A semiconductor device and a method for forming the same are disclosed. The semiconductor device includes a semiconductor substrate including an active region defined by a device isolation film, a bit line contact plug that is coupled to the active region and that includes a first ion implantation region buried in a first inner void, and a storage node contact plug that is coupled to the active region and includes a second ion implantation region buried in a second inner void. Although the semiconductor device is highly integrated, a contact plug is buried to prevent formation of a void, so that increase in contact plug resistance is prevented, resulting in improved semiconductor device characteristics.