Properties of thin Ta–N films reactively sputtered on Cu/SiO 2/Si substrates

Abstract

This work studied the thin film properties of 200 Å Ta and Ta–N films reactively sputtered on the Cu/SiO 2/Si substrates. The nitrogen atomic concentration in the Ta–N film was found to saturate at about 30%. Excessive sputtering gas flow, especially the N 2 gas, caused surface damage to the sputter deposited films. Thermal annealing in N 2 ambient at temperatures up to 700°C did not change the atomic concentrations and the chemical states of Ta and N in the Ta and Ta–N films. The thermal annealing resulted in the grain growth and the healing of sputter damage, but it also induced new defects in the Ta–N films due to thermal stress. This presents a reliability problem in process application involving high temperature thermal cycle.