A thick photoresist process for advanced wafer level packaging applications using JSR THB-151N negative tone UV photoresist

Abstract

The development of thick photoresist molds using JSR THB-151N negative tone UV photoresist for the electroplating of interconnects in advanced packaging technologies has been demonstrated. Two different thick photoresist molds 65 and 130 µm high with aspect ratios of up to 2.6 have been fabricated with good reproducibility using single and double coating processes. Optimized lithography parameters using a UV aligner to achieve straight and near-vertical side-wall profiles are also reported. Near-vertical side walls similar to that obtained using SU-8 photoresist have been obtained. JSR photoresist has been found to be easily striped with no residues in solvent stripper solutions, making it suitable for wafer bumping applications and the processing of MEMS devices. Through-mold electroplating of copper and solder is also demonstrated. The simultaneous fabrication of 1167 000 high density interconnects on 8 inch wafers, using lithography and electroplating technologies, is also reported.