Semiconductor device having high reliability

摘要

Semiconductor device comprises: (a) a semiconductor substrate (1); (b) an element insulation oxide film (7) in the surface of the substrate (1); and (c) a boundary layer (10) contg. nitrogen atoms and provided at the boundary between oxide film (7) and substrate (1). Also claimed are (I) an alternative device comprising: (i) a substrate; (ii) a trench in the surface of the substrate to insulate an element region from other element regions; (iii) a doping layer on the inner wall surface of the trench; (iv) an oxide film covering the inner wall surface of the trench; and (v) a boundary layer contg. nitrogen and provided on the boundary between oxide film and inner wall surface of the trench, and (II) the prodn. of the device.