SEMICONDUCTOR PRESSURE SENSOR

• US 20100164028A1
• Filed: 03/11/2010
• Published: 07/01/2010
• Est. Priority Date: 09/25/2007
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Adachi, Takuya, Fukuda, Tetsuya, Okawa, Hisanobu, Kikuiri, Katsuya, Minagawa, Takayuki
• Granted Patent: US 8,552,513 B2
• Time in Patent Office: Days
• US Class Current: 257/419
• 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: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

A semiconductor pressure sensor includes a cavity disposed in one silicon substrate of a SOI substrate having two silicon substrates bonded to each other with an oxide film therebetween and a diaphragm formed from the other silicon substrate and the oxide film, wherein the oxide film, bordering the cavity, of the diaphragm includes an arc-shaped section at the boundary portion to the one silicon substrate defining the inner wall side surface of the cavity, the arc-shaped section having the same diameter as the diameter of the cavity in the one silicon substrate and reducing the cavity diameter from the boundary portion toward the diaphragm center.

Claims

1. A semiconductor pressure sensor comprising:

a cavity disposed in one silicon substrate of a SOI substrate having two silicon substrates bonded to each other with an oxide film therebetween; and

a diaphragm formed from the other silicon substrate and the oxide film,

wherein the oxide film, bordering the cavity, of the diaphragm includes an arc-shaped section at the boundary portion to the one silicon substrate defining the inner wall side surface of the cavity, the arc-shaped section having the same diameter as the diameter of the cavity in the one silicon substrate and reducing the cavity diameter from the boundary portion toward the diaphragm center, and

an arc-shaped section of the one silicon substrate and the arc-shaped section of the oxide film of the diaphragm are disposed continuously at the boundary portion.

2. The semiconductor pressure sensor according to claim 1, wherein the oxide film, bordering the cavity, of the diaphragm has a thickness reducing from the boundary portion toward the central portion of the diaphragm and has a region with a small thickness.

3. The semiconductor pressure sensor according to claim 1, wherein the cavity is rectangular in the plan view.

4. The semiconductor pressure sensor according to claim 1, wherein the arc-shaped section is disposed all around the boundary portion of the cavity.

5. The semiconductor pressure sensor according to claim 1, wherein on the diaphragm portion of the SOI substrate, sensitive resistance elements are disposed along the outline of the diaphragm in such a way as to constitute a bridge circuit.

6. The semiconductor pressure sensor according to claim 1, wherein the inner wall side surface of the cavity is disposed almost perpendicularly to the diaphragm.

7. The semiconductor pressure sensor according to claim 1, wherein the sensitive resistance element is a piezo-resistance element having a resistance value changing in accordance with distortion of the diaphragm.

8. A semiconductor pressure sensor comprising:

a cavity disposed through digging in one silicon substrate of a SOI substrate having two silicon substrates bonded to each other with an oxide film therebetween; and

a diaphragm formed from the other silicon substrate and the oxide film,

wherein periodic unevenness is disposed, in the digging direction, on an inner wall surface of the cavity in the one silicon substrate,

the oxide film, bordering the cavity, of the diaphragm includes an arc-shaped section at the boundary portion to the one silicon substrate defining the inner wall side surface of the cavity, the arc-shaped section having the same diameter as the diameter of the cavity in the one silicon substrate and reducing the cavity diameter from the boundary portion toward the diaphragm center, and

the arc-shaped section is disposed continuously from the uneven section of the one silicon substrate.

9. The semiconductor pressure sensor according to claim 8, wherein the oxide film, bordering the cavity, of the diaphragm has a thickness reducing from the boundary portion toward the central portion of the diaphragm and has a region with a small thickness.

10. The semiconductor pressure sensor according to claim 8, wherein the cavity is rectangular in the plan view.

11. The semiconductor pressure sensor according to claim 8, wherein the arc-shaped section is disposed all around the boundary portion of the cavity.

12. The semiconductor pressure sensor according to claim 8, wherein on the diaphragm portion of the SOI substrate, sensitive resistance elements are disposed along the outline of the diaphragm in such a way as to constitute a bridge circuit.

13. The semiconductor pressure sensor according to claim 8, wherein the inner wall side surface of the cavity is disposed almost perpendicularly to the diaphragm.

14. The semiconductor pressure sensor according to claim 8, wherein the sensitive resistance element is a piezo-resistance element having a resistance value changing in accordance with distortion of the diaphragm.