A new cost effective packaging technique for optoelectronic devices

Reports results in the optimization of the bonding parameters, with different diffusion barriers, new multilayer structures, metallization of the transfer membrane, as well as new applications of our bonding technique. The bonded samples were investigated with several standard surface analysis techniques as well as mechanical tests. We achieved important improvements in reliability, yield, and in the planarity of the bonded devices. For a further enhancement of the bonding quality and to reduce the mechanical stress, induced by the mismatch of the coefficients of thermal expansion of the bonding partners, we investigated an annealing technique. The main advantages of our technology are thin bonding layers attained with a minimum use of gold and an outstanding bonding quality succeeded in the large temperature range between 235/spl deg/C and 286/spl deg/C without flux. A thin, void free AuSn bonding layer means low thermal resistance, which is especially important for laser diodes and high power devices: The threshold current of semiconductor laser diodes is very temperature sensitive. Further advantages of our new technique are the attainable precise control of the bonding layer thickness, which means very reproducible thermal resistance.