METHOD FOR FORMING ELEMENT ISOLATION LAYER OF SEMICONDUCTOR DEVICE

PURPOSE: A method for forming an element separation layer of a semiconductor device is provided to make a good element isolation layer by preventing a seam and void in burying an insulating layer into a trench. CONSTITUTION: A pad oxide layer(12), a pad nitride layer(13) are sequentially formed on a semiconductor substrate(11). The pad nitride layer, the pad oxide layer, and the semiconductor substrate are etched by a predetermined depth through an etching processing using an element isolation mask, thereby forming a trench(14). The semiconductor substrate inside of the trench is oxidized by an oxidation process in order to restore an inner wall of the trench etched. A plasma processing using NF3 gas is performed about the oxide layer, thereby forming a residual oxide layer(15a) of a thin thickness state. A cleaning process using a surphuric acid is performed, and an insulating layer(16) is formed to make the trench be fully buried.