Stress Control in Sputtered Silicon Nitride Films

Abstract

ABSTRACTWe show that stress in sputter-deposited silicon nitride films can be controlled, making either compressive or tensile stress films achievable. These films were deposited via reactive rf magnetron sputtering using an elemental Si target and N2 as a reactive gas in an Ar ambient. Variation of stress as a function of deposition pressure and N2/Ar gas mixture ratio was examined over a wider range of these two parameters than in previous work. More importantly, this parameter space includes conditions which produce near-stoichiometric Si3N4 films over a wide range of deposition pressures. We demonstrated that both low compressive stress and even tensile stress can be achieved at the proper deposition conditions. The film stresses as a function of deposition pressure or N2/Ar gas flow ratio are explained in the context of previously developed peening models.