Method for fabricating semiconductor device with improved refresh characteristics

摘要

Disclosed is a method for fabricating a semiconductor device wherein boron-halo ion implantation is performed only to a bit-line contact part while masking a storage node contact part. The method comprises the steps of: performing a first ion implantation into the semiconductor substrate to control the threshold voltage Vt; forming a gate electrode on the semiconductor substrate in which the first ion implantation has been performed; performing a second ion implantation with a tilt of desired degree, using the gate electrode as a mask in order to control the threshold voltage; and performing a third ion implantation to form an LDD region in the substrate region at both sides of the gate electrode. In this method, the first ion implantation is performed at a range of below 90% of the whole doping concentration required to control the threshold voltage, and the second ion implantation is performed with a degree of below 30° and in two directions or four directions vertical to the gate electrode.