A semiconductor device includes semiconductor substrate, a trench capacitor formed in the semiconductor substrate, a cell transistor formed so as to the trench capacitor and having a gate electrode formed on the semiconductor substrate and a source/drain region formed in a surface of the semiconductor substrate, an impurity diffusion region formed in the semiconductor substrate so as to be electrically connected between the trench capacitor and the source/drain region, and a Ge inclusion region formed between the impurity diffusion region and the trench capacitor.