Sputter-deposited low loss Mg₂SiO₄ thin films for multilayer hybrids

Mg₂SiO₄ (forsterite) thin films grown by rf magnetron sputtering from a ceramic target have been investigated particularly for thin film hybrids requiring a low loss dielectric layer. Understanding of the processing parameters and their correlations to dielectric properties is the main concern of this work. Fundamental parameters, such as working pressure and post-deposition annealing temperature, were found to influence phase evolution, morphology and dielectric properties. For example, polycrystalline α-Mg₂SiO₄ could be obtained above the annealing temperature of 500 C regardless of working pressure. The dielectric constant increased gradually while the dielectric loss showed a reverse trend of decrease with raising annealing temperature to 700 C. Dielectric constant of ~ 6.8 and dielectric loss of ~ 2.8 × 10^{- 3} were obtained at 1 MHz from the sample annealed at 700 C. A promising planarized thin film structure for fine line multilevel packaging was demonstrated without any significant inter-diffusion and damages between Mg₂SiO₄ and Pt layers.