Properties of thin Ta-N films reactively sputtered on Cu/SiO2/Si substrates

Abstract

This work studied the thin film properties of 200 Angstrom Ta and Ta-N films reactively sputtered on the Cu/SiO2/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 degrees 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. (C) 1998 Elsevier Science S.A. All rights reserved.