FORMING METHOD OF FIELD OXIDE FILM

摘要

A forming method of a field oxide is provied to increase an active region by decreasing a bird's beak of field oxide. The method comprises the steps of: sequentially forming a pad oxide(2) and polysilicon layer(3) on a silicon substrate(1); forming a first oxynitride layer(5) by annealing the surface of the polysilicon under NH3 or N2O gas; selective etching the nitride layer(4), the oxynitride layer(5) and the polysilicon layer(3) to form a field oxide region(6); forming a second oxynitride layer(5') on the surface and at side wall of the remained polysilicon by annealing under NH3 or N2O gas; and forming a field oxide(8) by thermal oxidation after removing the second oxynitride layer(5') on the pad oxide(2).