It is well established that thin film capacitors have good electrical characteristics; for that reason they are often used in high frequency applications. We have investigated planarization of bottom capacitive electrodes which must make direct contact with a co-fired ceramic surface, and adjustment and control of the Thermal Coefficient of Expansion (TCE) difference between high dielectric constant material and the base MCM ceramic substrate. Combining thin film capacitors with MCM substrates can result in high frequency decoupling capacitors (with 100/spl times/ the capacitance of comparable co-fired thin layer alumina constructions), space savings, and significant improvement in performance over conventional discrete chip capacitors. >