Differential pressure sensor

Patent metadata

Field	Value
Publication number	US-9310267-B2
Application number	US-201414194011-A
Country	US
Kind code	B2
Filing date	Feb 28, 2014
Priority date	Feb 28, 2014
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A differential pressure sensor includes a pressure sensing die comprising a semiconductor die, having a thinned portion forming a diaphragm. The diaphragm includes piezo-resistive elements that exhibit varying resistance based on force exerted on the diaphragm. A first support structure is bonded to a first surface of the semiconductor die, having an aperture defined through the support structure such that a first surface of the diaphragm is exposed through the aperture. A second support structure is bonded to the opposite side of the semiconductor die having an aperture aligned with the opposing side of the diaphragm. Electrical components in electrical communication with the piezo-resistive elements are arranged outside the region defined by the bond between the first and second support structures and the semiconductor die. An oil-filled volume may be defined between the semiconductor die and a harsh medium which transmits a fluid pressure to the die without the harsh medium contacting the die.

First claim

What is claimed is:

1. A differential pressure sensor comprising:
a differential pressure sensing die, having a semiconductor die including an integral sensing diaphragm, a piezo-resistive element being defined on the diaphragm, a first support structure bonded to a surface of the semiconductor die, the first support structure having a first aperture defined therethrough exposing said sensing diaphragm through the first aperture, and a second support structure bonded to an opposing surface of the semiconductor die, the second support structure having a second aperture defined therethrough exposing the sensing diaphragm through the second aperture;
an upper housing, defining an upper interior volume in fluid communication with said first aperture and having an upper flexible diaphragm defining a wall of the upper interior volume;
a lower housing defining a lower interior volume in fluid communication with said second aperture, and having a lower flexible diaphragm defining a wall of the lower interior volume; and
an electrical circuit coupled to the piezo-resistive element for determining a differential pressure applied to the sensing diaphragm.

2. The differential pressure sensor of claim 1 , wherein the upper and lower interior volumes are fluid-filled, whereby pressure applied to the upper and lower diaphragms is transmitted by the fluid to the sensing diaphragm.

3. The differential pressure sensor of claim 2 , wherein the fluid comprises an oil.

4. The differential pressure sensor of claim 1 , wherein said first support structure and said second support structure comprise silicon.

5. The differential pressure sensor of claim 4 , wherein said first support structure and said second support structure are bonded to said semiconductor die by an adhesive.

6. The differential pressure sensor of claim 1 , wherein said first support structure and said second support structure comprise glass.

7. The differential pressure sensor of claim 6 , wherein said first support structure and said second support structure are bonded to said semiconductor die by a glass frit bond.

8. The differential pressure sensor of claim 1 , wherein the upper and lower diaphragms are of stainless steel.

9. The differential pressure sensor of claim 1 , wherein a bond between the first support structure and the semiconductor die is impervious to a fluid within the first aperture of the first support structure.

10. The differential pressure sensor of claim 1 , wherein a bond between the second support structure and the semiconductor die is impervious to a fluid within the second aperture of the second support structure.

11. The differential pressure sensor of claim 10 , wherein bonds between the first support structure and the upper housing and between the second support structure and the lower housing are impervious to a fluid within the first aperture in the first support structure and a fluid within the second aperture in the second support structure.

12. A pressure sensor comprising:
a differential pressure sensing die, having a first semiconductor die having an integral sensing diaphragm, a first piezo-resistive element being defined on the sensing diaphragm, a first support structure bonded to a surface of the first semiconductor die, the first support structure having a first aperture defined therethrough exposing said sensing diaphragm through the first aperture, and a second support structure bonded to an opposing surface of the first semiconductor die, the second support structure having a second aperture defined therethrough exposing the sensing diaphragm through the second aperture;
an absolute pressure sensing die, having a second semiconductor die including an integral absolute pressure sensing diaphragm, a second piezo-resistive element being defined on the absolute pressure sensing diaphragm, a first absolute pressure support structure bonded to a surface of the second semiconductor die, the first absolute pressure support structure forming a seal around the second piezo-resistive element on the absolute pressure sensing diaphragm and a second absolute pressure support structure bonded to an opposing surface of the absolute pressure sensing semiconductor die, the second absolute pressure support structure having a third aperture defined therethrough exposing the absolute pressure sensing diaphragm through the third aperture,
an upper housing, defining an upper interior volume in fluid communication with said first aperture and having an upper flexible diaphragm defining a wall of the upper interior volume;
a lower housing defining a lower interior volume in fluid communication with said second aperture and said third aperture, and having a second flexible diaphragm defining a wall of the lower interior volume;
a first electrical circuit coupled to the piezo-resistive element of the differential pressure sensing die for determining a differential pressure applied to the diaphragm of the differential pressure sensing die; and
a second electrical circuit coupled to the piezo-resistive element of the absolute pressure sensing die for determining an absolute pressure applied to the diaphragm of the absolute pressure sensing die.

13. The pressure sensor of claim 12 , wherein the upper and lower interior volumes are fluid-filled.

14. The pressure sensor of claim 13 , wherein the fluid comprises an oil.

15. The pressure sensor of claim 12 , wherein said first and second support structures and said first and second absolute pressure support structures comprise silicon.

16. The pressure sensor of claim 15 , wherein said first support structure and said second support structure are bonded to said first semiconductor die by an adhesive, and said first and second absolute pressure support structures are bonded to said second semiconductor die by an adhesive.

17. The pressure sensor of claim 12 , wherein said first and second support structures and said first and second absolute pressure support structures comprise glass.

18. The pressure sensor of claim 17 , wherein said first and second support structures are bonded to said first semiconductor die by glass frit bonds, and said first and second absolute pressure support structures are bonded to said second semiconductor die by glass frit bonds.

19. The pressure sensor of claim 12 , wherein the upper and lower diaphragms are of stainless steel.

20. The pressure sensor of claim 12 , wherein bonds between the first and second support structures and the first semiconductor die, and a bond between the second absolute pressure support structure and the second semiconductor die, are impervious to fluid.

Assignees

• Measurement Spec Inc
• Measurement Specialities Inc

Inventors

• Wagner David E
• Kachenko Natasha V
• Wong Vincent M

Classifications

• G01L2009/0066

  Mounting arrangements of diaphragm transducers; Details thereof, e.g. electromagnetic shielding means · CPC title

• G01F1/38

  the pressure or differential pressure being measured by means of a movable element, e.g. diaphragm, piston, Bourdon tube or flexible capsule · CPC title

• G01F1/34 Primary

  by measuring pressure or differential pressure · CPC title

• G01L9/0054 Primary

  integral with a semiconducting diaphragm · CPC title

• G01L13/025

  using diaphragms · CPC title