| 摘要 |
PURPOSE:To form two kinds of diffusion layers having the desired impurity concentrations between which there is a difference in concentration by a heat treatment of one time by combining an impurity concentration in said layer, a thickness of that layer, and the existence of a nitride film on the layer while employing a doped oxide layer or a doped polysilicon layer as a diffusion source. CONSTITUTION:After forming a silicon oxide film 2 on a surface of a P-type semiconductor wafer 1, openings 3 and 4 are formed on the silicon oxide film 2. A doped oxide layer 5 (or doped polysilicon layer) is formed and a nitride film 6 (or doped CVD oxide film) is subsequently formed. Furthermore, the nitride film 6 is selectively removed so as to leave only the film 6 present in the part on the opening 3 for forming a high-concentration diffusion layer. By a drive-in, diffusion layers 7 and 8 are formed in the surface of the semiconductor wafer 1 corresponding to the openings 3 and 4. Accordingly, the surface impurity concentration of the diffusion layer 7 corresponding to the opening 4 becomes lower than that of the diffusion layer 8 corresponding to the opening 3. |
