| 摘要 |
PURPOSE:To eliminate the partial injection of an impurity having gettering action while removing the remaining of a film, and to clean the surface of a base body by each diffusing the impurity to the first and second main surfaces of the base body, forming a protective layer on the second main surface and polishing the first main surface side until an impurity diffusion layer is removed. CONSTITUTION:With a silicon wafer 11, a wafer such as a lapped and chemical etching-finished wafer is used, phosphorus is diffused to both surface and back main surfaces of the silicon wafer 11, and N<+> type diffusion layers 13 are formed. Two layer structure of Si3N4 films and polycrystalline silicon films or protective layers 14 consisting of pure polycrystalline silicon films are deposited on both main surfaces of the silicon wafer 11 through a decompression CVD method. Said structure or layer may be deposited only on the back side through a normal pressure CVD method. One surface, the surface side, of the silicon wafer 11 is mirror-ground. The quantity of the surface side ground at that time shall be sufficient to completely remove the diffusion layer 14 of phosphorus. |
