Microelectromechanical device with reset electrode

• US 20060227405A1
• Filed: 06/07/2006
• Published: 10/12/2006
• Est. Priority Date: 04/02/2004
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Michael J. Regan
• Inventors: Regan, Michael J.
• Granted Patent: US 7,298,542 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• 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
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A microelectromechanical device having a reset electrode for use in various devices including display devices such as those employing spatial light modulators. The device includes an optically transmissive substrate, a semiconductor substrate, and a member deflectable between a rest position and an operative position supported by one of the substrates. The deflectable member returns to an undeflected position by operation of the reset electrode.

Claims

1-15. -15. (canceled)

16. A micro-electromechanical device, comprising:

a substrate;

an optically transmissive layer disposed a spaced distance from the substrate, wherein the substrate and the optically transmissive layer define at least one cavity, the at least one cavity containing a dielectrophoretic fluid;

a support structure coupled to one of the substrate or the optically transmissive layer, the support structure contained within the at least one cavity;

a transparent conductive material positioned on the optically transmissive layer; and

a reflective element coupled to the support structure, the reflective element configured to;

deflect between a rest position and at least one operative position when electrostatically attracted to an address electrode located on the substrate; and

return to the rest position when subjected to an electrostatic force generated by the transparent conductive material.

17. The micro-electromechanical device of claim 16 wherein the reflective element comprises a substantially rigid reflective plate.

18. The micro-electromechanical device of claim 16 wherein the support structure further comprises a ground electrode attached to the reflective element, wherein the ground electrode is electrically coupled to the substrate and configured for selective actuation of electronic circuitry.

19. The micro-electromechanical device of claim 16 wherein the support structure comprises at least one hinge and at least one post, the at least one post connected to at least one of the optically transmissive layer or the substrate, and wherein the at least one hinge extends from the at least one post and into connection with the reflective element.

37. The micro-electromechanical device of claim 16, further comprising a voltage controller, the voltage controller operable on the address electrode and a power source connected to the transparent conductive material to actuate deflection and return to the rest position of the reflective element.

38. The micro-electromechanical device of claim 16 wherein the transparent conductive material has a voltage potential sufficient to overcome electrostatic attraction between the reflective element and the address electrode.

39. The micro-electromechanical device of claim 16 wherein the substrate includes circuitry to control the address electrode, and wherein the transparent conductive material is connected to a power source independent of the substrate circuitry.

40. The micro-electromechanical device of claim 16 wherein the transparent conductive material exhibits optical transmission greater than about 70% at a material thickness of about 200 angstroms.

20. A display device, comprising:

a light source for providing a beam of light along a light path;

a micromirror device on the light path for selectively reflecting a portion of the beam of light along a second light path in response to image data signals; and

a controller for providing image data signals to the micromirror device, wherein the micromirror device includes;

a semiconductor substrate;

an optically transmissive layer connected to and disposed a spaced distance from the semiconductor substrate;

at least one deflectable mirror member supported by at least one of the semiconductor substrate or the optically transmissive layer, the mirror member deflectable between a rest position and at least one operative position; and

at least one reset electrode operative on the mirror member to move the mirror member from the at least one operative position to the rest position, the reset electrode positioned on one of the semiconductor substrate and the optically transmissive layer.

21. The display device of claim 20 wherein the at least one reset electrode is disposed between the mirror member and the optically transmissive layer, the at least one reset electrode composed of a transparent electroconductive material.

22. The display device of claim 20 wherein the semiconductor substrate and optically transmissive layer form a sealed cavity, the sealed cavity containing the deflectable mirror member and a dielectrophoretic fluid.

23. The display device of claim 20 wherein the at least one reset electrode is a high voltage electrode.

41. The display device of claim 20, further comprising a voltage controller, the voltage controller operable on a power source connected to the reset electrode to actuate deflection of the mirror member between the rest position and the at least one operative position.

42. The display device of claim 20 wherein the semiconductor substrate includes circuitry to control an address electrode located on the semiconductor substrate, and wherein the reset electrode is connected to a power source independent of the substrate circuitry.

43. The display device of claim 21 wherein the transparent electroconductive material exhibits optical transmission greater than about 70% at a material thickness of about 200 angstroms.

24-29. -29. (canceled)

30. A method of making a digital micromirror device, comprising the steps of:

establishing spacer layers and patterns on a semiconductor substrate having address circuitry;

constructing elements of the digital micromirror device on the semiconductor substrate, the micromirror device including an address electrode and a micromirror;

establishing an optically transparent substrate in sealed overlying relationship with the micromirror after removal of the spacer layers; and

establishing at least one reset electrode, the reset electrode connected to at least one of the optically transparent substrate or the semiconductor substrate, the reset electrode operating independent of the address electrode and generating a bias voltage sufficient to overcome a bias voltage produced by the address electrode.

31. The method of claim 30 wherein the reset electrode establishing step comprises attaching an optically transparent conductive material to at least one region of the optically transparent substrate.

32. The method of claim 30, further comprising the step of introducing a dielectrophoretic fluid into a sealed chamber formed between the optically transparent substrate and the semiconductor substrate.

33-36. -36. (canceled)