METHOD FOR FORMING ISOLATION LAYER OF SEMICONDUCTOR DEVICE TO PREVENT MOAT BY ADDITIONALLY FORMING THICK OXIDE LAYER AT TRENCH TOP CORNER USING FIELD OXIDATION PROCESSING

摘要

PURPOSE: A method for forming an isolation layer of a semiconductor device is provided to prevent moat by forming additionally a thick oxide layer at a trench top corner using field oxidation processing. CONSTITUTION: A pad oxide layer and a pad nitride layer are sequentially formed on a substrate(21). By selectively etching the pad nitride layer, the pad oxide layer of a field region is exposed. A field oxide layer(24) with a bird's beak is formed by field oxidation processing. A trench is formed by etching the field oxide layer and the substrate using the pad nitride pattern as an etch barrier. An oxide layer(26) is filled in the trench. An isolation layer(26a) is then formed by polishing the oxide layer.