| 摘要 |
PURPOSE:To obtain high density and to improve characteristics by providing a diffusing mask containing an oxidation resisting film, coating poly Si after prediffusion, performing heat treatment, suppressing spread of a selective diffusion layer in the lateral direction, and make it possible to perform selective oxidization. CONSTITUTION:For example, a mask pattern comprising an SiO2 film 21 and an Si3N4 film 22 are provided on an N type Si substrate 20, and a prediffustion layer 24 is formed by, e.g., a BSG film 23. Then, the BSG film 23 is removed, a polycrystalline Si layer 25 is deposited on the entire surface, heat treatment in unoxidized atmosphere at a temperature of about 1,000 deg.C is performed, and a P type diffused layer 26 is formed in a substrate 20. The spread of said diffusion layer 26 in the lateral direction on the surface is suppressed by the impurity absorbing effect of the polycrystalline Si 25. Therefore, the layer 26 is suitable for forming fine junction. Then, polycrystalline Si 25 is removed and an oxidizing process is performed, and a structure, wherein a diffused layer 28 is embeded by a selective oxide film 27, can be formed. |
