Integrated getter area for wafer level encapsulated microelectromechanical systems

• US 20060258039A1
• Filed: 07/11/2006
• Published: 11/16/2006
• Est. Priority Date: 02/12/2004
• Status: Active Grant

• Current Assignee: Aaron Patridge, Markus Lutz
• Original Assignee: Aaron Patridge, Markus Lutz
• Inventors: Patridge, Aaron, Lutz, Markus
• Granted Patent: US 7,923,278 B2
• Time in Patent Office: Days
• 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.

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.

23. 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.

24. 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.

9-22. -22. (canceled)

25. A method of manufacturing a microelectromechanical device having a mechanical structure, a periphery area and a fixed electrode that are disposed over 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;

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

sealing the chamber by depositing the thin film encapsulation structure.

26. The method of claim 25 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.

27. The method of claim 25 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.

28. The method of claim 27 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.

29. The method of claim 27 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.

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

31. The method of claim 30 further including depositing a fourth encapsulation layer on the third encapsulation layer wherein the fourth encapsulation layer is a metal.

32. The method of claim 25 wherein the first encapsulation layer comprises a polycrystalline silicon, monocrystalline silicon, amorphous silicon, porous silicon, germanium, silicon/germanium and/or gallium arsenide.

33. The method of claim 32 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.

34. 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;

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

sealing the chamber by depositing the thin film encapsulation structure.

35. The method of claim 34 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.

36. The method of claim 34 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.

37. The method of claim 36 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.

38. The method of claim 36 wherein the first encapsulation layer comprises a polycrystalline silicon, monocrystalline silicon, amorphous silicon, porous silicon, germanium, silicon/germanium and/or gallium arsenide.

39. The method of claim 38 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.

40. The method of claim 39 further including depositing a third encapsulation layer on the second encapsulation layer wherein the third encapsulation layer is an insulating material.

41. The method of claim 40 further including depositing a fourth encapsulation layer on the third encapsulation layer wherein the fourth encapsulation layer is a metal.