Nitrogen ion dose dependence of surface morphology of titanium nitride films deposited on gallium arsenide by an ion beam assisted deposition technique

A thin titanium film was deposited on GaAs surfaces by an ion beam assisted deposition technique, and subsequently a titanium nitride film was deposited on the Ti/GaAs structure. The nitrogen ions were accelerated to an energy of 500 eV. The TiN films were deposited under a constant N ion current of 0.1 mA/cm², and the fraction of nitrogen ions in nitrogen beams was varied by varying nitrogen flow rate. The Ti layers changed to a Ti-rich TiN layer during the TiN deposition because nitrogen ions were implanted and diffused into the Ti layer. The surface morphologies of the structures varied with the dose of nitrogen ions and on annealing temperature. The film deposited at a flow rate of 10 sccm had a surface smoother than that at 20 sccm even after it was annealed at 1000°C. Neither blister nor crack run on the surface of the former annealed structures. That is, the nitrogen ions contributed to keep the smooth TiN film surface during high temperature annealing and to prevent blistering and cracking of the films