PROCESS FOR A SEALED MEMS DEVICE WITH A PORTION EXPOSED TO THE ENVIRONMENT

• US 20130001710A1
• Filed: 06/28/2012
• Published: 01/03/2013
• Est. Priority Date: 06/29/2011
• Status: Abandoned Application

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: DANEMAN, Michael J., LIM, Martin, SEEGER, Joseph, TCHERTKOV, Igor, NASIRI, Steven S.
• Application Number:
  US13/536,896
• Publication Number:
  US 20130001710A1
• Time in Patent Office: Days
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 2207/115 Protective layers applied directly to the device before packaging
• CPC Class Codes: B81C 1/00238 Joining a substrate with an electronic processing unit and a substrate with a micromechanical structure
• CPC Class Codes: B81C 2203/0109 Bonding an individual cap on the substrate
• CPC Class Codes: B81C 2203/0145 Hermetically sealing an opening in the lid
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• 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 2924/1461 MEMS

Abstract

A method and system for providing a MEMS device with a portion exposed to an outside environment are disclosed. The method comprises bonding a handle wafer to a device wafer to form a MEMS substrate with a dielectric layer disposed between the handle and device wafers. The method includes lithographically defining at least one standoff on the device wafer and bonding the at least one standoff to an integrated circuit substrate to form a sealed cavity between the MEMS substrate and the integrated circuit substrate. The method includes defining at least one opening in the handle wafer, standoff, or integrated circuit substrate to expose a portion of the to expose a portion of the device wafer to the outside environment.

Claims

1. A method for providing a Microelectromechanical Systems (MEMS) device with a portion exposed to an outside environment, the method comprising:

bonding a handle wafer to a device wafer to form a MEMS substrate, wherein a dielectric layer is disposed between the handle and device wafers;

lithographically defining at least one standoff on the device wafer;

bonding the at least one standoff to an integrated circuit substrate to form a sealed cavity between the MEMS substrate and the integrated circuit substrate;

etching at least one opening in the handle wafer to expose a portion of the dielectric layer; and

etching the exposed portion of the dielectric layer to expose a portion of the device wafer to the outside environment.

2. The method of claim 1, wherein the integrated circuit substrate comprises a CMOS wafer with at least one electrode and at least one circuit coupled to the at least one electrode.

3. The method of claim 1, wherein a gap of the sealed cavity is defined by a height of the at least one standoff.

4. The method of claim 1, further comprising:

creating an electrical connection between the device wafer and the integrated circuit substrate by utilizing a conductive bond between the at least one standoff and the integrated circuit substrate.

5. The method of claim 1, wherein the exposed portion of the device wafer is a flexible plate, wherein at least one region of the flexible plate is a surface of the sealed cavity.

6. The method of claim 1, further comprising:

partially etching the exposed portion of the device wafer to reduce thickness of the device wafer.

7. The method of claim 1, further comprising:

completely etching the exposed portion of the device wafer to expose a surface of the integrated circuit substrate.

8. The method of claim 1, further comprising:

bonding a substrate with fluidic channels to a top surface of the MEMS substrate.

9. The method of claim 1, further comprising:

packaging the MEMS device using a Through-Silicon-Via process.

10. The method of claim 1, further comprising:

packaging the MEMS device in a plastic molded package using the handle wafer as a dam to prevent a molding compound from entering a membrane area of the sealed cavity.

11. The method of claim 1, further comprising:

packaging the MEMS device in a plastic molded package using adhesion tape to prevent a molding compound from entering a membrane area of the sealed cavity.

12. The method of claim 1, wherein etching the at least one opening in the handle wafer further produces sloped sidewalls.

13. A method for providing a Microelectromechanical Systems (MEMS) device with a portion exposed to an outside environment, the method comprising:

bonding a handle wafer to a device wafer to form a MEMS substrate, wherein a dielectric layer is disposed between the handle and device wafers;

lithographically defining at least one standoff on the device wafer;

providing a channel extending to an edge of a device;

bonding the at least one standoff to an integrated circuit substrate to form a sealed cavity between the MEMS substrate and the integrated circuit substrate;

singulating the MEMS device by cut through a portion of at least one channel thereby exposing the at least one channel to the outside environment.

14. The method of claim 13 wherein the provided channel is defined by etching one or more cavities in the handle wafer.

15. The method of claim 13 wherein the provided channel is defined by one or more gaps in the at least one standoff.

16. The method of claim 13 wherein the provide channel is created by etching one or more cavities in the integrated circuit substrate.

17. A Microelectromechanical Systems (MEMS) device with a portion exposed to an outside environment comprising:

a CMOS substrate;

a MEMS substrate bonded to the CMOS substrate, wherein the MEMS substrate includes a handle substrate bonded to a device substrate with a dielectric layer disposed between the handle and device substrates; and

at least one opening in the handle substrate, wherein the at least one opening exposes a surface of the device substrate to the outside environment.

18. The MEMS device of claim 17, wherein a section of the at least one opening extends to an edge of the handle substrate.

19. The MEMS device of claim 18, wherein the at least one opening is a fluidic channel that allows fluid flow.

20. The MEMS device of claim 17, wherein a sealed cavity is formed between the MEMS substrate and the CMOS substrate and is defined by a height of at least one standoff lithographically defined on the device substrate.

21. The MEMS device of claim 20 wherein the sealed cavity is smaller than the opening in the handle wafer located over the frame

22. The MEMS device of claim 20 wherein the sealed cavity is larger than the opening in the handle wafer located over the frame

23. The MEMS device of claim 20, wherein the at least one opening is located over the sealed cavity.

24. The MEMS device of claim 17, wherein the device substrate further comprises:

a top structural layer bonded to a bottom structural layer with a second dielectric layer disposed between the top and bottom structural layers, wherein the top structural layer is disposed between the dielectric layer and the second dielectric layer.

25. The MEMS device of claim 24, wherein the at least one opening extends through the dielectric layer and the top structural layer to expose a region of the second dielectric layer to the outside environment.

26. The MEMS device of claim 17, comprising at least one cavity in the handle substrate wherein the at least one opening in the handle substrate extends into the at least one cavity in the handle substrate.

27. The MEMS device of claim 17, wherein the at least one opening extends to the edge of the device.