Tumbling barrel plasma processor

• US 5,945,012 A
• Filed: 02/17/1998
• Issued: 08/31/1999
• Est. Priority Date: 02/18/1997
• Status: Expired due to Term

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Chan, Chung
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US09/024,283
• Time in Patent Office: 560 Days
• Field of Search: 219/121.4, 219/121.43, 219/121.48, 219/121.52, 156/345, 156/643.1, 156/646.1, 118/723 I, 118/723 R, 373/18-22
• US Class Current: 219/121.43
• CPC Class Codes: H01J 37/32752 for moving the material across the discharge
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

A tumbling barrel plasma processing method and apparatus are presented. The tumbling barrel plasma processor includes a vacuum chamber, a plasma source, a power supply, a rotatable barrel which is disposed within the vacuum chamber and a barrel rotation mechanism for rotating the barrel. The plasma source generates a plasma surrounding the rotatable barrel. The barrel is made up of at least one conductive screen of a certain transparency that allows ions to pass therethrough. The power supply provides a negative voltage which is applied to the screens of the barrel to extract ions from a plasma surrounding the rotatable barrel. Alternately a positive voltage can be applied to the screens of the barrel to extract electrons from the plasma surrounding the rotatable barrel. The barrel is rotated by the barrel rotation mechanism such that the samples disposed within the barrel are tumbled, thereby the samples receive plasma treatment on all sides. Insulative samples can also be processed since the voltage is applied between the plasma and the screens and, since no voltage is applied directly to the samples themselves, there is no need to capacitively couple the voltage to the insulative samples. An advantage of the present method and apparatus is that the ions or electrons are coming from all directions due to the cylindrical symmetry of the electric field provided between the screens and the plasma. The ion current density is approximately the same for an ion beam of a plasma source ion implantation and the present invention, however the total ion current is higher for the present invention due to the large area of the rotatable barrel. Accordingly, throughput for the tumbling barrel plasma processor is much higher.

Claims

1. A plasma processor comprising:

a rotatable barrel comprising a screen of conductive elements disposed within said rotatable barrel, said rotatable barrel receiving at least one sample to be processed within said screen;

a plasma source operative and coupled to said rotatable barrel to generate a plasma surrounding said rotatable barrel;

a voltage source in electrical communication with said screen of conductive elements and operative to provide a voltage to said screen of conductive elements to implant ions from said plasma into said one sample; and

a barrel rotation mechanism coupled to said rotatable barrel and operative to rotate said rotatable barrel.

2. The plasma processor of claim 1 further comprising a vacuum chamber surrounding said rotatable barrel, and wherein the plasma is generated within said vacuum chamber.

3. The plasma processor of claim 1 wherein said voltage source provides a D.C. voltage.

4. The plasma processor of claim 1 wherein said voltage source provides an A.C. voltage.

5. The plasma processor of claim 1 wherein said voltage source provides a positive voltage.

6. The plasma processor of claim 1 wherein said voltage source provides a negative voltage.

7. The plasma processor claim 1 wherein said voltage source is pulsed.

8. The plasma processor of claim 1 wherein said plasma is at a voltage of approximately ten volts.

9. A method of plasma processing comprising the steps of:

disposing at least one sample within a rotatable barrel comprising a screen of conductive elements disposed within said rotatable barrel, said one sample being disposed within said rotatable barrel;

generating a plasma surrounding said rotatable barrel using a plasma source;

providing a voltage on said first screen of conductive elements to implant ions from said plasma into said one sample; and

rotating said rotatable barrel such that said at least one sample receives ions from said plasma on its entire surface.

10. The method of claim 9 further comprising the step of generating a vacuum about said barrel and said plasma.

11. The method of claim 9 wherein said step of providing a voltage comprises providing a D.C. voltage.

12. The method of claim 9 wherein said step of providing a voltage comprises providing an A.C. voltage.

13. The method of claim 9 wherein said step of providing a voltage comprises providing a positive voltage.

14. The method of claim 9 wherein said step of providing a voltage comprises providing a negative voltage.

15. The method of claim 9 wherein said step of providing a voltage comprises providing a pulsed voltage.

16. The method of claim 9 wherein said step of generating a plasma comprises generating a plasma having a voltage of approximately ten volts.