| 摘要 |
PURPOSE: A method for fabricating a semiconductor device is provided to prevent a punch-through phenomenon by horizontally isolating a source/drain region, and to reduce an occupied area of the device by increasing the length of a channel as compared with the width of a gate. CONSTITUTION: A stack structure of an oxide layer and a nitride layer is formed on a semiconductor substrate(100). The stack structure of the oxide layer and the nitride layer in a portion reserved for a gate electrode(700) is etched to form a stack structure of an oxide pattern and a nitride pattern that expose the substrate. A sidewall spacer is formed on the sidewall of the stack structure of the oxide pattern and the nitride pattern. The substrate is etched to form a trench by using the stack structure pattern and the sidewall spacer as a mask. The sidewall spacer is eliminated. A gate oxide layer(600) is formed on the exposed substrate including the sidewall of the trench. A polysilicon layer is formed on the substrate to fill the trench. The polysilicon layer is planarized to expose the nitride pattern. The nitride pattern is removed to form the gate electrode. The source/drain region(950) is formed in the substrate at both sides of the gate.
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