Method for fabricating a semiconductor transistor device

A method for fabricating a transistor of a semiconductor device is disclosed. The method for fabricating a transistor of a semiconductor device according to the present invention comprises the steps of forming an LDD region using an ion implantation after depositing a first insulating layer on a semiconductor substrate; forming a trench in the substrate after patterning the first insulating layer; forming a trench gate by depositing and planarizing a second insulating layer and a conductor on the substrate with the trench; forming a source/drain region by forming a photoresist pattern on the substrate with the trench gate and performing an ion implantation using the photoresist pattern as a mask; and removing the photoresist pattern and the first insulating layer. Thus, a method for fabricating a transistor of a semiconductor device according to the present invention can lower source/drain resistance and gate resistance without any additional process by forming a trench type gate and can efficiently control a short channel effect.