| 摘要 |
PURPOSE: To form a PN junction of diffusion barrier added with impurities by adding impurities having a relatively small diffusion coefficient to a third semiconductor layer in order to form a diffusion barrier between first and second conductor layers. CONSTITUTION: In order to form a diffusion barrier between a P conductivity type first conductor layer 28 and an N conductivity type second conductor layer 52, a P conductivity type third conductor layer 30 added with impurities having a relatively small diffusion coefficient is formed between them. Since the P type impurities have no possibility to be diffused undesirably into an adjacent N type semiconductor layer, a large quantity of impurities can be added to the P type layer. Consequently, a diffusion barrier added with impurities can be provided as a PN junction.
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