DIFFERENTIAL TEMPERATURE AND ACCELERATION COMPENSATED PRESSURE TRANSDUCER

• US 20110239772A1
• Filed: 03/31/2010
• Published: 10/06/2011
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Kulite Semiconductor Products Inc
• Original Assignee: Kulite Semiconductor Products Inc
• Inventors: Stefanescu, Sorin, Kurtz, Anthony D., Ned, Alexander A., Kurtz, Nora
• Granted Patent: US 8,631,707 B2
• Time in Patent Office: Days
• US Class Current: 73/721
• CPC Class Codes: G01L 13/025 using diaphragms
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 19/04 Means for compensating for effects of changes of temperature , i.e. other than electric compensation
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A dual diaphragm pressure transducer, or sensor, with compensation for non-pressure effects is disclosed. The pressure sensor can include two pressure transducers located on separate portions of a chip. The first pressure transducer can be a differential pressure transducer, which produces a signal proportional to one or more applied pressures and includes other non-pressure effects. The second pressure transducer can be sealed in a hermetic chamber and thus can produce a signal proportional only to non-pressure effects. The signals can be combined to produce a signal proportional to the applied pressures with no non-pressure effects. The first and second pressure transducers can be physically and/or electrically isolated to improve sealing between the two pressure transducers and prevent pressure leaks therebetween.

Claims

1. A pressure sensor comprising:

a chip;

a first pressure sensing device, disposed on a first portion of the chip;

a second pressure sensing device, disposed on a second portion of the chip;

a bridge disposed between the first pressure sensing device and the second pressure sensing device, and

a contact glass bonded to the chip in an overlying manner;

wherein the bridge creates a seal between the contact glass and the chip to prevent pressure leaks between the first pressure sensing device and the second pressure sensing device.

2. The pressure sensor of claim 1,

the first pressure sensing device comprising a differential pressure sensor;

and

the second pressure sensing device comprising a reference pressure sensor;

wherein the differential pressure sensor outputs a first signal proportional to the difference between a first applied pressure and a second applied pressure, including non-pressure effects; and

wherein the reference pressure sensor outputs a second signal proportional to non-pressure effects.

3. The pressure sensor of claim 2, wherein

the first signal and the second signal can be combined to create a third signal proportional to the difference between the first applied pressure and the second applied pressure.

4. The pressure sensor of claim 3, further comprising:

a first set of three contacts disposed on the chip and electrically connected to the differential sensor to form a first half of an isolated Wheatstone bridge; and

a second set of three contacts disposed on the chip and electrically connected to the reference sensor to form a second half of the isolated Wheatstone bridge;

wherein the first set and the second set of contacts can be connected to form an isolated Wheatstone bridge; and

wherein the output of the isolated Wheatstone bridge is the third signal.

5. The pressure sensor of claim 4, further comprising:

a first span resistor electrically connected to the first half of the isolated Wheatstone bridge; and

a second span resistor electrically connected to the second half of the isolated Wheatstone bridge;

wherein the first and second span resistors compensate for differences between the sensitivities of the first and second half bridges.

6. The pressure sensor of claim 2, wherein the reference sensor is disposed in a hermetically sealed chamber such that a first reference pressure exists on both sides of a reference diaphragm.

7. The pressure sensor of claim 1, wherein the bridge between the first and second pressure sensing devices comprises a P+ sealing pattern.

8. The pressure sensor of claim 1, further comprising one or more isolation moats, disposed in the chip, to physically isolate the first pressure sensing device from the second pressure sensing device.

9. A pressure sensor comprising:

a chip;

a first deflectable diaphragm, disposed on a first portion of the chip;

a first set of two or more piezoresistors disposed on the first deflectable diaphragm for measuring the deflection thereof;

a second deflectable diaphragm, disposed on a second portion of the chip in a hermetically sealed chamber such that a first reference pressure exists on both sides of the second deflectable diaphragm,

a second set of two or more piezoresistors disposed on the second deflectable diaphragm for measuring the deflection thereof;

an interconnect for electrically connecting the first set of two or more piezoresistors to the second set of two or more piezoresistors to form a Wheatstone bridge;

a contact glass disposed in an overlying manner to the chip; and

a P+ sealing pattern, disposed in an overlying manner to the interconnect to provide a sealing surface for the contact glass to prevent pressure leaks between the first deflectable diaphragm and the second deflectable diaphragm through gaps caused by the interconnects.

10. The pressure sensor of claim 9, wherein the output of the Wheatstone bridge is proportional to the difference between a first applied pressure and a second applied pressure.

11. The pressure sensor of claim 9, further comprising:

one or more electrical contacts, disposed on the chip, for providing connections to the first and second sets of piezoresistors; and

one or more gaps for electrically isolating each electrical contact on the chip;

wherein the P+ sealing pattern forms a sealing surface over the gaps for the contact glass to prevent pressure leaks between the first and second deflectable diaphragms.

12. The pressure sensor of claim 9, wherein the chip comprises silicon.

13. The pressure sensor of claim 9, wherein the first and second deflectable diaphragms comprise thinned areas in the chip.

14. A method of manufacturing a pressure sensor comprising:

disposing a first deflectable diaphragm on a first portion of a chip;

disposing a second deflectable diaphragm on a second portion of the chip;

mounting a first set of one or more piezoresistors on the first diaphragm;

mounting a second set of one or more piezoresistors on the second diaphragm;

connected the first set of piezoresistors to the second set of piezoresistors using one or more interconnects with gaps between these interconnects to provide electrical isolation, each gap comprising at least one narrowed portion disposed between the first portion of the chip and the second portion of the chip;

oxidizing the chip to form a non-conductive oxide layer to seal over the narrowed portions of the gaps to prevent pressure leaks between the first diaphragm and the second diaphragm on the chip; and

bonding a contact glass to the surface of the non-conductive oxide layer.

15. The method of manufacture of claim 14, wherein

the first deflectable diaphragm is exposed to one or more applied pressures;

and

the second deflectable diaphragm is disposed in an hermetically sealed chamber such that it measures only non-pressure effects.