Effect of annealing ambience on the chemical stability of Zr-Si-N diffusion barrier

Zr-Si-N films were deposited by RF magnetron sputtering technique. A Cu film on the top of Zr-Si-N films was prepared by DC pulsed magnetron sputtering. The Cu/Zr-Si-N systems were annealed in vacuum and N₂/H₂gas mixture at 800°C respectively. The structure of the films were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES) and four-point probe method. The sheet resistance of the Cu/Zr-Si-N/Si contact systems annealed in N₂/H₂ gas mixture was lower than that of the specimens annealed in vacuum at 800°C. The residual oxygen contamination from vacuum annealing ambience influences the sheet resistance of the Cu/Zr-Si-N/Si contact systems due to residual oxygen contamination and/or voids in Cu films. Though thermal stability of the Cu/Zr-Si-N/Si systems was maintained up to 800°C when annealed in vacuum and N₂/H₂ gas mixture, the change of thermal stability of specimens was noticeable. The vacuum can accelerate the oxidation and decomposition of Zr-Si-N barrier. On the contrary, N₂/H₂ gas mixture prevents from the Zr-Si-N barrier oxidation and decomposition.