Anti-stiction technique for electromechanical systems and electromechanical device employing same

• US 20060246631A1
• Filed: 04/27/2005
• Published: 11/02/2006
• Est. Priority Date: 04/27/2005
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus, Metz, Matthias, Stark, Brian, Yama, Gary, Ulm, Markus, Frey, Wilhelm
• Granted Patent: US 7,449,355 B2
• Time in Patent Office: Days
• US Class Current: 438/127
• 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: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/1461 MEMS

Abstract

A mechanical structure is disposed in a chamber, at least a portion of which is defined by the encapsulation structure. A first method provides a channel cap having at least one preform portion disposed over or in at least a portion of an anti-stiction channel to seal the anti-stiction channel, at least in part. A second method provides a channel cap having at least one portion disposed over or in at least a portion of an anti-stiction channel to seal the anti-stiction channel, at least in part. The at least one portion is fabricated apart from the electromechanical device and thereafter affixed to the electromechanical device. A third method provides a channel cap having at least one portion disposed over or in at least a portion of the anti-stiction channel to seal an anti-stiction channel, at least in part. The at least one portion may comprise a wire ball, a stud, metal foil or a solder preform. A device includes a substrate, an encapsulation structure and a mechanical structure. An anti-stiction layer is disposed on at least a portion of the mechanical structure. An anti-stiction channel is formed in at least one of the substrate and the encapsulation structure. A cap has at least one preform portion disposed over or in at least a portion of the anti-stiction channel to seal the anti-stiction channel, at least in part.

Claims

1. A method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a mechanical structure disposed in the chamber;

the method comprising;

forming at least one anti-stiction channel through at least one of the substrate and the encapsulation structure;

introducing an anti-stiction fluid into the chamber via the anti-stiction channel; and

providing a channel cap having at least one preform portion disposed over or in at least a portion of the anti-stiction channel to seal the anti-stiction channel, at least in part.

2. The method of claim 1 wherein the anti-stiction fluid forms an anti-stiction layer on at least a portion of the mechanical structure.

3. The method of claim 1 wherein providing a channel cap having at least one preform portion comprises affixing the at least one preform portion to the electromechanical device.

4. The method of claim 3 wherein affixing comprises providing force to cause contact between the at least one preform portion and the electromechanical device.

5. The method of claim 3 wherein affixing comprises stamping the preform onto the electromechanical device.

6. The method of claim 3 wherein affixing comprises bonding the at least one preform portion to the electromechanical device.

7. The method of claim 6 wherein bonding comprises ultrasonically bonding the at least one preform portion to the electromechanical device.

8. The method of claim 3 wherein affixing comprises applying heat to cause at least one portion of the preform portion to reflow.

9. The method of claim 8 wherein affixing further comprises providing force to cause contact between the at least one preform portion and the electromechanical device.

10. The method of claim 8 wherein the anti-stiction fluid forms an anti-stiction layer on at least a portion of the mechanical structure and applying heat comprises keeping the amount of heat low enough to prevent destruction of the anti-stiction layer.

11. The method of claim 10 wherein the at least one preform portion has a reflow temperature less than about 450 degrees centigrade.

12. The method of claim 1 wherein the at least one preform portion has a width greater than a width of the anti-stiction channel.

13. The method of claim 1 wherein the at least one preform portion comprises at least one metal portion.

14. The method of claim 13 wherein the at least one metal portion comprises metal foil.

15. The method of claim 13 wherein the at least one metal portion comprises a wire ball.

16. The method of claim 13 wherein the at least one metal portion comprises a metal stud.

17. The method of claim 13 wherein providing a channel cap having at least one preform portion comprises affixing the at least one metal portion to the electromechanical device.

18. The method of claim 17 wherein affixing comprises providing force to cause contact between the at least one preform portion and the electromechanical device.

19. The method of claim 18 wherein affixing further comprises bonding the at least one metal portion to the electromechanical device.

20. The method of claim 18 wherein affixing comprises applying heat to cause one or more portions of the at least one metal portion to reflow.

21. The method of claim 1 wherein the at least one preform portion comprises at least one solder preform.

22. The method of claim 21 wherein affixing comprises applying heat to cause one or more portions of the at least one metal portion to reflow.

23. The method of claim 1 wherein the encapsulation structure comprises silicon and wherein providing a channel cap having at least one preform portion comprises providing at least one metal preform portion on the encapsulation structure.

24. The method of claim 23 wherein affixing comprises applying heat to cause metal silicide to form at an interface between the at least one metal preform portion and the encapsulation structure.

25. The method of claim 1 wherein the at least one preform portion has one or more portions that define a tapered contour.

26. The method of claim 1 wherein the at least one preform portion has one or more portions that define a conical contour.

27. The method of claim 1 wherein the at least one preform portion has one or more portions that define a wedged shaped contour.

28. The method of claim 1 further comprising:

providing a bond member superjacent to at least one of the substrate and the encapsulation structure; and

wherein providing a channel cap having at least one preform portion comprises bonding the at least one preform portion to the bond member.

29. The method of claim 28 wherein the bond member comprises a metal bond member.

30. The method of claim 29 wherein the metal bond member comprises a metal ring.

31. A method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a mechanical structure disposed in the chamber;

the method comprising;

forming at least one anti-stiction channel through at least one of the substrate and the encapsulation structure;

introducing an anti-stiction fluid into the chamber via the anti-stiction channel; and

providing a channel cap having at least one portion disposed over or in at least a portion of the anti-stiction channel to seal the anti-stiction channel, at least in part,

wherein providing a channel cap comprises fabricating the at least one portion apart from the electromechanical device and thereafter affixing the at least one portion to the electromechanical device.

32. The method of claim 31 wherein affixing comprises providing force to cause contact between the at least one portion and the electromechanical device.

33. The method of claim 32 further comprising removing the force.

34. The method of claim 31 wherein affixing comprises applying heat to cause one or more portions of the at least one portion to reflow.

35. A method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a mechanical structure disposed in the chamber;

the method comprising;

forming at least one anti-stiction channel through at least one of the substrate and the encapsulation structure;

introducing an anti-stiction fluid into the chamber via the anti-stiction channel; and

providing a channel cap having at least one portion disposed over or in at least a portion of the anti-stiction channel to seal the anti-stiction channel, at least in part,

wherein the at least one portion comprises a wire ball, a stud, metal foil or a solder preform.

36. A method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a mechanical structure disposed in the chamber;

the method comprising;

forming at least one anti-stiction channel through at least one of the substrate and the encapsulation structure;

introducing an anti-stiction fluid into the chamber via the anti-stiction channel;

depositing a preform on the electromechanical device; and

reflowing at least a portion of the preform to seal the anti-stiction channel, at least in part.

37. An electromechanical device comprising:

a substrate;

an encapsulation structure disposed over at least a portion of the substrate and defining at least a portion of a chamber;

a mechanical structure disposed in the chamber;

an anti-stiction layer disposed on at least a portion of the mechanical structure;

an anti-stiction channel formed in at least one of the substrate and the encapsulation structure, the anti-stiction channel being in fluid communication with the chamber; and

a cap, the cap having at least one preform portion disposed over or in at least a portion of the anti-stiction channel to seal the anti-stiction channel, at least in part.