Thermal Stability of Reactively Sputtered TiN on InP as a Diffusion Barrier

The stability of rcactively sputtered TiN films on InP for application as a diffusion barrier has been examined using electrical measurements, Auger profiling and scanning electron microscopy (SEM). The samples were subjected to rapid-thermal-annealing (RTA) in a N2 atmosphere at temperatures between 400°C and 900°C. The SEM pictures of “as deposited” and RTA stoichiometric films show that the morphology is smooth, fine-grained and stable until 800°C. Auger depth profiling shows little interdiffusion between TiN and InP for RTA below 800°C. Annealing at temperatures of about 700°C reduces the sheet resistance of TiN relative to the “as-deposited” films by about 50%. Annealing at temperatures above 800°C results in a large sheet resistance. This may be associated with the deterioration of the TiN/InP morphology at high anneal temperatures as observed by SEM.