METHOD FOR FORMING ISOLATION LAYER OF SEMICONDUCTOR DEVICE TO AVOID LOSS OF NITRIDE LAYER

摘要

PURPOSE: A method for forming an isolation layer of a semiconductor device is provided to avoid a loss of a nitride layer by preventing the nitride layer on the bottom of a trench from being nitridized in depositing an HDP(high density plasma) oxide layer. CONSTITUTION: A pad oxide layer(22) and a pad nitride layer are sequentially formed on a semiconductor substrate(21). The pad nitride layer and the pad oxide layer are patterned to expose a substrate region corresponding to an isolation region. The exposed substrate region is etched to form a trench. A thermal oxide layer is formed on the surface of the trench. A nitride layer(26) is deposited on the resultant structure by a thickness so as to have an inherent physical property. A predetermined thickness of the nitride layer is removed by a wet etch process. A buried oxide layer is deposited on the resultant structure to completely fill the trench. A CMP(chemical mechanical polishing) process is performed on the buried oxide layer until the pad nitride layer is exposed. The pad nitride layer is eliminated.