Semiconductor capacitive acceleration sensor

• US 5,665,915 A
• Filed: 07/27/1994
• Issued: 09/09/1997
• Est. Priority Date: 03/25/1992
• Status: Expired due to Term

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Ueyanagi, Katsumichi, Kobayashi, Mitsuo
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Kwok, Helen C.
• Application Number:
  US08/281,100
• Time in Patent Office: 1,140 Days
• Field of Search: 73/517 R, 73/517 AV, 73/510, 73/514, 73/514.32, 73/514.18
• US Class Current: 73/514.32
• CPC Class Codes: G01P 1/006 used for thermal compensation
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

A semiconductor capacitive acceleration sensor is configured so that it can be constructed in a small size, it has a high detection sensitivity, and the detection output characteristic is linear. The sensor comprises a semiconductor substrate 1; supporters 21A to 21D each of which is made of a conductive semiconductor, and which are disposed on the upper face of the semiconductor substrate 1 through an insulating layer 1A so as to be placed at positions corresponding to corners of a quadrilateral; beams 26A to 26D which respectively have ends connected with the supporters, which coincide with each other when the beams are rotated, and which elongate in the side directions of the quadrilateral; a movable electrode 23 which has a quadrilateral shape, and which is disposed so as to be separated from the beams by a predetermined distance; connectors 27A to 27D which respectively connect the movable electrode 23 with the beams; and a stationary electrode 31 which is disposed so as to be separated from the lower face of the movable electrode 23 by a predetermined distance.

Claims

1. A semiconductor capacitive acceleration sensor comprising:

a semiconductor substrate;

a plurality of supporters made of a conductive semiconductor and disposed on an upper face of said semiconductor substrate through an insulating layer, said supporters being placed at positions which correspond to corners of a regular polygon, respectively;

beams respectively connected with said supporters at one end, each of said beams extending along a side of the regular polygon from the one end to an opposite end, said beams being rotationally symmetrical about the center of the regular polygon;

a movable electrode located within the regular polygon and spaced from said beams;

connecting means for connecting said movable electrode with the opposite ends of said beams, respectively; and

a stationary electrode disposed on said upper face of said semiconductor substrate through said insulating layer, said stationary electrode being separated from a lower face of said movable electrode by a predetermined distance.

2. A semiconductor capacitive acceleration sensor as claimed in claim 1, wherein a metal film is attached to said movable electrode.

3. A semiconductor capacitive acceleration sensor as claimed in claim 1, further comprising:

a first terminal electrically connected with said movable electrode through at least one of said connecting means, said beams and said supporters respectively, being connected to each other, and

a second terminal electrically connected with said stationary electrode.

10. A semiconductor capacitive acceleration sensor as claimed in claim 1, wherein the movable electrode has substantially the shape as the regular polygon.

4. A semiconductor capacitive acceleration sensor comprising:

a semiconductor substrate;

a plurality of first supporters made of a conductive semiconductor and disposed on an upper face of said semiconductor substrate through an insulating layer, said first supporters being placed at positions which correspond to corners of a regular polygon, respectively;

beams respectively connected with said first supporters at one end, each of the beams extending along a side of the regular polygon from the one end to an opposite end, said beams being rotationally symmetrical about the center of the regular polygon;

a movable electrode located within the regular polygon and spaced from said beams;

connecting means for connecting said movable electrode with the opposite ends of said beams, respectively;

a first stationary electrode disposed on said upper face of said semiconductor substrate through said insulating layer, said first stationary electrode being separated from a lower face of said .movable electrode by a predetermined distance;

a plurality of second supporters disposed on said upper face of said semiconductor substrate through said insulating layer, each of said second supporters being located between the movable electrode and a corresponding one of said beams; and

a second stationary electrode connected at a periphery with said second supporters, and separated from an upper face of said movable electrode by a predetermined distance.

5. A semiconductor capacitive acceleration sensor as claimed in claim 4, wherein a metal film is attached to said movable electrode.

6. A semiconductor capacitive acceleration sensor as claimed in claim 4, further comprising:

a first terminal electrically connected with said movable electrode through at least one of said connecting means, said beams and said first supporters respectively being connected to each other;

a second terminal electrically connected with said first stationary electrode; and

a third terminal drawn out from said second stationary electrode through said second supporters.

7. A semiconductor capacitive acceleration sensor as claimed in claim 6, wherein values of electrostatic capacities between said first and second terminals, and between said first and third terminals are obtained, said values being subjected to a signal processing by a differential amplifier.

8. A semiconductor capacitive acceleration sensor as claimed in claim 4, wherein said first and second stationary electrodes occupy areas substantially equal to each other.

9. A semiconductor capacitive acceleration sensor as claimed in claim 8, wherein the areas of said first and second stationary electrodes are substantially equal to an area occupied by said movable electrode.

11. A semiconductor capacitive acceleration sensor as claimed in claim 4, wherein the movable electrode has substantially the shape as the regular polygon.