Blister formation in ZrN/SiN multilayers after He irradiation
Résumé
The work is dedicated to the investigation of blister formation in ZrN/SiNx multilayer films irradiated with He ions (30 keV) and annealed in a vacuum at 600 °C. Multilayer films were prepared by reactive magnetron sputter-deposition on Si wafers under Ar + N2 plasma discharges. ZrN/SiNx films were deposited by sequential sputtering from elemental Zr and Si3N4 targets at substrate temperature of 300 °C, with ZrN and SiNx layer thickness varying from 2 to 10 nm. According to transmission electron microscopy (TEM), the multilayer films consist of nanocrystalline (002)-oriented ZrN and amorphous SiNx layers. Surface morphology changes of ZrN/SiNx films irradiated with He ions (30 keV) and annealed in a vacuum at 600 °C were studied by scanning electron (SEM) and atomic-force microscopy (AFM) methods. It has been found that under He ions (30 keV) irradiation ZrN/SiNx multilayer films remain resistant to blistering and flaking up to fluence of 8·1016 cm−2. The investigations have shown influence of the crystalline and amorphous layer thicknesses on the character and damage degree of the multilayer films surface as a result of post-radiation annealing at 600 °C. In this work potential processes (mechanisms) of blister formation and flacking in ZrN/SiNx multilayer systems are discussed.