Microwave dielectric properties of the BaTi₅O₁₁ thin film grown on the poly-Si substrate using rf magnetron sputtering

BaTi₅O₁₁ thin films were grown on the poly-Si/ SiO₂/Si substrate using rf magnetron sputtering. The BaO-TiO₂ thin film deposited on the poly-Si substrate had an amorphous phase even though the growth temperature was high at 550 °C. The amorphous film was crystallized into the BaTi₅ O₁₁ phase when the film was post annealed above 800 °C. The post annealing temperature is one of the most important factors for the formation of the crystalline BaTi₅O₁₁ thin film. The homogeneous BaTi₅O₁₁ thin film was obtained when the film was grown at 550 °C and rapid thermal annealed (RTA) at 900 °C for 3 min. The dielectric constant (ε_r) of the BaTi₅O₁₁ film measured at 100 kHz was about 35 and the dissipation factors of all the films were smaller than 4.0%. The dielectric properties of the BaTi₅O₁₁ thin film were also measured at microwave frequencies. For the BaTi₅O₁₁ thin film grown at 550 °C and RTA at 900 °C for 3 min, the ε_r of 34-30 and dielectric loss of 0.025 ± 0.005 were obtained at 1-6 GHz.