Abstract
The purpose of this thesis is focused on the characteristics of silicon nitride films on silicon wafer. The optical, surface roughness, the stress behaviors and mechanical properties were investigated under different processing parameters of RF magnetron sputtering; The effects of stress state and the coefficient of thermal expansion of SiNx films on magnetic properties of trilayer magneto-optical structure, SiNx/TbFeCo/SiNx,were studied. By changing the processing parameters, the composition, binding condition and the density of the films were varied. The refraction index of silicon nitride films depended strongly on deposition conditions. When the nitrogen content is decreased, refraction index is decreased due to the change of binding energy and the increase in film density. The surface roughness became larger for the films deposited at higher total pressure, higher Ar/N2 ratio or lower RF power. Due to the effect of gas scattering, and atomic peening, the stress state can be manipulated by changing sputtering parameters, film thickness, total pressures, Ar/N2 ratios and RF powers. For the measurement of coefficient of thermal expansion (CTE), MEMs technique - the microcantilever beams method, was used. According to the curvature change before and after thermal heating, the film CTE was obtained. The CTE values is strongly correlated to the magnitude of stress. Furthermore, the stress after thermal cycling was examined by bending beam methods. The stress was gradually changed from compressive state to tensile state. It is the result of different CTE values and thermal activation behaviors between the film and the substrate. Finally, the effects of different stress state of SiNx film on magnetic properties of trilayer magneto-optical structure were investigated. The trilayers with compressive stress in silicon nitride films have larger perpendicular anisotropy than those with stress tensile.