Device with vertically integrated sensors and method of fabrication

Patent metadata

Field	Value
Publication number	US-2016297673-A1
Application number	US-201514682282-A
Country	US
Kind code	A1
Filing date	Apr 9, 2015
Priority date	Apr 9, 2015
Publication date	Oct 13, 2016
Grant date	—

Abstract

A device includes vertically and laterally spaced sensors that sense different physical stimuli. Fabrication of the device entails forming a device structure having a first and second wafer layers with a signal routing layer interposed between them. Active transducer elements of one or more sensors are formed in the first wafer layer and a third wafer layer is attached with the second wafer layer to produce one or more cavities in which the active transducer elements are located. A trench extends through the second wafer and through a portion of the signal routing layer. The trench electrically isolates a region of the second wafer layer surrounded by the trench from a remainder of the second wafer layer. Another active transducer element of another sensor is formed in this region. The transducer element formed in the second wafer layer may be a diaphragm for a pressure sensor of the sensor device.

First claim

1 . A method of producing a sensor device comprising:
forming a device structure having a first wafer layer, a second wafer layer, and a signal routing layer interposed between said first and second wafer layers; forming a first active transducer element of a first sensor in said first wafer layer; forming a trench extending through said second wafer layer and extending through a portion of said signal routing layer, said trench fully surrounding a region of said second wafer layer, and said trench electrically isolating said region of said second wafer layer surrounded by said trench from a remainder of said second wafer layer; and forming a second active transducer element of a second sensor in said region of said second wafer layer to produce said sensor device that includes both of said first and second sensors each being capable of sensing a different physical stimulus.

2 . The method of claim 1 wherein said forming said device structure comprises:
forming said signal routing layer on a first surface of said first wafer layer;
producing a cavity in said signal routing layer; and
bonding said signal routing layer with said second wafer layer such that said cavity is vertically aligned with said region of said second wafer layer surrounded by said trench.

3 . The method of claim 2 wherein said bonding operation comprises hermetically sealing said cavity.

4 . The method of claim 2 wherein said second wafer layer comprises a single crystal silicon, a topmost layer of said signal routing layer comprises a polysilicon layer, and said bonding operation comprises performing direct bonding of said polysilicon layer to said single crystal silicon to provide electrical contact between said polysilicon layer to said single crystal silicon.

5 . The method of claim 1 wherein said forming said second active transducer element comprises etching said second wafer layer from a first side of said second wafer layer at said region, said etching stopping prior to breaching a second side of said second wafer layer such that a remainder of said second wafer at said second side is said second active transducer element.

6 . The method of claim 5 wherein said second sensor is a pressure sensor, and said second active transducer element comprises a diaphragm of said pressure sensor.

7 . The method of claim 1 wherein said second active transducer element in said second wafer layer is vertically spaced apart from said first active transducer element in said first wafer layer.

8 . The method of claim 1 further comprising forming a third active transducer element of a third sensor in said first wafer layer, said third active transducer element being laterally spaced apart from said first active transducer element of said first sensor.

9 . The method of claim 1 further comprising attaching a third wafer layer with said first wafer layer, said attaching operation producing a cavity in which said first active transducer element is located.

10 . The method of claim 9 wherein:
said method further comprises forming a conductive via extending through said third wafer layer; and
said attaching operation comprises utilizing a conductive bonding layer to form a conductive interconnection between said third wafer layer and said first wafer layer, said conductive via being electrically coupled with said conductive bonding layer.

11 . The method of claim 9 wherein said trench is a first trench and said forming said trench further comprises forming a second trench extending through said second wafer layer and extending through an entirety of said signal routing layer to said cavity.

12 . The method of claim 11 wherein:
prior to forming said second trench, said cavity exhibits a first pressure;
following said forming said second trench said cavity exhibits a second pressure that is different from said first pressure; and
said method further comprises depositing a sealant material in said second trench such that said cavity is sealed at said second pressure.

13 . The method of claim 1 further comprising depositing a sealant material in said trench.

14 . The method of claim 13 wherein said forming said second active transducer element occurs following said depositing said sealant material in said trench.

15 . A method of producing a sensor device comprising:
forming a device structure having a first wafer layer, a second wafer layer, and a signal routing layer interposed between said first and second wafer layers; forming a first active transducer element of a first sensor in said first wafer layer; attaching a third wafer layer with said first wafer layer, said attaching operation producing a transducer cavity in which said first active transducer element is located; forming a trench extending through said second wafer layer and extending through a portion of said signal routing layer, said trench fully surrounding a region of said second wafer laver, and said trench electrically isolating said region of said second wafer layer surrounded by said trench from a remainder of said second wafer layer; and forming a second active transducer element of a second sensor in said region of said second wafer layer to produce said sensor device that includes both of said first and second sensors each being capable of sensing a different physical stimulus, wherein said forming said second active transducer element comprises etching said second wafer layer from a first side of said second wafer layer at said region, said etching stopping prior to breaching a second side of said second wafer layer such that a remainder of said second wafer at said second side is said second active transducer element.

16 . The method of claim 15 wherein said second sensor is a pressure sensor, said second active transducer element comprises a diaphragm of said pressure sensor, and said forming said device structure comprises:
forming said signal routing layer on a first surface of said first wafer layer;
producing a pressure cavity in said signal routing layer; and
bonding said signal routing layer with said second wafer layer such that said pressure cavity is vertically aligned with said diaphragm.

17 . The method of claim 15 wherein said trench is a first trench and said forming said trench further comprises forming a second trench extending through said second wafer layer and extending through an entirety of said signal routing layer to said transducer cavity to expose said first active transducer to an external environment.

18 . The method of claim 17 wherein:
prior to forming said second trench, said transducer cavity exhibits a first pressure;
following said forming said second trench said transducer cavity exhibits a second pressure that is different from said first pressure; and
said method further comprises depositing a sealant material in each of said first and second trenches, wherein said depositing seals said transducer cavity at said second pressure.

19 . A sensor device comprising:
a device structure having a first wafer layer, a second wafer layer, and a signal routing layer interposed between said first and second wafer layers; a first active transducer element of a first sensor formed in said first wafer layer; and a second active transducer element of a second sensor formed in said second wafer layer, wherein a trench extends through said second wafer layer and through a portion of said signal routing layer, said trench fully surrounding a region of said second wafer layer and electrically isolating said region of said second

Assignees

• Freescale Semiconductor Inc

Inventors

• Lagouge Matthieu
• Chowdhury Mamur

Classifications

• B81C1/00301

  Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias · CPC title

• B81B7/0074 Primary

  3D packaging, i.e. encapsulation containing one or several MEMS devices arranged in planes non-parallel to the mounting board · CPC title

• B81B2201/0264

  Pressure sensors · CPC title

• B81B7/0006

  Interconnects · CPC title

• B81B7/0041

  maintaining a controlled atmosphere with techniques not provided for in B81B7/0038 · CPC title