FIELD OXIDE FORMATION METHOD OF SEMICONDUCTOR DEVICE

摘要

A method for forming a field oxide which can minimize the bird's beak and achieve the local flatness is disclosed. An HSG(Hemispherical Grain) polysilicon layer(13) is formed in a region being form a field oxide(18) in a silicon substrate(11). Then a plurality of groove(17) are formed in the silicon substrate(11) by dry etching the substrate(11) using the residue HSG polysilicon layer(13A) and a pad oxide(12A) as a mask. After remove the residue HSG layer(13A), the field oxide(18) is formed by using a LOCOS(locoal oxidation) process of the residue pad oxide(12A). Using the HSG polysilicon layer(13) as the etching mask, the length of the bird's beak(Lbb) of the field oxide(18) is minimized.