Electrical characterization of flip-chip interconnects formed using a novel conductive-adhesive-based process

Using conventional microfabrication techniques, we have developed a new, low-cost wafer bumping process that enables a high degree of control over patterning of conductive adhesive interconnects. This approach obviates the need for development of dispensing and scraping head equipment that may otherwise be required for mass fabrication of lithographically patterned adhesive bumps. Flip-chip interconnects formed using this new process offer better electrical performance as compared to those formed by squeegee-based definition techniques. This is inferred in this paper by experimentally demonstrating lower contact resistance with the polished bumps as compared to the squeegeed bumps. Furthermore, in order to study the high-speed electrical performance characteristics of these conductive adhesive bumps, a 10-GHz 1.55-mum p-i-n photodetector fabricated in the antimonide material system was used as case study. The results from the bandwidth characterization of the polymer flip-chip-integrated detector showed minimum degradation in the high-speed performance characteristics of the detector