VCSEL/Micro LED Sacrificial GaAs Etch

Abstract:
During the manufacturing process for VCSEL’s and Mini/Micro LED devices, the majority of the GaAs substrate, on which the device is built, must be removed. As part of this process the device side of the wafer is bonded to a support substrate such as sapphire or glass. The GaAs wafer must then be removed from the device structure. This substrate can be partially removed by CMP to around 50-70um then etched away by chemical means. A thin etch hard stop layer typically 150nm is utilized to help protect the device structures as this GaAs substrate is removed. However etch uniformity, oxide formations and low productivity are serious challenges during this process.