Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

• US 7,510,664 B2
• Filed: 11/01/2001
• Issued: 03/31/2009
• Est. Priority Date: 01/30/2001
• Status: Expired due to Fees

• Current Assignee: Imreal Enterprises, LLC
• Original Assignee: Rapt Industries, Inc.
• Inventors: Carr, Jeffrey W.
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US10/002,035
• Publication Number:
  US 20020148560A1
• Time in Patent Office: 2,707 Days
• Field of Search: 216/24, 216/67, 264/1.36, 219/121.51
• US Class Current: 216/24
• CPC Class Codes: B23K 1/206 Cleaning
• CPC Class Codes: C03C 15/00 Surface treatment of glass, not in the form of fibres or filaments, by etching etching or surface-brightening compositions, in general C09K13/00
• CPC Class Codes: C04B 35/117 Composites
• CPC Class Codes: C04B 35/565 based on silicon carbide
• CPC Class Codes: C04B 41/0054 Plasma-treatment, e.g. with gas-discharge plasma
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/53 involving the removal of at least part of the materials of the treated article, e.g. etching, drying of hardened concrete C04B41/0036 - C04B41/0054 take precedence
• CPC Class Codes: C04B 41/91 involving the removal of part of the materials of the treated articles, e.g. etching
• CPC Class Codes: C23C 16/047 using irradiation by energy or particles
• CPC Class Codes: C23C 16/513 using plasma jets
• CPC Class Codes: H01L 21/67092 Apparatus for mechanical treatment or grinding or cutting, see the relevant groups in subclasses B24B or B28D
• CPC Class Codes: H05H 1/30 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/28 takes precedence

Abstract

Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

Claims

1. A method for shaping optical elements, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface.

2. A method for shaping elements out of silicon, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface.

3. A method for shaping silica glass optics, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface.

4. A method for shaping aspheric optics, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface.

5. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface; and

operating so as not to leave behind a contaminated redeposition layer.

6. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface; and

monitoring an emission spectrum to determine process rates.

7. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube to create at least one reactive species;

using reactive atom plasma processing for the damage-free shaping of a surface; and

using carbon tetrafluoride (CF4) in argon to create the plasma.

8. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface; and

using C2F6 in argon to create the plasma.

9. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface; and

using sulfur hexafluoride (SF6) in argon to create the plasma.

10. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free and deterministic shaping of the surface by at least one of;

selecting a part of the surface to shape;

selecting a material to shape on the surface; and

controlling the removal rate of a material on the surface under shaping.

11. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species for the damage-free shaping of the surface to fit a pre-determined contour.

12. The method of claim 11 operated at one of above and below atmospheric pressure.

13. The method of claim 11 operable on a conductive surface.

14. The method of claim 11 wherein the step of using reactive atom plasma processing to selectively shape the surface is a deterministic step which can be selectively in one of an additive mode and a subtractive mode.

15. The method of claim 11 operated at about atmospheric pressure and at one of above and below room temperature.

16. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

shaping the surface deterministically and damage-free with the at least one reactive species to fit a pre-determined contour.

17. The method of claim 16 including the step of moving at least one of the plasma and the surface relative to the other.

18. The method of claim 16 operated at one of above and below atmospheric pressure.

19. The method of claim 16 operable on a non-conductive surface.

20. The method of claim 16 wherein the step of using reactive atom plasma processing to selectively shape the surface is a deterministic step which can be selectively in one of an additive mode and a subtractive mode.

21. The method of claim 16 operated at about atmospheric pressure and at one of above and below room temperature.

22. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

shaping a surface deterministically and damage-free with the at least one reactive species by at least one of;

selecting a part of the surface to shape;

selecting a material to shape on the surface; and

controlling the removal rate of a material on the surface under shaping.

23. The method of claim 22 including the step of moving at least one of the plasma and the surface relative to the other.

24. The method of claim 22 operated at one of above and below atmospheric pressure.

25. The method of claim 22 operable on a semiconductor surface.

26. The method of claim 22 wherein the step of using reactive atom plasma processing to selectively shape the surface is a deterministic step which can be selectively in one of an additive mode and a subtractive mode.

27. The method of claim 22 operated at about atmospheric pressure and at one of above and below room temperature.

28. A method for shaping surfaces, comprising:

positioning a distal end of a plasma torch in proximity to a surface so that at least one reactive species from the plasma torch affects the surface, the plasma torch including an outer gas inlet tube, an auxiliary gas inlet tube concentrically arranged within the outer gas inlet tube, an inner gas inlet tube concentrically arranged within the auxiliary gas inlet tube, and a load coil arranged at a distal end of the outer gas inlet tube so that the outer gas inlet tube is nested within the load coil;

injecting a plasma gas into the outer gas inlet tube;

applying a current to the load coil to inductively couple a radio frequency (RF) power to the plasma gas to create an annular plasma;

creating an annular plasma;

injecting an auxiliary gas into the auxiliary gas inlet tube to at least partially shield the inner gas inlet tube from the annular plasma;

injecting a reactive precursor into the inner gas inlet tube;

exciting the precursor with the radio frequency (RF) power via the annular plasma to create the at least one reactive species; and

using the at least one reactive species to shape and polish the surface.

29. The method of claim 28 operating in a subtractive manner.

30. The method of claim 28 using a plume of the plasma.

31. The method of claim 28 using a plume of the plasma operating as a sub-aperture tool.

32. The method of claim 28 wherein a plume of the plasma is translated across a workpiece.

33. The method of claim 28 operating in an additive manner.

34. The method of claim 28 for removing damage introduced by previous process steps.

35. The method of claim 28 for removing surface roughness.

36. The method of claim 28, further comprising:

using the at least one reactive species to react with selected materials which comprise the surface.