ISOLATION FORMING METHOD OF SEMICONDUCTOR

摘要

A buffer oxide layer is formed on a semiconductor substrate of a first conductive type and polysilicon and nitride layers sequentially formed on the buffer oxide layer. Then, part of the nitride layer formed on a predetermined element insulating region is selectively removed, and a polysilicon layer of which the thickness is similar to that of the nitride layer, is formed between the inner side walls of the remaining nitride layer portions. The polysilicon layer is oxidised and then the remaining nitride layer and polysilicon layer are removed, to thereby form an insulating oxide layer without affecting the substrate. Bird's beak phenomenon and stress on substrate are reduced in insulating region.