PRESSURE SENSOR AND METHOD FOR MANUFACTURING THE PRESSURE SENSOR

• US 20110221014A1
• Filed: 03/10/2011
• Published: 09/15/2011
• Est. Priority Date: 03/11/2010
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: NAKATANI, Goro
• Granted Patent: US 8,359,928 B2
• Time in Patent Office: Days
• US Class Current: 257/417
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• 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 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture

Abstract

A pressure sensor of the present invention includes a substrate inside which a reference pressure chamber is formed, a closing body filled in a through-hole formed in the substrate such that the closing body penetrates through a portion between the surface of the substrate and the reference pressure chamber, and hermetically closes the reference pressure chamber, and a strain gauge provided inside the substrate between the surface of the substrate and the reference pressure chamber, and the electric resistance thereof being capable of changing by strain deformation of the substrate.

Claims

1. A pressure sensor comprising:

a substrate inside which a reference pressure chamber is formed;

a closing body filled in a through-hole formed in the substrate such that the closing body penetrates through a portion between the surface of the substrate and the reference pressure chamber, and hermetically closes the reference pressure chamber; and

a strain gauge provided inside the substrate between the surface of the substrate and the reference pressure chamber, and the electric resistance thereof being capable of changing by strain deformation of the substrate.

2. The pressure sensor according to claim 1, wherein the substrate is made of silicon.

3. The pressure sensor according to claim 2, wherein the strain gauge includes piezoresistances formed by selectively doping the surface layer portion of the substrate with an impurity.

4. The pressure sensor according to claim 1, wherein the inside of the reference pressure chamber is in a vacuum.

5. The pressure sensor according to claim 1, wherein the closing body is made of aluminum.

6. The pressure sensor according to claim 1, wherein the through-hole has a diameter of 0.2 μ

m to 0.5 μ

m.

7. The pressure sensor according to claim 1, wherein a protective film is interposed between a side surface of the through-hole and the closing body.

8. The pressure sensor according to claim 7, wherein the protective film is made of silicon oxide.

9. The pressure sensor according to claim 1, wherein a plurality of through-holes are formed.

10. The pressure sensor according to claim 9, wherein the plurality of through-holes are formed to have circular shapes with the same size in a plan view, and arranged so as to be distributed uniformly in a plan view.

11. The pressure sensor according to claim 1, wherein the area of the reference pressure chamber is larger than the total area of the regions occupied by the through-holes.

12. A method for manufacturing a pressure sensor comprising:

a step of forming piezoresistances by selectively doping an impurity into the surface layer portion of a substrate made of silicon;

a step of forming a plurality of recesses dug into portions in the middle of the thickness direction from the surface of the substrate in predetermined regions including the regions having the piezoresistances;

a step of forming a protective film made of silicon oxide on inner surfaces of the plurality of recesses;

a step of selectively removing the protective film from the bottom surfaces of the plurality of recesses;

a step of forming a reference pressure chamber by digging the plurality of recesses by anisotropic etching and linking lower portions of the plurality of recesses to each other by isotropic etching; and

a step of hermetically closing the reference pressure chamber by embedding closing bodies between the surface of the substrate and the reference pressure chamber in the plurality of recesses.

13. The method for manufacturing a pressure sensor according to claim 12, wherein embedding of the closing bodies is performed in a vacuum.

14. The method for manufacturing a pressure sensor according to claim 12, wherein the closing bodies are formed by coating aluminum on the inner surfaces of the recesses by the sputtering method and performing reflow.

15. The method for manufacturing a pressure sensor according to claim 12, wherein the closing body is formed by filling aluminum in the inner surfaces of the recesses by the CVD method.

16. A semiconductor device comprising:

a semiconductor substrate inside which a space is formed; and

a trough-hole penetrating between a surface the semiconductor substrate and the space;

wherein

the space is larger than the trough-hole.

17. The semiconductor device according to claim 16 further comprising:

a closing body filled in the through-hole and hermetically closes the space.

18. The semiconductor device according to claim 16, wherein a plurality of through-holes are formed, and the space is formed such that the space links lower ends of the plurality of through-holes.

19. The semiconductor device according to claim 16 further comprising:

a strain gauge provided inside the semiconductor substrate between the surface of the semiconductor substrate and the space, and the electric resistance thereof being capable of changing by strain deformation of the semiconductor substrate.

20. The semiconductor device according to claim 19, wherein the strain gauge includes piezoresistances formed by selectively doping the surface layer portion of the semiconductor substrate with an impurity.

21. The semiconductor device according to claim 17, wherein the closing body is made of aluminum.