MEMS suspension and anchoring design
View Patent ↗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.
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;
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,
wherein the at least one suspension structure is formed by a set of n segments that extend completely between the movable mass and the at least one anchor, wherein n is at least three and an odd integer, the segments being generally parallel to one another, each segment being generally straight and having two ends, each of the ends being coupled to one of the movable mass, the at least one anchor, or another segment end; and
at least one suspension link positioned on the at least one suspension structure for controlling the sensitivity of the MEMS device.
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 only three segments.
4. The MEMS device of claim 1 , wherein the at least one suspension link effectively shortens the at least one suspension structure.
5. The MEMS device of claim 1 , 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.
6. 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.
7. The MEMS device of claim 1 , 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, or
a third suspension link that links the third segment to the movable mass at a position other than the movable mass attachment point.
8. 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, wherein the at least one suspension structure is formed by a set of n segments that extend completely between the movable mass and the at least one anchor, wherein n is at least three and an odd integer, the segments being generally parallel to one another, each segment being generally straight and having two ends, each of the ends being coupled to one of the movable mass, the at least one anchor, or another segment end; and
at least one suspension link positioned on the at least one suspension structure for controlling the sensitivity of the MEMS device.
9. The MEMS device of claim 8 , wherein the at least one suspension link effectively shortens the at least one suspension structure.
10. The MEMS device of claim 8 , wherein the at least one suspension link is positioned at a position other than the ends.
11. The MEMS device of claim 8 , 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.
12. The MEMS device of claim 8 , farther 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, or
a third suspension link that links the third segment to the movable mass at a position other than the movable mass attachment point.
13. The MEMS device of claim 8 , wherein the device further comprises at least one stiffening link that links two segments of the movable mass at a position other than the ends.
14. A method of manufacturing a MEMS device having a sensitivity to a stimulus in at least one sensing direction, comprising:
providing a substrate;
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 by a suspension structure, the suspension structure being formed by a set of n segments that extend completely between the movable mass and the at least one anchor, wherein n is at least three and an odd integer, the segments being generally parallel to one another, each segment being generally straight and having two ends, each of the ends being coupled to one of the movable mass, the at least one anchor, or another segment end; and
positioning at least one suspension link on the at least one suspension structure to control the sensitivity of the MEMS device.
15. The method of claim 14 , wherein the positioning step includes positioning the at least one suspension link at a position other than the ends.
16. 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, wherein the at least one suspension structure is formed by a set of n segments that extend completely between the movable mass and the at least one anchor, wherein n is at least three and an odd integer, the segments generally parallel to one another, each segment being generally straight with two ends, each of the ends being coupled to one of the movable mass, at least one anchor, or another segment end; and
at least one stiffening link that links two segments of the movable mass at a position other than the end portions.
17. The MEMS device of claim 16 , 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, or
a third suspension link that links the third segment to the movable mass at a position other than the movable mass attachment point.
18. 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, wherein the MEMS device includes a movable mass coupled to an anchor with a suspension structure, the suspension structure being formed by a set of n segments that extend completely between the movable mass and the at least one anchor, wherein n is at least three and an odd integer, the segments being generally straight and having two ends, each of the ends being coupled to one of the movable mass, at least one anchor, or another segment end.