Anchors for microelectromechanical systems having an SOI substrate, and method of fabricating same

• US 6,952,041 B2
• Filed: 07/25/2003
• Issued: 10/04/2005
• Est. Priority Date: 07/25/2003
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus, Kronmueller, Silvia
• Primary Examiner(s): Prenty, Mark V.
• Application Number:
  US10/627,237
• Publication Number:
  US 20050019974A1
• Time in Patent Office: 802 Days
• Field of Search: 257415-417, 257/254, 735/142.1
• US Class Current: 257/415
• CPC Class Codes: B81B 2203/0307 Anchors
• CPC Class Codes: B81B 3/0054 For holding or placing an element in a given position
• CPC Class Codes: B81C 1/00126 Static structures not provided for in groups B81C1/00031 - B81C1/00119

Abstract

There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a MEMS device, and technique of fabricating or manufacturing a MEMS device having mechanical structures and anchors to secure the mechanical structures to the substrate. The anchors of the present invention are comprised of a material that is relatively unaffected by the release processes of the mechanical structures. In this regard, the etch release process are selective or preferential to the material(s) securing the mechanical structures in relation to the material comprising the anchors. Moreover, the anchors of the present invention are secured to the substrate in such a manner that removal of the insulation layer has little to no affect on the anchoring of the mechanical structures to the substrate.

Claims

1. An electromechanical device comprising:

a substrate;

an insulation layer disposed on the substrate;

a first semiconductor layer disposed on or above the insulation layer;

an anchor that is disposed in an opening in the insulation layer and the first semiconductor layer and contacts the substrate, wherein the anchor includes a material that is different than the insulation layer;

a second semiconductor layer, disposed on the anchor and on the first semiconductor layer; and

a fixed electrode, formed, in part, from the first and second semiconductor layers, wherein the fixed electrode is affixed to the substrate via the anchor.

2. The device of claim 1 wherein the anchor includes silicon nitride, silicon carbide, germanium, silicon/germanium or gallium arsenide.

3. The device of claim 1 wherein the insulation layer includes silicon nitride or silicon oxide.

4. The device of claim 1 further including a moveable electrode, juxtaposed the fixed electrode, wherein the moveable electrode is formed in part from the second semiconductor layer.

5. The device of claim 4 wherein the insulation layer includes silicon oxide and the anchor material includes silicon nitride, silicon carbide, germanium, silicon/germanium or gallium arsenide.

6. The device of claim 4 wherein the insulation layer includes silicon oxide and the anchor material includes silicon, silicon carbide, germanium, silicon/germanium, or gallium arsenide.

7. The device of claim 4 wherein the insulation layer includes silicon nitride and the anchor material includes silicon, silicon oxide, silicon carbide, germanium, silicon/germanium or gallium arsenide.

8. The device of claim 1 wherein a substantial portion of the fixed electrode overlying the anchor material is a monocrystalline silicon.

9. The device of claim 1 wherein a substantial portion of the fixed electrode overlying the anchor material is a polycrystalline silicon.

10. The device of claim 1 further including:

a chamber defined in part by a first encapsulation layer having at least one vent;

a moveable electrode disposed in the chamber and juxtaposed the fixed electrode;

a second encapsulation layer, deposited over or in the at least one vent, to thereby seal the chamber, wherein the second encapsulation layer includes a semiconductor material.

11. The device of claim 10 wherein the second encapsulation layer includes polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium or gallium arsenide.

12. The device of claim 11 wherein the first encapsulation layer includes polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, silicon nitride or silicon carbide.

13. The device of claim 10 wherein:

the first encapsulation layer is a semiconductor material that is doped with a first impurity to provide a first region of a first conductivity type, and

the semiconductor material of the second encapsulation layer is doped with a second impurity to provide a second region with a second conductivity type and wherein the first conductivity type is opposite the second conductivity type.

14. The device of claim 10 further including a contact having at least a portion that is disposed outside the chamber.

15. The device of claim 10 wherein a first portion of the first encapsulation layer is a monocrystalline silicon and a second portion of the first encapsulation layer is a polycrystalline silicon.

16. The device of claim 10 wherein a first portion of the first encapsulation layer is a monocrystalline silicon and a second portion of the first encapsulation layer is a porous or amorphous silicon.

17. The device of claim 16 wherein the second encapsulation layer overlying the second portion of the first encapsulation layer is a polycrystalline silicon.

18. The device of claim 17 includes a field region disposed outside and above the chamber wherein the field region is a monocrystalline silicon.

19. An electromechanical device comprising:

a substrate;

an insulation layer disposed on the substrate;

a first semiconductor layer disposed on or above the insulation layer;

an anchor that is disposed in an opening in the insulation layer and the first semiconductor layer and contacts the substrate, wherein the anchor includes a material that is different than the insulation layer;

a second semiconductor layer, disposed on the anchor;

a fixed electrode, formed, in part, from the second semiconductor layer, wherein the fixed electrode is affixed to the substrate via the anchor;

a moveable electrode, formed in part from the second semiconductor layer, wherein the moveable electrode is disposed in a chamber wherein the chamber is defined in part by a first encapsulation layer;

a second encapsulation layer, deposited over or in at least one vent, to thereby seal the chamber, wherein the second encapsulation layer includes a semiconductor material;

a contact; and

a trench, disposed around at least a portion of the contact, wherein the trench is disposed outside the chamber and wherein the trench includes a first material disposed therein to electrically isolate the contact.

20. The device of claim 19 wherein the second encapsulation layer includes polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

21. The device of claim 20 wherein the first encapsulation layer includes polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, silicon nitride or silicon carbide.

22. The device of claim 19 wherein the first material is disposed on at least the outer surfaces of the trench.

23. The device of claim 22 wherein a semiconductor material is disposed in the trench, wherein the semiconductor material surrounded by the first material in the trench.

24. The device of claim 22 wherein the trench is disposed on an etch stop region.

25. The device of claim 22 wherein the etch stop region is a silicon nitride or silicon dioxide.

26. The device of claim 22 wherein the first material is a silicon nitride or silicon dioxide.

27. The device of claim 22 wherein the trench surrounds the contact.

28. The device of claim 19 wherein the anchor includes silicon nitride, silicon carbide, germanium, silicon/germanium or gallium arsenide.

29. The device of claim 19 wherein the insulation layer includes silicon nitride or silicon oxide.

30. The device of claim 19 wherein the insulation layer includes silicon oxide and the anchor material includes silicon nitride, silicon carbide, germanium, silicon/germanium or gallium arsenide.

31. The device of claim 19 wherein the insulation layer includes silicon nitride and the anchor material includes silicon, silicon oxide, silicon carbide, germanium, silicon/germanium or gallium arsenide.

32. The device of claim 19 wherein a substantial portion of the fixed electrode overlying the anchor material is a monocrystalline silicon.

33. The device of claim 19 wherein a substantial portion of the fixed electrode overlying the anchor material is a polycrystalline silicon.

34. An electromechanical device comprising:

a substrate;

an insulation layer disposed on the substrate;

a first semiconductor layer disposed on or above the insulation layer;

an anchor that is disposed in an opening in the insulation layer and the first semiconductor layer an contacts the substrate, wherein the anchor includes a material that is different than the insulation layer;

a second semiconductor layer, disposed on the anchor and on the first semiconductor;

a fixed electrode, formed, in part, from the first and second semiconductor layers, wherein the fixed electrode is affixed to the substrate via the anchor;

a moveable electrode, formed in part from the second semiconductor layer, wherein the moveable electrode is disposed in a chamber wherein the chamber is defined in part by a first encapsulation layer;

a second encapsulation layer, deposited over or in at least one vent, to thereby seal the chamber, wherein the second encapsulation layer includes a semiconductor material;

a contact; and

a trench, disposed around at least a portion of the contact, wherein the trench is disposed outside the chamber and wherein the trench includes an insulating material disposed therein.

35. The device of claim 34 wherein the second encapsulation layer includes polycrystalline silicon, porous polycrystalline silicon, amorphous silica , silicon carbide, silicon/germanium, germanium, or gallium arsenide.

36. The device of claim 35 wherein the first encapsulation layer includes polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, silicon nitride or silicon carbide.

37. The device of claim 34 wherein the insulating material is disposed on at least the outer surfaces of the trench.

38. The device of claim 37 wherein a semiconductor material which is disposed in the trench, wherein the semiconductor material is surrounded in the trench by the insulating material.

39. The device of claim 37 wherein the trench is disposed on an etch stop region.

40. The device of claim 37 wherein the etch stop region is a silicon nitride or silicon dioxide.

41. The device of claim 37 wherein the insulating material is a silicon nitride or silicon dioxide.

42. The device of claim 37 wherein the trench surrounds the contact.

43. The device of claim 34 wherein the anchor includes silicon nitride, silicon carbide, germanium, silicon/germanium or gallium arsenide.

44. The device of claim 34 wherein the insulation layer includes silicon nitride or silicon oxide.

45. The device of claim 34 wherein the insulation layer includes silicon oxide and the anchor material includes silicon nitride, silicon carbide, germanium, silicon/germanium or gallium arsenide.

46. The device of claim 34 wherein the insulation layer includes silicon nitride and the anchor material includes silicon, silicon oxide, silicon carbide, germanium, silicon/germanium or gallium arsenide.

47. The device of claim 34 wherein a substantial portion of the fixed electrode overlying the anchor material is a monocrystalline silicon.

48. The device of claim 34 wherein a substantial portion of the fixed electrode overlying the anchor material is a polycrystalline silicon.