Anti-stiction gas-phase lubricant for micromechanical systems

• US 20070114882A1
• Filed: 12/22/2005
• Published: 05/24/2007
• Est. Priority Date: 11/23/2005
• Status: Active Grant

• Current Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Original Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Inventors: Chen, Dongmin, Xiong, Fulin
• Granted Patent: US 7,580,174 B2
• Time in Patent Office: Days
• US Class Current: 310/311
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/0005 Anti-stiction coatings
• CPC Class Codes: B81C 1/0096 For avoiding stiction when the device is in use, i.e. after manufacture has been completed
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• 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: H02N 1/006 of the gap-closing type H02N1/004 takes precedence

Abstract

One embodiment of an micromechanical device includes a first contact surface, a moveable component having a second contact surface, where the second contact surface interacts with the first contact surface during device operation, and a gas-phase lubricant disposed between the first contact surface and the second contact surface, where the gas-phase lubricant is adapted to reduce stiction-related forces between the first contact surface and the second contact surface. One advantage of the disclosed device is that a gas-phase lubricant has a high diffusion rate and, therefore, is self-replenishing, meaning that it can quickly move back into a contact region after being physically displaced from the region by the contacting surfaces of the device during operation. Consequently, the gas-phase lubricant is more reliable than conventional solid or liquid lubricants in preventing stiction-related device failures.

Claims

1. A micromechanical device assembly comprising:

a first contact surface;

a moveable component having a second contact surface, wherein the second contact surface interacts with the first contact surface during device operation; and

a gas-phase lubricant disposed between the first contact surface and the second contact surface, wherein the gas-phase lubricant is adapted to reduce stiction-related forces between the first contact surface and the second contact surface.

2. The micromechanical device assembly of claim 1, wherein the gas-phase lubricant is selected from a group consisting of sulfur hexafluoride, silicon tetrafluoride and a haloalkane.

3. The micromechanical device assembly of claim 1, wherein the gas-phase lubricant is in a gaseous state at temperatures greater than about −

30°

C.

4. The micromechanical device assembly of claim 1, wherein the gas-phase lubricant is in a gaseous state at temperatures greater than −

30°

C. and less than about 70°

C.

5. The micromechanical device assembly of claim 1, wherein the gas-phase lubricant is a fluorinated compound that has a molecular weight greater than about 100 amu.

6. The micromechanical device assembly of claim 1, further comprising a coating that is adapted to cover at least a portion of either or both the first contact surface and the second contact surface, wherein the coating is a self-assembled-monolayer coating or is formed by exposing the first contact surface and/or the second contact surface to a hexamethyldisilazane (HMDS) containing gas.

7. The micromechanical device assembly of claim 1, wherein the moveable component comprises a mirror.

8. The micromechanical device assembly of claim 7, wherein the device forms part of an optical image processor or a spatial light modulator.

9. The micromechanical device assembly of claim 1, wherein the gas-phase lubricant has a dielectric constant greater than argon, nitrogen, air, helium or combinations thereof.

10. The micromechanical device assembly of claim 1, wherein the gas-phase lubricant is further adapted to minimize the interaction between the first contact surface and the second contact surface.

11. A micromechanical device assembly comprising:

a device package having one or more walls that form a processing region;

a micromechanical device positioned within the processing region, wherein

the micromechanical device includes;

a moveable component having a first contact surface and a conductive region,

an electrode coupled to a base, and

a power supply that is adapted to supply a sufficient electrical bias to the electrode relative to the conductive region to cause the moveable component to deflect relative to the base such that the first contact surface interacts with a second contact surface; and

a gas-phase lubricant disposed within the processing region that is adapted to reduce stiction-related forces between the first contact surface and the second contact surface.

12. The micromechanical device assembly of claim 11, wherein the gas-phase lubricant is gas containing a haloalkane.

13. The micromechanical device assembly of claim 11, wherein the gas-phase lubricant is selected from a group consisting of sulfur hexafluoride, silicon tetrafluoride and perfluorocyclobutane.

14. The micromechanical device assembly of claim 11, wherein the gas-phase lubricant is a fluorinated compound that has a molecular weight greater than about 100 amu.

15. The micromechanical device assembly of claim 11, further comprising a surface coating that is disposed on the first contact surface and the second contact surface, wherein the surface coating is a self-assembled-monolayer coating or is formed by exposing the first contact surface and the second contact surface to a hexamethyldisilazane (HMDS) containing gas.

16. The micromechanical device assembly of claim 11, further comprising a gas-phase lubricant source that is fluidly coupled to the processing region, wherein the gas-phase lubricant source is adapted to deliver a flow of a gas-phase lubricant to the processing region to reduce stiction between the first contact surface and the second contact surface.

17. The micromechanical device assembly of claim 16, further comprising a gas-phase lubricant collection device that is fluidly coupled to the processing region and adapted to receive a flow of gas-phase lubricant from the processing region.

18. The micromechanical device assembly of claim 16, wherein the gas-phase lubricant source is adapted to deliver gas-phase lubricant to the processing region continuously or intermittently during device operation.

19. The micromechanical device assembly of claim 11, wherein the device package further comprises a lid assembly having a transparent region, and the base has the moveable component formed thereon and includes the second contact surface.

20. The micromechanical device assembly of claim 11, wherein the device package further comprises a lid assembly having a transparent region that includes the second contact surface and to which the moveable component is coupled.

21. The micromechanical device assembly of claim 11, wherein the moveable component comprises a mirror.

22. The micromechanical device assembly of claim 11, wherein the gas-phase lubricant is adapted to increase the capacitance of the circuit formed between the electrode and the conductive region.

23. The micromechanical device assembly of claim 11, wherein the processing region does not contain a getter material, the getter material being adapted to retain an amount of a solid or liquid lubricant.

24. The micromechanical device assembly of claim 11, wherein the gas-phase lubricant is further adapted to minimize the interaction between the first contact surface and the second contact surface.

25. A micromechanical device assembly comprising:

a moveable component having a first contact surface;

a second contact surface, wherein the moveable component is coupled to the second contact surface, and the first contact surface interacts with the second contact surface during device operation;

an enclosure having one or more walls that form an operating region; and

a gas-phase lubricant disposed in the operating region between the first contact surface and the second contact surface, wherein the gas-phase lubricant is adapted to reduce stiction-related forces between the first contact surface and the second contact surface.

26. The micromechanical device assembly of claim 25, wherein the second contact surface is a region of a base component that is positioned within the operating region.

27. The micromechanical device assembly of claim 25, wherein the second contact surface is a region on one of the one or more walls of the enclosure.

28. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant is selected so that it will adsorb on the surface of the first or second contact surfaces and the gas-phase lubricant is a fluorinated compound that has a molecular weight greater than about 100 amu.

29. The micromechanical device assembly of claim 25, wherein the adsorbed gas-phase lubricant disposed on the first or second contact surfaces has a surface energy that is lower than the surface energy of the first or second contact surfaces.

30. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant is adapted to reduce friction between contacting surfaces.

31. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant has a viscosity between about 10 and about 100 micropoise.

32. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant does not react with the materials from which the first or second contact surfaces are made during device operation.

33. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant is hydrophobic.

34. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant exists in a gaseous state at standard temperature and pressure conditions.

35. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant exists in a gaseous state at temperature between about 0°

C. and about 70°

C. and a pressure up to about 800 Torr.

36. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant exists in a gaseous state at temperatures between about 0°

C. and about 40°

C.

37. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant exists in a gaseous state when it is introduced into the operating region.

38. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant exists in a gaseous state at temperatures between about 0°

C. and about 70°

C.

39. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant forms a monolayer on the first and second surfaces when they are at a temperature between about 0°

C. and about 70°

C. and a pressure of gas-phase lubricant disposed between the first contact surface and the second contact surface is up to about 800 Torr.

40. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant repairs a solid or liquid lubricant layer on the first or second contact surfaces under normal operating conditions.

41. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant is non-polar.

42. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant is selected so that it will not breakdown due to the exposure to optical radiation.

43. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant is selected so that it will not ionize in an electric field up to about 300 Volts/μ

m.

44. The micromechanical device assembly of claim 25, wherein the gas-phase lubricant has permittivity greater than argon, nitrogen and air.