Method and system for optical figuring by imagewise heating of a solvent

• US 6,936,182 B2
• Filed: 02/28/2002
• Issued: 08/30/2005
• Est. Priority Date: 02/28/2002
• Status: Expired due to Fees

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Rushford, Michael C.
• Primary Examiner(s): Hassanzadeh, P.
• Assistant Examiner(s): CULBERT, ROBERTS P
• Application Number:
  US10/087,493
• Publication Number:
  US 20030160025A1
• Time in Patent Office: 1,279 Days
• Field of Search: 216/24, 216/26, 216/31, 216/55, 216/85, 216/87, 216/94, 216/97, 216/65, 219/121.2, 219/121.19, 219/121.33, 219/121.35, 219/121.68, 219/121.69, 219/121.84, 219/628, 219/656, 219/635, 219/638, 219/660, 219/672, 359/648, 134/1, 134/105, 134/61, 134/88, 134/90, 134/84, 156/345.1, 156/345.11, 156/345.22, 156/345.24, 156/345.27
• US Class Current: 216/85
• 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

Abstract

A method and system of imagewise etching the surface of a substrate, such as thin glass, in a parallel process. The substrate surface is placed in contact with an etchant solution which increases in etch rate with temperature. A local thermal gradient is then generated in each of a plurality of selected local regions of a boundary layer of the etchant solution to imagewise etch the substrate surface in a parallel process. In one embodiment, the local thermal gradient is a local heating gradient produced at selected addresses chosen from an indexed array of addresses. The activation of each of the selected addresses is independently controlled by a computer processor so as to imagewise etch the substrate surface at region-specific etch rates. Moreover, etching progress is preferably concurrently monitored in real time over the entire surface area by an interferometer so as to deterministically control the computer processor to image-wise figure the substrate surface where needed.

Claims

1. A method of figuring a substrate surface comprising the steps of:

contacting the substrate surface with an etchant solution, wherein an etch rate of the etchant solution increases with temperature; and

independently controlling the generation of a local thermal gradient in each of a plurality of selected local regions of a boundary layer of the etchant solution independent of other selected local regions, to imagewise etch the substrate surface in a parallel process.

2. The method as in claim 1,

wherein the step of independently controlling the generation of a local thermal gradient in each selected local region comprises locally heating each selected local region independent of other selected local regions so that region-specific heating gradients are produced in the boundary layer, whereby the selected local regions etch the substrate surface at region-specific etch rates higher than non-selected local regions.

3. The method as in claim 2,

wherein a computer processor is provided to independently control the local heating of each selected local region.

4. The method as in claim 2,

further comprising the step of macro-cooling the etchant solution to prevent appreciable etching of the substrate surface not due to the local heating of the selected local regions.

5. The method as in claim 4,

wherein the etchant solution is macro-cooled to a null etch rate, whereby no etching takes place prior to the local heating of the selected local regions.

6. The method as in claim 4,

wherein the etchant solution is macro-cooled by fluid convection.

7. The method as in claim 2,

wherein the step of locally heating each selected local region independent of other selected local regions comprises projecting region-specific electromagnetic radiation towards the selected local regions of the boundary layer to simultaneously locally heat the selected local regions with region-specific heating gradients.

8. The method as in claim 7,

wherein a computer processor is provided to independently control the region-specific electromagnetic radiation projected towards each selected local region.

9. A method of figuring a substrate surface comprising the steps of:

contacting the substrate surface with an etchant solution, wherein an etch rate of the etchant solution increases with temperature;

activating a plurality of selected heaters corresponding to a plurality of selected local regions of a boundary layer of the etchant solution, and chosen from an indexed array of heaters each for locally heating a corresponding local region of the boundary layer upon selective activation thereof; and

independently controlling by a computer processor the activation of each selected heater, to produce region-specific heating gradients in the selected local regions of the boundary layer and thereby imagewise etch the substrate surface at region-specific etch rates in a parallel process.

10. The method as in claim 9,

wherein each heater of the indexed array comprises a pair of electrodes for, upon selective activation thereof, resistively heating a corresponding selected local region and producing a local ionic concentration gradient in the corresponding selected local region to locally etch the substrate surface.

11. The method as in claim 9,

further comprising the step of interferometrically monitoring the substrate surface to deterministically control the computer processor and the region-specific etch rates.

12. The method as in claim 11,

wherein the interferometrically monitoring step occurs concurrently with the figuring of the substrate surface.

13. The method as in claim 9,

further comprising the step of macro-cooling the etchant solution to prevent appreciable etching of the substrate surface not due to the local heating of the selected local regions.

14. The method as in claim 13,

wherein the etchant solution is macro-cooled to a null etch rate, whereby no etching takes place prior to the local heating of the selected local regions.

15. The method as in claim 13,

wherein the etchant solution is macro-cooled by fluid convection.

16. A method of figuring a substrate surface comprising the steps of:

contacting the substrate surface with an etchant solution, wherein an etch rate of the etchant solution increases with temperature;

projecting region-specific electromagnetic radiation towards selected local regions of a boundary layer of the etchant solution to simultaneously locally heat the selected local regions independent of other selected local regions; and

independently controlling by a computer processor the region-specific electromagnetic radiation projected towards each selected local region, to simultaneously produce region-specific heating gradients in the boundary layer and thereby imagewise etch the substrate surface at region-specific etch rates in a parallel process.

17. The method as in claim 16,

wherein the projected region-specific electromagnetic radiation is directed on a heatable material in conductive contact with the boundary layer of the etchant solution to thereby transfer heat to the selected local regions.

18. The method as in claim 16,

further comprising the step of macro-cooling the etchant solution to prevent appreciable etching of the substrate surface not due to the local heating of the selected local regions.

19. The method as in claim 18,

wherein the etchant solution is macro-cooled to a null etch rate, whereby no etching takes place prior to the local heating of the selected local regions.

20. The method as in claim 18,

wherein the etchant solution is macro-cooled by fluid convection.

21. A method of figuring a substrate surface comprising the steps of:

contacting the substrate surface with an etchant solution, wherein an etch rate of the etchant solution increases with temperature;

generating a local thermal gradient in each of a plurality of selected local regions of a boundary layer of the etchant solution to imagewise etch the substrate surface in a parallel process, wherein the step of generating a local thermal gradient in each selected local region comprises locally heating each selected local region, whereby the selected local regions etch the substrate surface at higher etch rates than non-selected local regions; and

using a computer processor to independently control the local heating of each selected local region to produce region-specific heating gradients in the boundary layer and thereby imagewise etch the substrate surface at region-specific etch rates; and

interferometrically monitoring the substrate surface to deterministically control the computer processor and the region-specific etch rates.

22. The method as in claim 21,

wherein the interferometrically monitoring step occurs concurrently with the figuring of the substrate surface.

23. A method of figuring a substrate surface comprising the steps of:

contacting the substrate surface with an etchant solution, wherein an etch rate of the etchant solution increases with temperature;

generating a local thermal gradient in each of a plurality of selected local regions of a boundary layer of the etchant solution to imagewise etch the substrate surface in a parallel process, wherein the step of generating a local thermal gradient in each selected local region comprises locally heating each selected local region by activating a plurality of selected heaters corresponding to the selected local regions and chosen from an indexed array of heaters each locally heating a corresponding local region of the boundary layer upon selective activation thereof, whereby the selected local regions etch the substrate surface at higher etch rates than non-selected local regions.

24. The method as in claim 23,

further comprising the step of independently controlling the activation of each selected heater to produce region-specific heating gradients in the boundary layer and thereby imagewise etch the substrate surface at region-specific etch rates.

25. The method as in claim 24,

wherein a computer processor is provided to independently control the activation of each selected heater.

26. The method as in 23,

wherein each heater of the indexed array comprises a pair of electrodes for, upon selective activation thereof, resistively heating a corresponding selected local region and producing a local ionic concentration gradient in the corresponding selected local region to locally etch the substrate surface.

27. A method of figuring a substrate surface comprising the steps of:

contacting the substrate surface with an etchant solution, wherein an etch rate of the etchant solution increases with temperature;

projecting electromagnetic radiation towards selected local regions of a boundary layer of the etchant solution to locally heat the selected local regions;

independently controlling by a computer processor the electromagnetic radiation projected towards each selected local region, to produce region-specific heating gradients in the boundary layer and thereby imagewise etch the substrate surface at region-specific etch rates in a parallel process; and

interferometrically monitoring the substrate surface to deterministically control the computer processor and the region-specific etch rates.

28. The method as in claim 27,

wherein the interferometrically monitoring step occurs concurrently with the figuring of the substrate surface.