Micromechanical device having an improved beam

• US 5,696,619 A
• Filed: 02/27/1995
• Issued: 12/09/1997
• Est. Priority Date: 02/27/1995
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Yoshihara, Hidekazu, Knipe, Richard L., Tregilgas, John H., Orent, Thomas W.
• Primary Examiner(s): SHEEHAN, JOHN P
• Application Number:
  US08/395,562
• Time in Patent Office: 1,016 Days
• Field of Search: 359/224, 420/417, 420/431, 148/421, 148/423, 348/770, 348/771
• US Class Current: 359/224.1
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

An electrically addressable, integrated, monolithic, micromirror device (10) is formed by the utilization of sputtering techniques, including various metal and oxide layers, photoresists, liquid and plasma etching, plasma stripping and related techniques and materials. The device (10) includes a selectively electrostatically deflectable mass or mirror (12) of supported by one or more beams (18) formed by sputtering and selective etching. The beams (18) are improved by being constituted of an impurity laden titanium-tungsten layer (52) with an impurity such as nitrogen, which causes the beams to have lattice constant different from TiW. The improved beams (18) exhibit increased strength, and decreased relaxation and creep.

Claims

1. An improved deformable beam for a micromechanical device which includes a deflectable mass supported by the beam, the beam being deformed upon deflection of the mass, wherein the improvement comprises:

the dents being constituted of an electrically conductive layer of titanium-tungsten containing an alloying element at a level above 0.1% atomic, said beam being constituted of at least 90% by weight tungsten, wherein said alloying element is selected from the group of nitrogen, oxygen, boron, silicon and carbon.

2. An improved beam as in claim 1, wherein the layer has a lattice constant different from a lattice constant of a Ti:

W alloy.

3. An improved beam as specified in claim 2 wherein the layer has a crystalline structure other than BCC.

4. An improved beam as in claim 1, wherein the micromechanical device is an SLM, and the mass is a mirror.

5. An improved beam as in claim 1, wherein the alloying element is nitrogen and the layer has FCC crystalline structure.

6. An improved beam as in claim 1, wherein the layer is formed by reactive sputtering in an atmosphere which includes nitrogen.

7. An improved beam as in claim 5 wherein the nitrogen comprises 2% to 16% by volume of the sputtering atmosphere.

8. An improved beam as in claim 6, wherein the layer is a mixture of TiN, W₂ N and W.

9. An improved beam as in claim 6, wherein the nitrogen comprises 2% to 16% by volume of the sputtering atmosphere.

10. An improved beam as in claim 1, wherein the micromechanical device is an SLM, and the mass is a mirror.

11. An improved beam as in claim 1, wherein the layer is produced by co-sputtering, reactive sputtering, reactive evaporation, chemical vapor deposition, or co-evaporation.

12. An improved beam as in claim 11, wherein the micromechanical device is an SLM, and the mass is a mirror.