Stacked MEMS Device

• US 20080157339A1
• Filed: 12/19/2007
• Published: 07/03/2008
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Goggin, Raymond, O Suilleabhain, Liam, Murphy, Eva, Harney, Kieran
• Granted Patent: US 7,642,657 B2
• Time in Patent Office: Days
• US Class Current: 257/690
• CPC Class Codes: B81B 2201/014 having a cantilever fixed on one side connected to one or more dimples
• CPC Class Codes: B81B 2207/015 the micromechanical device and the control or processing electronics being integrated on the same substrate
• CPC Class Codes: B81B 2207/017 Smart-MEMS not provided for in B81B2207/012 - B81B2207/015
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/0023 Packaging together an electronic processing unit die and a micromechanical structure die MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261
• CPC Class Codes: B81C 2203/032 Gluing
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• 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 MEMS apparatus has a MEMS device sandwiched between a base and a circuit chip. The movable member of the MEMS device is attached at the side up against the circuit chip. The movable member may be mounted on a substrate of the MEMS device or formed directly on a passivation layer on the circuit chip. The circuit chip provides control signals to the MEMS device through wire bonds, vias through the MEMS device or a conductive path such as solder balls external to the MEMS device.

Claims

1. A MEMS apparatus comprising:

a base having electrical interconnects;

a MEMS device having a first side, a second side and a movable member attached at the second side, the first side being secured to the base; and

a circuit chip for electrically controlling the movable member secured to the second side of the MEMS device, the MEMS device being between the base and the circuit chip.

2. The MEMS apparatus of claim 1 wherein the MEMS device is flip-chip connected to the base.

3. The MEMS apparatus of claim 1 wherein wire bonds electrically connect the circuit chip to the base for carrying control signals from the circuit chip to the MEMS device.

4. The MEMS apparatus of claim 1 wherein the movable member is formed on the circuit chip.

5. The MEMS apparatus of claim 4 further comprising solder bumps electrically connecting the circuit chip to the base.

6. The MEMS apparatus of claim 4 wherein the circuit chip and the MEMS device are arranged such that control signals pass directly from the circuit chip to the MEMS device.

7. The MEMS apparatus of claim 4 further comprising electrically connecting the circuit chip to the base through vias in the MEMS device and solder bumps from the vias to the base.

8. The MEMS apparatus of claim 1 wherein the MEMS device is a switch and the movable member is made of gold.

9. The MEMS apparatus of claim 8 wherein the MEMS device comprises vias of conductive material.

10. The MEMS apparatus of claim 9 wherein the conductive material has a resistivity of less than 0.01 ohm per square.

11. The MEMS apparatus as defined by claim 1 further comprising encapsulating material substantially completely covering the circuit chip and the MEMS device.

12. A MEMS switch comprising:

a MEMS device having a movable gold beam suspended from a semiconductor substrate and a semiconductor cap enclosing a chamber about the beam;

a plurality of conductive vias through the semiconductor cap;

a plurality of conductive bumps on the semiconductor cap, each in electrical connection with one of the vias; and

a circuit chip for electrically controlling movement of the movable gold beam between an open position breaking an electrical connection with the vias and a closed position completing an electrical connection with the vias, the circuit chip being secured parallel to and on the semiconductor substrate.

13. The MEMS switch of claim 12 further comprising a base having electrical interconnects, wherein the plurality of conductive bumps are mounted on the base.

14. The MEMS switch of claim 13 further comprising wire bonds from the circuit chip to the base for supplying control signals from the circuit chip through at least one of the electrical interconnects to the MEMS device.

15. The MEMS switch of claim 13 wherein the conductive vias have a resistivity of less than 0.01 ohm per square.

16. The MEMS switch of claim 12 further comprising a layer of seal glass securing the circuit chip to the semiconductor substrate.

17. A MEMS apparatus comprising:

a circuit chip having circuitry and a passivated surface;

MEMS microstructure formed on the passivated surface of the circuit chip; and

a cap over the MEMS microstructure, the cap having a first conductive path for providing electrical communication with the MEMS microstructure.

18. The MEMS apparatus of claim 17 wherein the MEMS microstructure is suspended from the plane of the passivated surface.

19. The MEMS apparatus of claim 17 further comprising a second conductive path for electrically communicating with the circuitry on the circuit chip.

20. The MEMS apparatus of claim 19 wherein the second conductive path extends through the cap.

21. The MEMS apparatus of claim 19 wherein the second conductive path is external to the cap.

22. The MEMS apparatus of claim 19 further comprising a base having electrical interconnects and a conductive bump mounted between the second conductive path and the base in electrical connection with at least one of the electrical interconnects.

23. The MEMS apparatus of claim 22 wherein the second conductive path supplies control signals from the circuit chip through the at least one of the electrical interconnects to control movement of the MEMS microstructure.

24. The MEMS apparatus of claim 22 further comprising encapsulating material substantially completely covering the circuit chip and the cap.

25. The MEMS apparatus of claim 17 wherein the MEMS microstructure is made of gold.

27. The MEMS apparatus of claim 17 wherein the circuit chip and MEMS microstructure are arranged such that control signals pass directly from the circuit chip to the MEMS microstructure.

26. The MEMS apparatus of 25 wherein the first conductive path comprises a conductive material with a resistivity less than 0.01 ohm per square.