SOI wafer, manufacturing method therefor, and MEMS device
View Patent ↗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 ( 1 b ) 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.
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.