Interfacial Layers between Si and Ru Films Deposited by Sputtering in Ar/O2 Mixture Ambient.

Ru films are fabricated by dc magnetron sputtering in Ar/O2 ambient for the bottom electrode of Ba0.5Sr0.5TiO3 thin film capacitors. The Ru films deposited on Si in ambient of 10% O2 do not form Ru2Si3 following thermal process 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. A contact resistance of 1.6×10-7 Ω cm2 between Ru and n+-Si is obtained after annealing at 700°C. The effective SiO2 film thickness of 0.42 nm is obtained for 42 nm actual Ba0.5Sr0.5TiO3 film thickness and the leakage current is less than 1×10-8 A/cm2 in the range between -1.5 V and +1.8 V for Ru/Ba0.5Sr0.5TiO3/Ru/n+-Si capacitor.