Method of fabricating electromechanical device having a controlled atmosphere

• US 7,514,283 B2
• Filed: 03/20/2003
• Issued: 04/07/2009
• Est. Priority Date: 03/20/2003
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus, Kronmueller, Silvia
• Primary Examiner(s): Fahmy; Wael
• Assistant Examiner(s): Rao; Shrinivas H.
• Application Number:
  US10/392,528
• Publication Number:
  US 20040183214A1
• Time in Patent Office: 2,210 Days
• Field of Search: 438/48, 438/50, 438/52, 438/411, 257/417, 216/2, 216/80
• US Class Current: 438/48
• CPC Class Codes: B81C 1/00293 maintaining a controlled atmosphere with processes not provided for in B81C1/00285
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer

Abstract

There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a technique of fabricating or manufacturing MEMS having mechanical structures that operate in controlled or predetermined mechanical damping environments. In this regard, the present invention encapsulates the mechanical structures within a chamber, prior to final packaging and/or completion of the MEMS. The environment within the chamber containing and/or housing the mechanical structures provides the predetermined, desired and/or selected mechanical damping. The parameters of the encapsulated fluid (for example, the gas pressure) in which the mechanical structures are to operate are controlled, selected and/or designed to provide a desired and/or predetermined operating environment.

Claims

1. A method of sealing a chamber of an electromechanical device having a mechanical structure, wherein the mechanical structure is in the chamber and wherein the chamber includes a fluid that is capable of providing mechanical damping for the mechanical structure, the method comprising:

depositing a sacrificial layer over at least a portion of the mechanical structure;

depositing a first encapsulation layer over the sacrificial layer;

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

removing at least a portion of the sacrificial layer to form the chamber;

introducing at least one relatively stable gas into the chamber; and

depositing a second encapsulation layer in the at least one vent to seal the chamber wherein the second encapsulation layer is a semiconductor material and wherein the fluid within the chamber includes the relatively stable gas.

2. The method of claim 1 wherein the at least one relatively stable gas is helium, nitrogen, neon, argon, krypton, xenon or perfluorinated hydrofluorocarbons.

3. The method of claim 2 wherein the electromechanical device is a microelectromechanical device or nanoelectromechanical device.

4. The method of claim 2 wherein the second encapsulation layer is monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon/germanium, germanium, or gallium arsenide.

5. The method of claim 1 wherein the second encapsulation layer includes a silicon-bearing compound.

6. The method of claim 5 wherein the silicon-bearing compound is at least one of monocrystalline silicon or polycrystalline silicon.

7. The method of claim 1 wherein depositing a second encapsulation layer includes using an epitaxial or a CVD reactor.

8. The method of claim 1 wherein the relatively stable gas includes a low diffusivity.

9. The method of claim 1 further including heating the fluid in, or diffusing a gas into, the chamber to adjust the pressure of the fluid to be within a predetermined range of pressures.

10. The method of claim 1 wherein the electromechanical device is an accelerometer and the method further includes adjusting the pressure of the fluid in the chamber to provide sufficient mechanical damping for the mechanical structure.

11. A method of sealing a chamber of an electromechanical device having a mechanical structure, wherein the mechanical structure resides in the chamber and wherein the chamber includes a fluid having a pressure that provides mechanical damping for the mechanical structure, the method comprising:

depositing a first encapsulation layer over the mechanical structure;

forming at least one vent through the first encapsulation layer;

forming the chamber;

depositing a second encapsulation layer by introducing at least one gaseous deposition reagent into an epitaxial or a CVD reactor to thereby deposit a second encapsulation layer in the vent to seal the chamber wherein the second encapsulation layer is a semiconductor material; and

wherein the fluid within the chamber includes at least one by-product resulting from depositing a second encapsulation layer and wherein the pressure of the fluid is sufficient to provide a predetermined mechanical damping for the mechanical structure.

12. The method of claim 11 wherein the at least one by-product includes a low diffusivity.

13. The method of claim 11 wherein the electromechanical device is a microelectromechanical device or a nanoelectromechanical device.

14. The method of claim 13 further including:

introducing at least one relatively stable gas into the chamber while depositing the second encapsulation layer.

15. The method of claim 14 wherein the at least one relatively stable gas is helium, nitrogen, neon, argon, krypton, xenon or perfluorinated hydrofluorocarbons.

16. The method of claim 15 wherein the second encapsulation layer includes a silicon-bearing compound.

17. The method of claim 16 wherein the silicon-bearing compound is polycrystalline silicon.

18. The method of claim 15 wherein the second encapsulation layer is polycrystalline silicon, amorphous silicon, silicon/germanium, germanium, or gallium arsenide.

19. The method of claim 11 wherein further including heating the fluid in, or diffusing a gas into, the chamber to adjust the pressure of the fluid to be within a predetermined range of pressures.

20. The method of claim 11 wherein the electromechanical device is an accelerometer and the method further includes adjusting the pressure of the fluid in the chamber to provide sufficient mechanical damping for the mechanical structure.

21. A method of sealing a chamber of a microelectromechanical device having a mechanical structure, wherein the mechanical structure resides in the chamber and wherein the chamber includes a fluid having a pressure that provides mechanical damping for the mechanical structure, the method comprising:

depositing a first encapsulation layer on a sacrificial layer disposed on the mechanical structure;

removing at least a portion of the sacrificial layer to form a chamber;

introducing at least one relatively stable gas into the chamber; and

depositing a second encapsulation layer on the first encapsulation layer to seal the chamber wherein the second encapsulation layer is a semiconductor material and wherein the fluid within the chamber includes the relatively stable gas.

22. The method of claim 21 wherein the at least one relatively stable gas is helium, nitrogen, neon, argon, krypton, xenon or perfluorinated hydrofluorocarbons.

23. The method of claim 21 wherein the second encapsulation layer is monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon/germanium, germanium, or gallium arsenide.

24. The method of claim 21 wherein the second encapsulation layer includes a silicon-bearing compound.

25. The method of claim 24 wherein the silicon-bearing compound is at least one of monocrystalline silicon or polycrystalline silicon.

26. The method of claim 21 wherein depositing a second encapsulation layer includes using an epitaxial or a CVD reactor.

27. The method of claim 21 wherein the relatively stable gas includes a low diffusivity.

28. The method of claim 21 further including heating the fluid in, or diffusing a gas into, the chamber to adjust the pressure of the fluid to be within a predetermined range of pressures.

29. The method of claim 21 wherein the microelectromechanical device is an accelerometer and the method further includes adjusting the pressure of the fluid in the chamber to provide sufficient mechanical damping for the mechanical structure.

30. The method of claim 21 wherein the first encapsulation layer is silicon.

31. The method of claim 30 wherein the second encapsulation layer includes a monocrystalline silicon.

32. The method of claim 30 wherein the second encapsulation layer includes a polycrystalline silicon.