| 摘要 |
A method for forming an isolation layer of a semiconductor device is provided to guarantee reliability of an isolation layer and an STI(shallow trench isolation) process by preventing a void generated in filling an HDP(high density plasma)-oxide layer from influencing a subsequent process. A pad oxide layer(22) and a pad nitride layer are sequentially formed on a semiconductor substrate(21) and are patterned to expose a predetermined region of the substrate. The exposed region of the substrate is etched to form the first trench. A spacer is formed on the patterned pad nitride layer, the patterned oxide layer and the sidewall of the trench. The substrate under the front surface of the first trench is etched to form the second trench by using the spacer. The spacer is removed. A thermal oxide layer(28) is formed on the second and first trenches. A linear nitride layer(29) and a linear oxide layer(30) are sequentially formed on the resultant structure. A buried oxide layer is deposited on the linear oxide layer to fill the first and second trenches. 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.
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