Method for manufacturing direct bonded SOI wafer and direct bonded SOI wafer manufactured by the method
A direct bonded SOI wafer having an entire buried oxide film layer covered and not exposed is manufactured by: (A) forming a laminated body by laminating a semiconductor wafer and a support wafer via an oxide film; and (B) forming a thin-film single crystal silicon layer on the support wafer using a buried oxide film layer by film-thinning the semiconductor wafer to a predetermined thickness. In a process (C) the entire buried oxide film layer is covered by a main surface on the laminating side of the support wafer and the single crystal silicon layer. The covering of the entire buried film layer is carried out by, between process (A) and (B), removing the oxide film formed on the circumferential end edge of the main surface on the laminating side and the chamfered portion to leave the oxide film only on the laminated surface except the circumferential end edge.
1. A method for manufacturing a direct bonded SOI wafer comprising forming a laminated body having first and second main surfaces by laminating a semiconductor wafer on a laminating side of a support wafer via an oxide film; and forming a thin-film single crystal silicon layer on said support wafer by thinning said semiconductor wafer on the side opposite the laminating side wherein:
before the laminated body is formed by lamination, only the center part of the semiconductor wafer is polished so as to form a circumferential end edge in a convex shape on the laminating side, and then an oxide film which is an insulating film, is formed on the surface of the semiconductor wafer by thermal oxidation, and the oxide film formed on the circumferential end edge is removed and the oxide film is left on the laminating side except for the circumferential end edge thereby forming a buried oxide layer, and the entire buried oxide film layer is covered by a main surface on the laminating side of said support wafer and said single crystal silicon layer.
2. The method for manufacturing the direct bonded SOI wafer of claim 1 , wherein the film-thinning of the semiconductor wafer is carried out by mechanical processing, chemical etching or gas-phase etching of said semiconductor wafer.
3. The method for manufacturing the direct bonded SOI wafer of claim 2 , wherein the film-thinning of the semiconductor wafer is carried out by mechanical processing comprising grinding and polishing the side opposite to the laminating side of said semiconductor wafer after the laminating step.
4. The method for manufacturing the direct bonded SOI wafer of claim 2 , wherein the film-thinning of the semiconductor wafer is carried out by mechanical processing comprising cutting said semiconductor wafer parallel to the main surface after the laminating step.
5. The method for manufacturing the direct bonded SOI wafer of claim 1 , wherein the removal of the oxide film formed on the circumferential end edge is carried out by polishing.
6. The method for manufacturing the direct bonded SOI wafer of claim 1 , wherein the removal of the oxide film formed on the circumferential end edge is carried out by chemical etching.
7. The method for manufacturing the direct bonded SOI wafer of claim 6 , wherein the chemical etching is carried out with an HF solution with the weight ratio of HF:H 2 O within a range of 1:0 to 10.
8. The method for manufacturing the direct bonded SOI wafer of claim 1 , wherein the main surface of the laminating side of the semiconductor wafer, the support wafer or both is laminated after washing with an SC-1 solution under an oxidized atmosphere.
9. The method for manufacturing the direct bonded SOI wafer of claim 1 , wherein the main surface of the laminating side of the semiconductor wafer, the support wafer or both is laminated after washing with a solution containing an organic acid and ozone under an oxidized atmosphere.
10. The method for manufacturing the direct bonded SOI wafer of claim 1 , wherein the main surface of the laminating side of the semiconductor wafer, the support wafer or both is laminated after washing with a diluted HF solution wherein the weight ratio of HF:H 2 O is within a range of 1:50 to 400.
11. A direct bonded SOI wafer manufactured by the method of claim 1 .
12. A direct bonded SOI wafer manufactured by the method of claim 2 .
13. A direct bonded SOI wafer manufactured by the method of claim 3 .
14. A direct bonded SOI wafer manufactured by the method of claim 4 .
15. A direct bonded SOI wafer manufactured by the method of claim 5 .
16. A direct bonded SOI wafer manufactured by the method of claim 6 .
17. A direct bonded SOI wafer manufactured by the method of claim 7 .
18. A direct bonded SOI wafer manufactured by the method of claim 8 .
19. A direct bonded SOI wafer manufactured by the method of claim 9 .
20. A direct bonded SOI wafer manufactured by the method of claim 10 .