Advanced ceramic substrates for multichip modules with multilevel thin film interconnects

Two ceramic materials systems, cofired 99.6% alumina/tungsten and aluminum nitride, are presented as options for use as the base of a multichip module. The 99.6% alumina system addresses the limitations of conventional 90-94% alumina systems by providing ±0.2% dimensional control combined with a smooth, defect-free surface that is compatible with fine-line thin-film processing. In addition, the 99.6% alumina/tungsten system exhibits an enhanced flexural strength which the critical to producing large-area, thin-cross-section substrates designed to be compatible with automated silicon wafer handling equipment. The injection molded aluminum nitride produced using the binderless QUICKSET process is characterized by an average thermal conductivity of 230 W/m K with a standard deviation of 7.3. The controlled microstructure of the AlN material also produces a smooth, defect-free surface after lapping and polishing for thin-film compatibility. Precise dimensional tolerance control of ±0.2% for substrate features such as cavities or through-holes is also provided