Patent ID: 8377808

Claim:
A method for manufacturing a semiconductor device, comprising: preparing a one-conductivity-type semiconductor substrate; forming an opposite-conductivity-type epitaxial layer on the semiconductor substrate after implanting ions of an impurity for forming a first one-conductivity-type buried diffusion layer into the semiconductor substrate; and forming an isolation region by firstly implanting ions of an impurity for forming a second one-conductivity-type buried diffusion layer from a surface of the epitaxial layer, then continuously implanting ions of an impurity for forming a one-conductivity-type diffusion layer, and finally performing thermal diffusion, so as to connect the first one-conductivity-type buried diffusion layer, the second one-conductivity-type buried diffusion layer and the one-conductivity-type diffusion layer with one another, wherein, after a LOCOS oxide film is formed in the epitaxial layer, ions of the impurity for forming the second one-conductivity-type buried diffusion layer and ions of the impurity for forming the one-conductivity-type diffusion layer are implanted from above the LOCOS oxide film.