Microstructure And Properties Study Of TiN Thin Films Deposited Via Substrate Biased Magnetron Sputtering

The TiN film is widely focused by researchers worldwide for its superior facilities and versatile applications.In recent years,massive works have been dedicated on the TiN film's texture changes,morphologies,colors and properties of the TiN film whereas the deep analysis on the microstructure is still absent.In this work,a series of TiN films were prepared on silicon substrate at various bias voltages(Vb)by magnetron sputtering.The effects of bias voltage on the structure,composition,preferred orientation,surface morphology and electrical properties of TiN thin films were systematically studied.Furthermore,the microstructure of the film was investigated by high-resolution transmission electron microscopy(HRTEM)and the microstructural evolution during the film growth was also revealed on an atomic scale.The main contents and results are as follows:Firstly,the structure,chemical conposition and properties of the film were characterized by XRD,XPS,AFM etc.The results show that all the films exhibit a typical fcc-NaCl structure.Under the circumstance that no external bias being applied to the substrates,a preferred(111)growth orientation of the film could be observed,with the increase of the bias voltage,the texture evolves from(111)to(220).The roughness of the film decreases and the film surface becomes smoother.The electrical resistivity decreases and the film shows superior electric conductivity at Vb =-80 V In terms of mechanical properties,the increasing bias voltage has significant positive effect on the film's hardness and anti-deformation property,peak values could be observed at Vb =-60VSecondly,we investigated on the growth of the columnar crystal.The results show that at low bias voltages the film appears to be the non-compact structure.With increasing bias voltage the film becomes more dense and TiN crystals show a change tendency from columnar toequiaxed crystals.According to the structure zone model,the film shows a typical Zone I structure when no external bias being applied to the substrates,while at Vb--80 V it shows Zone T structure.Finally,we also made deep investigation on the defects of the film by HRTEM,results show that dislocation density increase with increasing bias voltage,we were surprised to observe a massive twin formation,especially within the TiN films prepared with Vb =-40 V and-80 V However,for the film prepared with Vb =-60 V no significant twin formation could be observed.By calculation we proved that the possibility of the occurrence of twins is closely related to the N/Ti ratio of the film.In this paper,we investigated the influence of bias voltage on the microstructure and properties of TiN film.By applying HRTEM and other approaches we deeply researched the growth of the film and constructed the relationship the film's microstructure and the visible performances,which is of great significance for the development of TiN materials.