Process of forming a micromechanical system containing an anti-stiction gas-phase lubricant

• US 7,471,439 B2
• Filed: 12/22/2005
• Issued: 12/30/2008
• 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
• Primary Examiner(s): Mack; Ricky
• Assistant Examiner(s): Thomas; Brandi N
• Application Number:
  US11/315,920
• Publication Number:
  US 20070115530A1
• Time in Patent Office: 1,104 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/296, 359/298
• US Class Current: 359/290
• 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: B81C 2201/112 Depositing an anti-stiction or passivation coating, e.g. on the elastic or moving parts
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 21/32 Micromanipulators structurally combined with microscopes
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B

Abstract

Embodiments of the present invention generally relate to a process of forming a device that has an improved usable lifetime due to the addition of a gas-phase lubricant that reduces the likelihood of stiction occurring between the various moving parts in an electromechanical device. 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 process for forming a micromechanical device assembly, the process comprising:

providing a lid assembly having one or more walls;

providing a base;

forming a micromechanical device that comprises a moveable component having a first contact surface, wherein the first contact surface interacts with a second contact surface during device operation;

forming a processing region by bonding the lid assembly to the base, wherein the micromechanical device is positioned in the processing region;

removing contaminants from the micromechanical device assembly that is free of a lubricating material; and

after the step of removing contaminants, disposing a gas-phase lubricant within the processing region at a predetermined pressure, wherein the gas-phase lubricant is adapted to reduce stiction-related forces between the first contact surface and the second contact surface.

2. The process of claim 1, wherein the moveable component comprises a mirror.

3. The process of claim 1, wherein the moveable component comprises a yoke that has a surface that is the first contacting surface.

4. The process of claim 1, wherein the base is a semiconductor substrate on which the moveable component is formed.

5. The process of claim 1, wherein the step of forming a processing region by bonding the lid assembly to the base is performed at a temperature less than about 250°

C.

6. The process of claim 1, wherein the gas-phase lubricant is adapted to reduce the stiction-related forces between the first contact surface and the second contact surface without performing an activation step, wherein the activation step requires heating the micromechanical device to a temperature greater than about 300°

C.

7. The process of claim 1, further comprising exposing a surface of the micromechanical device to electromagnetic radiation, wherein the electromagnetic radiation in adapted to modify the surface of the micromechanical device to facilitate the formation of a gas-phase lubricant monolayer on the surface.

15. The process of claim 1, wherein the predetermined pressure is atmospheric pressure or greater.

16. The process of claim 1, further comprising removing outgassed contaminants from the processing region prior to providing the gas-phase lubricant.

17. The process of claim 16, wherein the step of removing outgassed contaminants from the processing region comprises flowing a gas through the processing region.

18. The process of claim 16, wherein the step of removing outgassed contaminants from the processing region comprises evacuating the processing region to a pressure below atmospheric pressure.

19. The process of claim 16, wherein the step of removing outgassed contaminants from the processing region comprises evacuating the processing region to a pressure between 10⁻

6 Torr and 10<sup>−

3</sup> Torr at least one time and backfilling the processing region with a gas.

20. The process of claim 1, wherein the only lubricant disposed in the processing region is the gas-phase lubricant.

23. The process of claim 1, wherein the gas-phase lubricant is selected from a group consisting of sulfur hexafluoride, silicon tetrafluoride and perfluorocyclobutane.

8. A process for forming a micromechanical device assembly, the process comprising:

providing a packaging chamber having one or more walls that form a packaging chamber processing region;

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

positioning a lid assembly having one or more walls in the packaging chamber processing region;

positioning a base in the packaging chamber processing region;

positioning the formed micromechanical device in the packaging chamber processing region;

removing contaminants from the packaging chamber processing region that is free of a lubricating material;

after the step of removing contaminants, disposing a gas-phase lubricant within the packaging chamber processing region to a predetermined pressure, wherein the gas-phase lubricant is adapted to reduce stiction-related forces between the first contact surface and the second contact surface; and

forming an operating region having the micromechanical device and the gas-phase lubricant positioned therein by bonding the lid assembly to the base.

9. The process of claim 8, wherein the step of removing contaminants from the packaging chamber processing region comprises evacuating the packaging chamber processing region to pressure below atmospheric pressure or flowing a gas through the packaging chamber processing region.

10. The process of claim 8, wherein the predetermined pressure of gas-phase lubricant disposed within the packaging chamber processing region is between about 700 Torr and about 800 Torr.

21. The process of claim 8, wherein the only lubricant disposed in the processing region is the gas-phase lubricant.

24. The process of claim 8, wherein the gas-phase lubricant is selected from a group consisting of sulfur hexafluoride, silicon tetrafluoride and perfluorocyclobutane.

11. A process for forming a plurality of micromechanical device assemblies, the process comprising:

providing a packaging chamber having one or more walls that form a packaging chamber processing region;

forming a plurality of micromechanical devices on a surface of a substrate, wherein the micromechanical devices include a moveable component having a first contact surface that interacts with a second contact surface during device operation;

positioning a lid assembly having a plurality of recesses formed therein in the packaging chamber processing region;

removing contaminants from the packaging chamber processing region that is free of a lubricating material;

after the step of removing contaminants, disposing a gas-phase lubricant within the packaging chamber processing region to a predetermined pressure, wherein the gas-phase lubricant is adapted to reduce stiction-related forces between the first contact surface and the second contact surface;

bonding the lid assembly to the surface of the substrate so that a recess is positioned over each micromechanical device such that the gas-phase lubricant is disposed within a sealed operating region formed between the recess and the surface of the substrate; and

dicing the substrate to form a plurality of micromechanical device assemblies, wherein each micromechanical device assembly that contain a recess, a portion of the substrate and a micromechanical device positioned in the sealed operating region.

12. The process of claim 11, wherein the gas contains argon (Ar), nitrogen (N2) or helium (He).

13. The process of claim 11, wherein the step of removing contaminants from the packaging chamber processing region comprises evacuating the packaging chamber processing region to pressure below atmospheric pressure or flowing a gas through the packing chamber processing region.

14. The process of claim 11, wherein the predetermined pressure of gas-phase lubricant disposed within the packaging chamber processing region is between about 700 Torr and about 800 Torr.

22. The process of claim 11, wherein the only lubricant disposed in the processing region is the gas-phase lubricant.

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