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 BaTi5O11 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 (ɛr) 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 ɛr of 34–30 and dielectric loss of 0.025 ± 0.005 were obtained at 1–6 GHz.