MEMS suspension and anchoring design

• US 20080000297A1
• Filed: 06/30/2006
• Published: 01/03/2008
• Est. Priority Date: 06/30/2006
• Status: Active Grant

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: McNeil, Andrew C., Koury, Daniel N.
• Granted Patent: US 7,637,160 B2
• Time in Patent Office: Days
• US Class Current: 73/514.32
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0094 Constitution or structural means for improving or controlling physical properties not provided for in B81B3/0067 - B81B3/0091
• 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 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

A MEMS device that has a sensitivity to a stimulus in at least one sensing direction includes a substrate, a movable mass with corner portions suspended in proximity to the substrate, at least one suspension structure coupled approximately to the corner portions of the movable mass for performing a mechanical spring function, and at least one anchor for coupling the substrate to the at least one suspension structure. The at least one anchor is positioned approximately on a center line in the at least one sensing direction.

Claims

1. A MEMS device having a sensitivity to a stimulus in at least one sensing direction, comprising:

a substrate;

a movable mass suspended in proximity to the substrate, wherein the movable mass has corner portions;

at least one suspension structure coupled approximately to the corner portions of the movable mass for performing a mechanical spring function; and

at least one anchor for coupling the substrate to the at least one suspension structure, wherein the at least one anchor is positioned approximately on a center line in the at least one sensing direction.

2. The MEMS device of claim 1, wherein the movable mass is generally rectangular and includes four exterior sides intersecting at the corner portions.

3. The MEMS device of claim 1, wherein the at least one suspension structure has an odd number of segments.

4. The MEMS device of claim 3, wherein the at least one suspension structure has a single segment.

5. The MEMS device of claim 3, wherein the at least one suspension structure has three segments.

6. The MEMS device of claim 1, further comprising at least one suspension link positioned on the at least one suspension structure for controlling the sensitivity of the MEMS device.

7. The MEMS device of claim 6, wherein the at least one suspension link effectively shortens the at least one suspension structure.

8. The MEMS device of claim 6, wherein the at least one suspension structure comprises at least one segment with two end portions, and wherein the at least one suspension link is positioned at a position other than the two end portions.

9. The MEMS device of claim 1, further comprising a plurality of fixed electrodes, wherein the movable mass and the plurality of fixed electrodes form at least one sensing capacitor that measures acceleration of the MEMS device in the at least one sensing direction.

10. A MEMS device having a sensitivity to a stimulus in at least one sensing direction, comprising:

a substrate;

a movable mass suspended in proximity to the substrate;

at least one suspension structure coupled to the movable mass for performing a mechanical spring function; and

at least one suspension link positioned on the at least one suspension structure for controlling the sensitivity of the MEMS device.

11. The MEMS device of claim 10, wherein the at least one suspension link effectively shortens the at least one suspension structure.

12. The MEMS device of claim 10, wherein the at least one suspension structure comprises at least one segment with two end portions, and wherein the at least one suspension link is positioned at a position other than the two end portions.

13. The MEMS device of claim 10, wherein the at least one suspension structure is coupled to the movable mass at least one first attachment point, and wherein the suspension link additionally couples the at least one suspension structure to the movable mass at a position other than the at least one first attachment point.

14. The MEMS device of claim 10, further comprising at least one anchor for coupling the at least one suspension structure to the substrate,

wherein the at least one suspension structure has first, second, and third segments,

wherein the first segment is connected to the anchor at an anchor attachment point and to the second segment at a first elbow, the second segment is connected to the third segment at a second elbow, and the third segment is connected to the movable mass at a movable mass attachment point, and

wherein the at least one suspension link comprises at least one of:

a first suspension link that links the first and second segments at a position other than the first elbow,

a second suspension link that links the second and third segments at a position other than the second elbow, and

a third suspension link that links the third segment to the movable mass at a position other than the movable mass attachment point.

15. The MEMS device of claim 10, wherein the movable mass includes a plurality of parallel segments, each with end portions, and

wherein the device further comprises at least one stiffening link that links two segments of the movable mass at a position other than the end portions.

16. A method of manufacturing a MEMS device having a sensitivity to a stimulus in at least one sensing direction, comprising:

providing a substrate; and

providing a movable mass suspended in proximity to the substrate on at least one suspension structure coupled to the substrate with at least one anchor approximately on a center line in the sensing direction, wherein the movable mass is suspended approximately at corner portions.

17. The method of claim 16, further comprising the step of positioning at least one suspension link on the at least one suspension structure to control the sensitivity of the MEMS device.

18. The method of claim 17, wherein the suspension structure comprises at least one segment with two end portions, and wherein the positioning step includes positioning the at least one suspension link at a position other than the two end portions.

19. A MEMS device having a sensitivity to a stimulus in at least one sensing direction, comprising:

a substrate;

a movable mass suspended in proximity to the substrate and including a plurality of parallel segments, each with end portions;

at least one suspension structure coupled to the movable mass for performing a mechanical spring function; and

at least one stiffening link that links two segments of the movable mass at a position other than the end portions.

20. A method for designing and fabricating a MEMS device having a movable mass suspended in proximity to a substrate by suspension structures, the method comprising:

obtaining a MEMS design;

determining a desired spring constant;

positioning at least one suspension link on the suspension structures at a position to obtain the desired spring constant; and

fabricating the MEMS device according to the design with the at least one suspension link.