Methods and structures of integrated MEMS-CMOS devices

• US 9,276,080 B2
• Filed: 03/07/2013
• Issued: 03/01/2016
• Est. Priority Date: 03/09/2012
• Status: Active Grant

• Current Assignee: mCube, Inc.
• Original Assignee: mCube, Inc.
• Inventors: Sridharamurthy, Sudheer S., Lee, Te-Hse Terrence, Rastegar, Ali J., Stancu, Mugurel, Yang, Xiao Charles
• Primary Examiner(s): Garber, Charles
• Assistant Examiner(s): PATERSON, BRIGITTE A
• Application Number:
  US13/788,503
• Publication Number:
  US 20130236988A1
• Time in Patent Office: 1,090 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B81B 2203/0163 Spring holders
• CPC Class Codes: B81B 2207/094 Feed-through, via
• CPC Class Codes: B81B 3/0013 Structures dimensioned for mechanical prevention of stiction, e.g. spring with increased stiffness
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B81B 7/0022 Protection against electrostatic discharge electrostatic discharge protection for electronic semiconductor circuits H01L27/0248; circuit arrangements for protecting electronic switching circuits used for pulse technique against overcurrent or overvoltage H03K17/08
• CPC Class Codes: B81B 7/0064 for protecting against electromagnetic or electrostatic interferences
• 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 1/00801 Avoid alteration of functional structures by etching, e.g. using a passivation layer or an etch stop layer B81C1/00595, B81C1/00468 take precedence
• CPC Class Codes: B81C 2201/0132 Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
• CPC Class Codes: B81C 2201/05 Temporary protection of devices or parts of the devices during manufacturing
• CPC Class Codes: B81C 2203/0735 Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit
• CPC Class Codes: H01L 27/0688 Integrated circuits having a three-dimensional layout

Abstract

A method for fabricating an integrated MEMS-CMOS device uses a micro-fabrication process that realizes moving mechanical structures (MEMS) on top of a conventional CMOS structure by bonding a mechanical structural wafer on top of the CMOS and etching the mechanical layer using plasma etching processes, such as Deep Reactive Ion Etching (DRIE). During etching of the mechanical layer, CMOS devices that are directly connected to the mechanical layer are exposed to plasma. This sometimes causes permanent damage to CMOS circuits and is termed Plasma Induced Damage (PID). Embodiments of the present invention presents methods and structures to prevent or reduce this PID and protect the underlying CMOS circuits by grounding and providing an alternate path for the CMOS circuits until the MEMS layer is completely etched.

Claims

1. A method for fabricating an integrated MEMS-CMOS device comprising:

providing a substrate member having a surface region;

forming a CMOS IC layer overlying the surface region, the CMOS IC layer having at least one CMOS device;

forming a MEMS layer overlying the CMOS IC layer, the MEMS layer having a MEMS contact region, a CMOS contact region, and at least one MEMS device, wherein the at least one MEMS device is electrically coupled to the MEMS contact region that is electrically decoupled from the CMOS IC layer during formation of the MEMS layer, and at least one CMOS device is electrically coupled to the CMOS contact region, wherein the at least one MEMS device is electrically decoupled from the CMOS device during formation of the MEMS contact region, and the MEMS contact region is electrically decoupled from the CMOS contact region, wherein MEMS contact region and the CMOS contact region form a MEMS jumper contact region; and

coupling the MEMS contact region and the CMOS contact region via a MEMS jumper structure being applied to the MEMS jumper contact region after the forming of the MEMS layer, the MEMS jumper structure electrically coupling the at least one MEMS device and the at least one CMOS device.

2. The method of claim 1 wherein forming the MEMS layer further comprises forming a grounded contact region within a vicinity of the CMOS contact region, the grounded contact region being separate from the MEMS device and being electrically coupled to ground and being part of the MEMS jumper contact region, the grounded contact region being configured as a low resistance path to reduce plasma damage during the formation of the MEMS layer.

3. The method of claim 2 wherein the MEMS contact region, CMOS contact region, and grounded contact regions are formed as electrodes or via structures.

4. The method of claim 1 further comprising forming at least one ESD protection diode coupled to the at least one CMOS device.

5. The method of claim 1 further comprising forming and electrode ground ring structure overlying the at least one CMOS device, the electrode ground ring structure being electrically coupled to ground and the at least one CMOS device.

6. The method of claim 5 wherein the electrode ground ring structure is configured to direct plasma induced charge from a MEMS etching process to ground.

7. The method of claim 1 wherein the at least one MEMS device comprises an inertial sensor, an accelerometer, a gyrometer, a magnetic field sensor, a pressure sensor, a humidity sensor, a temperature sensor, a chemical sensor, or a biosensor.

17. The method of claim 1 further comprising forming the MEMS contact region and the CMOS contact region in the MEMS layer before forming the at least one MEMS device.

18. The method of claim 1 wherein the at least one MEMS device is formed below the MEMS contact region and the CMOS contact region in the MEMS layer.

8. A method for fabricating an integrated MEMS-CMOS device comprising:

providing a substrate member having a surface region;

forming a CMOS IC layer overlying the surface region, the CMOS IC layer having at least one CMOS device;

forming a MEMS layer overlying the CMOS IC layer, the MEMS layer having a MEMS contact region that is electrically decoupled from the CMOS IC layer, a CMOS contact region, and at least one MEMS device, wherein the at least one MEMS device is electrically coupled to the MEMS contact region and at least one CMOS device is electrically coupled to the CMOS contact region, wherein the at least one MEMS device being is electrically decoupled from the CMOS device during formation of the MEMS contact region, wherein the MEMS contact region is configured at the top of the MEMS layer;

wherein the CMOS contact region is configured at the top of the MEMS layer;

wherein MEMS contact region and the CMOS contact region form a MEMS jumper contact region; and

coupling the MEMS contact region and the CMOS contact region via a MEMS jumper structure being applied to the MEMS jumper contact region after the forming of the at least one MEMS device, the MEMS jumper structure electrically coupling the at least one MEMS device and the at least one CMOS device.

9. The method of claim 8 wherein forming the MEMS layer further comprises forming a grounded contact region within a vicinity of the CMOS contact region and separate from the MEMS device, the grounded contact region being electrically coupled to ground and being part of the MEMS jumper contact region, the grounded contact region being provided at the top of the MEMS layer and being configured as a low resistance path to reduce plasma damage during the formation of the MEMS layer.

10. The method of claim 9 wherein the MEMS contact region, CMOS contact region, and grounded contact regions are formed as electrodes or via structures.

11. The method of claim 8 further comprising forming at least one ESD protection diode coupled to the at least one CMOS device.

12. The method of claim 8 further comprising forming and electrode ground ring structure overlying the at least one CMOS device, the electrode ground ring structure being coupled to ground and the at least one CMOS device.

13. The method of claim 12 wherein the electrode ground ring structure is configured to direct plasma induced charge from a MEMS etching process to ground.

14. The method of claim 8 wherein the at least one MEMS device comprises an inertial sensor, an accelerometer, a gyrometer, a magnetic field sensor, a pressure sensor, a humidity sensor, a temperature sensor, a chemical sensor, or a biosensor.

15. The method of claim 8 further comprising forming the MEMS contact region and the CMOS contact region in the MEMS layer before forming the at least one MEMS device.

16. The method of claim 8 wherein the at least one MEMS device is formed below the MEMS contact region and the CMOS contact region in the MEMS layer.