Packaging microelectromechanical systems

• US 20030183916A1
• Filed: 03/27/2002
• Published: 10/02/2003
• Est. Priority Date: 03/27/2002
• Status: Abandoned Application

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Wong, Daniel, Heck, John, Rao, Valluri, Berry, Michele J.
• Application Number:
  US10/107,624
• Publication Number:
  US 20030183916A1
• Time in Patent Office: Days
• US Class Current: 257/684
• CPC Class Codes: B81C 1/00293 maintaining a controlled atmosphere with processes not provided for in B81C1/00285
• CPC Class Codes: B81C 1/00936 Releasing the movable structure without liquid etchant
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: H01L 23/315 the encapsulation having a cavity
• 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

A packaged microelectromechanical system may be formed in a hermetic cavity by forming the system on a semiconductor structure and covering the system with a thermally decomposing film. That film may then be covered by a sealing cover. Subsequently, the thermally decomposing material may be decomposed, forming a cavity, which can then be sealed to hermetically enclose the system.

Claims

1. A method comprising:

forming a microelectromechanical system on a semiconductor structure;

covering said system with a thermally decomposing layer;

forming a cover over said thermally decomposing layer; and

thermally decomposing the thermally decomposing layer underneath said cover.

2. The method of claim 1 wherein thermally decomposing includes causing the thermally decomposing layer to sublimate.

3. The method of claim 2 including forming openings in said cover to allow the release of said sublimated layer.

4. The method of claim 3 including closing said openings after said film has been thermally decomposed.

5. The method of claim 4 including coating said cover to close said openings.

6. The method of claim 4 including depositing a sealing material over said openings without covering the entire cover.

7. The method of claim 1 including allowing the thermally decomposing material to escape through said cover and thereafter sealing said cover.

8. The method of claim 1 including removing the thermally decomposing layer and forming a hermetic cavity between said cover and said structure around said microelectromechanical system.

9. The method of claim 1 including providing an electrical connection to said microelectromechanical system through said semiconductor structure.

10. The method of claim 1 including forming an electrical connection to said system without penetrating said cover.

11. A microelectromechanical structure comprising:

a semiconductor layer;

a microelectromechanical system formed on said layer;

a thermally decomposing layer formed over said system; and

a cover over said thermally decomposing layer.

12. The structure of claim 11 wherein said structure is a semiconductor wafer.

13. The structure of claim 11 wherein said thermally decomposing layer is formed of a material that decomposes at a temperature above 350°

C.

14. The structure of claim 13 wherein said material includes polynorbornene.

15. The structure of claim 11 wherein said thermally decomposing layer is formed of a material that sublimates to form a gas when heated.

16. The structure of claim 11 wherein said cover is sufficiently non-porous to define a hermetic cavity.

17. The structure of claim 11 wherein said cover includes a plurality of apertures through said cover.

18. The structure of claim 11 including a buried interconnection layer extending through said semiconductor layer and electrically coupling said system.

19. The structure of claim 11 including a first sublayer of thermally decomposing material formed at least partially beneath said system and a second sublayer of thermally decomposing material formed over said system.

20. A packaged microelectromechanical structure comprising:

a semiconductor layer;

a microelectromechanical system formed on said layer;

a cover over said system defining a hermetic cavity between said cover and said layer and surrounding said system; and

a sealing material over said cover to maintain said hermetic cavity.

21. The structure of claim 20 wherein said structure is a semiconductor die.

22. The structure of claim 20 wherein said cover includes an aperture through said cover.

23. The structure of claim 22 including a sealing patch over said aperture.

24. The structure of claim 20 wherein said material extends over said entire cover.

25. The structure of claim 20 including a buried interconnection layer coupled to said system and extending outwardly of said cover.