An interdisciplinary, group effort to synthesize, characterize, and optimize the properties of photosensitive and non-photosensitive polyimides for use as the multilayer dielectric for multi-chip module substrates has been proposed. The next generation of supercomputers will require an increase in speed. Unfortunately, since the residual stress in the dielectric increases with the number of layers, the reliability of the dielectric layer based on current polyimides will decrease. The increase in layers and the decrease in the width of the circuit paths necessitates the use of photosensitive polyimides which typically exhibit a reduction in properties. Thus, there is a pressing need to 1) produce polyimides with lower residual stress and 2) learn how to optimize a mechanical design utilizing these materials using structural analysis methods. First, DuPont will prepare a number of new, non-photosensitive polyimides that have low stress. Then, DuPont, IBM, UMass, and UNH will characterize the elastic, optical, and electrical properties using several new and several well established techniques. These properties will be used as input to IBM's finite element model of the multilayer dielectric to predict the stress level and hence the reliability of the new substrates. The effect of processing variables (heat, solvents, etc.) on the critical physical properties will also be determined. Once a suitable range of techniques and properties have been established, DuPont will synthesize photosensitive polyimides and the properties will be characterized again. Then, a model substrate will be fabricated by IBM and the thermo-mechanical performance will be characterized by UNH. The failure modes, if any exist, will also be observed at UMass using hot-stage optical microscopy. This combined interdisciplinary effort has been made possible by the recent advances in experimental methods to characterize thin film materials that have been pioneered at UNH
