Thermo-mechanical stress analysis of lamination-based silicon monolithic MCM-D substrates

Abstract

The thermo-mechanical behavior of multilayer structures is a subject of perennial interest. A vast literature exists on this topic. While some useful closed-form expressions have been developed under certain sets of assumptions and using different approximations, most of them are rarely supported by experimental investigation. Among various multi-layer structures, this dissertation provided a thorough investigation on the lamination-based thick-film multilayer substrates, or the multichip module (MCM) substrates. As an increasing number of layers were laminated, the thermo-mechanical behavior was measured layer-by-layer using a laser profilometry during thermal cycling. One of the key thermo-mechanical issues during the MCM-D substrate fabrication is substrate bowing, and another important con-cern is the thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). The thermal stress causes mechanical failure of films, such as adhesion reduction, contact peel-off, and variations in electrical properties, and the substrate bowing makes the fabrication process difficult, for example, vacuum mounting for handling and substrate sawing after fabrication. It also causes a stress concentration problem in internal structures such as via, and flip chip bump failure due to repeated thermal loading. Consequently, precise descriptions of the thermo-mechanical behavior of the thick-film multilayer substrates were necessarily required to realize high-density, high-yield, high-reliability, and low-cost MCM-D substrates. In Chapter 1, while the majority of reports in the literature have focused on single-layer analysis using the well-known Stoney````s formula, this chapter examined the extended usage of Stoney````s formula for the multilayer analysis. A simple model, the multilayer-modified Stoney````s formula, which predicts a stress contribution from each individual layer was proposed and verified through the numerical analysis and experiments using...