Functional graded high-K (Ba1-xSrx)TiO3 thin films for capacitor structures with low temperature coefficient

The high dielectric constant of perovskite-type alkaline earth titanates ma kes them attractive for use in integrated thin film capacitors for microwav e circuits. The application temperatures of those devices such as resonator s, filters and phase shifters range from cryogenic temperatures for superco nducting devices up to 250 degrees C for semiconducting ICs. Significant ma terial modifications have to be introduced to bring the pure components suc h as BaTiO3 and SrTiO3 into formulations which have a suitable temperature coefficient of the dielectric constant. For conventional powder based indus trial processes, usually solid solution adaptations and heterogeneous mixtu res are employed. The deposition processes of thin films, especially the low cost Chemical So lution Deposition (CSD) technique, offer the possibility to build thin film s of graded compositions. We will show that in those films the composition gradient can be tailored in order to fit the designated temperature charact eristics.