A semi-empirical growth model study of W–C induced by focused ion beam with a Gaussian–Holtsmarkian distribution

Focused-ion-beam chemical vapour deposition (FIB-CVD) is a very useful direct fabrication technique for nano-structures. We focus on studying the growth model of FIB-CVD-based conducting W–C. An initial model is developed to simulate the distribution of secondary electrons generated from the collision process of ions crash into the solid. The experimental results show that the profile of the deposition has a minute but very long tail that can extend as far as 100 nm. Our model reveals that the Gaussian–Holtsmarkian distribution of the ion beam is responsible for the long tail of the profile. Additionally, the growth speed decreases as the deposition grows, since the occupancy of adsorbed gas molecules is reduced by the Joule heating effect. A semi-empirical model is finally established by revising the initial model with the experimental data. We believe the proposed model is very useful for exploring the growth mechanism and fabrication limit of FIB-CVD.