| 摘要 |
PURPOSE: A method for fabricating an isolation layer of a semiconductor device is provided to improve a rounding characteristic of an upper corner of a trench and prevent a moat from being generated by replacing a pad nitride layer with a pad polysilicon layer in a chemical mechanical polishing(CMP) process and by implanting BF2 ions so that the sidewall of the pad polysilicon layer is oxidized in a trench sidewall oxidation process. CONSTITUTION: A pad oxide layer(110) and the pad polysilicon layer are sequentially formed on a silicon substrate(100). BF2 ions are implanted into the pad polysilicon layer. A photoresist pattern is formed on the resultant structure and is etched to form a trench in the silicon substrate. A precleaning process is performed on the resultant structure. A dry oxidation process is performed on the resultant structure to form a sacrificial oxide layer on the sidewall of the trench. A gap-fill oxide layer is deposited on the resultant structure to fill the trench and a heat treatment process is performed. The gap-fill oxide layer is planarized by a CMP process. The pad polysilicon layer is removed by a cleaning process.
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