SEMICONDUCTOR DEVICE AND METHODS OF MANUFACTURING THE SEMICONDUCTOR DEVICE

A semiconductor device includes a buried gate structure including: a gate trench formed in a substrate; a gate insulating layer conformally formed over a bottom surface and an inner wall of the gate trench; a dipole inducing layer conformally formed over a bottom surface and an inner wall of the gate insulating layer; a dipole diffusion barrier layer conformally formed over a bottom surface and an inner wall of the dipole inducing layer; and a gate electrode formed over the dipole diffusion barrier layer to fill a lower region of the gate trench.