The effect of sputtering bias on the properties of Nb-Si-N film

Nb-Si-N films were sputtered by RF reactive magnetron sputtering with different bias voltages. The effect of sputtering bias on the properties of Nb-Si-N film was studied. Energy dispersive X-ray spectroscopy, atomic force microscope, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, four-point probe method and microhardness tester were employed to characterize the microstructure and properties of the Nb-Si-N films. 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 crystallites embedded in amorphous SiN_x phase. High sputtering bias is in favor of the growth of NbN grains in the Nb-Si-N film. As the bias increases the ε-NbN phase increases. The sheet resistance and microhardness of Nb-Si-N film also change as the bias varies. These phenomenons may be related with the ε-NbN phase in some degree.