Influence of sputtering bias on the microstructure and properties of Nb–Si–N films

Nb–Si–N films were sputtered by radio frequency powered reactive magnetron sputtering with different bias voltages. The influence of sputtering bias on the microstructure and properties of Nb–Si–N films was studied. The results reveal that as the bias voltage increases the Nb/Si ratio and the surface roughness increase. The microstructure of Nb–Si–N films is the nano-composite structure with nano-sized NbN grains embedded in amorphous SiNx phase. High sputtering bias is in favor of the growth of NbN grains in the Nb–Si–N films. As the bias increases the ε-NbN phase increases. The sheet resistance and microhardness of Nb–Si–N films also change as the bias varies. This phenomenon may be related with the ε-NbN phase in some degree.