Digital micromirror device having mirror-attached spring tips

• US 20030117686A1
• Filed: 12/12/2002
• Published: 06/26/2003
• Est. Priority Date: 12/12/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: DiCarlo, Anthony
• Granted Patent: US 6,856,446 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A micromirror array 110 fabricated on a semiconductor substrate 11. The array 110 is comprised of three operating layers 12, 13, 14. An addressing layer 12 is fabricated on the substrate. A hinge layer 13 is spaced above the addressing layer 12 by an air gap. A mirror layer 14 is spaced over the hinge layer 13 by a second air gap. The hinge layer 13 has a hinge 13a under and attached to the mirror 14a, the hinge 13a permitting the mirror 14a to tilt. Spring tips 13c under the mirror 14a are attached to the underside of the mirror 14a. These spring tips 13c tilt with the mirror 14a and provide a landing point for the mirror 14a onto a surface of the underlying pixel element structure.

Claims

1. An array of digital micro pixel elements, comprising:

a mirror layer having a mirror associated with each pixel element;

a hinge layer spaced under the mirror layer, the hinge layer having a torsion hinge under each mirror and attached to the mirror such that the mirror may tilt above the hinge layer; and

an address layer spaced under the hinge layer, the address layer having circuitry for controlling operation of the pixel elements;

wherein the hinge layer further has spring tips under each mirror and mechanically connected to and moveable with the mirror.

2. The array of claim 1, wherein the hinge layer has two spring tips.

3. The array of claim 1, wherein each mirror is rectangular in shape, wherein the hinge is under the diagonal axis of the mirror such that the mirror tilts around the diagonal axis, and the spring tips are located under the tilting corners of the mirror.

4. The array of claim 1, wherein the spring tips and the hinge are fabricated from the same material.

5. The array of claim 1, wherein the spring tips are fabricated from a metallic material.

6. The array of claim 1, wherein the spring tips extend from at least one spring tip beam that is connected to the address layer with one or more spring tip support vias.

7. The array of claim 6, wherein the hinge and the spring tip beams form a continuous pattern of the hinge layer.

8. The array of claim 6, wherein the address layer has a void region under each of the spring tips.

9. A micro pixel array, comprising:

a substrate having electrical components fabricated on the surface of the substrate;

an array of pixel elements, each element comprising a mirror, a hinge under the mirror spaced under the mirror by an air gap and mechanically connected to the mirror such that the mirror may tilt above the hinge, an address layer spaced under the hinge and in electrical connection with the electrical components of the substrate, and spring tips mechanically connected to the underside of the mirror, such that the spring tips may move with the mirror and provide landing points for the mirror.

10. The array of claim 9, wherein the hinge layer has two spring tips.

11. The array of claim 9, wherein each mirror is rectangular in shape, wherein the hinge is under the diagonal axis of the mirror such that the mirror tilts around the diagonal axis, and the spring tips are located under the tilting corners of the mirror.

12. The array of claim 9, wherein the spring tips and the hinge are fabricated from the same material.

13. The array of claim 9, wherein the spring tips are fabricated from a metallic material.

14. The array of claim 9, wherein the spring tips extend from at least one spring tip beam that is connected to the address layer with one or more spring tip support vias.

15. A method of forming a micro pixel array, comprising the steps of:

forming control circuitry on a semiconductor substrate;

depositing a first spacer layer on the substrate;

patterning the first spacer layer to define hinge support vias and spring tip support vias;

depositing a hinge layer over the first spacer layer;

forming at least one hinge etch mask on the hinge layer;

patterning the hinge layer to form at least one hinge and at least two spring tips;

depositing a second spacer layer over the hinge layer;

patterning the second spacer layer to define mirror support vias;

depositing a metal mirror layer over the second spacer layer;

patterning the metal mirror layer to form an array of micromirrors; and

removing the first and the second spacer layers.

16. The method of claim 15, wherein the hinge layer has two spring tips.

17. The method of claim 15, wherein the spring tips are located at the ends of spring tip beams orthogonally connected to the hinge.

18. The method of claim 15, wherein each mirror is rectangular in shape, wherein the hinge is under the diagonal axis of the mirror such that the mirror tilts around the diagonal axis, and the spring tips are located under the tilting corners of the mirror.

19. A display system, comprising:

a light source for producing a light beam along a light path; and

a micromirror device in the light path for selectively reflecting portions of the light beam along a second light path toward an image plane, the micromirror device comprising;

a substrate having electrical components fabricated on the surface of the substrate;

an array of mirror elements, each element comprising a reflective mirror, a hinge under the mirror spaced under the mirror by an air gap and mechanically connected to the mirror such that the mirror may tilt above the hinge, an address layer spaced under the hinge and in electrical connection with the electrical components of the substrate, and spring tips mechanically connected to the underside of the mirror such that the spring tips move with the mirror and provide a landing surface for the mirror.

20. The display system of claim 19, further comprising a projection lens in the second light path for receiving the selectively reflected light and focusing the selectively reflected light on the image plane.

21. The display system of claim 19, further comprising a controller for providing image data to the micromirror device.