TEMPERATURE ENHANCED ELECTROSTATIC CHUCKING IN PLASMA PROCESSING APPARATUS

• US 20120052690A1
• Filed: 04/05/2011
• Published: 03/01/2012
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: BELOSTOTSKIY, Sergey G., CHAFIN, Michael G., LIU, Jingbao, PALAGASHVILI, David
• Granted Patent: US 8,580,693 B2
• Time in Patent Office: Days
• US Class Current: 438/715
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the objects or the material; Means for adjusting diaphragms or lenses associated with the support introducing the objects H01J37/18
• CPC Class Codes: H01J 37/32715 Workpiece holder
• CPC Class Codes: H01J 37/32724 Temperature
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/6831 using electrostatic chucks

Abstract

Methods and systems for temperature enhanced chucking and dechucking of resistive substrates in a plasma processing apparatus are described herein. In certain embodiments, methods and systems incorporate modulating a glass carrier substrate temperature during a plasma etch process to chuck and dechuck the carrier at first temperatures elevated relative to second temperatures utilized during plasma etching. In embodiments, one or more of plasma heat, lamp heat, resistive heat, and fluid heat transfer are controlled to modulate the carrier substrate temperature between chucking temperatures and process temperatures with each run of the plasma etch process.

Claims

1. A method for clamping a workpiece in a plasma etch process, comprising:

providing a workpiece on an electrostatic chuck (ESC) disposed with a plasma etch chamber;

heating the workpiece to a chucking temperature;

clamping the workpiece to the ESC upon reaching the chucking temperature;

cooling the workpiece from the chucking temperature to a process temperature;

plasma etching a feature into the workpiece while at the process temperature;

heating the workpiece from the process temperature up to a dechucking temperature; and

unclamping the workpiece from the ESC upon reaching the dechucking temperature.

2. The method of claim 1, wherein the workpiece comprises a semiconductor substrate affixed to a glass carrier substrate.

3. The method of claim 1, wherein the difference between the process temperature and at least one of the chucking and dechucking temperatures is at least 35°

C.

4. The method of claim 3, wherein the process temperature is below 15°

C. and both the chucking and dechucking temperatures are above 50°

C.

5. The method of claim 1, wherein heating the workpiece to the chucking and the dechucking temperatures further comprises at least one of plasma heating, radiative heating, or conductive heating from the ESC.

6. The method of claim 5, wherein heating the workpiece to the chucking temperature further comprises providing a heat transfer fluid at a first temperature to the ESC, wherein cooling the workpiece from the chucking temperature to the process temperature further comprises providing a heat transfer fluid at a second temperature to the ESC, and wherein heating the workpiece from the process temperature up to the dechucking temperature further comprises providing a heat transfer fluid at the first temperature to the ESC.

7. The method of claim 6, wherein providing the heat transfer fluid at the first and second temperatures further comprises modulating a pulse width modulation (PWM) duty cycle of a first valve through which a cooled fluid flows and a second valve through which a heated fluid flows.

8. The method of claim 6, wherein providing the heat transfer fluid at the first and second temperatures further comprises switching the heat transfer fluid source between a first heat exchanger operating at the first temperature and a second heat exchanger operating at the second temperature.

9. The method of claim 5, wherein the plasma heating comprises energizing a plasma with a bias power to induce ion bombardment of the workpiece.

10. The method of claim 9, wherein heating the workpiece to the chucking temperature further comprises energizing a plasma with both a source power exceeding 1000 W and a bias power under 1000 W.

11. The method of claim 10, wherein heating the workpiece to the dechucking temperature further comprises energizing a plasma with both a source power exceeding 1000 W and a bias power under 1000 W.

12. The method of claim 1, wherein unclamping the workpiece from the ESC further comprises changing a DC voltage applied to the ESC while plasma etching the feature, wherein the voltage change is performed prior to heating the workpiece to the dechucking temperature.

13. The method of claim 1, wherein unclamping the workpiece from the ESC further comprises changing a backside helium pressure applied to the workpiece while plasma etching the feature, wherein the backside helium change is performed prior to heating the workpiece to the dechucking temperature.

14. A computer readable storage media with instructions stored thereon, which when executed by a processing system, cause the system to perform the method of claim 1.

15. A plasma processing apparatus, comprising:

an electrostatic chuck (ESC) disposed with a plasma etch chamber to clamp a workpiece during a plasma process;

a first heat exchanger coupled to the ESC; and

a heat source to heat the workpiece to a first temperature that is greater than a setpoint of the first heat exchanger, wherein the heat source is to heat the workpiece to the first temperature until completion of a workpiece chucking sequence, and wherein the first heat exchanger is to cool the ESC to a second temperature following completion of the workpiece chucking sequence.

16. The apparatus of claim 15, wherein the heat source is at least one of:

a second heat exchanger, a lamp, an RF plasma bias power generator.

17. The apparatus of claim 16, further comprising:

one or more switched valves to decouple the first heat exchanger from the ESC and to couple the second heat exchanger to the ESC to cool the ESC from the first temperature to the second temperature in response to completion of a workpiece chucking sequence.

18. The apparatus of claim 17, wherein a setpoint of the first heat exchanger is at least 35°

C. higher than a setpoint of the second heat exchanger.

19. The apparatus of claim 16, further comprising a controller to reduce a backside helium pressure while the RF plasma bias power is heating the workpiece.

20. The apparatus of claim 16, further comprising a controller to discontinue the RF plasma bias power in response to a backside helium leak rate increase during execution of a dechucking sequence.