Integrated differential pressure sensor

• US 8,008,738 B2
• Filed: 06/29/2010
• Issued: 08/30/2011
• Est. Priority Date: 05/06/2005
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Corona, Pietro, Barlocchi, Gabriele, Villa, Flavio Francesco, Baldo, Lorenzo
• Primary Examiner(s): Nguyen; Ha Tran T
• Assistant Examiner(s): WHITE, SHAKA SHAKAR
• Application Number:
  US12/826,388
• Publication Number:
  US 20100269595A1
• Time in Patent Office: 427 Days
• Field of Search: 438/50, 438/53, 438/509
• US Class Current: 257/415
• CPC Class Codes: G01L 13/025 using diaphragms
• CPC Class Codes: G01L 9/0045 Diaphragm associated with a buried cavity

Abstract

An integrated differential pressure sensor includes, in a monolithic body of semiconductor material, a first face and a second face, a cavity extending at a distance from the first face and delimited therewith by a flexible membrane formed in part by epitaxial material from the monolithic body and in part by annealed epitaxial material from the monolithic body, an access passage in fluid communication with the cavity, and in the flexible membrane at least one transduction element configured so as to convert a deformation of the flexible membrane into electrical signals. The cavity is formed in a position set at a distance from the second face and is delimited at the second face with a portion of the monolithic body.

Claims

1. An integrated differential pressure sensor, comprising:

a monolithic body of semiconductor material having a first face and a second face;

a cavity buried within the monolithic body and extending in the monolithic body a distance from the first face and delimited at the first face by a flexible membrane integral with the monolithic body and including epitaxial material from the monolithic body and annealed epitaxial silicon from the monolithic body, the cavity delimited at the second face by a portion of the monolithic body;

an access passage in fluid communication with the cavity, the access passage having an access trench extending through the monolithic body and not the flexible membrane; and

at least one transduction element formed on the flexible membrane and configured so as to convert a deformation of the flexible membrane into electrical signals.

2. The sensor of claim 1, wherein the access trench extends between the second face and the cavity.

3. The sensor of claim 1, wherein the access passage further comprises a buried connection channel, formed within the monolithic body, laterally with respect to, and in fluid communication with, the cavity.

4. The sensor of claim 3, wherein the access trench extends between the second face and the connection channel.

5. The sensor of claim 3, wherein the access trench extends between the first face and the connection channel.

6. The sensor of claim 1, wherein the at least one transduction element is one of either a piezoresistive element or a capacitive element.

7. A pressure sensor system comprising:

an integrated differential pressure sensor, the integrated differential pressure sensor including

a monolithic body of semiconductor material having a first face and a second face,

a cavity buried within the monolithic body and extending into the monolithic body a distance from the first face and delimited at the first face by a flexible membrane integrally formed with the monolithic body having a first part substantially identical in crystalline structure to epitaxial material from the monolithic body and having a second part substantially identical in crystalline structure to annealed epitaxial material from the monolithic body, the cavity delimited at the second face by a portion of the monolithic body,

an access passage in fluid communication with the cavity, the access passage having

a buried connection channel formed within the monolithic body laterally with respect to, and in fluid communication with, the cavity, and

an access trench extending through the monolithic body between the first face and the connection channel and not through the flexible membrane, and

at least one transduction element formed in the flexible membrane and configured so as to convert a deformation of the flexible membrane into electrical signals; and

a package that houses the monolithic body, the package including a first portion and a second portion mechanically coupled and defining an internal space facing the flexible membrane, the internal space in fluid communication with a first opening in the package and insulated from fluid communication with the access trench via a fluid-tight seal.

8. The pressure sensor system of claim 7, wherein the fluid-tight seal comprises a seal ring made of elastomeric material arranged between the package and the monolithic body.

9. The pressure sensor system of claim 7, wherein the package comprises a second opening in fluid communication with the access trench.

10. The pressure sensor system of claim 7, wherein the at least one transduction element comprises one of either a piezoresistive element or a capacitive element.

11. A device, comprising:

an integrated differential pressure sensor that comprises;

a monolithic body of semiconductor material having a first face and a second face;

a cavity buried within the monolithic body and delimited at the first face by a flexible membrane having epitaxial silicon atoms from the body and annealed epitaxial silicon from the monolithic body, the cavity delimited at the second face by a portion of the monolithic body, the cavity further delimited by oxidized internal walls;

an access passage formed through the monolithic body and not the flexible membrane and in fluid communication with the cavity; and

at least one transduction element formed in a surface portion of the flexible membrane and configured to convert a deformation of the flexible membrane into electrical signals.

12. The sensor according to claim 11, wherein the access passage comprises an access trench extending between the second face and the cavity.

13. The sensor according to claim 11, wherein the access passage comprises an access trench extending between the first face and the cavity.

14. The sensor according to claim 11, wherein the access passage comprises a buried connection channel formed within the monolithic body, the buried connection channel being in fluid communication with the cavity.

15. The sensor according to claim 14, wherein the access passage further comprises an access trench extending between the second face and the buried connection channel.

16. The sensor according to claim 14, wherein the access passage further comprises an access trench extending between the first face and the buried connection channel.