Evaluation and characterization of high-performance filling encapsulants for system chips application

An innovative Precisely Interconnected Chips (PIC) technology is currently under development at IBM to seek more effective means of creating system chips. This development focuses on developing fabrication methods to permit the realization of high yielding large area chips, as well as chips that may contain very diverse technologies. Another focus is to realize system chips which have their basic chip characteristics compromised as is the case in many of today´s system chip concepts. This paper reports on the use of a high performance filling encapsulant based on epoxy resin, which is used to connect the different chip sector macros that make up the system chip. This novel encapsulant remains thermally stable through the subsequent processing temperature hierarchies during the system chips fabrication. Spherical SiO₂ powders (with special morphology and size distribution) are incorporated into the epoxy resin to improve its mechanical properties, reduce coefficient of thermal expansion, and increase thermal conductivity. Adhesion and rheological properties of the formulated materials are evaluated. Microstructure of the filled Epoxy system is investigated to confirm the thermal reliability of the encapsulants. The formulated EPOXY A resin is qualified for manufacturing process based on the filling process, mechanical integrity, and thermal reliability