Preparation of WNx thin films using RF-DC coupled magnetron sputtering and diffusion barrier properties for Cu/WNx/Si samples

Tungsten nitride (WNx) thin films have been prepared using an RF-DC coupled magnetron sputtering system, in which the incident ion energy on the target can be controlled by the target DC bias voltage. The films were applied to Cu/WNxSi samples and the obtained Cu(500 nm)/W2N(25 nm)/Si samples were stable without Cu-Si reaction after annealing at 700°C for 30 min. It was shown that the film composition (N/W) can be controlled by the target DC bias voltage without changing the gas flow ratio (N2/(Ar+N2)), and the N/W ratio was decreased from 0.8 to 0.2 only by increasing the target DC bias voltage from -100 V to -500 V, respectively, at the N2/(Ar+N2) ratio of 0.2.