Material parameters of rf magnetron sputtered SiO2 thin films for temperature stable SiO2/LiNbO3 saw devices

SAW propagation characteristics, velocity and temperature coefficient of delay (TCD) of a 128degrees Y-X LiNbO3 SAW device integrated with an over-layer of rf magnetron sputtered SiO2 film have been studied. A deviation in the experimental observations with respect to the theoretical calculations on the layered structure SiO2/LiNbO3 are identified mainly due to the difference in the material parameters of the deposited SiO2 film. Influence of deposition conditions on the materials parameters Of SiO2 thin film have been studied, and the representative values of density, dielectric constant, elastic constants (C-11 and C-44) and their temperature coefficients have been determined, required for the design of a temperature stable SAW device.