Method of processing a workpiece in a plasma reactor with independent wafer edge process gas injection

• US 20090057269A1
• Filed: 09/05/2007
• Published: 03/05/2009
• Est. Priority Date: 09/05/2007
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Todorow, Valentin N., Willwerth, Michael D., Paterson, Alexander M., Palagashvili, David, Katz, Dan
• Granted Patent: US 7,879,250 B2
• Time in Patent Office: Days
• US Class Current: 216/67
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

The disclosure concerns a method of processing a workpiece or in a plasma reactor chamber, using independent gas injection at the wafer edge.

Claims

1. A method of processing a workpiece in a plasma reactor, comprising:

placing the workpiece on a workpiece support in chamber of the plasma reactor;

introducing a first process gas through a workpiece support process gas injector adjacent and surrounding the peripheral edge of said workpiece; and

coupling plasma RF source power into the plasma reactor to generate a plasma in said plasma reactor chamber.

2. The method of claim 1 further comprising:

introducing a second process gas into the chamber through a ceiling process gas disperser located at a ceiling of the chamber that overlies the workpiece support; and

controlling the gas flow rate through said workpiece support process gas injector independently of the gas flow rate through said ceiling process gas disperser.

3. The method of claim 2 wherein said ceiling process gas disperser comprises an outer gas disperser and an inner process gas disperser, said method further comprising:

adjusting gas flow rates through said inner and outer process gas dispersers to optimize process uniformity over a major portion of said workpiece; and

adjusting process gas flow rate through said workpiece support process gas injector to optimize processing at a peripheral zone of said workpiece.

4. The method of claim 3 wherein said peripheral zone corresponds to an outer 1% of the diameter of said workpiece.

5. The method of claim 1 wherein introducing a first process gas through a workpiece support process gas injector comprises supplying said first process gas through gas flow channels inside a portion of said workpiece support.

6. The method of claim 5 wherein introducing a first process gas through a workpiece support process gas injector further comprises conducting process gas received from said gas flow channels through a process ring surrounding said workpiece.

7. The method of claim 4 further comprising limiting gas flow rate through said workpiece support gas injector to confine the effect of the first process gas to said peripheral zone of said workpiece.

8. A method of etching a thin film on a workpiece, comprising:

placing the workpiece on a workpiece support in a plasma reactor chamber having a ceiling facing the workpiece support;

introducing an etchant species process gas through a ceiling gas disperser at said ceiling; and

introducing a selected gas toward the peripheral edge of the workpiece through a process ring adjacent and surrounding said edge of said workpiece.

9. The method of claim 8 wherein said selected gas is suitable for reducing gas residency time in a narrow zone over said peripheral edge of said workpiece.

10. The method of claim 8 wherein said selected gas comprises an inert gas.

11. The method of claim 8 wherein said selected gas comprises oxygen.

12. The method of claim 8 wherein said selected gas is suitable for increasing polymerization in a narrow zone at the peripheral edge of said workpiece.

13. The method of claim 8 wherein said selected gas comprises a polymerizing species.

14. The method of claim 13 wherein said polymerizing species comprises one of CH₂F₂ or CHF₃.

15. The method of claim 8 wherein said thin film comprises silicon and said etchant species process gas comprises at least one of HBr and Cl₂.

16. The method of claim 8 further comprising applying an electrostatic chuck voltage to an electrode beneath a workpiece support surface of said workpiece support.

17. The method of claim 8 wherein said ceiling process gas disperser comprises an outer gas disperser and an inner process gas disperser, said method further comprising:

adjusting gas flow rates through said inner and outer process gas dispersers to optimize process uniformity over a major portion of said workpiece; and

adjusting process gas flow rate through said workpiece support process gas injector to optimize processing at a peripheral zone of said workpiece.

18. The method of claim 9 or 12 wherein said peripheral zone corresponds to an outer 1% of the diameter of said workpiece.

19. The method of claim 8 wherein introducing the selected gas through the workpiece support process gas injector comprises supplying said selected gas through gas flow channels inside a portion of said workpiece support.

20. The method of claim 19 wherein introducing the selected gas through a workpiece support process gas injector further comprises conducting gas received from said gas flow channels through a process ring surrounding said workpiece.