| 摘要 |
PURPOSE:To permit a high-impurity density n type conductive layer and a low- impurity density n type conductive layer to be simultaneously formed in one diffusion heat treatment without any restriction on the pattern size and density. CONSTITUTION:No oxide film is formed in a high-impurity density region A of a silicon substrate 1. On the other hand, in a low-impurity density region B, an oxide film 2b of thickness T1, as a mask, is formed on the surface of the silicon substrate 1, and in a region C where no n type impurities are diffused, an oxide film 2c of thickness T2 (larger than T1), as a mask, is formed on the surface of the silicon substrate 1. Under this state, P and As are implanted. As a result, P is implanted into both the regions A and B, while As is implanted into only the region A. After the implantation of P and As, the oxide films 2b and 2c are removed by etching, and a heat treatment is applied to form a P-diffused layer 5 and an As-diffused layer 6. In this case, the allowable range of the thickness T1 of the ion transmission control film 2b provided on the low-density region B is considerably wide. |
