Method of manufacturing semiconductor device having elements isolated by trench

摘要

This invention relates to a method of manufacturing a semiconductor device having elements isolated by a trench. A trench is formed to surround an element region of a silicon substrate by anisotropic etching. A nonoxide film such as a silicon nitride film is selectively formed on the upper surface of the element region. Thermal oxidation is performed using the nonoxide film as a mask to form an oxide film on the inner face of the trench and the upper surface of a field region. Thereafter, a polysilicon layer is buried in the trench, and after the surface of the polysilicon layer is flattened, a capping oxide film is formed on the upper surface of the trench. In addition, a non-oxide film is formed to have an interval between the end of the nonoxide film and the trench of 2 mu m or more.