Dual absolute pressure sensor and method thereof

• US 5,437,189 A
• Filed: 05/03/1994
• Issued: 08/01/1995
• Est. Priority Date: 05/03/1994
• Status: Expired due to Term

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Wallace, Daniel J., Brown, Clem H.
• Primary Examiner(s): Raevis, Robert
• Assistant Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US08/237,527
• Time in Patent Office: 455 Days
• Field of Search: 73/720, 73/721, 73/726, 73/727, 73/708
• US Class Current: 73/721
• CPC Class Codes: G01L 19/0038 being part of the housing other details about the housing G01L19/14
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A dual absolute pressure sensor independently converts first and second external pressures to first and second electrical signals respectively. A package body has first and second openings for receiving the first and second external pressures to outside surfaces of first and second sensor die attached to opposite surfaces of an internal glass substrate that separates the first and second openings. The first sensor die includes a first cavity having a reference pressure to measure against the first external pressure and develop a first differential pressure. A first piezoelectric network converts the first differential pressure to the first electrical signal representative of that pressure. The second sensor die includes a second cavity having a reference pressure to independently measure against the second external pressure and develop a second differential pressure. A second piezoelectric network converts the second differential pressure to the second electrical signal representative of that pressure.

Claims

1. A dual absolute pressure sensor, comprising:

a glass substrate having first and second surfaces wherein said glass substrate distribute a common temperature to said first and second surfaces for increased accuracy of the dual absolute pressure sensor;

a first sensor die attached to said first surface of said glass substrate to form a first cavity having a first reference pressure, said first sensor die measuring a first differential pressure between said first reference pressure and an outside surface of said first sensor die at which is applied a first external pressure for providing a first electrical signal representative of said first differential pressure and

a second sensor die attached to said second surface of said glass substrate to form a second cavity having a second reference pressure, said second sensor die measuring a second differential pressure between said second reference pressure and an outside surface of said second sensor die at which is applied a second external pressure for providing a second electrical signal representative of said second differential pressure.

2. The dual absolute pressure sensor of claim 1 wherein said first sensor die includes a first diaphragm separating said first reference pressure and said first external pressure, said first diaphragm flexing in response to said first differential pressure between said first cavity and said outside surface of said first sensor die.

3. The dual absolute pressure sensor of claim 2 wherein said first sensor die further including a first piezoelectric network for measuring said first differential pressure between said first reference pressure and said first external pressure and providing said first electrical signal representative of said first differential pressure.

4. The dual absolute pressure sensor of claim 3 wherein said second sensor die includes a second diaphragm separating said second reference pressure and said second external pressure, said second diaphragm flexing in response to said second differential pressure between said second cavity and said outside surface of said second sensor die.

5. The dual absolute pressure sensor of claim 4 wherein said second sensor die further including a second piezoelectric network for measuring said second differential pressure between said second reference pressure and said second external pressure and providing said second electrical signal representative of said second differential pressure.

6. The dual absolute pressure sensor of claim 5 further including a package body for housing said glass substrate with said first and second sensor die, said package body including first and second openings for receiving said first and second external pressures to said outside surfaces of said first and second sensor die respectively.

7. The dual absolute pressure sensor of claim 6 wherein said package body includes:

a first bondwire having a first end coupled to said first piezoelectric network for receiving said first electrical signal; and

a first lead coupled to a second end of said first bondwire for transmitting said first electrical signal.

8. The dual absolute pressure sensor of claim 7 wherein said package body further includes:

a second bondwire having a first end coupled to said second piezoelectric network for receiving said second electrical signal; and

a second lead coupled to a second end of said second bondwire to transmitting said second electrical signal.

9. A method of sensing first and second external pressures, comprising the steps of:

providing a glass substrate having first and second surfaces where said glass substrate distributes a common temperature to said first and second surfaces for increased accuracy in reading the first and second external pressures;

attaching a first sensor die to said first surface of said glass substrate to form a first cavity having a first reference pressure where said first sensor die measures a first differential pressure between said first reference pressure and an outside surface of said first sensor die at which is applied a first external pressure for providing a first electrical signal representative of said first differential pressure; and

attaching a second sensor die to said second surface of said glass substrate to form a second cavity having a second reference pressure such that said second sensor die measures a second differential pressure between said second reference pressure and an outside surface of said second sensor die at which is applied a second external pressure for providing a second electrical signal representative of said second differential pressure.

10. The method of claim 9 further including the step of separating said first reference pressure and said first external pressure with a first diaphragm that flexes in response to said first differential pressure between said first cavity and said outside surface of said first sensor die.

11. The method of claim 10 further including the step of measuring said first differential pressure between said first reference pressure and said first external pressure with a first piezoelectric network and providing said first electrical signal representative of said first differential pressure.

12. The method of claim 11 further including the step of separating said second reference pressure and said second external pressure with a second diaphragm that flexes in response to said second differential pressure between said second cavity and said outside surface of said second sensor die.

13. The method of claim 12 further including the step of measuring said second differential pressure between said second reference pressure and said second external pressure with a second piezoelectric network and providing said second electrical signal representative of said second differential pressure.

14. The method of claim 13 further including the step of housing said glass substrate with said first and second sensor die in a package body that includes first and second openings for receiving said first and second external pressures to said outside surfaces of said first and second sensor die respectively.

15. A dual absolute pressure sensor, comprising:

a glass substrate having first and second surfaces wherein said glass substrate distributes a common temperature to said first and second surfaces for increased accuracy of the dual absolute pressure sensor;

a first sensor die attached to said first surface of said glass substrate to form a first cavity having a first reference pressure, said first sensor die measuring a first differential pressure between said first reference pressure and an outside surface of said first sensor die at which is applied a first external pressure for providing a first electrical signal representative of said first differential pressure;

a second sensor die attached to said second surface of said glass substrate to form a second cavity having a second reference pressure, said second sensor die measuring a second differential pressure between said second reference pressure and an outside surface of said second sensor die at which is applied a second external pressure for providing a first electrical signal representative of said second differential pressure; and

a package body for housing said glass substrate with said first and second sensor die, said package body including first and second openings for receiving said first and second external pressures to said outside surfaces of said first and second sensor die respectively.

16. The dual absolute pressure sensor of claim 15 wherein said first sensor die includes:

a first diaphragm separating said first reference pressure and said first external pressure, said first diaphragm flexing in response to said first differential pressure between said first cavity and said outside surface of said first sensor die; and

a first piezoelectric network for measuring said first differential pressure between said first reference pressure and said first external pressure and providing said first electrical signal representative of said first differential pressure.

17. The dual absolute pressure sensor of claim 16 wherein said second sensor die includes:

a second diaphragm separating said second reference pressure and said second external pressure, said second diaphragm flexing in response to said second differential pressure between said second cavity and said outside surface of said second sensor die; and

a second piezoelectric network for measuring said second differential pressure between said second reference pressure and said second external pressure and providing said second electrical signal representative of said second differential pressure.

18. The dual absolute pressure sensor of claim 17 wherein said package body includes:

a first bondwire having a first end coupled to said first piezoelectric network for receiving said first electrical signal; and

a first lead coupled to a second end of said first bondwire to transmitting said first electrical signal.

19. The dual absolute pressure sensor of claim 18 wherein said package body further includes:

a second bondwire having a first end coupled to said second piezoelectric network for receiving said second electrical signal; and

a second lead coupled to a second end of said second bondwire to transmitting said second electrical signal.