Integrated getter area for wafer level encapsulated microelectromechanical systems

• US 7,923,278 B2
• Filed: 07/11/2006
• Issued: 04/12/2011
• Est. Priority Date: 02/12/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus
• Primary Examiner(s): Loke; Steven
• Assistant Examiner(s): NEWTON, VALERIE N
• Application Number:
  US11/484,431
• Publication Number:
  US 20060258039A1
• Time in Patent Office: 1,736 Days
• Field of Search: None
• US Class Current: 438/50
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

There are many inventions described and illustrated herein. In one aspect, present invention is directed to a thin film encapsulated MEMS, and technique of fabricating or manufacturing a thin film encapsulated MEMS including an integrated getter area and/or an increased chamber volume, which causes little to no increase in overall dimension(s) from the perspective of the mechanical structure and chamber. The integrated getter area is disposed within the chamber and is capable of (i) “capturing” impurities, atoms and/or molecules that are out-gassed from surrounding materials and/or (ii) reducing and/or minimizing the adverse impact of such impurities, atoms and/or molecules (for example, reducing the probability of adding mass to a resonator which would thereby change the resonator'"'"'s frequency). In this way, the thin film wafer level packaged MEMS of the present invention includes a relatively stable, controlled pressure environment within the chamber to provide, for example, a more stable predetermined, desired and/or selected mechanical damping of the mechanical structure.

Claims

1. A method of manufacturing a microelectromechanical device having a mechanical structure and a periphery area that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure;

forming the periphery area having a plurality of gaps therein; and

sealing the chamber by depositing the thin film encapsulation structure,

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate, and

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.

2. The method of claim 1 wherein sealing the chamber by depositing the thin film encapsulation structure includes:

depositing a sacrificial layer on or around at least a portion of the mechanical structure and the periphery area;

depositing a first encapsulation layer over the sacrificial layer;

forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer;

removing at least a portion of the sacrificial layer juxtaposed the mechanical structure and the periphery area; and

depositing a second encapsulation layer in the vent to seal the chamber.

3. The method of claim 2 wherein the substrate includes a sacrificial layer, and wherein removing at least a portion of the deposited sacrificial layer juxtaposed the mechanical structure and the periphery area further includes removing at least a portion of the sacrificial layer of the substrate that is disposed beneath the mechanical structure and the gaps of the periphery area.

4. The method of claim 2 wherein the second encapsulation layer is a semiconductor material which comprises of polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium and/or gallium arsenide.

5. The method of claim 2 wherein the first encapsulation layer comprises a polycrystalline silicon, amorphous silicon, germanium, silicon/germanium and/or gallium arsenide.

6. The method of claim 1 wherein the mechanical structure includes a plurality of fixed electrodes that are disposed over or in the substrate and in the chamber, the method further comprises forming the fixed electrodes having a plurality of gaps therein.

7. The method of claim 1 wherein the mechanical structure includes a plurality of anchor regions that are disposed over or in the substrate, the method further comprises forming the anchor regions having a plurality of gaps therein.

8. The method of claim 1 wherein the mechanical structure includes a plurality of fixed electrodes and a plurality of anchor regions that are disposed over or in the substrate and in the chamber, the method further comprises:

forming the fixed electrodes having a plurality of gaps therein;

forming the anchor regions having a plurality of gaps therein; and

wherein sealing the chamber by depositing the thin film encapsulation structure includes;

depositing a sacrificial layer on or around at least a portion of the mechanical structure and the fixed electrodes, the anchor region, and the periphery area, including the gaps therein;

depositing a first encapsulation layer over the sacrificial layer;

forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer;

removing at least a portion of the sacrificial layer juxtaposed the mechanical structure and the gaps in the fixed electrodes, the anchor region and the periphery area; and

depositing a second encapsulation layer over or in the vent to seal the chamber.

9. The method of claim 5 further including depositing a third encapsulation layer on the second encapsulation layer wherein the third encapsulation layer is an insulating material.

10. The method of claim 5 further including depositing a fourth encapsulation layer on the third encapsulation layer wherein the fourth encapsulation layer is a metal.

11. The method of claim 1, further comprising:

depositing a fluid in the chamber, wherein the mechanical structure includes an electrode exposed to the fluid.

12. The method of claim 11, further comprising:

depositing a fluid in the chamber, wherein the mechanical structure includes an electrode which, with respect to at least one path, is separated from each of the plurality of gaps by only the fluid.

13. The method of claim 1, wherein at least a portion of the periphery area is disposed directly over and in contact with the substrate.

14. The method of claim 1, wherein the plurality of gaps is proximal to or adjacent to the mechanical structure.

15. The method of claim 1, wherein the plurality of gaps is formed by removing a portion of the periphery area.

16. The method of claim 1, wherein the plurality of gaps forms repeating patterns.

17. The method of claim 1, wherein the plurality of gaps extends to a sacrificial layer.

18. The method of claim 1, wherein a first portion of the periphery area at a first side of the mechanical structure includes a plurality of components formed with gaps extending therebetween.

19. The method of claim 1, further comprising:

depositing a fluid in the chamber, wherein any point in the chamber, with respect to at least one path, is separated from any other point in the chamber by only the fluid.

20. The method of claim 1, wherein the plurality of gaps increases a volume of the chamber by at least 10 times.

21. The method of claim 1, wherein the sealing is performed such that the resulting sealed chamber includes the mechanical structure and the periphery area having the plurality of gaps.

22. A method of manufacturing a microelectromechanical device having a mechanical structure, a periphery area and a fixed electrode that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming the periphery area disposed over the substrate, wherein the periphery area includes a plurality of gaps therein, and wherein the plurality of gaps is disposed in the chamber and exposed to the fluid;

forming the fixed electrode having a plurality of gaps therein; and

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber,

wherein the fluid is contained in the chamber after the chamber is sealed,

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate, and

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.

23. The method of claim 22 wherein the mechanical structure includes an anchor region that is disposed over or in the substrate, the method further comprises forming the anchor region having a plurality of gaps therein.

24. The method of claim 22 wherein sealing the chamber by depositing the thin film encapsulation structure includes:

depositing a sacrificial layer on or around at least a portion of the mechanical structure, the periphery area and the fixed electrode;

depositing a first encapsulation layer over the sacrificial layer;

forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer;

removing at least a portion of the sacrificial layer juxtaposed the mechanical structure, the periphery area and the fixed electrode; and

depositing a second encapsulation layer over or in the vent to seal the chamber.

25. The method of claim 24 wherein the substrate includes a sacrificial layer, and wherein removing at least a portion of the deposited sacrificial layer juxtaposed the mechanical structure and the periphery area further includes removing at least a portion of the sacrificial layer of the substrate that is disposed beneath (i) the mechanical structure and (ii) the gaps of the periphery area.

26. The method of claim 24 wherein the second encapsulation layer is a semiconductor material which comprises of polycrystalline silicon, amorphous silicon, silicon carbide, silicon oxide, silicon nitride, silicon/germanium, germanium and/or gallium arsenide.

27. The method of claim 24 further including depositing a third encapsulation layer on the second encapsulation layer wherein the third encapsulation layer is an insulating material.

28. The method of claim 27 further including depositing a fourth encapsulation layer on the third encapsulation layer wherein the fourth encapsulation layer is a metal.

29. The method of claim 22 wherein the first encapsulation layer comprises a polycrystalline silicon, monocrystalline silicon, amorphous silicon, porous silicon, germanium, silicon/germanium and/or gallium arsenide.

30. The method of claim 29 wherein the second encapsulation layer is a semiconductor material which comprises of polycrystalline silicon, monocrystalline silicon, amorphous silicon, silicon carbide, silicon oxide, silicon nitride, silicon/germanium, germanium and/or gallium arsenide.

31. A method of manufacturing a microelectromechanical device having a mechanical structure and a fixed electrode that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming a periphery area disposed over the substrate, wherein the periphery area includes a plurality of gaps therein;

forming the fixed electrode having a plurality of gaps therein; and

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure, to partially define and seal the chamber,

wherein the fluid is contained in the chamber after the chamber is sealed;

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate, and

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.

32. The method of claim 31 wherein sealing the chamber by depositing the thin film encapsulation structure includes:

depositing a sacrificial layer on or around at least a portion of the mechanical structure and the fixed electrode;

depositing a first encapsulation layer over the sacrificial layer;

forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer;

removing at least a portion of the sacrificial layer juxtaposed the mechanical structure and the fixed electrode; and

depositing a second encapsulation layer over or in the vent to seal the chamber.

33. The method of claim 31 wherein sealing the chamber by depositing the thin film encapsulation structure includes:

depositing a sacrificial layer on or around at least a portion of the mechanical structure and the fixed electrodes, including the gaps therein;

depositing a first encapsulation layer over the sacrificial layer;

forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer;

removing at least a portion of the sacrificial layer juxtaposed the mechanical structure and the gaps in the fixed electrodes; and

depositing a second encapsulation layer over or in the vent to seal the chamber.

34. The method of claim 33 wherein the second encapsulation layer is a semiconductor material which comprises of polycrystalline silicon, amorphous silicon, silicon carbide, silicon oxide, silicon nitride, silicon/germanium, germanium and/or gallium arsenide.

35. The method of claim 33 wherein the first encapsulation layer comprises a polycrystalline silicon, monocrystalline silicon, amorphous silicon, porous silicon, germanium, silicon/germanium and/or gallium arsenide.

36. The method of claim 35 wherein the second encapsulation layer is a semiconductor material which comprises of polycrystalline silicon, monocrystalline silicon, amorphous silicon, silicon carbide, silicon oxide, silicon nitride, silicon/germanium, germanium and/or gallium arsenide.

37. The method of claim 36 further including depositing a third encapsulation layer on the second encapsulation layer wherein the third encapsulation layer is an insulating material.

38. The method of claim 37 further including depositing a fourth encapsulation layer on the third encapsulation layer wherein the fourth encapsulation layer is a metal.

39. A method of manufacturing a microelectromechanical device having a mechanical structure, a periphery area and a fixed electrode that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming the periphery area disposed over the substrate, wherein the periphery area includes a plurality of gaps therein, and wherein the plurality of gaps is disposed in the chamber and exposed to the fluid; and

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber, wherein the fluid is contained in the chamber after the chamber is sealed,

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate, and

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.

40. A method of manufacturing a microelectromechanical device having a mechanical structure, a periphery area, a getter area, moveable and fixed electrodes that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein the mechanical structure includes the moveable and fixed electrodes;

forming the periphery area disposed over the substrate;

forming the getter area including a plurality of gaps, wherein the plurality of gaps is disposed in predetermined portions of the periphery area and the fixed electrode;

forming the chamber, wherein at least a portion of the mechanical structure and the getter area are disposed in the chamber, and wherein the getter area is exposed to a fluid in the chamber; and

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber,

wherein the fluid is contained in the chamber after the chamber is sealed; and

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate, and

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.

41. A method of manufacturing a microelectromechanical device having a mechanical structure and a periphery area that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming the periphery area disposed over the substrate, wherein the periphery area includes a plurality of gaps therein, and wherein the plurality of gaps is disposed in the chamber and exposed to the fluid; and

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber, wherein the fluid is contained in the chamber after the chamber is sealed, and wherein the thin film encapsulation structure includes;

a first encapsulation layer comprising polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, silicon carbide, silicon nitride, silicon/germanium, germanium, or gallium arsenide; and

a second encapsulation layer, disposed on or over the first encapsulation layer, the second encapsulation layer comprising polycrystalline silicon, porous polycrystalline silicon, amorphous silicon, germanium, silicon/germanium, gallium arsenide, or silicon carbide; and

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate, and

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.