| 摘要 |
PURPOSE:To obtain the impurity layer whose diffusion depth can be controlled and which has an ohmic contact by a method wherein a polysilicon thick film is laminated on an insulating film of the predetermined shape present on an Si substrate and a heat diffusion is effected to arrange a layer of reverse conductive type followed by the overall etching for patterning. CONSTITUTION:Holes are opened on an SiO2 film 12 present on P-type Si substrate 11 and polysilicon 13 is laminated on that by CVD method. An N<+> layer 14 is formed by P-diffusion at 1,000 deg.C with POCl3 as a diffusion source. After thinning the polysilicon layer 13A by the overall RIE, the layer 13A is patterned to be the predetermined shape followed by a heat treatment to eliminate distortion. In this constitution, because the polysilicon layer 13 is thick, the N<+> layer 14 does not expand over the predetermined size even if a diffusion temperature becomes high and the high temperature offers an ohmic contact on a boundary of the polysilicon 13 and the N<+> layer 14. |
