The principal driver behind advanced hardware development in the communications and computer industries can be reduced to an optimal set of parameters related to performance, cost and reliability. High performance systems typically have high functional density. For example, the continuing trend of VLSI is toward reduced feature size, increased wiring density and larger chip size to achieve increasingly higher levels of on-chip functionality. At some point in the cost structure, however, the single chip solution is no longer viable, and monolithic integration gives way to hybrid integration. In this respect, the multichip module fills a void in the packaging/ integration hierarchy between the ever-larger single chip and the printed wiring board.
An analogous situation is emerging in optoelectronics. The single chip package with its relatively low system functionality and high cost is giving way to the multi-technology module that integrates optical and electronic functions within a single package. One of the most interesting approaches to the multi-technology module uses a silicon substrate as the platform for hybrid integration of electronics and optoelectronics. It will be argued that this “silicon waferboard” approach is the cost-effective route to manufacturability of high-performance modules for communications and computer systems. Enhanced reliability follows from applying standard IC processing technology at the platform level in the packaging hierarchy.