Heterogeneous Integration of Thin-Film Optical Devices Utilizing Fluidic Self-Assembly and Micro-Pick-and-Place Technique

This paper demonstrates the heterogeneous integration of thin-film photonic devices onto a silicon-based host substrate by the combination of surface tension-driven fluidic self-assembly (FSA) and modified micro-pick-and-place (PAP) technique. FSA offers self-alignment and integration capability of thin-film devices onto a host substrate with high precision, while the PAP technique provides an efficient guiding mechanism by coarse positioning of the device and improves efficiency and yield of the integration by overcoming the stochastic limitation of FSA. An array integration of thin-film GaAs metal–semiconductor–metal photodetectors (PDs) onto a silicon-based host substrate has been successfully demonstrated with the proposed integration approach. Electrical measurement was performed to confirm the metal-to-metal contact between the integrated PD and its substrate. Misalignment of the PD from the optimal desired location was also analyzed. In addition, specific contact resistance of the Au-to-Au bonding was investigated. The proposed integration method can be further developed with the help of a high-speed automation technique for PAP to be compatible with batch wafer processing.