Stress isolation platform for MEMS devices
A MEMS product includes a stress-isolated MEMS platform surrounded by a stress-relief gap and suspended from a substrate. The stress-relief gap provides a barrier against the transmission of mechanical stress from the substrate to the platform.
1. A microelectromechanical systems (MEMS) device with stress-relief structures, comprising:
a MEMS device platform suspended from a substrate by a plurality of flexible bridges such that the MEMS device platform is separated from a peripheral portion of the substrate by a stress-relief gap;
a micro-scale movable component of a MEMS device positioned on and configured to move relative to the MEMS device platform; and
a flexible electrical conductor configured to couple an electrical signal between a component on the MEMS device platform and a component on the peripheral portion of the substrate.
2. The MEMS device of claim 1 , wherein the micro-scale movable component is disposed out-of-plane from the MEMS device platform.
3. The MEMS device of claim 1 , wherein the micro-scale movable component comprises a component of an accelerometer or a gyroscope.
4. The MEMS device of claim 1 , wherein the plurality of flexible bridges are shaped so as to not provide a straight line path from the peripheral portion of the substrate to the MEMS device platform.
5. The MEMS device of claim 1 , wherein a resonant frequency of a first flexible bridge of the plurality of flexible bridges is higher than a resonant frequency of the micro-scale movable component.
6. The MEMS device of claim 1 , wherein a resonant frequency of a first flexible bridge of the plurality of flexible bridges is at least twenty-five times greater than a resonant frequency of the micro-scale movable component.
7. The MEMS device of claim 1 , wherein the flexible electrical conductor is formed on at least one bridge of the plurality of flexible bridges.
8. The MEMS device of claim 1 , wherein the flexible electrical conductor comprises a jumper not formed on a flexible bridge.
9. A stress-tolerant microelectromechanical systems (MEMS) apparatus, comprising:
a substrate having a stress-relief gap therein defining a platform and a peripheral region;
a sensing structure disposed on the platform and comprising a member movable relative to the platform;
a plurality of flexible bridges configured to flex in response to substrate stress; and
an electrical conductor physically contacting the peripheral region and physically contacting an electrical structure on the platform, the electrical conductor being configured to carry an electrical signal across the stress-relief gap.
10. The stress-tolerant MEMS apparatus of claim 9 , wherein a resonant frequency of a first flexible bridge of the plurality of flexible bridges is higher than a resonant frequency of the member.
11. The stress-tolerant MEMS apparatus of claim 9 , wherein a ratio of a resonant frequency of a first flexible bridge of the plurality of flexible bridges to a resonant frequency of the member is at least 25:1.
12. The stress-tolerant MEMS apparatus of claim 9 , wherein a ratio of a resonant frequency of a first flexible bridge of the plurality of flexible bridges to a resonant frequency of the member is greater than about 40:1.
13. The stress-tolerant MEMS apparatus of claim 9 , wherein a resonant frequency of a first flexible bridge of the plurality of flexible bridges is greater than about 200 kHz.
14. The stress-tolerant MEMS apparatus of claim 9 , wherein the plurality of flexible bridges are configured to be rigid in response to an acceleration condition causing motion of the member.
15. A microelectromechanical systems (MEMS) device with stress-relief structures, comprising:
a semiconductor substrate;
a platform suspended from the semiconductor substrate and separated from the semiconductor substrate by a stress-relief gap;
a structure disposed on the platform comprising a member movable relative to the platform; and
a flexible electrical conductor physically contacting the semiconductor substrate and physically contacting the platform or a structure on the platform, the flexible electrical conductor being configured to carry an electrical signal across the stress-relief gap.
16. The MEMS device of claim 15 , wherein the semiconductor substrate comprises a portion of a wafer.
17. The MEMS device of claim 15 , wherein the semiconductor substrate comprises a silicon-on-insulator substrate.
18. The MEMS device of claim 15 , wherein the semiconductor substrate comprises a bulk semiconductor substrate.
19. The MEMS device of claim 15 , wherein the semiconductor substrate has a thickness between about 500 and about 780 microns.
20. The MEMS device of claim 15 , further comprising a top cap bonded to a top surface of the semiconductor substrate and a bottom cap bonded to a bottom surface of the semiconductor substrate, such that the platform is disposed between the top cap and the bottom cap.