Study On Ferroelectric Thin Films Prepared By RF Magnetron Sputtering And Liquid Source Misted Chemical Deposition

Due to the pyro-, piezo-, ferro- electricity and the compatibility with planar technology of semiconductors, ferroelectric thin films are applied in a wide range of devices, including ferroelectric random access memories, pyroelectric infrared sensors infrared thermal imaging devices , electro-optic modulators , ultrasonic transducers. The perovskite PZT and BST ceramic targets are prepared. Pt/Ti bottom electrodes are prepared on SiO2/Si substrate by facing-target magnetron sputtering system. The PZT and BST ferroelectric thin films with perovskite are prepared on Pt/Ti/SiO2/Si substrate by RF magnetron sputtering. Electric hysteresis loop showed that coercive field (Ec), remnant polarization (Pr) and spontaneous polarization (Ps) of PZT thin films deposited in Ar ambience and annealed at 700oC are 50KV/cm, 10μC/cm2 and 13μC/cm2, respectively. Electric hysteresis loop showed that coercive field (Ec), remnant polarization (Pr) and spontaneous polarization (Ps) of BST thin films deposited in Ar ambience and annealed at 800oC are 100KV/cm, 5μC/cm2 and 12μC/cm2, respectively. Expermint results indicate that PZT thin film is disadvantage to turn into perovskite structure after RTA but BST thin film is advantage to turn into perovskite structure after RTA when O2 is introduce to the sputtering system. The effect on the PZT thin films electrical performance of the magnetron sputtering process parameters are studied by uniform experiment design. The linear quadratic regression equations are established by stepwise regression. Two most prominent factors in the linear quadratic regression equations are analyzed by three-dimensional respond surface figure. The effect on the PZT thin films surface morphography of different magnetron sputtering process parameters was studied by atomic force microscope. Experiment result indicate that the substrate temperature have little effect on the PZT thin films surface topography. The crystal size of PZT thin films increase with atmospheric pressure and sputtering power increasing. The crystal size of PZT thin films decrease with distance of target and substrate increasing. The Root Mean Square roughness and Mean roughness of PZT thin films decrease with atmospheric pressure and distance of target and substrate increasing. The Root Mean Square roughness and Mean roughness of PZT thin films increase with sputtering power increasing. Three kinds of different structure (BaxSr1-x)TiO3 ferroelectric thin films were prepared on Pt/Ti/SiO2/Si by liquid sourse misted chemical deposition. XRDshows that the thin films have good crystallization behavior and a perovskite structure. The surface morphography and crystal grain size of the BST ferroelectric thin film is analyzed by SEM. The crystal grain size of the BST is about 20-100nm. The ferroelectric hysteresis loops of three kinds of different structure (BaxSr1-x)TiO3 were measured. The coercive field (Ec), spontaneous polarization (Ps) and remnant polarization (Pr) of the BST gradient thin films of sample 3 is 100kV/cm, 12.5μC/cm2 and 7.5μC/cm2, As test frequency was 1 kHz, the dielectric constant (ε) and dielectric loss (tanδ) of BST gradient thin films is 526 and 0.06.