Multilayer ceramic packaging alternatives

The state of the art in multilayer substrates for integrated circuit (IC) packaging is reviewed. The characteristics, advantages, and disadvantages of the following materials systems are presented: αAl₂O₃, BeO, AlN, SiC, Si₃N₄ , BN, mullite, cordierite, glass-ceramics, low-K composites, and polymer systems such as polyimide. These are discussed in single dielectric configurations and more complex systems such as the thin-film multichip module (TFMCM), Si-on-Si wafer-scale integration (SOSWSI), and packaging schemes that incorporate passive components such as capacitors in the substrate. The following conclusions are drawn: (1) the package is less and less just a protective environment and more and more a key functional part of the entire electronic system; (2) the systems manufacturer will play an increasingly important role as the creator of the package; (3) the multichip module (MCM) will slowly be replaced by such schemes as SOSWSI and especially TFMCM; and (4) while Al₂O₃ will continue to dominate the materials field, a number of other materials will be increasingly used, especially AlN and SiC, wherethermal dissipation is key, and Cu/polymer systems, where low dielectric constants are required