Pressure sensor and manufacturing method therefor

• US 20090090190A1
• Filed: 10/02/2008
• Published: 04/09/2009
• Est. Priority Date: 07/10/2006
• Status: Abandoned Application

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Ueya, Yuki
• Application Number:
  US12/286,870
• Publication Number:
  US 20090090190A1
• Time in Patent Office: Days
• US Class Current: 73/724
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence

Abstract

A pressure sensor (e.g., a condenser microphone) includes a plate having a fixed electrode, a diaphragm having a moving electrode positioned opposite to the fixed electrode, and a support, wherein the diaphragm is subjected to displacement due to pressure variations applied thereto, and the support has a first interior wall forming a first cavity, in which the end portions of the plate are fixed, and a second interior wall, in which a step portion is formed in the thickness direction of the diaphragm in relation to the first interior wall and which forms a second cavity whose cross-sectional area is larger than the cross-sectional area of the first cavity in the plane direction of the diaphragm. The first and second cavities can be redesigned to communicate with each other via a passage, whereby it is possible to improve both of low-frequency characteristics and high-frequency characteristics in the pressure sensor.

Claims

1. A pressure sensor comprising:

a plate having a fixed electrode;

a diaphragm having a moving electrode positioned opposite to the fixed electrode, wherein the diaphragm is subjected to displacement due to pressure variations applied thereto; and

a support having an opening, on which end portions of the plate are fixed, and an interior wall, in which a step portion is formed and which forms a cavity whose cross-sectional area is larger than a cross-sectional area of the opening in any plane of the cavity parallel to the plate.

2. The pressure sensor according to claim 1, wherein the cross-sectional area of the cavity in a plane direction parallel to the plate is enlarged in a direction opposite to the plate by way of the step portion, which the interior wall forms in the thickness direction of the diaphragm.

3. A pressure sensor comprising:

a plate having a fixed electrode;

a diaphragm having a moving electrode positioned opposite to the fixed electrode, wherein the diaphragm is subjected to displacement due to pressure variations applied thereto;

a support having an interior wall, which end portions of the plate are fixed to, wherein a first cavity is formed inwardly of the interior wall of the support and the diaphragm; and

a sub-cavity forming portion for forming a second cavity communicating with the first cavity via a passage having an opening communicating the first cavity.

4. The pressure sensor according to claim 3, wherein the sub-cavity forming portion is arranged in the support, and wherein the passage and the second cavity are formed inwardly of a recess of the support.

5. The pressure sensor according to claim 3, wherein the sub-cavity forming portion forms a plurality of second cavities and a plurality of passages having different resistances, via which the first cavity communicates with the second cavities.

6. The pressure sensor according to claim 4, wherein the sub-cavity forming portion forms a plurality of second cavities and a plurality of passages having different resistances, via which the first cavity communicates with the second cavities.

7. The pressure sensor according to claim 5, wherein the plurality of second cavities have different volumes.

8. The pressure sensor according to claim 6, wherein the plurality of second cavities have different volumes.

9. A pressure sensor comprising:

a substrate having a first surface and a second surface, which are positioned opposite to each other;

a plate having a fixed electrode, which is constituted of a thin film formed on the first surface of the substrate;

a diaphragm having a moving electrode positioned opposite to the fixed electrode, wherein the diaphragm is constituted of a thin film formed on the first surface of the substrate and is subjected to displacement due to pressure variations applied thereto;

a support constituted of a thin film, which is composed of a material that can be selectively removed from the substrate by way of wet etching and which is formed on the first surface of the substrate, wherein the support supports the plate such that a gap is formed between the fixed electrode and the moving electrode;

a through-hole that is formed to run through the substrate in its thickness direction so as to expose the diaphragm, wherein the through-hole has a first opening, which is formed on the first surface of the substrate in conformity with a two-dimensional shape of the diaphragm, and a second opening whose shape is substantially identical to a shape of the first opening and which is formed on the second surface of the substrate; and

a recess, which is formed on the second surface of the substrate and which forms a third opening communicating with the second opening in its periphery.

10. A pressure sensor comprising:

a substrate having a first surface and a second surface, which are positioned opposite to each other;

a plate having a fixed electrode, which is constituted of a thin film formed on the first surface of the substrate;

a diaphragm having a moving electrode positioned opposite to the fixed electrode, wherein the diaphragm is constituted of a thin film formed on the first surface of the substrate and is subjected to displacement due to pressure variations applied thereto;

a support constituted of a thin film, which is composed of a material that can be selectively removed from the substrate by way of wet etching and which is formed on the first surface of the substrate, wherein the support supports the plate such that a gap is formed between the fixed electrode and the moving electrode;

a first through-hole that is formed to run through the substrate in its thickness direction so as to expose the diaphragm, wherein the first through-hole has a first opening, which is formed on the first surface of the substrate in conformity with a two-dimensional shape of the diaphragm, and a second opening whose shape is substantially identical to a shape of the first opening and which is formed on the second surface of the substrate; and

a second through-hole that is formed to run through the substrate in its thickness direction, wherein the second through-hole forms a third opening communicating with the first opening in its periphery on the first surface of the substrate and a fourth opening whose shape is substantially identical to a shape of the third opening on the second surface of the substrate.