Method of etching sacrificial layer, method of manufacturing MEMS device, MEMS device and MEMS sensor

• US 20100065930A1
• Filed: 09/17/2009
• Published: 03/18/2010
• Est. Priority Date: 09/18/2008
• Status: Abandoned Application

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakatani, Goro
• Application Number:
  US12/585,552
• Publication Number:
  US 20100065930A1
• Time in Patent Office: Days
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81C 1/00476 removing a sacrificial layer B81C1/00912 takes precedence
• CPC Class Codes: B81C 1/00801 Avoid alteration of functional structures by etching, e.g. using a passivation layer or an etch stop layer B81C1/00595, B81C1/00468 take precedence
• CPC Class Codes: B81C 2201/053 Depositing a protective layers
• CPC Class Codes: H01L 28/40 Capacitors
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182

Abstract

The method of etching a sacrificial layer according to the present invention includes the steps of forming a sacrificial layer having a protrusive shape on a base layer, forming a covering film covering the sacrificial layer, forming a protective film made of a material whose etching selection ratio to the sacrificial layer is greater than the etching selection ratio of the covering film to the sacrificial layer on a portion of the covering film opposed to the side surface of the sacrificial layer, and etching the sacrificial layer after the formation of the protective film.

Claims

1. A method of etching a sacrificial layer, comprising the steps of:

forming a sacrificial layer having a protrusive shape on a base layer;

forming a covering film covering the sacrificial layer;

forming a protective film made of a material whose etching selection ratio to the sacrificial layer is greater than the etching selection ratio of the covering film to the sacrificial layer on a portion of the covering film opposed to the side surface of the sacrificial layer; and

etching the sacrificial layer after the formation of the protective film.

2. The method of etching a sacrificial layer according to claim 1, wherein

the step of forming the protective film includes the steps of depositing the material for the protective film on the overall surface of the covering film and leaving the material on a portion of the covering film opposed to the side surface of the sacrificial layer by etching back the deposited material.

3. A method of manufacturing an MEMS device, comprising the steps of:

forming a sacrificial layer having a protrusive shape on a surface of a substrate;

forming a covering film covering the sacrificial layer;

forming a protective film made of a material whose etching selection ratio to the sacrificial layer is greater than the etching selection ratio of the covering film to the sacrificial layer on a portion of the covering film opposed to the side surface of the sacrificial layer; and

working the covering film into a hollow supporting film supported in a state having a hollow portion between the same and the surface of the substrate by removing the sacrificial layer by etching thereby forming a space between the covering film and the substrate.

4. An MEMS device comprising:

a substrate;

a hollow supporting film, integrally having an opposed portion opposed to a surface of the substrate at an interval, a step portion formed on the surface of the substrate and a side portion connecting the opposed portion and the step portion with each other, supported in a state having a hollow portion between the same and the surface of the substrate; and

a protective film selectively formed on the side portion of the hollow supporting film.

5. An MEMS sensor comprising:

a substrate;

a vibrating film opposed to the substrate at an interval on a side of the substrate and vibratile in the opposed direction; and

a counter electrode, made of a conductive material, opposed to the vibrating film at an interval on a side of the vibrating film opposite to the substrate, wherein

the vibrating film includes a metal electrode and a resin material film covering the metal electrode.

6. The MEMS sensor according to claim 5, wherein

the vibrating film has a main portion on which the metal electrode is arranged and supporting portions extending from a plurality of positions of the peripheral edge of the main portion in directions along the surface of the substrate.

7. The MEMS sensor according to claim 5, wherein

the resin material film is made of a photosensitive organic material.