A method for fabricating a semiconductor device includes etching a substrate to form a plurality of trenches, forming first liner layers over bottom surfaces and inner sidewalls of the trenches to a first height, forming sacrificial liner layers on one of the inner sidewalls of the trenches where the first liner layers are formed, forming third sacrificial layers to a second height, so that the third sacrificial layers are buried over the trenches where the sacrificial liner layers are formed, removing portions of the sacrificial liner layers exposed by the third sacrificial layers to form sacrificial patterns, forming second liner layers on the inner sidewalls of the trenches exposed by the third sacrificial layers, and removing the third sacrificial layers to form side contact regions opening one of the inner sidewalls of the trenches in a line form.