MEMS Integrated Pressure Sensor and Microphone Devices and Methods of Forming Same

• US 20160060104A1
• Filed: 11/06/2015
• Published: 03/03/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Chu, Chia-Hua, Cheng, Chun-Wen
• Granted Patent: US 9,650,239 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: B81C 1/00309 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 21/764 Air gaps H01L21/76264 takes precedence

Abstract

A method embodiment for forming a micro-electromechanical (MEMS) device includes providing a MEMS wafer, wherein a portion of the MEMS wafer is patterned to provide a first membrane for a microphone device and a second membrane for a pressure sensor device. A carrier wafer is bonded to the MEMS wafer, and the carrier wafer is etched to expose the first membrane for the microphone device to an ambient environment. A MEMS substrate is patterned and portions of a first sacrificial layer are removed of the MEMS wafer to form a MEMS structure. A cap wafer is bonded to a side of the MEMS wafer opposing the carrier wafer to form a first sealed cavity including the MEMS structure. A second sealed cavity and a cavity exposed to an ambient environment on opposing sides of the second membrane for the pressure sensor device are formed.

Claims

1. A micro-electromechanical systems (MEMS) device comprising:

a MEMS wafer comprising;

a membrane layer comprising a first membrane for a microphone device and a second membrane for a pressure sensor device; and

a MEMS structure;

a carrier wafer bonded to the MEMS wafer, the carrier wafer comprising first and second cavities exposed to an ambient environment, wherein the first cavity includes the first membrane, and wherein the second cavity includes a first surface of the second membrane; and

a cap wafer bonded to a surface of the MEMS wafer opposing the carrier wafer, wherein the cap wafer and the MEMS wafer define third and fourth sealed cavities, and wherein;

the MEMS structure is disposed in the third sealed cavity; and

a second surface of the second membrane is exposed to a sealed pressure level of the fourth cavity.

2. The MEMS device of claim 1, wherein the carrier wafer is fusion bonded to the MEMS wafer, and the cap wafer is eutectic bonded to the MEMS wafer.

3. The MEMS device of claim 1, wherein the membrane layer comprises polysilicon.

4. The MEMS device of claim 1, wherein the MEMS structure comprises a flexible portion of the MEMS wafer.

5. The MEMS device of claim 1, wherein the cap wafer comprises active circuitry.

6. The MEMS device of claim 1, wherein the cap wafer further comprises an additional sealed cavity adjacent the third sealed cavity.

7. A micro-electromechanical systems (MEMS) device comprising:

a MEMS substrate having a membrane layer on a first side, the membrane layer comprising a first membrane disposed over a first opening in the MEMS substrate and a second membrane disposed over a second opening in the MEMS substrate, the first opening and the second opening extending from the first side to a second side of the MEMS substrate, the MEMS substrate having a MEMS structure region, the MEMS structure region comprising a flexible structure;

a carrier substrate bonded to the MEMS substrate, the carrier substrate having a first cavity exposing the first membrane and a second cavity exposing the second membrane; and

a cap substrate bonded to the MEMS substrate, the MEMS substrate being interposed between the carrier substrate and the cap substrate, the cap substrate having a third cavity exposed to the first opening and a fourth cavity exposed to the second opening, wherein the first membrane, the first cavity, and the third cavity form a pressure sensor, and wherein the second membrane, the second cavity, and the fourth cavity form a microphone.

8. The MEMS device of claim 7, wherein the second opening comprises a plurality of openings.

9. The MEMS device of claim 7, wherein the membrane layer comprises a polysilicon layer.

10. The MEMS device of claim 7, wherein the MEMS substrate acts as an electrode for the pressure sensor and the microphone.

11. The MEMS device of claim 7, wherein the first cavity extends completely through the carrier substrate and the third cavity extends only partially through the cap substrate.

12. The MEMS device of claim 7, wherein the first cavity extends only partially through the carrier substrate and the third cavity extends completely through the cap substrate.

13. The MEMS device of claim 7, wherein the second cavity extends completely through the carrier substrate and the fourth cavity extends completely through the cap substrate.

14. A micro-electromechanical systems (MEMS) device comprising:

a MEMS substrate having a first opening, a second opening, and a third opening extending from a first side to a second side of the MEMS substrate, the MEMS substrate having a first membrane extending over the first opening, a second membrane extending over the second opening and a third membrane extending over the third opening;

a carrier substrate bonded to MEMS substrate; and

a cap substrate bonded to the MEMS substrate, wherein a first surface of the first membrane covers a first sealed cavity and a second surface of the first membrane is exposed to ambient, wherein the carrier substrate and the cap substrate have openings exposing opposing sides of the second membrane to ambient, and wherein the third membrane seals a cap cavity formed in the cap substrate.

15. The MEMS device of claim 14, wherein the cap cavity comprises a mechanical bump to limit movement of a moving element.

16. The MEMS device of claim 14, wherein the second membrane is exposed to ambient through an opening in the carrier substrate.

17. The MEMS device of claim 14, wherein the second membrane is exposed to ambient through an opening in the cap substrate.

18. The MEMS device of claim 14, wherein the first membrane and the second membrane comprises polysilicon.

19. The MEMS device of claim 18, wherein the MEMS substrate acts as electrodes.

20. The MEMS device of claim 14, wherein the MEMS substrate over the third membrane comprises flexible elements.