A SENSOR AND METHOD FOR FABRICATING THE SAME

• US 20110309458A1
• Filed: 06/18/2010
• Published: 12/22/2011
• Est. Priority Date: 06/18/2010
• Status: Active Grant

• Current Assignee: Amphenol Thermometrics, Inc. (Amphenol Corporation)
• Original Assignee: Amphenol Thermometrics, Inc. (Amphenol Corporation)
• Inventors: GAMAGE, Sisira Kankanam, Mantravadi, Naresh Venkata, Klitzke, Michael, Cookson, Terry Lee
• Granted Patent: US 8,569,851 B2
• Time in Patent Office: Days
• US Class Current: 257/419
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

A sensor and method for fabricating a sensor is disclosed that in one embodiment bonds an etched semiconductor substrate wafer to an etched first device wafer comprising a silicon on insulator wafer which is then bonded to a second device wafer comprising a silicon on insulator wafer to create a vented, suspended structure, the flexure of which is sensed by an embedded sensing element to measure differential pressure. In one embodiment, interconnect channels embedded in the sensor facilitate streamlined packaging of the device while accommodating interconnectivity with other devices.

Claims

1. A method for fabricating a sensor comprising the steps of:

forming a vent cavity in a substrate wafer extending from the top surface of said substrate wafer to an exterior surface of said substrate wafer;

bonding said top surface of said substrate wafer to the bottom surface of a first device wafer, wherein said first device wafer comprises a first device layer whose bottom surface forms the bottom surface of said first device wafer, a first handle, and a first insulator layer located between said first device layer and said first handle;

removing said first handle and said first insulator layer from said first device wafer exposing the top surface of said first device layer;

forming a diaphragm cavity extending through said first device layer to said vent cavity;

bonding the top surface of said first device layer to the bottom surface of a second device wafer forming a diaphragm over said diaphragm cavity, wherein said second device wafer comprises a second device layer whose bottom surface forms the bottom surface of said second device wafer, a second handle, and a second insulator layer located between said second device layer and said second handle;

removing said second handle and said second insulator layer from said second device wafer exposing the top surface of said second device layer; and

placing a sensing element in said second device layer proximate said diaphragm to sense flexure in said diaphragm.

2. The method for fabricating a sensor of claim 1, further comprising the step of forming an interconnect channel in a portion of said second device layer.

3. The method for fabricating a sensor of claim 1, further comprising the step of forming an interconnect channel in a portion of said first device layer and said second device layer.

4. The method for fabricating a sensor of claim 1, wherein said substrate wafer comprises a device layer, an insulator layer, and a handle, wherein said insulator layer is located between said device layer and said handle.

5. The method for fabricating a sensor of claim 4, further comprising the step of removing said handle and said insulator layer from said substrate wafer.

6. The method for fabricating a sensor of claim 1, wherein said sensor measures differential pressure.

7. The method for fabricating a sensor of claim 1, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through a side of said substrate wafer.

8. The method for fabricating a sensor of claim 1, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through both a side and said bottom surface of said substrate wafer.

9. The method for fabricating a sensor of claim 1, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through said bottom surface of said substrate wafer.

10. The method for fabricating a sensor of claim 1, wherein said step of forming a vent cavity in a substrate wafer extending from the top surface of said substrate wafer to an exterior surface of said substrate wafer comprises the step of thinning said substrate wafer to expose said vent cavity.

11. The method for fabricating a sensor of claim 10, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through both a side and said bottom surface of said substrate wafer.

12. The method for fabricating a sensor of claim 10, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through said bottom surface of said substrate wafer.

13. A sensor for measuring environmental forces, said sensor comprising:

a vent cavity in a substrate wafer extending from the top surface of said substrate wafer to an exterior surface of said substrate wafer;

a first device layer, wherein the bottom surface of said first device layer is bonded to said top surface of said substrate wafer;

a diaphragm cavity extending through said first device layer to said vent cavity;

a second device layer, wherein the bottom surface of said second device layer is bonded to the top surface of said first device layer to form a diaphragm over said diaphragm cavity; and

a sensing element in said second device layer proximate said diaphragm to sense flexure in said diaphragm.

14. The sensor of claim 13, further comprising an interconnect channel extending through a portion of said second device layer.

15. The sensor of claim 13, further comprising an interconnect channel extending through a portion of said first device layer and through a portion of said second device layer.

16. The sensor of claim 13, wherein said substrate wafer comprises a device layer from a silicon on insulator wafer.

17. The sensor of claim 13, wherein said environmental force is differential pressure.

18. The sensor of claim 13, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through a side of said substrate wafer.

19. The sensor of claim 13, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through both a side and said bottom surface of said substrate wafer.

20. The sensor of claim 13, wherein said vent cavity comprises a hollow cavity within said sensor that extends from said diaphragm cavity through said bottom surface of said substrate wafer.