MECHANISMS FOR FORMING MICRO-ELECTRO MECHANICAL SYSTEM DEVICE

• US 20150097215A1
• Filed: 10/09/2013
• Published: 04/09/2015
• Est. Priority Date: 10/09/2013
• 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 9,617,150 B2
• Time in Patent Office: Days
• US Class Current: 257/254
• CPC Class Codes: B81B 7/0035 for maintaining a controlled atmosphere inside of the chamber containing the MEMS
• CPC Class Codes: B81B 7/0041 maintaining a controlled atmosphere with techniques not provided for in B81B7/0038
• 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 1/00277 for maintaining a controlled atmosphere inside of the cavity containing the MEMS
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 1/00793 Avoid contamination, e.g. absorption of impurities or oxidation
• CPC Class Codes: B81C 2201/013 Etching
• CPC Class Codes: B81C 2201/053 Depositing a protective layers
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure

Abstract

Embodiments of mechanisms for forming a micro-electro mechanical system (MEMS) device are provided. The MEMS device includes a CMOS substrate and a MEMS substrate bonded with the CMOS substrate. The CMOS substrate includes a semiconductor substrate, a first dielectric layer formed over the semiconductor substrate, and a plurality of conductive pads formed in the first dielectric layer. The MEMS substrate includes a semiconductor layer having a movable element and a second dielectric layer formed between the semiconductor layer and the CMOS substrate. The MEMS substrate also includes a closed chamber surrounding the movable element. The MEMS substrate further includes a blocking layer formed between the closed chamber and the first dielectric layer of the CMOS substrate. The blocking layer is configured to block gas, coming from the first dielectric layer, from entering the closed chamber.

Claims

1. A micro-electro mechanical system (MEMS) device, comprising:

a CMOS substrate, wherein the CMOS substrate comprises;

a semiconductor substrate;

a first dielectric layer formed over the semiconductor substrate; and

a plurality of conductive pads formed in the first dielectric layer; and

a MEMS substrate bonded with the CMOS substrate, wherein the MEMS substrate comprises;

a semiconductor layer having a movable element;

a second dielectric layer formed between the semiconductor layer and the CMOS substrate;

a closed chamber surrounding the movable element; and

a blocking layer formed between the closed chamber and the first dielectric layer of the CMOS substrate, wherein the blocking layer is configured to block gas, coming from the first dielectric layer, from entering the closed chamber.

2. The MEMS device as claimed in claim 1, further comprising an etch stop layer surrounding the closed chamber.

3. The MEMS device as claimed in claim 2, wherein the etch stop layer is made of silicon nitride, and the etch stop layer has a stress in a range from about −

50 MPa to about 50 MPa.

4. The MEMS device as claimed in claim 1, further comprising a conductive plug penetrating through the semiconductor layer and the second dielectric layer and electrically connected to one of the conductive pads.

5. The MEMS device as claimed in claim 4, wherein the blocking layer penetrates through the second dielectric layer, and the conductive plug penetrates through the blocking layer.

6. The MEMS device as claimed in claim 4, wherein the blocking layer does not penetrate through the second dielectric layer.

7. The MEMS device as claimed in claim 4, wherein the conductive plug is in direct contact with the blocking layer.

8. The MEMS device as claimed in claim 1, wherein the blocking layer is made of polysilicon.

9. The MEMS device as claimed in claim 1, further comprising:

a cap substrate bonded with the MEMS substrate through a bonding structure;

a cavity between the cap substrate and the semiconductor layer; and

a sealing element separating the cavity and the closed chamber.

10. The MEMS device as claimed in claim 1, further comprising a cap substrate bonded with the MEMS substrate through a bonding structure, wherein the movable element is hermetically sealed by the cap substrate and the bonding structure, and the closed chamber is between the cap substrate and the second dielectric layer.

11. A micro-electro mechanical system (MEMS) device, comprising:

a semiconductor substrate;

a dielectric layer formed over the semiconductor substrate; and

a MEMS substrate bonded with the dielectric layer, wherein the MEMS substrate comprises;

a semiconductor layer having a sensing element;

a closed chamber surrounding the sensing element; and

a blocking layer formed between the closed chamber and the dielectric layer, wherein the blocking layer is configured to block gas, coming from the dielectric layer, from entering the closed chamber.

12. The MEMS device as claimed in claim 11, wherein the blocking layer is made of a semiconductor material.

13. The MEMS device as claimed in claim 11, wherein the closed chamber has a pressure in a range from about 10E-7 torr to about 760 torr.

14. The MEMS device as claimed in claim 11, further comprising an etch stop layer surrounding the closed chamber, wherein the etch stop layer is a low stress silicon nitride layer.

15. The MEMS device as claimed in claim 11, further comprising a cap substrate bonded with the MEMS substrate through a bonding structure, wherein the sensing element is hermetically sealed by the cap substrate and the bonding structure, and the closed chamber is between the cap substrate and the dielectric layer.

16. A method for forming a micro-electro mechanical system (MEMS) device, comprising:

forming a first dielectric layer over a semiconductor layer;

forming a blocking layer over the first dielectric layer;

bonding a CMOS substrate with the blocking layer, wherein the CMOS substrate comprises a second dielectric layer, and the blocking layer is configured to block gas coming from the second dielectric layer;

partially removing the first dielectric layer to form a cavity between the semiconductor layer and the blocking layer, wherein a portion of the semiconductor layer above the cavity becomes a movable element; and

sealing the cavity such that a closed chamber is formed to surround the movable element, wherein the cavity is a portion of the closed chamber.

17. The method for forming a MEMS device as claimed in claim 16, further comprising vacuumizing the cavity before the sealing of the cavity.

18. The method for forming a MEMS device as claimed in claim 16, further comprising annealing the first dielectric layer to outgas the first dielectric layer before the CMOS substrate is bonded with the blocking layer.

19. The method for forming a MEMS device as claimed in claim 16, further comprising forming an etch stop layer between the first dielectric layer and the blocking layer before the cavity is formed, wherein the etch stop layer surrounds the cavity after the cavity is formed.

20. The method for forming a MEMS device as claimed in claim 16, wherein the forming of the closed chamber comprises bonding a cap substrate over the semiconductor layer through a bonding structure to hermetically seal the movable element and form the closed chamber.