Improvement in Etching Rate for Epilayer Lift-Off Application with Low Surface Tension Fluid

Abstract

In this study, GaAs epilayer is quickly separated from GaAs substrate by epitaxial lift-off (ELO) process with mixture etchant solution. The HF solution mixes with low surface tension fluid as mixture etchant solution to etch sacrificial layer. The pattern array is not only used as etching path for the selective wet etching of AlAs sacrificial layer, but also used to define the cell size. The release time depends different the concentration ratio of mixture etchant solution and cell size. The concentration ratio of 1:1 mixture etchant shows the fastest lateral etching rate (13.2 μm/min) for 1 mm2 cell size. It is because HF mixture etchant solution provides hydrophilicity to modify the surface tension energy between GaAs epilayer and GaAs substrate. The low surface tension fluid enhances the fluid properties of the mixture etchant between GaAs epilayer and GaAs substrate. The results indicate that etching ratio and stability are improved by mixture etchant solution.