Stress-isolated absolute pressure sensor

Patent metadata

Field	Value
Publication number	US-10060820-B2
Application number	US-201615209185-A
Country	US
Kind code	B2
Filing date	Jul 13, 2016
Priority date	Dec 22, 2015
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

Suspending a microelectromechanical system (MEMS) pressure sensing element inside a cavity using spring-like corrugations or serpentine crenellations, reduces thermally-mismatched mechanical stress on the sensing element. Overlaying the spring-like structures and the sensing element with a gel further reduces thermally-mismatched stress and vibrational dynamic stress.

First claim

What is claimed is:

1. A stress-isolated pressure sensor comprising:
a cavity bounded by a rim;
a microelectromechanical system (MEMS) pressure sensing element configured to be suspended inside the cavity, the MEMS pressure sensing element comprising a thin diaphragm, which is formed from a semiconductor material;
a plurality of suspenders extending between the rim and the MEMS pressure sensing element and supporting the MEMS pressure sensing element in the cavity, the suspenders being flexible, doped to be electrically conductive and formed from the same semiconductor material, which comprises the thin diaphragm.

2. The stress-isolated pressure sensor of claim 1 , wherein the rim is attached to a substrate, the stress-isolated pressure sensor further comprising:
open space between exterior surfaces of:
the MEMS pressure sensing element and the rim bounding the cavity; and
the MEMS pressure sensing element and the substrate.

3. The stress-isolated pressure sensor of claim 2 , further comprising a gel overlaid the suspenders and the MEMS pressure sensing element, the gel also filling the open space, the gel being selected to transmit pressure applied thereon to the MEMS pressure sensing element.

4. The stress-isolated pressure sensor of claim 1 , wherein the MEMS pressure sensing element comprises a diaphragm, which is substantially rectangular with opposing top and bottom surfaces and four sides, at least one of the diaphragm surfaces having a plurality of piezoresistors connected to each other to form a Wheatstone bridge circuit, each piezoresistor being located adjacent to each side of the diaphragm.

5. The stress-isolated pressure sensor of claim 1 , wherein the suspenders are serpentine.

6. The stress-isolated pressure sensor of claim 1 , wherein the suspenders have cross-sectional shapes, which are corrugated.

7. The stress-isolated pressure sensor of claim 1 , further comprising a substrate, the substrate being sized, shaped and arranged to support the rim, the MEMS pressure sensing element and the suspenders.

8. The stress-isolated pressure sensor of claim 7 , wherein the substrate is glass.

9. The stress-isolated pressure sensor of claim 8 , wherein the substrate is anodically bonded to the rim.

10. The stress-isolated pressure sensor of claim 7 , wherein the substrate is silicon.

11. The stress-isolated pressure sensor of claim 10 , wherein the substrate is glass-frit bonded to the rim.

12. The stress-isolated pressure sensor of claim 10 , wherein the substrate is fusion bonded to the rim.

13. The stress-isolated pressure sensor of claim 7 , further comprising an overmold encapsulating the MEMS pressure sensing element, the substrate and the suspenders, the overmold having a cavity sized, shaped and arranged to receive the MEMS pressure sensing element, the substrate and the suspenders.

14. The stress-isolated pressure sensor of claim 13 , further comprising a bond wire extending between a conductive pad on the rim and an electrical conductor in the overmold.

15. The stress-isolated pressure sensor of claim 13 , further comprising a conductive through via connecting the MEMS pressure sensing element to an electrical conductor in the overmold.

16. The stress-isolated pressure sensor of claim 13 , further comprising a gel within the overmold cavity.

17. The stress-isolated pressure sensor of claim 16 , further comprising a membrane on the top of the gel, the membrane being configured to contact the gel and selected to transmit pressure applied thereon to the gel and the MEMS pressure sensing element.

18. The stress-isolated pressure sensor of claim 7 , further comprising an ASIC attached to an exterior surface of the substrate and electrically coupled to a Wheatstone bridge circuit via conductive through vias.

19. The stress-isolated pressure sensor of claim 18 , further comprising a plastic housing configured to accommodate the MEMS pressure sensing element, the substrate, the suspenders, and the ASIC.

20. The stress-isolated pressure sensor of claim 18 , further comprising a plastic housing configured to accommodate the ASIC attached to an exterior surface of the substrate and electrically coupled to the Wheatstone bridge circuit via conductive through vias.

21. A stress-isolated pressure sensor comprising:
a first substrate having a first side and a second side, wherein the second side of the first substrate is etched to form a first cavity;
a second substrate having a first side and a second side, wherein the second side of the first substrate is bonded to the first side of the second substrate;
a third substrate having a first side and a second side, wherein the second side of the third substrate having a second cavity to accommodate the first substrate, and the second side of the third substrate is bonded to the first side of the second substrate;
and
the second side of the second substrate is etched to form a diaphragm and a plurality of suspenders, the diaphragm forming a MEMS pressure sensing element and the plurality of suspenders supporting the MEMS pressure sensing element in the cavity of the third substrate, the suspenders being flexible and doped to be electrically conductive.

22. The stress-isolated pressure sensor of claim 21 , wherein the first substrate is a silicon substrate.

23. The stress-isolated pressure sensor of claim 22 , wherein the second substrate is a silicon-on-insulator (SOI) substrate.

24. The stress-isolated pressure sensor of claim 23 , wherein the second substrate is fusion-bonded with the first substrate.

25. The stress-isolated pressure sensor of claim 24 , wherein the third substrate is a silicon substrate.

26. The stress-isolated pressure sensor of claim 24 , wherein the third substrate is a glass substrate.

27. The stress-isolated pressure sensor of claim 25 , wherein the third substrate is fusion-bonded with the second substrate.

28. The stress-isolated pressure sensor of claim 26 , wherein the third substrate is anodically-bonded with the second substrate.

29. The stress-isolated pressure sensor of claim 21 , wherein the suspenders are serpentine.

30. The stress-isolated pressure sensor of claim 21 , wherein the suspenders have cross-sectional shapes, which are corrugated.

31. The stress-isolated pressure sensor of claim 21 , further comprising a gel overlaid the suspenders and the MEMS pressure sensing element, the gel also filling the open space, the gel being selected to transmit pressure applied thereon to the MEMS pressure sensing element.

Assignees

• Continental automotive systems inc

Inventors

• Chen Shiuh-Hui Steven
• Chiou Jen-Huang Albert
• Kosberg Robert C
• Empen Daniel Roy

Classifications

• B81B2207/012

  the micromechanical device and the control or processing electronics being separate parts in the same package · CPC title

• G01L19/147

  Details about the mounting of the sensor to support or covering means · CPC title

• G01L9/0054

  integral with a semiconducting diaphragm · CPC title

• G01L19/02

  Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means (for aneroid barometers G01L7/14) · CPC title

• G01L19/04

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title