SEMICONDUCTOR DEVICE AND ITS MANUFACTURE

摘要

An element isolation oxide film is formed in a way that an opening for exposing a prescribed area is formed at least in one of thin films formed on a silicon substrate leaving the other part of the thin films unopened, an oxide film corresponding to the prescribed area is formed by selectively oxidizing the silicon substrate through the opening, at least the oxide film is exposed by removing other thin films than the oxide film, the whole exposed surface is additonally oxidized, and the unnecessary part of the oxide film around the prescribed area is removed. The surface of the silicon substrate below the unopened part is substantially flat. Consequently, when transistors are formed, the semiconductor device has an improved degree of integration and an improved reliability.