MEMS Integrated Pressure Sensor Devices and Methods of Forming Same

Patent metadata

Field	Value
Publication number	US-2016159644-A1
Application number	US-201615043850-A
Country	US
Kind code	A1
Filing date	Feb 15, 2016
Priority date	Mar 14, 2013
Publication date	Jun 9, 2016
Grant date	—

Abstract

A method embodiment includes providing a micro-electromechanical (MEMS) wafer including a polysilicon layer having a first and a second portion. A carrier wafer is bonded to a first surface of the MEMS wafer. Bonding the carrier wafer creates a first cavity. A first surface of the first portion of the polysilicon layer is exposed to a pressure level of the first cavity. A cap wafer is bonded to a second surface of the MEMS wafer opposite the first surface of the MEMS wafer. The bonding the cap wafer creates a second cavity comprising the second portion of the polysilicon layer and a third cavity. A second surface of the first portion of the polysilicon layer is exposed to a pressure level of the third cavity. The first cavity or the third cavity is exposed to an ambient environment.

First claim

What is claimed is:

1 . A method comprising:
providing a device substrate comprising a membrane for a first micro-electromechanical (MEMS) device; bonding a carrier having a first cavity to the device substrate, wherein bonding the carrier includes aligning the first cavity with a first surface of the membrane; patterning the device substrate to define a first MEMS structure aligned with the membrane; bonding a cap to the device substrate to form a second cavity comprising a second surface of the membrane and the first MEMS structure; and patterning the carrier to expose the first cavity to ambient pressure.

2 . The method of claim 1 , wherein providing a device substrate comprises:
forming a polysilicon layer over a MEMS substrate, wherein patterning the device substrate to define the first MEMS structure comprises patterning the MEMS substrate; and patterning the polysilicon layer to define the membrane.

3 . The method of claim 1 , wherein bonding the cap to the device substrate comprises at least partially defining a sealed pressure level for the second cavity, wherein the second surface of the membrane is exposed to the sealed pressure level of the second cavity.

4 . The method of claim 3 , wherein bonding the cap to the device substrate comprises using an eutectic bonding process to define the sealed pressure level of the second cavity.

5 . The method of claim 1 , wherein patterning the device substrate further defines a second MEMS structure for a second MEMS device, and wherein bonding the cap to the device substrate further forms a third cavity comprising the second MEMS structure.

6 . The method of claim 5 , wherein the second MEMS device is a motion sensor, a gyroscope, or an accelerometer.

7 . The method of claim 1 , wherein the first MEMS device is a pressure sensor.

8 . The method of claim 1 , wherein the cap comprises an input/output contact pad, and wherein the method further comprises exposing the input/output contact pad by removing a portion of the carrier.

9 . A method comprising:
providing a device substrate comprising a membrane for a pressure sensor device; bonding a carrier to the device substrate to define a first cavity, wherein a first surface of the membrane is exposed to a pressure level of the first cavity; patterning the device substrate to define:
a first micro-electromechanical (MEMS) structure aligned with the membrane; and
a second MEMS structure adjacent the first MEMS structure; and
bonding a cap to an opposing side of the device substrate as the carrier, wherein bonding the cap defines:
a second cavity comprising the first MEMS structure, wherein a second surface of the membrane is exposed to an ambient pressure level through the second cavity; and
a third cavity comprising the second MEMS structure.

10 . The method of claim 9 , wherein providing the device substrate comprises
forming a polysilicon layer over a MEMS substrate, wherein patterning the device substrate to define the first MEMS structure and the second MEMS structure comprises patterning the MEMS substrate; and patterning the polysilicon layer to define the membrane and a trench in the polysilicon layer, wherein the trench provides a leak path allowing ambient air flow into the second cavity.

11 . The method of claim 10 further comprising:
forming an oxide release layer over the polysilicon layer; and
after patterning the device substrate to define the first MEMS structure and the second MEMS structure, removing at least a portion of the oxide release layer using a vapor HF etching process.

12 . The method of claim 11 , wherein forming the oxide release layer comprises filling the trench with a first portion of the oxide release layer, and wherein the vapor HF etching process removes the first portion of the oxide release layer from the trench.

13 . The method of claim 9 , wherein bonding the carrier to the device substrate comprises a fusion bonding process, and wherein a sealed pressure level of the first cavity is at least partially defined by the fusion bonding process.

14 . A micro-electromechanical (MEMS) device comprising:
a device substrate comprising:
a membrane for a pressure sensor, wherein a first surface of the membrane is exposed to a sealed pressure level of a first cavity and a second surface of the membrane is exposed to an ambient pressure level; and
a first MEMS structure over and aligned with the membrane;
a cap over first MEMS structure and bonded to the device substrate by a plurality of eutectic bonds; and a carrier bonded to an opposing side of the device substrate as the cap.

15 . The MEMS device of claim 14 , wherein the first cavity is defined by the plurality of eutectic bonds between the cap and the device substrate.

16 . The MEMS device of claim 15 , wherein the second surface of the membrane is exposed to the ambient pressure level through a second cavity in the carrier.

17 . The MEMS device of claim 15 , wherein the first MEMS structure is disposed in the first cavity.

18 . The MEMS device of claim 17 , wherein the second surface of the membrane is exposed to the ambient pressure level through a third cavity connected to a leak path in the device substrate.

19 . The MEMS device of claim 18 , wherein the first MEMS structure is disposed in the third cavity.

20 . The MEMS device of claim 14 further comprising:
a fourth cavity defined by the cap and the device substrate; and
a second MEMS structure adjacent the first MEMS structure and disposed in the fourth cavity.

Assignees

• Taiwan Semiconductor Mfg

Inventors

• Chu Chia-Hua
• Cheng Chun-Wen

Classifications

• G01C19/56

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• G01L9/0044

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• G01C19/5769

  Manufacturing; Mounting; Housings · CPC title

• G01P15/00

  Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration · CPC title

• G01P15/0802

  Details · CPC title