| 摘要 |
A transistor of a semiconductor device and a method for fabricating the same are provided to improve a write operation of a DRAM cell transistor by forming a gate dielectric whose thickness at a part of a sidewall of a groove for a gate contacted to a bit line contact region is thicker than other parts. An isolation layer defining an active region is formed in a semiconductor substrate(100). The active region includes a gate forming region, a bit line contact region, and a storage contact region. A source/drain ion implantation is performed on the semiconductor substrate where the isolation layer is formed to form a junction region(104). The gate forming region of the active region of the semiconductor substrate including a junction region is etched to form a groove(H) for a gate. An oxygen ion implantation is selectively performed only on a sidewall of the groove for a gate that is contacted to the bit line contact region. A gate dielectric(110) is formed on the whole surface of the substrate including the groove for a gate. The gate dielectric is thicker at a sidewall of the groove for a gate where oxygen ion is selectively implanted than other parts. A gate conduction layer(112) is formed on the gate dielectric. The gate conduction layer and the gate dielectric are etched to form a gate(116) on the groove for a gate.
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