Development of aluminum compatible photoresist stripper for high density pillar bump technology

Reported in the paper are our recent efforts in developing stripper formulations that are specifically designed for aluminum compatible photoresist stripper in high density pillar bump technology. Through the passivation mechanism of both Al and Cu, strip formulation utilizing a delicately designed inhibitor system is found to be competent to control the etch rate below 3Å/min under given conditions. The wetting behavior in Cu and Sn/Ag is also studied. The contact angle is <;10° on Cu substrate, which also shows a complete wetting on the Sn/Ag surface. All those characters above induce effective cleaning capability for dry film photoresist with good substrate protection in high density pillar bump technology.