Method and apparatus for tuning field for plasma processing using corrected electrode

• US 5,716,486 A
• Filed: 04/19/1996
• Issued: 02/10/1998
• Est. Priority Date: 01/13/1994
• Status: Expired due to Fees

• Current Assignee: Gary S. Selwyn, Gary W. Rubolff, Guarnieri C. Richard, James J. Mcgill, Maheswaran Surendra, Manoj Dalvie
• Original Assignee: Gary S. Selwyn, Gary W. Rubolff, Guarnieri C. Richard, James J. Mcgill, Maheswaran Surendra, Manoj Dalvie
• Inventors: Surendra, Maheswaran, Selwyn, Gary S., Guarnieri, C. Richard, McGill, James J., Dalvie, Manoj, Rubolff, Gary W.
• Primary Examiner(s): Nguyen, Nam
• Assistant Examiner(s): MCDONALD, RODNEY GLENN
• Application Number:
  US08/635,056
• Time in Patent Office: 662 Days
• Field of Search: 156/345, 118/723 E, 118/725, 118/728, 118/729, 204/298.06, 204/298.15, 204/298.31, 204/298.32, 204/298.34, 204/298.37
• US Class Current: 156/345.28
• CPC Class Codes: H01J 37/32532 Electrodes
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01J 37/32697 Electrostatic control
• CPC Class Codes: H01L 21/6831 using electrostatic chucks

Abstract

A device for reducing plasma irregularities includes an electrode assembly capable of applying an electric potential to said plasma. The electrode assembly includes a portion for reducing the plasma irregularities. The portion which reduces the plasma irregularities includes alternately a buried portion which is capable of altering the potential within the buried element, or else a conditioned portion of the surface which controls reflectivity and/or emissivity of portions of a surface of the electrode assembly differently.

Claims

1. An apparatus for controlling plasma irregularities, that are created in a local region of an otherwise substantially uniform plasma formed above, and being applied to, the surface of a workpiece, and that result from the local presence of said workpiece, comprising:

an electrode assembly, having a surface in contact with said workpiece, capable of applying an electric potential to said plasma, said electrode assembly comprising;

means for applying an AC potential to said plasma to produce a substantially uniform AC field therein; and

means for controlling the plasma irregularities in said local region, said controlling means comprising;

means, disposed in said electrode assembly in the vicinity of said local region and out of direct electrical contact with said workpiece and said plasma, for modifying said electrical potential at said local region to control the plasma irregularities therein without otherwise effecting said substantially uniform plasma formed above said surface of said workpiece, said modifying means comprising;

a buried element in said electrode assembly;

means for applying a potential to said buried element in said electrode assembly to render said buried element active and means for making the potential applied to said buried element variable to cause said active buried element to interact with said AC field to produce an AC time varying potential for modifying said electrical potential at said local region.

2. The apparatus as described in claim 1, wherein said buried element is a portion of an electrostatic chuck.

3. The apparatus as described in claim 1 wherein said potential applying means and said means for making the potential variable comprise means for applying a radio frequency potential to said buried element whereby said buried element affects a radio frequency coupling between the electrode assembly and the plasma.

4. The apparatus as described in claim 1, wherein said workpiece has an edge adjacent said local region and said buried element is contained within said surface of the electrode assembly and disposed near the edge of said workpiece in the vicinity of said local region.

5. The apparatus as described in claim 4, wherein said potential applying means and said means for making the potential variable comprise means for applying a radio frequency potential to said buried element whereby said buried element affects a radio frequency coupling between the electrode assembly and the plasma creating a substantially uniform trap-limited plasma above the electrode assembly in said local region.

6. The apparatus as described in claim 4, wherein said buried element is disposed in said electrode assembly so as to affect capacitance between the electrode assembly and the plasma.

7. The apparatus as described in claim 1, wherein said buried element is disposed in said electrode assembly so as to affect capacitance between the electrode assembly and the plasma.

8. The apparatus as described in claim 7, wherein said potential applying means and said means for making the potential variable comprise means for applying a radio frequency potential to said buried element and said buried element is disposed in said electrode assembly so as to affect a radio frequency coupling between the electrode assembly and the plasma, thereby producing said AC time varying potential and achieving a desired variation of the plasma properties.

9. The apparatus as described in claim 1, wherein said means for making said potential variable comprises:

pulse means for creating an electrical pulse which is capable of driving particles that are suspended in the plasma in the vicinity of the workpiece away from the workpiece.

10. An apparatus for controlling plasma irregularities, that are created in a local region of an otherwise substantially uniform plasma formed above, and being applied to, the surface of a workpiece, and that result from the local presence of said workpiece, comprising:

an electrode assembly, having a surface in contact with said workpiece, capable of applying an electric potential to said plasma, said electrode assembly comprising;

means for applying an AC potential to said plasma to produce a substantially uniform AC field therein; and

means for controlling the plasma irregularities in said local region, said controlling means comprising;

means, disposed in said electrode assembly in the vicinity of said local region and out of direct electrical contact with said workpiece and said plasma, for modifying said electrical potential at said local region to control the plasma irregularities therein without otherwise effecting said substantially uniform plasma formed above said surface of said workpiece, wherein said modifying means comprises;

a plurality of electrically isolated sections in said surface of said electrode assembly, which sections are capable of being powered independently; and

means for applying different time varying potentials to different sections to cause the potentials at said sections to interact with said AC field to produce an AC time varying potential for modifying said electrical potential at said local region.

11. An apparatus for controlling plasma irregularities, that are created in a local region of an otherwise substantially uniform plasma formed above, and being applied to, the surface of a workpiece, and that result from the local presence of said workpiece, comprising:

an electrode assembly, having a surface in contact with said workpiece, capable of applying an electric potential to said plasma, said electrode assembly comprising;

means for applying an AC potential to said plasma to produce a substantially uniform AC field therein and

means for controlling the plasma irregularities in said local region, said controlling means comprising;

means, disposed in said electrode assembly in the vicinity of said local region and out of direct electrical contact with said workpiece and said plasma, for modifying said electrical potential at said local region to control the plasma irregularities therein without otherwise effecting said substantially uniform plasma formed above said surface of said workpiece, wherein said modifying means comprises;

externally and independently controllable power distribution elements for in-process programmable, or feed back controlled tuning of the plasma field uniformity using time varying potentials applied to said distribution elements to cause the potentials at said elements to interact with said AC field to produce an AC time varying potential for modifying said electrical potential at said local region.

12. An apparatus for controlling plasma irregularities, that are created in a local region of an otherwise substantially uniform plasma formed above, and being applied to, the surface of a workpiece, and that result from the local presence of said workpiece, comprising:

an electrode assembly, having a surface in contact with said workpiece, capable of applying an electric potential to said plasma, said electrode assembly comprising;

means for applying an AC potential to said plasma to produce a substantially uniform AC field therein; and

means for controlling the plasma irregularities in said local region, said controlling means comprising;

means, disposed in said electrode assembly in the vicinity of said local region and out of direct electrical contact with said workpiece and said plasma, for modifying said electrical potential at said local region to control the plasma irregularities therein without otherwise effecting said substantially uniform plasma formed above said surface of said workpiece, wherein said modifying means comprises;

independently tuned power distribution elements for in-process, programmable, or feed back controlled tuning of the plasma field uniformity using time varying potentials applied to said distribution elements to cause the potentials at said elements to interact with said AC field to produce an AC time varying potential for modifying said electrical potential at said local region.

13. An apparatus for controlling plasma irregularities, that are created in a local region of an otherwise substantially uniform plasma formed above, and being applied to, the surface of a workpiece, and that result from the local presence of said workpiece, comprising:

an electrode assembly, having a surface in contact with said workpiece, capable of applying an electric potential to said plasma, said electrode assembly comprising;

means for applying an AC potential to said plasma to produce a substantially uniform AC field therein; and

means for controlling the plasma irregularities in said local region, said controlling means comprising;

means, disposed in said electrode assembly in the vicinity of said local region and out of direct electrical contact with said workpiece and said plasma, for modifying said electrical potential at said local region to control the plasma irregularities therein without otherwise effecting said substantially uniform plasma formed above said surface of said workpiece, wherein said modifying means comprises;

sublayer elements contained in the electrode assembly and independently powered for in-process, programmable, or feed-back controlled tuning of the plasma field uniformity using time varying potentials applied to said sublayer elements to cause the potentials at said elements to interact with said AC field to produce an AC time varying potential for modifying said electrical potential at said local region.

14. An apparatus for controlling plasma irregularities, that are created in a local region of an otherwise substantially uniform plasma formed above, and being applied to, the surface of a workpiece, and that result from the local presence of said workpiece, comprising:

an electrode assembly, having a surface in contact with said workpiece, capable of applying an electric potential to said plasma, said electrode assembly comprising;

means for applying an AC potential to said plasma to produce a substantially uniform AC field therein; and

means for controlling the plasma irregularities in said local region, said controlling means comprising;

means, disposed in said electrode assembly in the vicinity of said local region and out of direct electrical contact with said workpiece and said plasma, for modifying said electrical potential at said local region to control the plasma irregularities therein without otherwise effecting said substantially uniform plasma formed above said surface of said workpiece, wherein said modifying means comprises;

plasma field control means independently powered for creating a potential gradient capable of driving particles that are suspended in the plasma in the vicinity of the workpiece away from the workpiece, after said plasma is active using time varying potentials applied to said control means to cause the potentials at said control means to interact with said AC field to produce an AC time varying potential for modifying said electrical potential at said local region.

15. An apparatus for controlling irregularities in a plasma created above and being applied to the surface of a workpiece, which irregularities are caused in a local region of the otherwise substantially uniform plasma by the presence of said workpiece at said local region, comprising:

an electrode assembly for supporting said workpiece in said plasma, wherein said electrode assembly comprises;

means for applying an AC potential to said plasma to produce an AC field that causes a uniformity in said plasma above the surface of said workpiece; and

means, disposed in said electrode assembly in the vicinity of said local region, out of direct electrical contact with said workpiece and said plasma, and having a time varying potential applied thereto to cause interaction with said AC field, for modifying said AC potential in said local region at said workpiece to control irregularities in said plasma in said local region caused by the presence of said workpiece without otherwise effecting said substantially uniform plasma above said surface of said workpiece.

16. The apparatus of claim 15, wherein said modifying means comprises a member disposed in said electrode assembly below a portion of said surface for supporting said workpiece in the vicinity of said local region.

17. The apparatus of claim 16, further comprising means for applying a time varying potential and wherein said time varying potential applying means comprises means for applying a potential to said member.

18. The apparatus of claim 17, wherein said means for applying a time varying potential applies an AC potential to said member.

19. The apparatus of claim 15, wherein said modifying means comprises means, connected to said potential applying means for affecting a radio frequency coupling between the electrode assembly and the plasma in said local region.

20. The apparatus of claim 15, wherein said modifying means produces a substantially uniform trap-limited plasma at said surface of the workpiece in said local region.

21. The apparatus of claim 15, wherein said modifying means affects capacitance between the electrode assembly and the plasma in said local region.

22. The apparatus of claim 15, wherein said modifying means comprises a plurality of electrically isolated sections in said electrode assembly surface, and said potential applying means comprises means for independently applying a potential to said sections.

23. The apparatus of claim 15, wherein said modifying means comprises externally controllable power distribution elements in the vicinity of said local region for tuning the plasma field uniformity in said local region.

24. The apparatus of claim 15, wherein said modifying means comprises plasma field control means for creating a potential gradient capable of driving particles, that are suspended in the plasma in the vicinity of the workpiece, away from the workpiece in said local region, after said plasma is active.

25. The apparatus of claim 15, wherein said modifying means further comprises pulse means for creating an electrical pulse which is capable of driving particles, that are suspended in the plasma in the vicinity of the workpiece, away from the workpiece in said local region.

26. The apparatus of claim 15, wherein said modifying means comprises a surface which is configured differently in distinct regions, to control the rate of the passage of electrons thereto from said plasma per given area, at the distinct regions.

27. The apparatus of claim 26, wherein said surface configuring is achieved by varying the roughness of the distinct regions of said surface.

28. The apparatus of claim 26, wherein said surface configuring is achieved by coating the distinct regions of said surface differently.

29. The apparatus of claim 15, wherein said modifying means comprises means for controlling plasma irregularities in said local region by altering a secondary electron emission coefficient of a surface adjacent said plasma in the vicinity of said local region.

30. The apparatus of claim 15, wherein said modifying means comprises means for controlling plasma irregularities in said local region by altering an electron reflection coefficient of a surface adjacent said plasma in the vicinity of said local region.