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

• US 20020148560A1
• Filed: 11/01/2001
• Published: 10/17/2002
• Est. Priority Date: 01/30/2001
• Status: Active Grant

• Current Assignee: Imreal Enterprises, LLC
• Original Assignee: Rapt Industries, Inc.
• Inventors: Carr, Jeffrey W.
• Granted Patent: US 7,510,664 B2
• Time in Patent Office: Days
• US Class Current: 156/345.24
• 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 surfaces comprising the steps of using reactive atom plasma processing for shaping damage free surfaces.

2. The method of claim 1 wherein the process is carried out at about atmosphere temperature.

3. The method of claim 1 for shaping optical elements.

4. The method of claim 1 for shaping elements out of silicon.

5. The method of claim 1 for shaping silica glass optics.

6. The method of claim 1 for shaping aspheric optics.

7. The method of claim 1 operating in a subtractive manner.

8. The method of claim 1 that does not leave behind a contaminated redeposition layer.

9. The method of claim 1 using a plume of plasma.

10. The method of claim 1 using a plume of plasma operating as a sub-aperture tool.

11. The method of claim 1 wherein a plume of plasma is translated across a workpiece.

12. The method of claim 1 wherein the emission spectrum is monitored to determine process rates.

13. The method of claim 1 using carbon tetrafluoride (CF₄) in argon to create the plasma.

14. The method of claim 1 using C₂F₆ in argon to create the plasma.

15. The method of claim 1 using silicon hexafluorine (SF₆) in argon to create the plasma.

17. The apparatus of claim 15 including:

a device for tuning the plasma.

18. The method of claim 1 operating an additive manner.

20. The method of claim 1 for removing surface roughness.

16. An apparatus for shaping surfaces comprising:

a chamber;

a torch located in a chamber that can produce a plume of plasma;

a device that holds a workpiece; and

a mechanism for translating the torch across the workpiece.

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