| 摘要 |
PURPOSE:To enable the inner wall part of groove in a semiconductor having a channel structure such as trench capacitor etc. to be doped with impurity in excellent controllability and evenness by a method wherein a layer with diffusion constant of impurity exceeding that in bulk silicon (substrate) is implanted with ion to be heat treated. CONSTITUTION:An SiO2 film 2 and an SiN film 3 are laminated on a p type silicon substrate 1 to be patterned. Then, a trench is dug out by reactive ion etching process using the two layer films as masks to form a thin oxide film 4 on the inner wall of trench by thermal oxidation process. Later, a polycrystalline silicon 5 is deposited. Next, the whole body is heat treated in proper atmosphere to diffuse As in the p type Si substrate 1. At this time, the diffusion constant of As in the polycrystalline silicon film 5 is set up to sufficiently exceed that in bulk silicon. The diffusion of As in the Si substrate 1 is restricted by the existing oxide film 4 but the trench sidewall part is doped with As to form an n<->layer 7. Through these procedures, the fused layer can be formed on the trench sidewall part in excellent controllability and evenness.
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