Microelectromechanical systems and devices having thin film encapsulated mechanical structures

• US 7,075,160 B2
• Filed: 06/04/2003
• Issued: 07/11/2006
• Est. Priority Date: 06/04/2003
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus, Kronmueller, Silvia
• Primary Examiner(s): Wilczewski, Mary
• Assistant Examiner(s): Lewis, Monica
• Application Number:
  US10/454,867
• Publication Number:
  US 20040248344A1
• Time in Patent Office: 1,133 Days
• Field of Search: 257414-420, 257/787, 257/788, 257/790
• US Class Current: 257/414
• CPC Class Codes: B81B 2207/015 the micromechanical device and the control or processing electronics being integrated on the same substrate
• CPC Class Codes: B81C 1/00261 Processes for packaging MEMS devices MEMS packages B81B7/0032, packaging of smart-MEMS B81C1/0023
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 2201/0176 Chemical vapour Deposition
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

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 encapsulated in a chamber prior to final packaging. The material that encapsulates the mechanical structures, when deposited, includes one or more of the following attributes: low tensile stress, good step coverage, maintains its integrity when subjected to subsequent processing, does not significantly and/or adversely impact the performance characteristics of the mechanical structures in the chamber (if coated with the material during deposition), and/or facilitates integration with high-performance integrated circuits. In one embodiment, the material that encapsulates the mechanical structures is, for example, silicon (polycrystalline, amorphous or porous, whether doped or undoped), silicon carbide, silicon-germanium, germanium, or gallium-arsenide.

Claims

1. A microelectromechanical device comprising:

a chamber;

a first encapsulation layer having at least one vent formed therein, wherein first encapsulation layer is at least a portion of a wall of the chamber;

a micromechanical structure, wherein at least a portion of the micromechanical structure is disposed in the chamber; and

a second encapsulation layer, disposed in the at least one vent to seal the chamber, wherein the second encapsulation layer is a semiconductor material.

2. The microelectromechanical device of claim 1 wherein the second encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

3. The microelectromechanical device of claim 2 wherein the first encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, silicon nitride or silicon carbide.

4. The microelectromechanical device of claim 1 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, wherein the first conductivity type is opposite the second conductivity type.

5. The microelectromechanical device of claim 1 further including a contact which is at least partially disposed outside the chamber.

6. The microelectromechanical device of claim 5 wherein the contact is a semiconductor material that is doped with an impurity to increase the electrical conductivity of the contact.

7. The microelectromechanical device of claim 1 wherein a first portion of the first encapsulation layer is monocrystalline silicon and a second portion is polycrystalline silicon, and wherein the second portion is at least the portion of the wall of the chamber.

8. The microelectromechanical device of claim 1 wherein a first portion of the first encapsulation layer is monocrystalline silicon and a second portion is porous or amorphous silicon, and wherein the second portion is a portion of the wall of the chamber.

9. The microelectromechanical device of claim 8 wherein the second encapsulation layer overlies the second portion of the first encapsulation layer and wherein the portion of the second encapsulation layer that overlies the second portion of the first encapsulation layer is polycrystalline silicon.

10. The microelectromechanical device of claim 9 further including a field region disposed outside and above the chamber wherein the field region includes monocrystalline silicon.

11. The electromechanical device of claim 5 further including an insulation layer disposed on at least the second encapsulation layer that is disposed in or on the at least one vent, wherein the insulation layer includes an opening over the contact and wherein the microelectromechanical device further includes a highly electrically conductive layer that is disposed in the opening and on the contact and on at least a portion of the insulation layer.

12. The microelectromechanical device of claim 1 wherein:

the first encapsulation layer includes a plurality of vents formed therein, and wherein the plurality of vents are substantially perpendicular to a substrate; and

a second encapsulation layer, disposed over and in the plurality of vents to seal the chamber.

13. The microelectromechanical device of claim 12 wherein the second encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

14. The microelectromechanical device of claim 13 wherein the first encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, silicon nitride or silicon carbide.

15. The microelectromechanical device of claim 12 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, wherein the first conductivity type is opposite the second conductivity type.

16. The microelectromechanical device of claim 12 further including a contact which is at least partially disposed outside the chamber, wherein the contact is a semiconductor material that is doped with an impurity to increase the electrical conductivity of the contact.

17. The microelectromechanical device of claim 16 further including an insulation layer disposed on the second encapsulation layer.

18. The microelectromechanical device of claim 17 wherein the insulation layer includes an opening over the contact and wherein the microelectromechanical device further includes a highly electrically conductive layer that is disposed in the opening, on the contact, and on at least a portion of the insulating layer.

19. The microelectromechanical device of claim 12 wherein a first portion of the first encapsulation layer is monocrystalline silicon and a second portion is porous or amorphous silicon, and wherein the second portion of the first encapsulation layer is at least the portion of the wall of the chamber.

20. The microelectromechanical device of claim 19 wherein the second encapsulation layer overlies the second portion of the first encapsulation layer and wherein the portion of the second encapsulation layer that overlies the second portion of the first encapsulation layer is polycrystalline silicon.

21. The microelectromechanical device of claim 1 wherein:

the first encapsulation layer includes a plurality of vents formed therein, and wherein the first encapsulation layer is a semiconductor material; and

a second encapsulation layer, disposed over or in the plurality of vents to seal the chamber.

22. The microelectromechanical device of claim 21 wherein:

the first encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, silicon nitride or silicon carbide, and

the second encapsulation layer is polycrystalline silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

23. The microelectromechanical device of claim 22 further including a third encapsulation layer disposed on the second encapsulation layer, wherein the third encapsulation layer is an insulation material.

24. The microelectromechanical device of claim 21 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, wherein the first conductivity type is opposite the second conductivity type.

25. The microelectromechanical device of claim 24 further including a contact which is at least partially disposed outside the chamber, wherein the contact is a semiconductor material that is doped with the first impurity.

26. The microelectromechanical device of claim 25 further including an insulation layer disposed on at least a portion of the first and second encapsulation layers.

27. The microelectromechanical device of claim 26 wherein the insulation layer includes an opening over the contact and wherein the microelectromechanical device further includes an electrically conductive layer that is disposed in the opening, on the contact and on at least a portion of a surface of the insulation layer such that the insulation layer electrically insolates the electrically conductive layer from the first and/or second encapsulation layers.

28. The microelectromechanical device of claim 1 wherein the second encapsulation layer includes polycrystalline silicon.

29. The microelectromechanical device of claim 28 wherein the polycrystalline silicon includes epitaxially deposited polycrystalline silicon.

30. The microelectromechanical device of claim 29 wherein a first portion of the first encapsulation layer is monocrystalline silicon and a second portion is polycrystalline silicon, and wherein the second portion is at least the portion of the wall of the chamber.

31. The electromechanical device of claim 28 further including:

a contact which is at least partially disposed outside the chamber; and

an insulation layer disposed on at least the second encapsulation layer that is disposed in or on the at least one vent, wherein the insulation layer includes an opening over the contact and wherein the microelectromechanical device further includes a highly electrically conductive layer that is disposed in the opening and on;

(i) the contact and (ii) at least a portion of the insulation layer.

32. The microelectromechanical device of claim 28 further including a third encapsulation layer disposed on the second encapsulation layer.

33. The microelectromechanical device of claim 32 wherein the third encapsulation layer is an insulating or metal material.

34. The microelectromechanical device of claim 32 wherein the third encapsulation layer is a metal material including aluminum, chromium, gold, silver, molybdenum, platinum, palladium, tungsten, titanium, silicide and/or copper.

35. The microelectromechanical device of claim 32 wherein the third encapsulation layer is an insulating material including silicon dioxide, silicon nitride, BPSG, PSG and/or SOG.

36. The microelectromechanical device of claim 12 wherein the second encapsulation layer includes polycrystalline silicon.

37. The microelectromechanical device of claim 36 wherein the polycrystalline silicon includes epitaxially deposited polycrystalline silicon.

38. The microelectromechanical device of claim 37 further including a third encapsulation layer disposed on the second encapsulation layer.

39. The microelectromechanical device of claim 37 wherein the third encapsulation layer is an insulating or metal material.

40. The microelectromechanical device of claim 21 wherein the second encapsulation layer includes polycrystalline silicon.

41. The microelectromechanical device of claim 40 wherein the polycrystalline silicon includes epitaxially deposited polycrystalline silicon.

42. The microelectromechanical device of claim 41 further including a third encapsulation layer disposed on the second encapsulation layer.

43. The microelectromechanical device of claim 42 wherein the third encapsulation layer is an insulating or metal material.