Method and apparatus for creating a phase step in mirrors used in spatial light modulator arrays

• US 20060139729A1
• Filed: 12/27/2004
• Published: 06/29/2006
• Est. Priority Date: 12/27/2004
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Roux, Steven
• Granted Patent: US 7,279,110 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B

Abstract

A method and apparatus for patterning an array of SLM mirrors with a phase step is disclosed. Additional embodiments of the present invention describe a method for processing a substrate, wherein the processed substrate is used in the apparatus for patterning an array of SLM mirrors with a phase step. The processed substrate is then placed in close proximity to the mirrors and the etching/deposition process is then done through openings in the substrate. In embodiments in which the processed substrate does not have a high enough density of openings, a stepping and repeating process is used in order to achieve complete process coverage of every mirror in an array of SLM mirrors.

Claims

1. A method, comprising:

(a) creating a plurality of cavities on a first major side of a wafer;

(b) patterning a second major side of the wafer with an etch-resistant layer; and

(c) etching portions of the wafer not patterned with the etch-resist layer to create openings between the first major side and the second major side of the wafer.

2. The method of claim 1, wherein step (a) comprises:

creating a plurality of cavities, each cavity having a width of approximately 0.1 millimeters to 1 millimeters.

3. The method of claim 1, wherein step (a) comprises:

creating a plurality of cavities, each cavity having a width of approximately 0.42 millimeters.

4. The method of claim 1, wherein step (c) comprises:

etching openings in the wafer, each opening having a width of approximately 2 micrometers to 6 micrometers.

5. The method of claim 1, wherein step (c) comprises:

etching openings in the wafer, each opening having a width of approximately 3 micrometers.

6. The method of claim 1, wherein step (a) comprises:

anisotropically etching the first major side of the wafer.

7. The method of claim 1, further comprising:

(d) directing a material towards an array of mirrors, each mirror having an area; and

(e) blocking at least a portion of the material from reaching the array of mirrors, such that the material only impinges upon a predetermined portion of the respective areas of given mirrors in the array.

8. The method of claim 7, wherein step (e) comprises using one of a mask, a silicon mask, and a molybdenum mask made according to steps (a)-(c).

9. The method of claim 7, wherein step (e) comprises etching a phase step in the mirrors by using one of an ion beam and a reactive ion beam as the material that impinges upon the mirrors.

10. The method of claim 9, wherein the reactive ion beam is substantially more reactive with a reflective coating of the mirrors than a substance from which the mask is comprised.

11. The method of claim 7, wherein step (e) comprises depositing a phase step on the mirrors by using aluminum as the material that impinges upon the mirrors.

12. The method of claim 7, further comprising:

(f) moving the array of mirrors in discrete steps so that, after a predetermined number of discrete steps is completed, the material impinges upon the predetermined portion of the respective areas of each mirror of the array.

21. The method of claim 1, wherein step (c) comprises etching slits in the wafer, each slit having a width of approximately 3 micrometers and a length of approximately 20 micrometers.

13. An apparatus, comprising:

a material source that directs material towards an array of mirrors, each mirror having an area; and

a mask that blocks at least a portion of the material from reaching the array of mirrors, such that the material only impinges upon a predetermined portion of the respective areas of given mirrors in the array.

14. The apparatus of claim 13, wherein the mask comprises a wafer having openings between a first major side and a second major side of the wafer.

15. The apparatus of claim 13, wherein the material that impinges upon the mirrors etches a phase step in the mirrors.

16. The apparatus of claim 15, wherein the material that etches a phase step in the mirrors is one of an ion beam and a reactive ion beam.

17. The apparatus of claim 16, wherein the reactive ion beam is substantially more reactive with a reflective coating on the mirrors than a substance from which the mask is comprised.

18. The apparatus of claim 13, wherein the material that impinges upon the mirrors deposits a phase step on the mirrors.

19. The apparatus of claim 18, wherein the material that deposits a phase step on the mirrors is aluminum.

20. The apparatus of claim 13, wherein the array of mirrors moves in discrete steps so that, after a predetermined number of discrete steps is completed, the material impinges upon the predetermined portion of the respective areas of each mirror of the array.

22. The apparatus of claim 14, wherein the wafer further comprises slits having a width of approximately 3 micrometers and a length of approximately 20 micrometers.