Packaging microelectromechanical structures

• US 20040051181A1
• Filed: 08/19/2003
• Published: 03/18/2004
• Est. Priority Date: 04/03/2002
• Status: Active Grant

• Current Assignee: John Heck, Li-Peng Wang, Qing Ma, Quan Tran, Valluri Rao
• Original Assignee: John Heck, Li-Peng Wang, Qing Ma, Quan Tran, Valluri Rao
• Inventors: Heck, John, Wang, Li-Peng, Ma, Qing, Rao, Valluri, Tran, Quan
• Granted Patent: US 6,903,452 B2
• Time in Patent Office: Days
• US Class Current: 257/778
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• 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 microelectromechanical system may be enclosed in a hermetic cavity defined by joined, first and second semiconductor structures. The joined structures may be sealed by a solder sealing ring, which extends completely around the cavity. One of the semiconductor structures may have the system formed thereon and an open area may be formed underneath said system. That open area may be formed from the underside of the structure and may be closed by covering with a suitable film in one embodiment.

Claims

1. A method comprising:

forming a microelectromechanical system on a first side of a first semiconductor structure;

combining the first semiconductor structure and a second semiconductor structure to form a cavity surrounding said system;

forming an opening underneath said system through a second side of said first semiconductor structure; and

covering said opening to form an open area under said system.

2. The method of claim 1 including surface mounting the first semiconductor structure to the second semiconductor structure.

3. The method of claim 2 including defining a solder bump on one of said first and second structures and surface mounting said solder bump to the other of said first and second structures.

4. The method of claim 3 including defining a sealed cavity between said first and second structures using said solder bump.

5. The method of claim 1 including thinning said first semiconductor structure.

6. The method of claim 5 including forming said opening from said second side of said thinned first semiconductor structure underneath said system.

7. The method of claim 6 including covering said opening with a plastic film.

8. The method of claim 1 including forming on said first side of said first semiconductor structure a film bulk acoustic resonator over said opening.

9. The method of claim 7 including forming on said first side of said first semiconductor structure a switch over said opening.

10. The method of claim 7 including forming on said first side of said first semiconductor structure a transmission line over said opening.

11. A device comprising:

a first structure having front and back sides;

a microelectromechanical system formed on said front side of said first structure;

a second structure bonded to said first structure by surface mount connection;

a cavity surrounding said system between said first and second structures; and

an open area in said first structure under said system.

12. The device of claim 11 including a cover over said back side of said first structure closing said open area.

13. The device of claim 12 wherein said cover is adhesively secured to said first structure.

14. The device of claim 12 wherein said cover includes a plastic film.

15. The device of claim 11 including a solder bump on one of said first and second structures surface mounted to the other of said first and second structures to form a hermetic cavity between said first and second structures.

16. The device of claim 11 wherein said system is a film bulk acoustic resonator.

17. The device of claim 11 wherein said system is a switch.

18. The system of claim 11 wherein said system is a transmission line.

19. The device of claim 11 wherein said second semiconductor structure is formed of glass.

20. The device of claim 19 including contacts which make an electrical connection to said system and extend through said second structure, said contacts including a surface mount bump.

21. A device comprising:

a first semiconductor structure having front and back sides;

a microelectromechanical system formed on said front side of said first structure;

a second structure bonded to said first structure by a surface mount connection, said connection including a solder bump that defines a hermetic cavity between said first and second structures surrounding said system;

an open area in said first structure under said system; and

a film applied to the back side of said first semiconductor structure forming said open area between said first semiconductor structure and said film.

22. The device of claim 21 wherein said film is a plastic film.

23. The device of claim 22 wherein said film is adhesively secured to said back side.

24. The device of claim 21 wherein said first and second structures are semiconductor structures.

25. The device of claim 21 wherein said second structure is an insulator.

26. The device of claim 25 wherein said second structure is glass.

27. The device of claim 26 including an aperture through said second structure said aperture being filled by a solder bump that extends completing through said second structure.

28. The device of claim 21 wherein said system is a film bulk acoustic resonator.

29. The device of claim 21 wherein said system is a switch.

30. The system of claim 21 wherein said system is a transmission line.