Methods for implementing highly efficient plasma traps

• US 8,048,329 B2
• Filed: 07/16/2009
• Issued: 11/01/2011
• Est. Priority Date: 12/23/2005
• Status: Expired due to Fees

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Kamarehi, Mohammad, Wang, Ing-Yann Albert
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US12/504,525
• Publication Number:
  US 20090278054A1
• Time in Patent Office: 838 Days
• Field of Search: None
• US Class Current: 216/70
• CPC Class Codes: H01J 37/32211 Means for coupling power to the plasma
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

A method for minimizing microwave leakage into processing chamber of a microwave plasma system is provided. The method includes securing plasma traps to a plasma tube assembly, which is a cylindrical structure positioned upstream from the processing chamber and has a plasma-sustaining region. The plasma traps are electrically conductive disks surrounding the cylindrical structure and are positioned upstream from the processing chamber. The plasma traps include at least two electrically conductive disks. Each electrically conductive disk includes corrugated outer surfaces with plurality of corrugated peaks. The corrugated outer surface of the first electrically conductive disk is facing a corrugated outer surface of the second electrically conductive disk in a space-apart relationship to form an interstitial region between the electrically conductive disks. Both electrically conductive disk and the interstitial region form one of a set of upstream plasma traps and a set of downstream plasma traps relative to the plasma-sustaining region.

Claims

1. A method for minimizing microwave leakage into a processing chamber of a microwave plasma system, wherein said microwave plasma system is configured for generating plasma and channeling at least a portion of said plasma downstream to said processing chamber, comprising:

providing a plasma tube assembly, wherein said plasma tube assembly is a cylindrical structure positioned upstream from said processing chamber, said plasma tube assembly including a plasma-sustaining region, wherein said plasma is formed when a gas mixture interacts with microwave power within said plasma-sustaining region; and

securing a first set of plasma traps to said plasma tube assembly, said first set of plasma traps being a first set of electrically conductive disks surrounding said cylindrical structure, wherein said first set of plasma traps being positioned upstream from said processing chamber and said first set of plasma traps including at least

a first electrically conductive disk with a first downstream corrugated outer surface and a first upstream corrugated outer surface, said first downstream corrugated outer surface and said first upstream corrugated outer surface including a plurality of corrugated peaks, and

a second electrically conductive disk with a second downstream corrugated outer surface and a second upstream corrugated outer surface, said second downstream corrugated outer surface and said second upstream corrugated outer surface including a plurality of corrugated peaks, wherein a corrugated outer surface of said second electrically conductive disk is facing a corrugated outer surface of said first electrically conductive disk in a space-apart relationship so as to form a first interstitial region between said first electrically conductive disk and said second electrically conductive disk, whereby said first electrically conductive disk, said second electrically conductive disk, and said first interstitial region form one of a set of upstream plasma traps and a set of downstream plasma traps relative to said plasma-sustaining region of said plasma tube assembly.

2. The method of claim 1 wherein said first set of plasma traps form said set of downstream plasma traps that is disposed downstream from said plasma-sustaining region, said method further including securing a second set of plasma traps to said plasma tube assembly, said second set of plasma traps being said set of upstream plasma traps, said set of upstream plasma traps being a second set of electrically conductive disks surround said cylindrical structure, wherein said set of upstream plasma traps being positioned upstream from said plasma-sustaining region and including at least

a third electrically conductive disk with a third downstream corrugated outer surface and a third upstream corrugated outer surface, said third downstream corrugated outer surface and said third upstream corrugated outer surface including a plurality of corrugated peaks, and

a fourth electrically conductive disk with a fourth downstream corrugated outer surface and a fourth upstream corrugated outer surface, said fourth downstream corrugated outer surface and said fourth upstream corrugated outer surface including a plurality of corrugated peaks, wherein said fourth electrically conductive disk is positioned upstream from said third electrically conductive disk, wherein said third upstream corrugated outer surface is facing said fourth downstream corrugated outer surface in a space-apart relationship so as to form a second interstitial region between said third electrically conductive disk and said fourth electrically conductive disk.

3. The method of claim 2 wherein said first set of electrically conductive disks is one of a set of hollow center electrically conductive disks and a set of solid center electrically conductive disks.

4. The method of claim 2 wherein said second set of electrically conductive disks is one of a set of hollow center electrically conductive disks and a set of solid center electrically conductive disks.

5. The method of claim 2 wherein said first interstitial region forms one of

an air gap, and

a solid material other than air.

6. The method of claim 2 wherein said second interstitial region forms one of

an air gap, and

a solid material other than air.

7. The method of claim 2 wherein said second electrically conductive disk is positioned downstream from said first electrically conductive disk, wherein said plurality of corrugated peaks of said first downstream corrugated outer surface are offset relative to said plurality of corrugated peaks of said second upstream corrugated outer surface.

8. The method of claim 2 wherein said set of downstream plasma traps further includes a fifth electrically conductive disk with a fifth downstream corrugated outer surface and a fifth upstream corrugated outer surface, said fifth downstream corrugated outer surface and said fifth upstream corrugated outer surface including plurality of corrugated peaks, wherein said fifth electrically conductive disk is positioned downstream from said second electrically conductive disk, wherein said fifth upstream corrugated outer surface is facing said second downstream corrugated outer surface in a space-apart relationship so as to form a third interstitial region between said second electrically conductive disk and said fifth electrically conductive disk.

9. The method of claim 2 further including securing a downstream cooling manifold to said plasma tubing arrangement, said downstream cooling manifold being disposed in at least one of a first assembly arrangement and a second assembly arrangement relative to said set of downstream plasma traps, said first assembly arrangement being characterized by having substantially no air gap between an upstream-facing surface of said downstream cooling manifold and a downstream-facing surface of said set of downstream plasma traps, said second assembly arrangement being characterized by said downstream cooling manifold being disposed adjacent to said set of downstream plasma traps.

10. A method for containing plasma within a plasma tube assembly of a downstream microwave plasma system, said downstream microwave plasma system being configured for generating plasma within a plasma-sustaining region of said plasma tube assembly and channeling at least a portion of said plasma downstream to a processing chamber of said downstream microwave plasma system, comprising:

providing a first hollow center electrically conductive disk surrounding a cylindrical structure that defines a plasma passage of said plasma tube assembly;

securing a second hollow center electrically conductive disk in a spaced-apart relationship relative to said first hollow center electrically conductive disk so as to form a first hollow center disk-shape interstitial region between said first hollow center electrically conductive disc and said second hollow center electrically conductive disc, said second hollow center electrically conductive disk also surrounding said cylindrical structure; and

securing a third hollow center electrically conductive disk in a spaced-apart relationship relative to said second hollow center electrically conductive disk so as to form a second hollow center disk-shape interstitial region between said third hollow center electrically conductive disc and said second hollow center electrically conductive disc, said third hollow center electrically conductive disk also surrounding said cylindrical structure, whereby said first hollow center electrically conductive disk, said second hollow center electrically conductive disk, said third hollow center electrically conductive disk, said first hollow center disk-shape interstitial region, and said second hollow center disk-shape interstitial region form one of a set of upstream plasma traps and a set of downstream plasma traps relative to said plasma-sustaining region of said plasma tube assembly.

11. The method of claim 10 wherein said first hollow center electrically conductive disk, said second hollow center electrically conductive disk and said third hollow center electrically conductive disk are formed of aluminum.

12. The method of claim 10 wherein said first hollow center electrically conductive disk has at least a first corrugated surface facing one of an upstream direction and a downstream direction.

13. The method of claim 10 wherein said second hollow center electrically conductive disk has at least a second corrugated surface facing said first corrugated surface.

14. The method of claim 10 wherein said cylindrical structure includes an inner cylindrical wall and an outer cylindrical wall, a space between said inner cylindrical wall and said outer cylindrical wall being employed to circulate a heat-exchange fluid to facilitate heat transfer from said cylindrical structure to said heat-exchange fluid.

15. The method of claim 10 wherein corrugated peaks in said first corrugated surface are offset relative to corrugated peaks in said second corrugated surface.

16. The method of claim 15 wherein said first hollow center disk-shape interstitial region and said second hollow center disk-shape interstitial region form air gaps.

17. The method of claim 15 wherein said first hollow center disk-shape interstitial region and said second hollow center disk-shape interstitial region are formed of a solid material other than air.

18. The method of claim 10 wherein said first hollow center electrically conductive disk, said second hollow center electrically conductive disk, and said first hollow center disk-shape interstitial region form said set of upstream plasma traps that is disposed upstream of a microwave waveguide, said method further including:

providing a fourth hollow center electrically conductive disk surrounding said cylindrical structure;

securing a fifth hollow center electrically conductive disk in a spaced-apart relationship relative to said fourth hollow center electrically conductive disk so as to form a third hollow center disk-shape interstitial region between said fourth hollow center electrically conductive disc and said fifth hollow center electrically conductive disc, said fifth hollow center electrically conductive disk also surrounding said cylindrical structure; and

securing a sixth hollow center electrically conductive disk in a spaced-apart relationship relative to said fifth hollow center electrically conductive disk so as to form a fourth hollow center disk-shape interstitial region between said sixth hollow center electrically conductive disc and said fifth hollow center electrically conductive disk, said sixth hollow center electrically conductive disk also surrounding said cylindrical structure, whereby said fourth hollow center electrically conductive disk, said fifth hollow center electrically conductive disk, said sixth hollow center electrically conductive disk, said third hollow center disk-shape interstitial region, and said fourth hollow center disk-shape interstitial region forming said set of downstream plasma traps that is disposed downstream relative to said microwave waveguide.

19. The method of claim 18 wherein said third hollow center disk-shape interstitial region and said fourth hollow center disk-shape interstitial region form air gaps.

20. The method of claim 18 wherein said third hollow center disk-shape interstitial region and said fourth hollow center disk-shape interstitial region are formed of a solid material other than air.