Effect of processing conditions on residual stress in sputtered transition metal nitrides (TiN, ZrN and TaN): Experiments and modeling

Abstract

Stress evolution during reactive DC magnetron sputtering deposition in TiN, ZrN and TaN films at different growth rates, pressures and relative gas flow rates was measured by a wafer curvature technique. The results indicate that, for a given growth rate, the stress in each material is tensile at higher pressures and becomes more compressive with lower pressures. At lower pressures, the stress tends to become more compressive with increasing growth rate. Increasing the gas flow rate of N2 relative to Ar is observed to enhance compressive stress generation in TaN but has a weaker effect on TiN and ZrN. At lower pressure, the compressive stress magnitude scales with TiN < ZrN < TaN. The stress at different processing conditions was analyzed in terms of a kinetic model that includes the effects of growth kinetics and energetic bombardment. The resulting parameters are compared with calculations from binary collision Monte-Carlo simulation codes.