SHIELDING FOR A MICRO ELECTRO-MECHANICAL DEVICE AND METHOD THEREFOR

• US 20100276766A1
• Filed: 04/29/2009
• Published: 11/04/2010
• Est. Priority Date: 04/29/2009
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Tang, Jinbang, Liu, Lianjun
• Granted Patent: US 8,330,239 B2
• Time in Patent Office: Days
• US Class Current: 257/419
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2207/017 Smart-MEMS not provided for in B81B2207/012 - B81B2207/015
• CPC Class Codes: B81B 7/0064 for protecting against electromagnetic or electrostatic interferences
• CPC Class Codes: H01L 2224/0554 External layer
• CPC Class Codes: H01L 2224/0555 Shape
• CPC Class Codes: H01L 2224/0556 Disposition
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16235 the bump connector connecting to a via metallisation of the item
• CPC Class Codes: H01L 24/12 Structure, shape, material or disposition of the bump connectors prior to the connecting process
• CPC Class Codes: H01L 24/16 of an individual bump connector
• 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 2924/00014 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
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/30105 : Capacitance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H04R 19/005 : using semiconductor materials
• CPC Class Codes: H04R 19/04 : Microphones H04R19/01 takes precedence

Abstract

A device comprises a conductive substrate, a micro electromechanical systems (MEMS) structure, and a plurality of bond pads. The conductive substrate has a first side and a second side, the second side opposite the first side. The MEMS structure is formed over the first side of the conductive substrate. The plurality of bond pads are formed over the first side of the conductive substrate and electrically coupled to the first side of the conductive substrate. The conductive substrate and plurality of bond pads function to provide electrostatic shielding to the MEMS structure.

Claims

1. A device comprising:

a conductive substrate having a first side and a second side, the second side opposite the first side;

a micro electromechanical systems (MEMS) structure formed over the first side of the conductive substrate; and

a plurality of bond pads formed over the first side of the conductive substrate and electrically coupled to the first side of the conductive substrate.

2. The device of claim 1, wherein the conductive substrate further comprises a cavity directly opposite the MEMS structure.

3. The device of claim 2, wherein the MEMS structure includes a diaphragm for a microphone.

4. The device of claim 1, wherein the device is flip-chip mounted to a printed circuit board (PCB), and wherein each of the plurality of bond pads is electrically coupled to a ground terminal of the PCB.

5. The device of claim 4, wherein the PCB further comprises a patterned metal layer coupled to the ground terminal of the PCB, and wherein the patterned metal layer, the plurality of bond pads, and the conductive substrate together form an electrostatic noise shield around the MEMS structure.

6. The device of claim 4, further comprising a second device flip-chip mounted to the PCB, the second device comprising a second conductive substrate.

7. The device of claim 4, wherein the PCB further comprises an acoustic hole positioned to admit sound to the microphone diaphragm.

8. The device of claim 1, wherein the conductive substrate has a resistivity of less than or equal to 0.02 ohm-centimeter.

9. The device of claim 1, wherein the conductive substrate comprises doped silicon.

10. A device comprising:

a conductive substrate having a first side and a second side, the second side opposite the first side, a cavity formed in the conductive substrate and having an opening on the first side;

a micro electromechanical systems (MEMS) microphone diaphragm formed over the opening on the first side, the MEMS microphone diaphragm electrically isolated from the conductive substrate;

a microphone backplate formed over and electrically isolated from the MEMS microphone diaphragm on the first side of the conductive substrate; and

a plurality of bond pads formed over the conductive substrate on the first side and around the MEMS microphone diaphragm, each of the plurality of bond pads electrically coupled to the conductive substrate.

11. The device of claim 10, wherein the conductive substrate comprises doped silicon having a resistivity less than or equal to 0.02 ohm-centimeter.

12. The device of claim 10, wherein the device is solder mounted to a printed circuit board (PCB) via the plurality of bond pads, and wherein the PCB further comprises a ground terminal electrically coupled to the plurality of bond pads.

13. The device of claim 12, wherein the PCB further comprises a patterned metal layer coupled to the ground terminal.

14. The device of claim 12, further comprising an integrated circuit mounted on the PCB, a first terminal of the integrated circuit electrically coupled to the MEMS microphone diaphragm, and a second terminal of the integrated circuit electrically coupled to the microphone backplate.

15. The device of claim 12, wherein the PCB further comprises an acoustic hole positioned to admit sound to the microphone diaphragm.

16. The device of claim 10, wherein the conductive substrate comprises silicon doped with a material from a group consisting of arsenic, antimony, boron, and phosphorus.

17. A method for forming a device, the method comprising:

providing a conductive substrate;

forming a micro electromechanical (MEMS) structure over a first side of the conductive substrate and electrically isolated from the conductive substrate;

forming a plurality of bond pads over the first side of the conductive substrate around the MEMS structure; and

electrically coupling each of the plurality of bond pads to the conductive substrate.

18. The method of claim 17, wherein providing a conductive substrate further comprises:

providing a silicon substrate; and

doping the silicon substrate with a material selected from a group consisting of arsenic, antimony, boron, and phosphorus.

19. The method of claim 17, further comprising:

forming solder balls on the plurality of bond pads;

attaching the plurality of bond pads to a corresponding plurality of bond pads on a printed circuit board (PCB) by reflowing the solder balls; and

coupling to the corresponding plurality of bond pads to ground terminal on the PCB.

20. The method of claim 19, wherein forming a MEMS structure further comprises forming a MEMS microphone diaphragm, and the method further comprising forming an acoustic hole in the PCB to admit sound to the MEMS microphone diaphragm.