Method for manufacturing semiconductor device

摘要

A method is provided for manufacturing a semiconductor device having a high breakdown voltage transistor and a low breakdown voltage transistor with different driving voltages in a common substrate. The method includes: (a) introducing an impurity of a second conductivity type in a specified region of a semiconductor substrate of a first conductivity type to form a first impurity layer and a second impurity layer; (b) further introducing an impurity of the second conductivity type in a region of the second impurity layer to form a third impurity layer; and (c) conducting a heat treatment to diffuse impurities of the first impurity layer and the third impurity layer to form a first well of the second conductivity type and a second well of the second conductivity type having an impurity concentration higher than the first well.