Effect of substrate bias voltages on the diffusion barrier properties of Zr–N films in Cu metallization

Zr–N diffusion barriers were deposited on the Si substrates by rf reactive magnetron sputtering under various substrate bias voltages. Cu films were subsequently sputtered onto the Zr–N films by dc pulse magnetron sputtering without breaking vacuum. The Cu/Zr–N/Si specimens were then annealed up to 650 8C inN2 ambient for an hour. The effects of deposition bias on growth rate, film resistivity, microstructure, and diffusion barrier properties of Zr–N films were investigated. An increase in negative substrate bias resulted in a decrease in deposition rate together with a decrease in resistivity. It was found that the sheet resistances of Cu/Zr–N( 200 V)/Si contact system were lower than those of Cu/Zr–N( 50 V)/Si specimens after annealing at 650 8C. Cu/Zr–N( 200 V)/Si contact systems showed better thermal stability so that the Cu3Si phase could not be detected.