Production method of a semiconductor device

摘要

The method of producing a semiconductor device, comprising the steps of forming an oxidation resistant layer (62) in an active layer of an element; forming a deep trench (100) in an element isolating region (200); forming a heavily doped layer (110) by self alignment in the side wall portions of the deep trench (100); oxidizing the trench side walls and a silicon surface using the oxidation resistant layer (62) as a selective oxidation mask; forming a gate oxide film (81) and a polysilicon gate electrode (2); forming a layer insulating film (120); and forming wiring of metal electrodes. The side-wall oxide films (105) of a deep isolation trench (100) formed in the active layer of a SOl substrate are extended on the surface of an active layer, and thereby the absolute misalignment of a gate polysilicon is remarkably reduced and fine processing is made possible. The electrode arranged in the neighborhood of the element isolation trench is isolated from the silicon surface by an insulating film (120) at least four times thicker than the oxide films on the trench side walls and thereby to avoid the dielectric breakdown of high dielectric breakdown voltage elements.