MANUFACTURE OF SILICON SEMICONDUCTOR SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To reprocess conductivity type and impurity concentration at a stage wherein a substrate is formed by making impurity concentration not less than its original impurity concentration by diffusing impurities from both surfaces of a substrate and changing an originally N-type substrate to an N-type and an originally P-type substrate to N-type. SOLUTION: When a substrate whose original conductivity type is N-type is made an N-type low resistivity substrate, phosphorus is deposited at a high concentration on an N-type wafer whose impurity concentration is 5×10<13> atoms/cc, for example and diffusion is carried out an a high temperature. Phosphorus concentration after diffusion is 0.9×10<30> atoms/cc and 1×10<19> atoms/cc at a substrate thickness central part. When an originally P-type substrate is made an N-type low resistivity substrate, phosphorus is deposited on a P-type wafer whose impurity concentration is 2×10<15> atoms/cc, for example at a high concentration and thereafter diffusion is carried out an high temperature. Phosphorus concentration after diffusion is 1×10<20> atoms/cc in a substrate surface and 1.5×10<19> atoms/cc at a substrate thickness central part.