INSITU STRESS MEASUREMENTS OF ION-ASSISTED MGF2 AND SIOX THIN-FILMS

An in situ stress measuring interferometer and in situ ellipsometer have been used to study the stress evolution and optical properties of MgF2 and SiO(x) optical thin films prepared by electron beam evaporation and 100 eV O2+ ion-assisted deposition (IAD). The maximum stress observed in thermal evaporation of MgF2 was found to be 240 MPa. The tensile stress in evaporated MgF2 could be modified by IAD to compressive stress. The optical properties and stress of SiO(x) were modified by IAD and also by the presence of a partial pressure of oxygen. The combination of stress interferometry and ellipsometry is shown to be a powerful method of monitoring and controlling the properties of optical materials deposited by IAD.