Pressure sensor with support structure for non-silicon diaphragm

• US 9,804,046 B2
• Filed: 10/27/2015
• Issued: 10/31/2017
• Est. Priority Date: 10/27/2015
• Status: Active Grant

• Current Assignee: Zhejiang Dun'An Artificial Environmental Company Limited
• Original Assignee: Dunan Sensing, LLC
• Inventors: Kwa, Tom
• Primary Examiner(s): ALLEN, ANDRE J
• Application Number:
  US14/924,631
• Publication Number:
  US 20170115175A1
• Time in Patent Office: 735 Days
• Field of Search: None
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: B81C 1/00523 Etching material
• CPC Class Codes: B81C 1/00626 Processes for achieving a desired geometry not provided for in groups B81C1/00563 - B81C1/00619
• CPC Class Codes: B81C 1/00785 Avoid chemical alteration, e.g. contamination, oxidation or unwanted etching B81C1/00563 - B81C1/00595 take precedence
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0052 of piezoresistive elements circuits therefor G01L9/06
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: H01L 21/823828 with a particular manufacturing method of the gate conductors, e.g. particular materials, shapes
• CPC Class Codes: H01L 21/823864 with a particular manufacturing method of the gate sidewall spacers, e.g. double spacers, particular spacer material or shape
• CPC Class Codes: H10N 30/03 Assembling devices that include piezoelectric or electrostrictive parts
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/88 Mounts; Supports; Enclosures; Casings
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

A pressure sensor and methods of making a pressure sensor are described. In preferred embodiments, the pressure sensor is designed for low-pressure and high-sensitivity applications. In some embodiments, the pressure sensor comprises: a frame made from a single-crystal silicon starting material, the frame surrounding a cavity; a diaphragm that covers the cavity, the diaphragm constructed from a separate layer of material deposited on the single-crystal silicon starting material; a support structure that spans the diaphragm wherein the support structure is formed from the single-crystal starting material; and, a piezoresistor formed across an intersection of the frame and the support structure.

Claims

1. A pressure sensor comprising:

a frame made from a single-crystal silicon starting material, the frame surrounding a cavity;

a diaphragm that covers the cavity, the diaphragm constructed from a separate layer of material deposited on the single-crystal silicon starting material;

a support structure that spans the diaphragm wherein the support structure is formed from the single-crystal starting material; and

,

a piezoresistor formed across an intersection of the frame and the support structure.

2. The pressure sensor of claim 1, wherein the separate layer of material is a dielectric material.

3. The pressure sensor of claim 2, wherein the separate layer of material is silicon nitride.

4. The pressure sensor of claim 1, wherein the piezoresistor is formed in the single-crystal silicon material.

5. The pressure sensor of claim 4, wherein the piezoresistor is formed by implanting a P+ material and a P−

material in the single-crystal silicon material, which is N-type.

6. The pressure sensor of claim 4, wherein the piezoresistor is formed by implanting a P+ material in the single-crystal silicon material, which is N-type.

7. The pressure sensor of claim 1, wherein the single-crystal starting material is part of a silicon-on-insulator (SOI) wafer.

8. The pressure sensor of claim 7, wherein the cavity is formed in the silicon on a first side of the insulator and the support structure is formed in the silicon on a second opposite side of the insulator.

9. The pressure sensor of claim 1, wherein the support structure is comprised of two spans that span the diaphragm in perpendicular directions to each other.

10. The pressure sensor of claim 1, wherein the support structure includes at least one window.

11. The pressure sensor of claim 1, wherein the diaphragm is smaller than the cavity.

12. The pressure sensor of claim 1, wherein the support structure comprises two spans in one direction and a third span in a second direction perpendicular to the first two spans.

13. The pressure sensor of claim 10, wherein the support structure comprises a plurality of windows and one of the windows is over the center of the diaphragm.

14. The pressure sensor of claim 9, further comprising a piezoresistor formed at each intersection of the spans and the frame.

15. The pressure sensor of claim 1, wherein the diaphragm is coated with a corrosion resistant coating.

24. The pressure sensor of claim 10, wherein the support structure includes a plurality of windows with at least one window positioned over the center of the diaphragm.

16. A pressure sensor formed from a silicon-on-silicon (SOI) wafer comprising:

a cavity formed in the silicon on a first side of the insulator and extending all the way to the insulator;

a diaphragm formed within the cavity, the diaphragm formed from a separate layer of material deposited on the first side of the SOI wafer;

a support structure formed from the silicon on a second opposite side of the insulator from the first side wherein the support structure spans the diaphragm and is formed by removing silicon on the second opposite side of the SOI wafer above the cavity and leaving the support structure; and

,

a piezoresistor formed across an intersection of the support structure and the SOI wafer at an outside edge of the diaphragm.

17. The pressure sensor of claim 16, wherein the separate layer of material is silicon nitride.

18. The pressure sensor of claim 16, wherein the support structure is formed from the silicon on the second opposite side of the SOI wafer.

19. The pressure sensor of claim 16, wherein the piezoresistor is formed by implanting a P+ material and a P−

material in the single-crystal silicon material, which is N-type.

20. The pressure sensor of claim 16, wherein the piezoresistor is formed by implanting a P+ material in the single-crystal silicon material, which is N-type.

21. The pressure sensor of claim 16, wherein the support structure comprises two spans that span the diaphragm in perpendicular directions to each other.

22. The pressure sensor of claim 16, wherein the support structure includes at least one window.

23. The pressure sensor of claim 22, wherein the support structure includes a plurality of windows with at least one window positioned over the center of the diaphragm.