JPS6467910A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress diffusion of impurities completely at the rear and the side of a substrate and obtain a semiconductor device having a high productivity as well, by depositing polysilicon at a part other than the main surface of the substrate after forming an oxide film for diffusion mask on a semiconductor substrate. CONSTITUTION:A silicon oxide film 2 which forms a mask in the case of diffusion of impurites grows on a silicon substrate 1. Then polysilicon is deposited. And then only a polysilicon film 3 formed on the surface of the silicon substrate 1 is removed by anisotropic etching. Further, impurity diffusion windows 4 are formed by wet etching through photolithography. As oxide films at the rear and the side of a wafer are protected by the polysilicon film 3, they are left without being etched. Then, after removing a resist, impurity diffusion regions 5 where no deposition of the impurities and drive are performed are formed. Since its drive is performed at an oxidizing atmosphere in such a case, the silicon film 3 becomes the oxide film on the whole. Then, even though the oxide film is removed wholly so as to treat the next process, regions where impurities are diffused are merely original diffused regions and no autodoping takes place even in the heat-treatment of next process.