| 摘要 |
PURPOSE:To make it possible to diffuse an impurity in a uniform concentration without making large-scaled facilities by a method wherein ultraviolet rays are irradiated on an impurity diffusion source layer in an ozone-containing atmosphere before the layer is subjected to heating treatment. CONSTITUTION:An impurity-containing liquid for forming a silica film is applied on a semiconductor substrate W to form an impurity diffusion source layer 10 and the impurity is diffused in the substrate W by performing a thermal diffusion treatment on the layer 10. In such a case, ultraviolet rays are irradiated on the layer 10 in an ozone-containing atmosphere before the above thermal diffusion treatment is performed. For example, the Si wafer W with the layer 10 formed thereon is placed on a stage 8 of an ultraviolet treating unit to be heated at 200 deg.C and is irradiated with ultraviolet rays from ultraviolet lamps 4 for 30 minutes while gas containing ozone of 2 wt. % in the air is fed through a gas introducing port 6. Then, after the Si wafer W is for 30 minutes at 400 deg.C, a thermal diffusion treatment is performed for 60 minutes 1200 deg.C in a nitrogen gas containing-atmosphere.
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