| 摘要 |
PROBLEM TO BE SOLVED: To readily form in a short time a shallow P-type semiconductor region, having relatively high impurity concentration and a deep P-type semiconductor region which has a relatively low impurity concentration. SOLUTION: A silicon oxide film 2 is formed on a silicon semiconductor base body 1. A liquefied impurity source 3, composed of a mixture of aluminum, boron, and an organic solvent, is coated on the silicon oxide film 2, and this is heated at temperatures lower than the diffusion temperatures of aluminum, and the organic solvent is evaporated to form a layer containing aluminum and boron. This layer is heated in the atmosphere containing oxygen. Thereafter, it is heated at temperatures higher than the thermal processing temperatures, and aluminum and boron are diffused in an N-type semiconductor substrate 1 to form first and second P-type semiconductor regions 9, 10 having different impurity concentrations.
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