SOI wafer, manufacturing method therefor, and MEMS device

• US 9,212,049 B2
• Filed: 01/17/2013
• Issued: 12/15/2015
• Est. Priority Date: 04/24/2012
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Yoshikawa, Eiji, Yoshida, Yukihisa, Ichikawa, Jyunichi
• Primary Examiner(s): Sandvik, Benjamin
• Assistant Examiner(s): ASSOUMAN, HERVE-LOUIS Y
• Application Number:
  US13/743,878
• Publication Number:
  US 20130277675A1
• Time in Patent Office: 1,062 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: H01L 21/76259 with separation/delamination along a porous layer
• CPC Class Codes: H01L 23/26 including materials for absorbing or reacting with moisture or other undesired substances , e.g. getters
• CPC Class Codes: H01L 29/16 including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

In order to obtain a SOI wafer having an excellent ability of gettering metal impurities, an efficient method of manufacturing a SOI wafer, and a highly reliable MEMS device using such a SOI wafer, provided is a SOI wafer including: a support wafer (1) and an active layer wafer (6) which are bonded together with an oxide film (3) therebetween, each of the support wafer (1) and the active layer wafer (6) being a silicon wafer; a cavity (1b) formed in a bonding surface of at least one of the silicon wafers; and a gettering material (2) formed on a surface on a side opposite to the bonding surface.

Claims

1. A method of manufacturing a SOI wafer including a support wafer grown as a single piece and an active layer wafer which are bonded together with an oxide film therebetween, each of the support wafer and the active layer wafer being a silicon wafer, the method comprising:

forming a cavity in a first surface of the support wafer, the first surface being a bonding surface of the SOI wafer;

forming a gettering material on a surface of the support wafer on a side opposite to the first surface;

carrying out thermal oxidation of one of the support wafer and the active layer wafer;

bonding together the first surface of the support wafer and the active layer wafer; and

carrying out bonding reinforcing heat treatment with respect to the support wafer and the active layer wafer which are bonded together;

wherein the oxide film is continuous across the first surface.

2. A method of manufacturing a SOI wafer according to claim 1, further comprising removing the gettering material formed on the one of the support wafer and the active layer wafer.

3. A method of manufacturing a SOI wafer according to claim 1, wherein:

the forming a gettering material comprises forming the gettering material on a surface of the support wafer on the side opposite to the first surface; and

the carrying out thermal oxidation comprises carrying out thermal oxidation of the support wafer.

4. A method of manufacturing a SOI wafer according to claim 1, wherein:

the forming a gettering material comprises forming the gettering material on a surface of the active layer wafer on the side opposite to the first surface; and

the carrying out thermal oxidation comprises carrying out thermal oxidation of the support wafer.

5. A method of manufacturing a SOI wafer according to claim 1, wherein:

the forming a gettering material comprises forming the gettering material on a surface of the support wafer on the side opposite to the first surface; and

the carrying out thermal oxidation comprises carrying out thermal oxidation of the active layer wafer.

6. A method of manufacturing a SOI wafer according to claim 1, wherein the gettering material comprises a crushed layer.

7. A method of manufacturing a SOI wafer according to claim 6, wherein the crushed layer is formed by back grinding.

8. A method of manufacturing a SOI wafer according to claim 6, wherein the crushed layer is formed by sandblasting.

9. A method of manufacturing a SOI wafer according to claim 6, wherein the crushed layer is formed by laser application.

10. A method of manufacturing a SOI wafer according to claim 1, wherein the gettering material comprises a polysilicon thin film.

11. A method of manufacturing a MEMS device comprising:

manufacturing the SOI wafer according to the method of claim 1;

forming a diaphragm by grinding a silicon wafer on a side opposed to the cavity; and

forming a distortion detecting unit on the diaphragm.

12. A MEMS device according to claim 11, including forming the distortion detecting unit with a piezoelectric resistance.