Capacitive pressure sensor with vertical electrical feedthroughs and method to make the same

• US 8,490,495 B2
• Filed: 05/05/2010
• Issued: 07/23/2013
• Est. Priority Date: 05/05/2010
• Status: Expired due to Fees

• Current Assignee: Consensic, Inc.
• Original Assignee: Consensic, Inc.
• Inventors: Lee, Steven
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US12/774,488
• Publication Number:
  US 20110271764A1
• Time in Patent Office: 1,175 Days
• Field of Search: 73715-721
• US Class Current: 73/718
• 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 9/0073 using a semiconductive diaphragm

Abstract

A sensing device capable of detecting pressure using micro-electro-mechanical system (“MEMS”) capacitive pressure sensor with vertical electric feed-through is disclosed. The sensing device includes a first sensing element, a second sensing element, and a sensing circuit. In one embodiment, the first sensing element is disposed over a semiconductor die and is configured to generate a first sensing signal upon detecting pressure. The second sensing element is also disposed over the semiconductor die adjacent to the first sensing element, and is configured to generate a second sensing signal upon sensing ambient conditions. The sensing circuit is capable of generating a pressure sensing signal in response to the first sensing signal and the second sensing signal.

Claims

1. A sensing device, comprising:

a first sensing element disposed over a semiconductor die and configured to generate a first sensing signal upon detecting pressure;

a second sensing element disposed over the semiconductor die adjacent to the first sensing element, and configured to generate a second sensing signal upon sensing ambient conditions; and

a sensing circuit coupled to the second sensing element and capable of generating a pressure sensing signal in response to the first sensing signal and the second sensing signal;

wherein the first sensing element includes a pressure diaphragm formed with flexible material able to deflect under pressure and functioned as a first capacitor electrode, a gap situated adjacent to the pressure diaphragm able to alter its physical shape in response to the pressure, a silicon pillar disposed on one side of the gap opposite from the pressure diaphragm, and a second capacitor electrode formed by directly doping in bottom doped sidewall of the silicon pillar adjacent to the gap via a doping process.

2. The sensing device of claim 1, further comprising a third sensing element disposed over the semiconductor die adjacent to the first sensing element, and configured to generate a third sensing signal indicating an absolute condition.

3. The sensing device of claim 2,

wherein a first sensing element is pressure sensor capable of sensing pressure;

wherein a second sensing element is a static sensor capable of sensing ambient conditions; and

wherein a third sensing element is an absolute sensor capable of sensing absolute conditions.

4. The sensor device of claim 1, wherein the first sensing element includes a pressure diaphragm formed with flexible material capable of deflecting under pressure.

5. The sensor device of claim 4, wherein the first sensing element includes a gap situated under the pressure diaphragm capable of altering its physical shape in response to deflection of the pressure diaphragm.

6. The sensor device of claim 5, wherein the first sensing element includes a first electric feed-through formed on a sidewall of a silicon pillar situated between the gap and an electrical contact for conducting electrical signals.

7. The sensing device of claim 1, wherein a first sensing element disposed over a semiconductor die and configured to generate a first sensing signal upon detecting pressure is a micro-electro-mechanical system (“

MEM”

) capacitive pressure sensor capable of measuring one of a gas pressure, a liquid pressure, a fluid pressure, and a chemical property change.

8. The sensing device of claim 7, wherein the sensing circuit adjusts measurements generated by the MEM capacitive pressure sensor in accordance with surrounding conditions provided by the second sensing element.

9. A pressure sensor, comprising:

a pressure diaphragm formed with flexible material capable of deflecting under pressure, wherein the pressure diaphragm is a first capacitor electrode;

a gap situated under the pressure diaphragm capable of altering its physical shape in response to deflection of the pressure diaphragm;

a silicon pillar disposed on one side of the gap opposite from the pressure diaphragm;

a second capacitor electrode formed by directly doping in bottom doped sidewall of the silicon pillar adjacent to the gap via a doping process; and

an electric feed-through formed on a vertical sidewall of the silicon pillar and configured to couple the second capacitor electrode to an electrical contact for conducting electrical signals.

10. The pressure sensor of claim 9, wherein the pressure diaphragm is a deflecting electrode able to conduct electrical signal.

11. The pressure sensor of claim 10, wherein the pressure diaphragm includes a first surface and a second surface, wherein the first surface exposes to a pressure port, wherein the second surface is adjacent to the gap.

12. The pressure sensor of claim 11, wherein the gap includes a first side and a second side, wherein the first side of the gap is adjacent to the second surface of the pressure diaphragm, and wherein the second side of the gap is adjacent to a first side of the silicon pillar.

13. The pressure sensor of claim 12, wherein the first side of the silicon pillar is electrically conductive via doping process, wherein the first side of the silicon pillar is a second electrode of the pressure sensor.

14. The pressure sensor of claim 10, wherein the electric feed-through is formed on a second side of the silicon pillar via doping process, wherein the electric feed-through is configured to transport capacitive charge from the deflecting electrode across the gap to the second electrode to reach an output terminal.

15. The pressure sensor of claim 10, further comprising a dielectric wall between one or more sidewalls for insulation and structure support.

16. A method of pressure sensing, comprising:

generating a first sensing signal from a micro-electro-mechanical system (“

MEMS”

) capacitive pressure sensor via deformation of an internal gap;

generating a second sensing signal from a static reference sensor capable of detecting ambient conditions;

obtaining the first sensing signal and the second sensing signal via a vertical electric feed-through formed on sidewall of a silicon pillar; and

identifying a pressure read in accordance with the first sensing signal and the second sensing signal;

wherein the MEMS capacitive pressure sensor includes a pressure diaphragm functioned as a first capacitor electrode, a gap situated adjacent to the pressure diaphragm able to alter its physical shape in response to the pressure, and a second capacitor electrode formed by directly doping in bottom doped sidewall of a silicon pillar adjacent to the gap via a doping process.

17. The method of claim 16, further comprising obtaining a third sensing signal from an absolute reference sensor and calibrating the MEMS capacitive pressure sensor with the third sensing signal.

18. The method of claim 17, wherein generating a first sensing signal from a MEMS capacitive pressure sensor includes sensing deflection of a deflecting electrode of the MEMS capacitive pressure sensor.

19. The method of claim 18, wherein obtaining the first sensing signal and the second sensing signal via a vertical electric feed-through formed on sidewall of a silicon pillar includes receiving electrical signals traveling from two electrodes to an output terminal via the sidewall.

20. The method of claim 19, wherein adjusting the first sensing signal in accordance with the second sensing signal for identifying pressure includes subtracting the second sensing signal from the first sensing signal.