a semiconductor device and a method for manufacturing the semiconductor device are provided in which a lower plug electrically connected with an active region of a wafer has a recession , and a conductive layer has a projection fitted into the recession of the lower plug , so that a contact area between the lower plug and the conductive layer increases without increasing a contact resistance therebetween . thus , the conductive layer can endure physical impacts applied in the formation of the conductive layer itself and in subsequent integration processes , without detaching from the lower plug or the wafer .