Layer Transfer Process Development For SiGe Based Microbolometer Integration

This paper presents the transfer of the SiGe multi quantum well (MQW) layer stack on top of a CMOS wafer for the integration of a microbolometer device. Due to the limitations of a thermal budget for the post processing of a CMOS wafer, a full layer transfer of high temperature grown (>600 C) SiGe layers stack is transferred on BiCMOS wafer on 200 mm wafer level. The full process flow of the layer transfer based on oxide-oxide fusion bonding and the critical process steps for surface conditions of the wafers in terms of roughness and the edge trimming process before the final grinding are detailed. After the optimization of those process steps, a successful full layer transfer of the SiGe MQW layers on top of a BiCMOS wafer is demonstrated by the realization of a SiGe MQW based microbolometers.