METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for manufacturing a semiconductor device is provided to improve an electric feature of the semiconductor device by forming an isolation film using a wet etching and by reducing the stress in a side wall of a trench. CONSTITUTION: A pad oxide layer(21) and a nitride layer(22) are sequentially formed on a semiconductor substrate(20). A non-active area of the semiconductor substrate(20) is exposed by etching the pad oxide layer(21) and the nitride layer(22). A trench(23) is formed by etching the exposed semiconductor substrate(20). Then, a surface of the trench(23) is firstly oxidized so as to form a first thermal oxide layer on the surface of the trench(23). After removing the first oxide layer, the surface of the trench(23) is secondly oxidized so as to form a second thermal oxide layer(24) on the surface of the trench(23). An insulation film(25) is filled in the trench(23). The insulation film(25) is etched until the nitride layer(22) is exposed. After removing the nitride layer(22), an isolation film(25A) is formed. Ions are implanted into the isolation film(25A), so a nitrogen ion injection layer is formed in the isolation film(25A) and the semiconductor substrate(20).