Microelectromechanical systems, and methods for encapsulating and fabricating same

• US 20060108652A1
• Filed: 12/30/2005
• Published: 05/25/2006
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Aaron Partridge, Markus Lutz, Silvia Kronmueller
• Original Assignee: Aaron Partridge, Markus Lutz, Silvia Kronmueller
• Inventors: Partridge, Aaron, Lutz, Markus, Kronmueller, Silvia
• Granted Patent: US 7,288,824 B2
• Time in Patent Office: Days
• 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

1-29. -29. (canceled)

30. A microelectromechanical device comprising:

a chamber;

a first encapsulation layer comprising a permeable material, wherein first encapsulation layer forms 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 on the first encapsulation layer to seal the chamber, wherein the second encapsulation layer is a semiconductor material.

31. The microelectromechanical device of claim 30 wherein the second encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

32. The microelectromechanical device of claim 31 wherein the first encapsulation layer includes a silicon bearing material.

33. The microelectromechanical device of claim 30 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.

34. The microelectromechanical device of claim 30 further including a contact which is at least partially disposed outside the chamber.

35. The microelectromechanical device of claim 34 wherein the contact includes a semiconductor material that is doped with an impurity to increase the electrical conductivity of the contact.

36. The microelectromechanical device of claim 30 wherein the first encapsulation layer is a semiconductor material.

37. The microelectromechanical device of claim 36 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.

38. The microelectromechanical device of claim 37 wherein a portion of the second encapsulation layer that is on the second portion of the first encapsulation layer is polycrystalline silicon.

39. The microelectromechanical device of claim 38 further including a field region disposed outside and above the chamber wherein the field region includes monocrystalline silicon.

40. The electromechanical device of claim 30 further including:

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

an insulation layer disposed on at least a portion of the second encapsulation layer, 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.

41. The microelectromechanical device of claim 30 wherein:

the first encapsulation layer includes a plurality of vents formed therein; and

the second encapsulation layer is disposed in the plurality of vents to seal the chamber.

42. The microelectromechanical device of claim 41 wherein the second encapsulation layer is polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

43. The microelectromechanical device of claim 42 wherein the first encapsulation layer includes a silicon bearing material.

44. The microelectromechanical device of claim 41 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.

45. The microelectromechanical device of claim 44 further including an insulation layer disposed on the second encapsulation layer.

46. The microelectromechanical device of claim 45 wherein:

the first encapsulation layer is a porous polycrystalline silicon or amorphous silicon, and

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

47. The microelectromechanical device of claim 46 further including a third encapsulation layer disposed on the second encapsulation layer, wherein the third encapsulation layer is an insulating material.

48. The microelectromechanical device of claim 30 wherein the second encapsulation layer includes polycrystalline silicon.

49. The microelectromechanical device of claim 48 wherein the polycrystalline silicon includes epitaxially deposited polycrystalline silicon.

50. The microelectromechanical device of claim 49 wherein the first encapsulation layer is porous polycrystalline silicon or amorphous silicon.

51. The electromechanical device of claim 48 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.

52. The microelectromechanical device of claim 48 further including a third encapsulation layer disposed on the second encapsulation layer.

53. The microelectromechanical device of claim 52 wherein the third encapsulation layer is an insulating or metal material.

54. The microelectromechanical device of claim 52 wherein the third encapsulation layer is a metal material including aluminum, chromium, gold, silver, molybdenum, platinum, palladium, tungsten, titanium, silicide and/or copper.

55. The microelectromechanical device of claim 52 wherein the third encapsulation layer is an insulating material including silicon dioxide, silicon nitride, BPSG, PSG and/or SOG.

56. The microelectromechanical device of claim 30 further including a third encapsulation layer, disposed on the second encapsulation layer, to further seal the chamber, wherein the third encapsulation layer is an insulating or metal material.