| 摘要 |
A method for producing a semiconductor device includes a step of patterning a surface of a semiconductor substrate of first conductivity-type, a step of injecting impurity ion of second conductivity-type, a step of forming a buried well by subjecting the injected substrate to a thermal treatment, a step of forming a semiconductor crystal layer of the second conductivity-type on the substate surface, and a step of forming semiconductor elements. A semiconductor device and a longitudinal transistor produced by the method are also disclosed. In the method, after the step of forming the semiconductor crystal layer, the impurity concentration of the buried well is controlled to be nearly the same as that of the semiconductor crystal layer. According to the present invention, a semiconductor crystal layer of reverse conductivity-type to that of the substrate can be formed on the substrate in different thickness at different regions.
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