A method for fabricating a semiconductor device includes forming a first conductive layer doped with an impurity for forming a cell junction over a semiconductor substrate, forming a second conductive layer over the first conductive layer, forming a plurality of active regions by etching the second conductive layer and the first conductive layer, the plurality of the active regions being separated from one another by trenches, forming a side contact connected to a sidewall of the first conductive layer, and forming a plurality of metal bit lines each connected to the side contact and filling a portion of each trench.