Yokeless hidden hinge digital micromirror device with double binge layer

• US 20030142382A1
• Filed: 01/16/2003
• Published: 07/31/2003
• Est. Priority Date: 01/31/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: DiCarlo, Anthony
• Granted Patent: US 7,088,486 B2
• Time in Patent Office: Days
• US Class Current: 359/223
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A micromirror array 110 fabricated on a semiconductor substrate 11. The array 110 is comprised of four operating layers 12, 13, 14, 15. An addressing layer 12 is fabricated on the substrate. A raised electrode layer 13 is spaced above the addressing layer by an air gap. A hinge layer 14 is spaced above the raised electrode layer 13 by another air gap. A mirror layer 15 is spaced over the hinge layer 14 by a third air gap.

Claims

1. An array of micromirror 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;

a raised electrode layer spaced under the hinge layer and having at least two raised electrodes, one under each of two opposing mirror edges; and

an address layer spaced under the raised electrode layer, the address layer having circuitry for controlling operation of the pixel elements.

2. 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.

3. The array of claim 1, wherein the raised electrode and the hinge are fabricated from the same material.

4. The array of claim 1, wherein the raised electrode is fabricated from a metallic material.

5. The array of claim 1, wherein the hinge layer further has spring tips under each mirror and mechanically connected to one or more of the underlying layers.

6. The array of claim 5, 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 5, wherein the hinge and the spring tip beams form a continuous pattern of the hinge layer.

8. The array of claim 1, further comprising a substrate having electrical components fabricated on the surface of the substrate.

9. The array of claim 1, wherein the raised electrode layer further has structure for supporting the hinges of the hinge layer.

10. The array of claim 1, wherein the raised electrode layer further has structure for supporting the spring tips of the hinge layer.

11. The array of claim 1, wherein the address layer has address electrodes connected to the raised electrodes.

12. The array of claim 1, wherein the raised electrodes are attached to the addressing layer by means of support posts.

13. The array of claim 1, wherein the raised electrodes extend to the outer tips of the mirrors.

14. The array of claim 1, wherein the hinge layer further has a raised electrodes under the mirrors.

15. A method of forming an array of micromirror elements, comprising the steps of:

depositing a first spacer layer on a substrate;

patterning the first spacer layer to define lower hinge support vias and raised electrode vias;

depositing a raised electrode layer over the first spacer layer;

patterning the raised electrode layer to form at least two raised electrodes associated with each micromirror elements;

depositing a second spacer layer over the patterned raised electrodes;

patterning the second spacer layer to form hinge support vias over the lower hinge support vias;

depositing a hinge layer over the second spacer layer;

patterning the hinge layer to form at least one hinge associated with each micromirror element;

depositing a third spacer layer over the hinge layer;

patterning the third spacer layer to define mirror support vias;

depositing a mirror layer over the third spacer layer;

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

removing the first, second, and third spacer layers.

16. The method of claim 15, wherein the hinge layer is further patterned to form at least two spring tips under each mirror.

17. The method of claim 15, wherein the patterning is accomplished by photolithographic processes.

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.

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, at least two raised electrodes spaced under the hinge, and an address layer spaced under the address electrodes and in electrical connection with the electrical components of the substrate.

20. The display system of claim 19, further comprising spring tips mechanically connected to and spaced above the address layer, such that the mirror may land on the spring tips.