| 摘要 |
PURPOSE: A method for forming an isolation region of a semiconductor device is provided to prevent a gate oxide layer from thinning over a trench structure. CONSTITUTION: In the method, the first and second insulating layers are formed on a semiconductor substrate(11) and selectively etched together with the substrate(11) to form the trench structure. A polysilicon layer(14) is then formed thereon and thermally oxidized to form a thermal oxide layer(15). Next, the third insulating layer(16) is formed thereon to fill the inside of the trench structure and then etched or polished until the underlying first insulating layer is exposed. After that, the remaining first insulating layer is removed, and a buffer oxide layer is wholly formed. The buffer oxide layer is removed after impurity ions are implanted to control threshold voltage. Next, the gate oxide layer(18) is formed by thermal oxidation, and a gate electrode(19) is formed thereon. The gate electrode(19) and the gate oxide layer(18) are then selectively etched.
|
