MEMS mass-spring-damper systems using an out-of-plane suspension scheme

• US 9,791,274 B2
• Filed: 02/03/2014
• Issued: 10/17/2017
• 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: Kamal Said Abdel Aziz, Ahmed, Sharaf, Abdel Hameed, Serry, Mohamed Yousef, Sedky, Sherif Salah
• Primary Examiner(s): HULS, NATALIE F
• Application Number:
  US14/171,691
• Publication Number:
  US 20150285633A1
• Time in Patent Office: 1,352 Days
• 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. A MEMS accelerometer, comprising:

a proof mass;

plural anchors distributed in a plane; and

a plurality of suspensions, the suspensions connecting between the proof mass and the plural anchors;

wherein a longest length of said plurality of suspensions extends out from said plane defined by said plural anchors, and

wherein said proof mass is located at least partially directly on top of said plural anchors.

2. The MEMS accelerometer of claim 1, wherein said MEMS accelerometer is an inertial grade MEMS accelerometer.

3. The MEMS accelerometer of claim 1, wherein said proof mass has a length and width ranging from 100 μ

m to 3 mm and a thickness ranging from 10 μ

m to 300 μ

m.

4. The MEMS accelerometer of claim 1, wherein said proof mass is comprised of an upper mass and a lower mass.

5. The MEMS accelerometer of claim 4, wherein said lower mass has a smaller length than said upper mass.

6. The MEMS accelerometer of claim 5, wherein said lower mass is 100 μ

m to 200 μ

m shorter in length than said upper mass.

7. The MEMS accelerometer of claim 4, wherein each of the plurality of suspensions attached to the plural anchors are also attached to one of the lower and upper masses.

8. The MEMS accelerometer of claim 1, wherein said proof mass has a mass ranging from 30 μ

g to 3 mg.

9. The MEMS accelerometer of claim 1, wherein said proof mass, said plural anchors, and said suspensions are comprised of crystalline Silicon.

10. The MEMS accelerometer of claim 1, wherein said proof mass rests on said suspensions.

11. The MEMS accelerometer of claim 1, wherein said suspensions have a cross-section ranging from 5×

5 μ

m² to 100×

100 μ

m².

12. The MEMS accelerometer of claim 1, wherein said suspensions have a length ranging from 250 μ

m to 600 μ

m.

13. The MEMS accelerometer of claim 1, wherein said MEMS accelerometer is bulk micromachined.

14. The MEMS accelerometer of claim 1, wherein the proof mass extends in another plane, different than, but parallel to the plane in which the plural anchors are distributed.

15. The MEMS accelerometer of claim 1, wherein each of the plurality of suspensions attached to the plural anchors are also attached to a single part of the proof mass.