MEMS MASS-SPRING-DAMPER SYSTEMS USING AN OUT-OF-PLANE SUSPENSION SCHEME

• US 20150285633A1
• Filed: 02/03/2014
• Published: 10/08/2015
• Est. Priority Date: 05/27/2009
• Status: Active Grant

• Current Assignee: King Abdullah University of Science and Technology
• Original Assignee: King Abdullah University of Science and Technology
• Inventors: Sharaf, Abdel Hameed, Serry, Mohamed Yousef, Sedky, Sherif Salah, Kamal Said Abdel Aziz, Ahmed
• Granted Patent: US 9,791,274 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/082 for two degrees of freedom of movement of a single mass

Abstract

MEMS mass-spring-damper systems (including MEMS gyroscopes and accelerometers) using an out-of-plane (or vertical) suspension scheme, wherein the suspensions are normal to the proof mass, are disclosed. Such out-of-plane suspension scheme helps such MEMS mass-spring-damper systems achieve inertial grade performance. Methods of fabricating out-of-plane suspensions in MEMS mass-spring-damper systems (including MEMS gyroscopes and accelerometers) are also disclosed.

Claims

1-11. -11. (canceled)

12. A MEMS accelerometer, comprising:

a. a proof mass;

b. one or more anchors; and

c. a plurality of suspensions;

d. wherein said plurality of suspensions are out-of-plane with said proof mass.

13. The MEMS accelerometer of claim 12, wherein said MEMS accelerometer is an inertial grade MEMS accelerometer.

14. The MEMS accelerometer of claim 12, wherein said proof mass has a length and width ranging from 100 jlm to 3 mm and a thickness ranging from 10 μ

m to 300 μ

m.

15. The MEMS accelerometer of claim 12, wherein said proof mass is comprised of an upper mass and a lower mass.

16. The MEMS accelerometer of claim 15, wherein said lower mass has a smaller length than said upper mass.

17. The MEMS accelerometer of claim 16, wherein said lower mass is 100 μ

m to 200 μ

m shorter in length than said upper mass.

18. The MEMS accelerometer of claim 12, wherein said proof mass has a weight ranging from 30 μ

g to 3 mg.

19. The MEMS accelerometer of claim 12, wherein said proof mass, said one or more anchors, and said suspensions are comprised of crystalline Silicon.

20. The MEMS accelerometer of claim 12, wherein said proof mass rests on said suspensions.

21. The MEMS accelerometer of claim 12, wherein said suspensions have a cross-section ranging from 5×

5 μ

m² to 100×

100 μ

m².

22. The MEMS accelerometer of claim 12, wherein said suspensions have a length ranging from 250 μ

m to 600 μ

m.

23. The MEMS accelerometer of claim 12, wherein said MEMS accelerometer is bulk micromachined.

24-29. -29. (canceled)

30. A method for fabricating a vertical suspension in a substrate in a MEMS mass-spring-damper system, said method comprising the steps of:

a. realizing a first side and a second side of said vertical suspension by selectively etching through a top surface of said substrate; and

b. realizing a third side and a fourth side of said vertical suspension by selectively etching through a bottom surface of said substrate.

31. The method of claim 30, wherein said etching in steps (a) and (b) is performed using DRIE.

32. The method of claim 30, wherein said MEMS mass-spring-damper system is an inertial grade MEMS gyroscope.

33. The method of claim 30, wherein said MEMS mass-spring damper system is an inertial grade MEMS accelerometer.