Micromirrors with mechanisms for enhancing coupling of the micromirrors with electrostatic fields

• US 6,974,713 B2
• Filed: 02/25/2005
• Issued: 12/13/2005
• Est. Priority Date: 08/11/2000
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Huibers, Andrew, Patel, Sataydev
• Primary Examiner(s): Mulpuri, Savitri
• Application Number:
  US11/067,562
• Publication Number:
  US 20050190430A1
• Time in Patent Office: 291 Days
• Field of Search: 438 22- 99, 438/703, 438/738, 216/2
• US Class Current: 438/29
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A micromirror device is disclosed, along with a method of making such a micromirror device that comprises a mirror plate, a hinge and an extension plate. The extension plate is formed on the mirror plate and between the mirror plate and the electrode associated with the mirror plate for rotating the mirror plate. The extension plate can be metallic or dielectric. Also disclosed is a method of making such a micromirror device. In particular, the extension plate is formed after the formation of the mirror plate. Moreover, also disclosed is a projection system that comprises a spatial light modulator having an array of such micromirrors, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.

Claims

1. A method of making a micromirror device, the method comprising:

depositing a first sacrificial layer on a substrate;

forming a mirror plate on the first sacrificial layer;

depositing a second sacrificial layer on the mirror plate;

forming a hinge, a hinge support and an extension plate, further comprising;

removing a first portion and a second portion of the second sacrificial layer at a first location and at second portion above the mirror plate so as to expose a first portion and a second portion of the mirror plate; and

depositing the extension plate over the second sacrificial layer and over the exposed first portion of the mirror plate depositing the hinge on the second sacrificial layer and on the exposed second portion of the mirror plate; and

removing the first and the second sacrificial layers.

2. The method of claim 1, further comprising:

before forming the extension plate,

depositing a third sacrificial layer; and

forming the extension plate on the third sacrificial layer; and

the step of removing the first and the second sacrificial layers further comprising;

removing the third sacrificial layer.

3. The method of claim 1, wherein the first location is away from a center of the mirror plate.

4. The method of claim 3, wherein the second location is away from a center of the mirror plate.

5. The method of claim 3, wherein the step of removing the first and second sacrificial layer further comprises:

etching the first and second sacrificial layers using a spontaneous vapor phase etching with non-plasma spontaneous chemical vapor-phase etchant.

6. The method of claim 5, wherein the chemical vapor-phase etchant is vapor-phase interhalogen.

7. The method of claim 5, wherein the chemical vapor-phase etchant is vapor-phase noble gas halide.

8. The method of claim 7, wherein the noble gas halide is xenon difluoride.

9. A method of making a micromirror device, comprising:

depositing a first sacrificial layer on a light transmissive substrate;

forming a reflective mirror plate on the first sacrificial layer;

depositing a second sacrificial layer on the mirror plate;

forming a first and second posts in the sacrificial layers;

forming a hinge and an extension plate on the second sacrificial layer and connected to the reflective mirror plate, wherein the first post connects the extension plate to the mirror plate, and the second post connects the hinge to the mirror plate; and

removing the first and second sacrificial layers so as to release the micromirror device.

10. The method of claim 9, wherein the location wherein the hinge is connected to the mirror plate via the second post is away from a center of the mirror plate.

11. The method of claim 9, wherein the location wherein the extension plate is connected to the mirror plate via the first post is away from a center of the mirror plate.

12. The method of claim 9, wherein the step of removing the first and second sacrificial layer further comprises:

etching the first and second sacrificial layers using a spontaneous vapor phase etching with non-plasma spontaneous chemical vapor-phase etchant.

13. The method of claim 12, wherein the chemical vapor-phase etchant is vapor-phase interhalogen.

14. The method of claim 12, wherein the chemical vapor-phase etchant is vapor-phase noble gas halide.

15. The method of claim 14, wherein the noble gas halide is xenon difluoride.