Plasma treatment system

• US 20050269031A1
• Filed: 07/08/2005
• Published: 12/08/2005
• Est. Priority Date: 04/19/2002
• Status: Active Grant

• Current Assignee: Nordson Corporation
• Original Assignee: Nordson Corporation
• Inventors: Getty, James D., Tyler, James Scott, Bolden, Thomas V. II, Condrashoff, Robert Sergei
• Granted Patent: US 8,613,827 B2
• Time in Patent Office: Days
• US Class Current: 156/345.480
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma

Abstract

A plasma treatment system for treating a workpiece with a downstream-type plasma. The processing chamber of the plasma treatment system includes a chamber lid having a plasma cavity disposed generally between a powered electrode and a grounded plate, a processing space separated from the plasma cavity by the grounded plate, and a substrate support in the processing space for holding the workpiece. A direct plasma is generated in the plasma cavity. The grounded plate is adapted with openings that remove electrons and ions from the plasma admitted from the plasma cavity into the processing space to provide a downstream-type plasma of free radicals. The openings may also eliminate line-of-sight paths for light between the plasma cavity and processing space. In another aspect, the volume of the processing chamber may be adjusted by removing or inserting at least one removable sidewall section from the chamber lid.

Claims

1. An apparatus for processing a workpiece with free radicals from a light-emitting plasma including ions and the free radicals, comprising:

a vacuum chamber including a processing space and a plasma cavity in communication with said processing space;

a workpiece holder positioned in said processing space;

a vacuum port in said vacuum chamber adapted to evacuate said processing space and said plasma cavity;

a process gas supply port in said vacuum chamber adapted to introduce a process gas to at least said plasma cavity; and

a plasma excitation source capable of exciting the process gas in said plasma cavity to generate the plasma, said plasma excitation source including a grounded plate positioned between said plasma cavity and said processing space, said grounded plate capable of prohibiting the transfer of at least a portion of ions in the plasma from said plasma cavity to said processing space, said grounded plate having a plurality of openings configured to transfer at least a portion of the free radicals in the plasma from said plasma cavity to said processing space, and said openings configured to block line-of-sight paths from said plasma cavity to said processing space for reducing light transfer from the plasma to the workpiece.

2. The apparatus of claim 1 wherein said openings are slots, and said grounded plate comprises a plurality of slotted plates each having a plurality of slots, said slotted plates being arranged to substantially eliminate direct line-of-sight paths from said plasma cavity to said processing space.

3. The apparatus of claim 2 wherein a first one of said slotted plates includes a plurality of first slots and a second one of said slotted plates includes a plurality of second slots, said first slots being offset from said second slots such that said first slots are not aligned with said second slots in a direction extending from said plasma cavity to said processing space.

4. The apparatus of claim 3 wherein said plasma excitation source further comprises:

a plurality of electrically-conductive spacers separating said first slotted plate from said second slotted plate in said direction extending from said plasma cavity to said processing space.

5. The apparatus of claim 3 wherein a third one of said slotted plates includes a plurality of third slots, said second slotted plate being arranged between said first and third slotted plates, and said third slots being offset from said second slots in said direction extending from said plasma cavity to said processing space.

6. The apparatus of claim 1 wherein said vacuum chamber includes a chamber lid, and said plasma cavity in located inside said chamber lid.

7. The apparatus of claim 6 wherein said chamber lid is movable between open and closed positions for permitting introduction and removal of the workpiece to and from said workpiece holder, and said chamber lid carries said grounded plate.

8. The apparatus of claim 6 wherein said chamber lid further includes said process gas supply port coupled in fluid communication with said plasma cavity.

9. The apparatus of claim 8 wherein said chamber lid further includes a plurality of passageways for distributing the process gas received from said process gas supply port to said plasma cavity, and said plasma excitation source includes an electrode insulator positioned between said powered electrode and said chamber lid, and said plurality of passageways includes a plurality of outlets proximate to said electrode insulator emitting the process gas that seeps around an outer periphery of said electrode insulator and an outer periphery of said first powered electrode for substantially uniform distribution into said plasma cavity.

10. The apparatus of claim 6 further comprising:

a loading station arranged in-line with said vacuum chamber, said loading station configured for introducing the workpiece to said workpiece holder when said chamber lid is in the open position; and

an exit station arranged in-line with said vacuum chamber and with said loading station, said exit station configured for removing the workpiece from said workpiece holder when said chamber lid is in the open position.

11. A method for processing a workpiece in a vacuum chamber having a plasma cavity and a processing space, the method comprising:

generating a plasma containing ions and free radicals from a process gas in the plasma cavity;

emitting light from the plasma inside the plasma cavity;

transferring free radicals in the plasma from the plasma cavity to the processing space;

prohibiting transfer of at least a portion of the ions in the plasma from the plasma cavity to the processing space;

substantially blocking transfer of the light from the plasma cavity to the processing space; and

processing the workpiece in the processing space with the free radicals.

12. The method of claim 11 wherein substantially blocking transfer of the light further comprises:

transferring light from the plasma inside the plasma cavity through a first set of slots; and

blocking the transferred light with a second set of slots offset from the first set of slots so that the first slots are not aligned with the second slots in a direction extending from the plasma cavity to the processing chamber.

13. A method of plasma treating a workpiece having a thickness and an exposed surface in a processing space of a vacuum chamber having a chamber lid and a treatment electrode positioned in the chamber lid, comprising:

varying a volume of the chamber lid to alter the distance from the exposed surface of the workpiece to the treatment electrode based upon the thickness of the workpiece;

placing a workpiece in the processing space; and

exposing the exposed surface of the workpiece to the plasma.

14. The method of claim 13 wherein the varying of the volume further comprises:

removing at least one sidewall section from the chamber lid.

15. The method of claim 13 wherein the varying of the volume further comprises:

adding at least one sidewall section to the chamber lid.