Sensor element placement for package stress compensation

• US 8,132,465 B1
• Filed: 07/31/2008
• Issued: 03/13/2012
• Est. Priority Date: 08/01/2007
• Status: Active Grant

• Current Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Original Assignee: Silicon Microstructures, Inc (TE Connectivity Limited)
• Inventors: Doelle, Michael B., Bergmann, Joachim
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US12/184,159
• Time in Patent Office: 1,321 Days
• Field of Search: None
• US Class Current: 73/754
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01L 27/002 Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

Circuits, methods, and systems that calibrate or account for packaging and related stress components in a pressure sensor. Further examples provide an improved sensor element or device. One example provides one or more sensing elements on the diaphragm and near the diaphragm-bulk boundary. Sensors near the diaphragm-bulk are used to estimate package-induced stress. This estimation can then be used in calibrating package stress from pressure measurements.

Claims

1. A pressure sensor comprising:

a silicon diaphragm;

a frame of thicker bulk silicon physically supporting the diaphragm;

a first sensing element located in the bulk; and

a second sensing element located in the diaphragm,

wherein the first sensing element and the second sensing element each comprise a single transistor having a single gate and more than four source-drain regions.

2. The pressure sensor of claim 1 wherein the second sensing element includes more than four source-drain regions.

3. The pressure sensor of claim 2 further comprising:

a third pressure sensing element located near a boundary between the bulk and the diaphragm, wherein the third pressure sensing includes more than four source-drain regions.

4. The pressure sensor of claim 3 further comprising:

circuitry to measure voltages at the first and third sensing elements and to use these voltages to determine an offset of the second sensing element.

5. The pressure sensor of claim 2 further comprising a plastic housing.

6. The pressure sensor of claim 3 wherein the first, second, and third sensing elements each include eight source-drain regions.

7. The pressure sensor of claim 1 wherein the first sensing element includes a nonconductive region located between the source-drain regions.

8. The pressure sensor of claim 1 wherein the first sensing element is used to calibrate an offset voltage of the second sensing element.

9. The pressure sensor of claim 1 wherein the first sensing element and the second sensing element are each used to calibration external parasitic mechanical stresses.

10. A pressure sensor comprising:

a silicon diaphragm;

a thicker bulk region physically supporting the diaphragm;

a first sensing element located in the bulk; and

a second sensing element located near a boundary between the bulk and the diaphragm;

a third sensing element located in the diaphragm; and

circuitry to measure voltages at the first and second sensing elements and to use these measured voltages to determine an offset of the third sensing element.

11. The pressure sensor of claim 10 wherein the first and second sensing elements each comprise a single transistor having a single gate and more than four source-drain regions.

12. The pressure sensor of claim 11 wherein the first and second sensing elements each include a nonconductive region located between the source-drain regions.

13. The pressure sensor of claim 10 further comprising a plastic housing.

14. The pressure sensor of claim 13 wherein the offset of the third sensing element is determined in order to calibrate for stress induced by the plastic housing.

15. The method of claim 10 wherein the first, second, and third sensing elements each include eight source-drain regions.

16. A method of calibrating an offset of a pressure sensor comprising:

measuring a first voltage of a first sensing element located in a thicker bulk region;

measuring a second voltage of a second sensing element located in a in a thinner diaphragm region; and

using the first voltage to calibrate an offset of the second sensing element,

wherein the first sensing element comprises a single transistor having a single gate and more than four source-drain regions.

17. The method of claim 16 further wherein measuring the first voltage of the first sensing element includes multiplexing the first voltage.

18. The method of claim 17 further wherein measuring the first voltage of the first sensing element further includes amplifying the first voltage.

19. The method of claim 18 further wherein measuring the first voltage of the first sensing element further includes converting the first voltage from an analog signal level to a digital signal domain.

20. A method of calibrating an offset of a pressure sensor comprising:

measuring a first voltage of a first sensing element located in a thicker bulk region;

measuring a second voltage of a second sensing element located in a in a thinner diaphragm region;

using the first voltage to calibrate an offset of the second sensing element,

measuring a third voltage of a third sensing element located near a boundary between the bulk and the diaphragm; and

using the first voltage and the third voltage to calibrate an offset of the second sensing element,

wherein the first sensing element includes more than four source-drain regions, and

wherein the third sensing element includes more than four source-drain regions.

21. The method of claim 20 wherein the first, second, and third or more sensing elements each include eight source-drain regions.