| 摘要 |
PURPOSE:To realize the fine structure of a semiconductor device, by arranging a coated insulating layer containing impurity on the whole surface, and heat- treating it after an insulating film containing no impurity is spread on the whole surface, and step-difference on an opening periphery is flattened, when an impurity diffusion mask having the opening is formed on the semiconductor surface. CONSTITUTION:By a thermal oxidizing method, an oxide film 2 for impurity diffusion mask is formed on a semiconductor substrate 1, and an opening 20 corresponding with a diffusion region is made by photolithography and etching. On the whole surface containing it, a coated insulating film 5 containing no impurity is spread. and step-difference on the periphery of the opening 20 is flattened. Then a coated insulating film 3 containing impurity is spread on the whole surface. By heat-treating, the impurity in the film 3 is diffused into the substrate 1 through the film 6 situated on the opening 20, to obtain a diffusion layer 4a, and the films 2, 5, 3 being unnecessary are eliminated. Thereby, the depth of the diffusion layer 4a is made uniform, and transversal spreading of diffusion also is reduced.
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