Mcm Substrate with High Capacitance

It is well established that thin film capacitors have good electrical characteristics and for that reason are often used in high frequency applications. Unfortunately, it is also very difficult to form thin film capacitors on the relatively rough surface of cofired ceramics. We have investigated planarization of bottom capacitive electrodes which must make direct contact with a cofired ceramic surface, and adjustment and control of the T.C.E. difference between high dielectric constant material and the bass MCM ceramic substrate. Combining thin film capacitors with MCM substrates can result in high frequency decoupling capacitors (with 100X the capacitance of comparable cofired thin layer alumina constructions); space saving, and significant improvements in performance over conventional discrete chip capacitors.