Ru Electrode Deposited by Sputtering in Ar/O2 Mixture Ambient

Ru films are fabricated by dc magnetron sputtering in an Ar/O2 ambient, as the bottom electrodes of Ba0.5Sr0.5TiO3 thin film capacitors. The Ru films deposited on Si in an Ar/O2 mixture ambient show low resistivity and low film stress and do not form Ru2Si3 following thermal processing even at 700°C. It becomes clear that there exist very thin amorphous and crystalline layers composed of Ru, Si and O between the Ru films and Si in the case of Ru films deposited in an Ar/O2 ambient. A low contact resistance at the Ru/n+-Si interface is obtained after annealing at 700°C. An effective SiO2 film thickness of 0.42 nm is obtained for an actual Ba0.5Sr0.5TiO3 film thickness of 42 nm with a leakage current of less than 1×10-8 A/cm2 in the range between -1.5 V and +1.8 V for a Ru/Ba0.5Sr0.5TiO3/Ru/n+-Si capacitor without a barrier metal layer.