Patent ID: 7221015

Claim:
A semiconductor device comprising: a first impurity diffusion region and a second impurity diffusion region formed in a surface region of a semiconductor substrate; a first insulating layer formed over the semiconductor substrate; a first hole and a second hole formed in the first insulating layer; a first conductive plug formed in the first hole and connected electrically to the first impurity diffusion region; a second conductive plug formed in the second hole and connected electrically to the second impurity diffusion region; an oxygen-barrier metal layer formed in a shape of an island on the first conductive plug and its peripheral area and on the first insulating layer, said oxygen barrier metal layer having a side surface; an oxidation preventing layer formed on the first insulating layer and side surface of the oxygen-barrier metal layer and made of material that prevents oxidation of the second conductive plug, an upper surface of the oxidation preventing layer being planarized around the oxygen-barrier metal layer; a capacitor having a lower electrode formed on the oxygen-barrier metal layer, a dielectric layer formed on the lower electrode, and an upper electrode formed on the dielectric layer; a second insulating layer covering the capacitor and the oxidation preventing layer; a third hole formed in the second insulating layer over the second conductive plug; and a third conductive plug formed in the third hole and connected electrically to the second conductive plug.