Next generation fine pitch Cu Pillar technology — Enabling next generation silicon nodes

There has been a growing need for fine pitch flip chip technology in support of next generation communication devices with increasing die complexities. The increase in functionality which drives a larger number of signal I/O's in combination with small die size requirements as a result of transistor size reductions have driven the need to investigate finer die interconnect pitches. Traditional solder or Cu Pillar interconnect pitches of 150um to 200um that are currently used in both low and high end flip chip applications are now facing a number of technical limitations as device scaling requirements push the limits of flip chip pad density per square mm of silicon. This paper will review the process development and advancement of several next generation fine pitch Cu Pillar bumping and assembly processes, with pitches less than 60um, that are focused on addressing the challenges seen on silicon nodes such as 65nm and beyond.