Patent ID: 8742479

Claim:
A semiconductor device comprising: a semiconductor substrate; a transistor formed on the semiconductor substrate; a first insulating film which is formed on the semiconductor substrate, and which thus covers the transistor; a ferroelectric capacitor formed on the first insulating film; a second insulating film covering an upper side of the ferroelectric capacitor, an upper surface of the second insulating film being planarized; a first contact hole which extends from the upper surface of the second insulating film, and which reaches one of a plurality of impurity regions constituting the transistor; a plug, which fully occupies the entire first contact hole, containing a first conductor and formed in the first contact hole, the plug being electrically connected to the impurity region, wherein the plug does not include a layer whose material is different from a material of the conductor and which is provided along with a cross section of the plug; a first hydrogen barrier layer which is formed on the second insulating film, and which thus prevents hydrogen and moisture from entering a portion under the first hydrogen barrier layer; a third insulating film formed on the first hydrogen barrier layer; a second contact hole which extends from an upper surface of the third insulating film, and which communicates with the ferroelectric capacitor; a third contact hole which extends from the upper surface of the third insulating film, and which communicates with the plug; and interconnections containing a second conductor different in material from the first conductor and formed on the third insulating film, one of the interconnections being connected to the ferroelectric capacitor through the second contact hole, and another one of the interconnections being connected to the plug through the third contact hole, wherein the interconnections include first to third portions, the first portion being formed on the third insulating film, the second portion being extending downward from the first portion in the second contact hole and being directly connected to the ferroelectric capacitor, and the third portion being extending downward from the first portion in the third contact hole and being directly connected to the plug.