Characterization of barium strontium titanate thin films for tunable microwave and DRAM applications

Ba0.5Sr0.5TiO3 thin films have been deposited on Pt/TiO2/SiO2/Si substrates by the pulsed laser deposition technique (PLD) while varying the temperature, oxygen pressure, substrate to target distance and laser energy. The structural characterization of the BST thin films was performed by X-ray diffraction (XRD) and atomic force microscopy (AFM). The electrical characteristic of the capacitors was assessed by the vector network analyzer (VNA). A tunability of 3.1:1 and loss tangent of 0.0121 were achieved at 0.4-0.8 GHz for tunable microwave applications. The effect of using strontium ruthenium oxide (SrRuO3) as electrodes for BST has been explored for DRAM applications. The SrRuO3 film was deposited by PLD and was used as bottom and top electrodes. The BST-based capacitors show reasonable dielectric constants and thus have been proven to be very reliable memory devices.