Influence of pulsed bias on TiO2 thin films prepared on silicon by arc ion plating: Experimental and simulation study

Abstract

Dielectric TiO2 thin films were fabricated on p-(100) Si substrates by arc ion plating (AIP). The effects of pulsed negative bias on phase structure and growth of TiO2 films were investigated by applying a pulsed bias ranging from 0V to −900V on the substrates. Phase, microstructure, and growth morphology of TiO2 films prepared at different bias voltages were evaluated with GIXRD and AFM. The results show that pulsed bias exerts an obvious influence on phase structure and growth morphology. High substrate bias facilitates the formation of rutile phase and a (220) preferred orientation is observed in TiO2 films obtained at −900V. AFM images show that pulsed substrate bias exerts a strong influence on the growth of TiO2 films. As for the TiO2 films obtained at 0V, surface islands are tiny, the density of islands is high and RMS roughness is about 1.1nm. While for the TiO2 films at −900V, surface islands are large, the island density is relative low and RMS roughness is around 3.8nm, three times larger than the case of 0V. To explain the phenomena observed in this study, pulsed plasma sheath model was used to simulate the ion sheath dynamics. The time evolutions within a pulsed period of the potential distribution and ion density distribution in the sheath were evaluated. By analyzing experimental and simulated results, it can be concluded that film growth and property relate close to ion density and energy in the sheath, which is dominantly governed by negative substrate bias.