General strength and sensitivity enhancement method for micromachined device

• US 20110115035A1
• Filed: 09/13/2010
• Published: 05/19/2011
• Est. Priority Date: 09/08/2009
• Status: Abandoned Application

• Current Assignee: Jung-Tang Huang
• Original Assignee: Jung-Tang Huang
• Inventors: Hsu, Hou-Jun, Huang, Jung-Tang, Lin, Ming-Jhe
• Application Number:
  US12/807,658
• Publication Number:
  US 20110115035A1
• Time in Patent Office: Days
• US Class Current: 257/414
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81B 2207/015 the micromechanical device and the control or processing electronics being integrated on the same substrate
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B81C 2201/0167 by adding further layers of materials having complementary strains, i.e. compressive or tensile strain
• CPC Class Codes: B81C 2201/0197 Processes for making multi-layered devices not provided for in groups B81C2201/0176 - B81C2201/0192
• CPC Class Codes: B81C 2203/0714 Forming the micromechanical structure with a CMOS process

Abstract

This invention disclosed a method to strengthen structure and enhance sensitivity for CMOS-MEMS micro-machined devices which include micro-motion sensor, micro-actuator and RF switch. The steps of the said method contain defining deposited region by metal and passivation layer, forming a cavity for depositing metal structure by lithography process, depositing metal structure on the top metal layer of micromachined structure by Electroless plating, polishing process and etching process. The method aims at strengthening structures and minimizing CMOS-MEMS device size. Furthermore, this method can also be applied to inertia sensors such as accelerometer or gyroscope, which can enhance sensitivity and capacitive value, and deal with curl issues for suspended CMOS-MEMS devices.

Claims

1. A CMOS-MEMS micromachined device comprising:

a micromachined structure comprising at least one proof mass, and at least one metal layer on the top of the proof mass;

at least one layer of the deposited metal structure on the micromachined structure by Electroless plating.

2. The device of claim 1, wherein the CMOS-MEMS micromachined device is a micro motion sensor.

3. The device of claim 1, wherein the CMOS-MEMS micromachined device is a micro actuator.

4. The device of claim 1, wherein the CMOS-MEMS micromachined device is a micro switch.

5. The device of claim 1, wherein the micromachined structure is suspended.

6. The device of claim 1, wherein the micromachined structure is non-suspended.

7. The device of claim 1, wherein the micromachined structure further comprises at least one pair of comb figure structure.

8. The device of claim 1, wherein the deposited metal structure is single layer.

9. The device of claim 1, wherein the deposited metal structure are multi-layers.

10. The device of claim 8, wherein the deposited metal structure are formed with combination of at least two of different materials such as Au, Co, Rh, Ni, Ag, Cu, Pd, Sn and Zn.

11. A method for enhancing CMOS-MEMS micromachined device'"'"'s strength and sensitivity, comprising the steps of:

providing a micromachined structure, comprising at least one proof mass structure;

providing a deposited region on the micromachined structure;

providing a deposited metal structure on the deposited region by Electroless plating;

wherein the deposited metal structure is on the deposited region of the micromachined structure to enhance sensitivity, strength and capacitive value of CMOS-MEMS micromachined device.

12. The method of claim 11, wherein the micromachined structure further comprises at least one pair of comb figure structure.

13. The method of claim 11, wherein the deposited region is defined by the top metal layer with passivation layer.

14. The method of claim 11, wherein the deposited region is defined by the top metal layer with photoresist.

15. The method of claim 11, wherein the deposited region is further comprising the step of surface treatment.

16. The method of claim 11, wherein the deposited metal structure is further comprising the step of polishing process.