Effects of substrate bias on the reactive sputtered Zr–Al–N diffusion barrier films

Zirconium aluminum nitride (Zr–Al–N) diffusion barrier films were deposited on Si substrates by DC-reactive magnetron sputtering under different substrate bias voltages. Cu films were subsequently sputtered onto the Zr–Al–N films without breaking vacuum. The effects of substrate bias voltage on the deposition rate, composition, microstructure, resistivity and diffusion barrier properties of Zr–Al–N films were investigated. Results indicated that the deposition rate and the contents of Al and O decreased with the increase of substrate bias voltages. The resputtering effect due to the high-energy ion bombardment on the film surface had significantly influenced the deposition rate and film's composition. With the increase of substrate bias voltage, the crystal orientation of films distributed more randomly. The substrate bias also decreased the resistivity and improved the diffusion barrier properties of films. The biased Zr–Al–N films could effectively prevent diffusion of Cu to Si wafer even up to 800 °C for 30 min.