Superior Stability of Ultrathin and Nanocrystalline TiZrN Films as Diffusion Barriers for Cu Metallization

Titanium zirconium nitride (TiZrN) films with nanocrystalline grains of 5 similar to 12 nm were prepared by DC reactive magnetron sputtering from a TiZr alloy (Ti:Zr = 95:5 at.%) target in a N(2)/Ar flow ratio of 2.75 and various substrate biases. 6 nm thick TiZrN ultrathin films were deposited as diffusion barriers between Cu thin films and Si substrates for the evaluation of thermal stability. Our results suggest that nanocrystalline (Ti,Zr)N(0.956) ultrathin films prepared at the condition of a N(2)/Ar flow ratio= 2.75 and a substrate bias of 0 W is applicable to be used as an attractive and promising diffusion barrier materials for Cu metallization, because of its lower resistivity of 59.3 mu Ohm-cm, higher theoretical density of 5.262 g/cm(3), and a superior thermal stability of barrier performance up to 750 degrees C, as well as a higher Cu adhesion energy of 2.17 N/m.