Pressure sensor and manufacturing method therefor

• US 7,932,117 B2
• Filed: 07/09/2007
• Issued: 04/26/2011
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Yamaha Corporation
• Inventors: Ueya, Yuki
• Primary Examiner(s): Caputo; Lisa M
• Assistant Examiner(s): ROY, PUNAM P
• Application Number:
  US11/825,797
• Publication Number:
  US 20080006093A1
• Time in Patent Office: 1,387 Days
• Field of Search: 737/54, 438/50, 438/53, 438/734, 438/735, 438/749, 438/750
• US Class Current: 438/53
• 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 manufacturing method of a pressure sensor including a plate having a fixed electrode, a diaphragm that has a moving electrode positioned opposite to the fixed electrode and that is subjected to displacement due to pressure variations applied thereto, and a support having at least one cavity for supporting the plate, said manufacturing method comprising:

depositing a thin film forming the plate and a thin film forming the diaphragm on a first surface of a substrate;

forming a first mask having a first opening on a second surface opposite to the first surface of the substrate;

forming a second mask having a second opening on the second surface of the substrate, wherein the second mask covers the first mask so that a prescribed portion of the substrate just above the thin film forming the plate is exposed in the second opening;

forming a recess by performing anisotropic etching on the substrate exposed in the second opening by use of the second mask;

removing the second mask while allowing the first mask to remain; and

performing anisotropic etching using the remaining first mask on the substrate exposed in the first opening such that a bottom of the recess is removed, thus forming a through-hole forming the cavity in the substrate.

2. A manufacturing method of a pressure sensor including a plate having a fixed electrode, a diaphragm that has a moving electrode positioned opposite to the fixed electrode and that is subjected to displacement due to pressure variations applied thereto, and a support having at least one cavity for supporting the pate, said manufacturing method comprising:

depositing a thin film forming the plate and a thin film forming the diaphragm on a first side of a substrate;

forming one mask having a first opening on a second side opposite to the first side of the substrate;

forming a recess by performing a first anisotropic etching on the substrate exposed in the first opening by using the one mask;

forming another mask having a second opening on the second side of the substrate, wherein an area of the second opening differs from an area of the first opening; and

performing a second anisotropic etching on the substrate exposed in the second opening by using the other mask such that a bottom of the recess is removed so as to form a through-hole forming the cavity.

3. The manufacturing method of the pressure sensor according to claim 2, wherein the area of the second opening is larger than the area of the first opening and the one mask is constituted of a plurality of layers, the other mask being formed by removing at least one of the layers constituting the one mask.

4. A manufacturing method of a pressure sensor including a plate having a fixed electrode, a diaphragm that has a moving electrode positioned opposite to the fixed electrode and that is subjected to displacement due to pressure variations applied thereto, and a support having at least one cavity for supporting the plate, said manufacturing method comprising:

depositing a thin film forming the plate and a thin film forming the diaphragm on a first side of a substrate;

forming a first mask having a first opening on a second side opposite to the first side of the substrate;

forming a second mask having a second opening on the second side of the substrate, wherein an area of the second opening is smaller than an area of the first opening;

forming a recess by performing a first anisotropic etching on the substrate exposed in the second opening by using the second mask;

removing the second mask; and

performing a second anisotropic etching on the substrate exposed in the first opening by using the first mask such that a bottom of the recess is removed so as to form a through-hole forming the cavity.

5. The manufacturing method of the pressure sensor according to claim 4, wherein the second mask is formed to cover the first mask.