Impact of High Temperature Annealing on Traps in Physical-Vapor-Deposited-TiN/SiO2/Si Analyzed by Positron Annihilation

The behavior of traps in physical-vapor-depostited-TiN/SiO2/Si, which had been created in annealing process, was investigated by positron annihilation spectroscopy and X-ray photoelectron spectroscopy. The traps were found to be located at both the TiN/SiO2 and SiO2/Si interfaces, and in the SiO2-bulk. The high-temperature annealing decreased the concentration of the traps in bulk SiO2 and at SiO2/Si interface. Backside X-ray photoelectron spectroscopy (XPS) analysis of TiN/SiO2 suggested the formation of titanium oxynitride (TiON) at the TiN/SiO2 interface, and the amount of TiON formation was reduced by high-temperature annealing. The number of traps at the TiN/SiO2 interface increased with high-temperature annealing, in the case of the increased TiN deposition temperature of 300 °C.