A new flip-chip bonding technique using micromachined conductive polymer bumps

Using micromachining techniques with thick photoresists, a new conductive polymer flip-chip bonding technique that achieves both a low processing temperature and a high bumping alignment resolution has been developed in this work. By the use of UV-based photolithography with thick photoresists, molds for the flip-chip bumps have been patterned, filled with conductive polymers, and then removed, leaving molded conductive polymer bumps. After flip-chip bonding with the bumps, the contact resistances measured for 25 /spl mu/m-high bumps with 300 /spl mu/m/spl times/300 /spl mu/m area and 400 /spl mu/m/spl times/400 /spl mu/m area were 35 m/spl Omega/ and 12 m/spl Omega/ respectively. The conductive polymer flip-chip bonding technique developed in this work shows a very low contact resistance, simple processing steps, a high bumping alignment resolution (</spl plusmn/5 /spl mu/m), and a lower bonding temperature (/spl sim/170/spl deg/C). This new bonding technique has high potential to replace conventional flip-chip bonding technique for sensor and actuator systems, bio/chemical /spl mu/-TAS, optical MEMS, OE-MCM's, and electronic system applications.