| 摘要 |
PURPOSE:To enable to manufacture an LSI containing a circuit of high withstand voltage by a method wherein the diffusion region formed on a second region is separated from the oxide film-silicon boundary region of a first region. CONSTITUTION:A first region has a thick oxide film 4 having an end part, the thickness of which is gradually reduced, formed on the surface of a semiconductor substrate. A second region has an oxide film which is thinner than the film 4. The oxide film-silicon interface of the first region is located inside the substrate than the oxide film-silicon interface of the second region. The diffusion region 5' formed on the second region is separated from the oxide film-silicon boundary region of the first region. Accordingly, if this mask pattern is formed aparting from a bird's beak in advance, it is unnecessary to increase a special mask, and no additional process is required in the manufacture of the device. As the diffusion region is formed separately from the boundary region, the LSI of high withstand voltage can be manufactured. |
