Workpiece carrier with adjustable pressure zones and barriers

• US 6,612,903 B2
• Filed: 01/22/2002
• Issued: 09/02/2003
• 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): NGUYEN, DUNG V
• Application Number:
  US10/053,974
• Publication Number:
  US 20020061716A1
• Time in Patent Office: 588 Days
• Field of Search: 451/9, 451/41, 451/285, 451/286, 451/287, 451/288, 451/289, 451/388, 451/398
• US Class Current: 451/9
• 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 method of planarizing a wafer comprising the steps of:

a) loading an incoming wafer into a carrier having a plurality of pressure adjustable concentric plenums and a pressure adjustable concentric barrier between every pair of neighboring plenums;

b) moving the carrier until the wafer is near or touches an abrasive surface;

c) determining a desired removal rate for a plurality of concentric zones on the wafer that correspond to the plurality of concentric plenums of the carrier;

d) pressing the wafer against the abrasive surface by pressurizing each concentric plenum of the carrier to correspond to a desired removal rate of material on a particular concentric zone on the wafer;

e) adjusting the pressure on each of the plurality of barriers between concentric plenums; and

f) causing relative motion between the wafer and the abrasive surface to planarize the wafer.

2. A method as in claim 1, wherein the barriers between neighboring plenums comprise elastic ribs.

3. A method as in claim 1, wherein the pressure on each of the plurality of barriers is equal to or greater than each of the pressures in the neighboring concentric plenums to prevent leakage between the neighboring plenums.

4. A method as in claim 1, wherein the pressure on each of the plurality of barriers is equal to or between the pressures in the neighboring concentric plenums to assist in a smooth transition of pressure on the backside of the wafer between neighboring plenums.

5. A method of planarizing a copper thin film deposited on a wafer or an STI wafer comprising the steps of:

a) loading an incoming wafer into a carrier comprising;

a pressure adjustable peripheral ring plenum;

a pressure adjustable intermediate ring plenum;

a pressure adjustable central disk plenum;

a pressure adjustable concentric barrier between the peripheral and intermediate plenum; and

a pressure adjustable concentric barrier between the intermediate and central disk plenum;

b) moving the carrier until the wafer is near or touches an abrasive surface;

c) pressing the wafer against the abrasive surface by pressurizing the peripheral, intermediate and central plenum, wherein the pressure in each of the peripheral and central plenums is at a higher pressure than the pressure in the intermediate plenum;

d) adjusting the pressure on each of the plurality of barriers between plenums; and

e) causing relative motion between the wafer and the abrasive surface to planarize the wafer.

6. A method as in claim 5, wherein the barriers between neighboring plenums comprise elastic ribs.

7. A method as in claim 5, wherein the pressure on each of the plurality of barriers is equal to or greater than each of the pressures in the neighboring plenums to prevent leakage between the neighboring plenums.

8. A method as in claim 5, wherein the pressure on each of the plurality of barriers is equal to or between the pressures in the neighboring plenums to assist in a smooth transition of pressure on the backside of the wafer between neighboring plenums.

9. A method of planarizing a copper thin film deposited on a wafer comprising the steps of:

a) loading an incoming wafer into a carrier comprising;

a pressure adjustable central ring plenum;

a pressure adjustable second ring plenum;

a pressure adjustable third ring plenum;

a pressure adjustable peripheral ring plenum;

a pressure adjustable first barrier between the central and second plenum;

a pressure adjustable second barrier between the second and third plenum; and

a pressure adjustable third barrier between the third and peripheral ring plenum;

b) moving the carrier until the wafer is near or touches an abrasive surface;

c) pressing the wafer against the abrasive surface by pressurizing the central, second, third and peripheral plenums, wherein the pressure in each of the central and peripheral plenums is at a higher pressure than the pressure in each of the second and third plenums;

d) adjusting the pressure on each of the plurality of barriers between plenums; and

e) causing relative motion between the wafer and the abrasive surface to planarize the wafer.

10. A method as in claim 9, wherein the barriers between neighboring plenums comprise elastic ribs.

11. A method as in claim 9, wherein the pressure on each of the plurality of barriers is equal to or greater than each of the pressures in the neighboring plenums to prevent leakage between the neighboring plenums.

12. A method as in claim 9, wherein the pressure on each of the plurality of barriers is equal to or between the pressures in the neighboring plenums to assist in a smooth transition of pressure on the backside of the wafer between neighboring plenums.

13. A method of planarizing an STI wafer comprising the steps of:

a) loading an incoming wafer into a carrier comprising;

a pressure adjustable central ring plenum;

a pressure adjustable second ring plenum;

a pressure adjustable third ring plenum;

a pressure adjustable peripheral ring plenum;

a pressure adjustable first barrier between the central and second plenum;

a pressure adjustable second barrier between the second and third plenum; and

a pressure adjustable third barrier between the third and peripheral ring plenum;

b) moving the carrier until the wafer is near or touches an abrasive surface;

c) pressing the wafer against the abrasive surface by pressurizing the central, second, third and peripheral plenums, wherein the pressure in each of the central, second and peripheral plenums is at a higher pressure than the pressure in the third plenum;

d) adjusting the pressure on each of the plurality of barriers between plenums; and

e) causing relative motion between the wafer and the abrasive surface to planarize the wafer.

14. A method as in claim 13, wherein the barriers between neighboring plenums comprise elastic ribs.

15. A method as in claim 13, wherein the pressure on each of the plurality of barriers is equal to or greater than each of the pressures in the neighboring plenums to prevent leakage between the neighboring plenums.

16. A method as in claim 13, wherein the pressure on each of the plurality of barriers is equal to or between the pressures in the neighboring plenums to assist in a smooth transition of pressure on the backside of the wafer between neighboring plenums.