Fabrication of deep vias/grooves as interconnection path by wet etching for wafer level packaging of GaAs based image sensor

摘要

GaAs wet etching was utilized for through substrate vias/grooves fabrication in wafer level packaging of GaAs based image sensor. In this work, GaAs wet etching was carried out on (100)-oriented substrates with PR mask as well as SiO2 mask. Three kinds of etching system i.e. (A) 1H2SO4 + 8H2O2 + 1H2O, (B) 9H3PO4 + 1H2O2 + 20H2O, (C) 1K2Cr2O7 + 1HBr + 4CH3COOH are tested at room temperature. Mask pattern of different shapes, dimensions and orientations for vias and grooves were designed. The etching for deep grooves was also carried out on thinned GaAs/Glass bonding substrate from the back side of the device. And some critical issues and problems were also discussed.