic ring shaped ribs may extend from the web diaphragm opposite the recesses. The plurality of ring shaped ribs thereby defines a central zone surrounded by one or more concentric surrounding zones. The zones and barriers may be individually pressurized by utilizing corresponding fluid communication paths during the planarization process.

A method for practicing the present invention starts by selecting a carrier with adjustable pressure zones that correspond to the number and locations of the bulges and troughs on the wafer. Zones that correspond to high regions receive greater pressure than zones that correspond to low regions on the wafer. The pressure on the barriers between zones may be optimized to prevent leakage between zones or to smooth the pressure distribution between neighboring zones on the back surface of the wafer.

Claims

1. A carrier for planarizing a surface of a wafer comprising:

a carrier housing;

a web diaphragm having a first and a second major surface supported by the carrier housing;

a plurality of ring shaped ribs each having a head and a foot, wherein the head of each rib is connected orthogonally to the first major surface of the web diaphragm thereby defining a plurality of concentric web plenums;

a plurality of individually controllable web fluid communication paths, each in fluid communication with one of the corresponding plurality of web plenums;

a plurality of recesses adjacent the second major surface of the web diaphragm, each of the plurality of recesses opposite one of the plurality of ring shaped ribs thereby defining a plurality of ring shaped carrier plenums; and

a plurality of individually controlled carrier fluid communication paths in fluid communication with the corresponding plurality of carrier plenums for controlling the pressure in the plurality of carrier plenums exerted on the plurality of spaced apart ring shaped ribs.

2. A carrier as in claim 1 wherein the web diaphragm and the plurality of ring shaped ribs are both made from a single piece of elastic material.

3. A carrier as in claim 1 further comprising:

a) plurality of clamping rings for connecting the web diaphragm or ribs to the carrier housing.

4. A carrier as in claim 1 wherein at least one of the rib feet is flat.

5. A carrier as in claim 1 wherein at least one of the rib feet is rounded.

6. A carrier as in claim 1 wherein at least one of the rib feet is adapted to be self-sealing.

7. A carrier as in claim 6 further comprising:

a) a rib vacuum line routed through a rib for communicating a vacuum near the rib foot.

8. A carrier as in claim 1 further comprising:

a retaining ring diaphragm connected to the periphery of the carrier housing;

a retaining ring connected to the retaining ring diaphragm; and

wherein the carrier housing has a retaining ring recess opposite the retaining ring diaphragm thereby defining a retaining ring diaphragm.

9. A carrier as in claim 8 further comprising:

a) a retaining ring fluid communication path in fluid communication with the retaining ring plenum for controlling the pressure on the retaining ring.

10. A carrier as in claim 8, wherein the inner diameter of the retaining ring is coated with a material softer than the wafer.

11. A carrier for planarizing a surface of a wafer comprising:

a carrier housing;

a wafer diaphragm having a first and a second major surface, the first major surface adapted for contacting a wafer;

a plurality of spaced apart ring shaped ribs, each coupled at one end to the second major surface of the wafer diaphragm and at the opposite end to the carrier housing thereby defining, in combination with the carrier housing and the wafer diaphragm, a plurality of concentric web plenums;

a plurality of individually controllable web fluid communication paths in fluid communication with the corresponding plurality of web plenums for controlling the pressure in each of the plurality of concentric web plenums;

a plurality of concentric ring shaped carrier plenums formed in the carrier housing and aligned with the plurality of spaced apart ring shaped ribs; and

a plurality of individually controlled carrier fluid communication paths in fluid communication with the corresponding plurality of carrier plenums for controlling the pressure in the plurality of carrier plenums exerted on the plurality of spaced apart ring shaped ribs.

12. A carrier as in claim 11 further comprising:

a plurality of clamping rings for connecting the ribs to the carrier housing.

13. A carrier as in claim 11 further comprising:

a retaining ring diaphragm connected to the periphery of the carrier housing;

a retaining ring connected to the retaining ring diaphragm; and

wherein the carrier housing has a retaining ring recess opposite the retaining ring diaphragm thereby defining a retaining ring diaphragm.