| 摘要 |
PURPOSE:To obtain a device having no fluctuation in threshold value by a method wherein a metallic silicide layer constituting a MOS type semiconductor device is formed in double layer structure such that, among the semiconductor layers forming the metallic silicide layer, the layer portion proximate to the substrate is made high in impurity concentration and the layer portion on the former is made low in impurity concentration. CONSTITUTION:A gate insulating film 32 made of SiO2 and a polycrystalline Si layer 33 are grown such as to be laminated on an Si substrate 31 of one conductivity type. A P impurity is then diffused into the layer 33 at a high concentration, thereby increasing the impurity concentration of the layer 33. A polycryst alline Si layer 37 of the same kind, which is low in impurity concentration, is deposited on the layer 33 and the entire surface thereof is overlaid with an Si3N4 film 38. A laminate composed of a film 38a and polycrystalline Si layers 37a, 33a is obtained by photoetching. Thereafter, the film 38a is removed and a heat treatment is effected on the laminate, thereby to surround the laminate with an SiO2 film connecting to the film 32. The surface alone is then removed, and a metallic layer 34 is deposited on the exposed portion of the laminate including the SiO2 film. Subsequently, the heat treatment is carried out, thereby to produce a metallic silicide layer 35 on the surface layer portion of the layer 37a by availing the layer 34. Then, the unnecessitated side layer 34 is removed. |
