Design and fabrication of hybrid optical receiver for free space optical interconnections using flip-chip bonding

The decrease in the feature size and the increase in the chip size due to the growth of integrated circuit complexity has led to an increase in the number of interconnections and the effective interconnect length, resulting in the shift of the main bottleneck of the system performance from the device delays to the interconnection delays. Optical interconnects have attempted to solve the interconnection problem at all architectural levels of electronic packaging including module-to-module, board-to-board, chip-to-chip and on-chip interconnections. The mounting of optical components, their relative orientation to the optical components, their precise alignment to the optical path, and compatibility with conventional packaging and interconnect technologies is the key to the realization of optical interconnects.; We show that a manufacturable and self aligned free space optical interconnect is achievable that is compatible with conventional packaging technology. The manufacturability issues of free space optical interconnects as related to alignment of microlenses to photodiode arrays is studied. The key manufacturing parameters have been determined through a design of experiments approach. The fabrication technology necessary to achieving alignment accuracy has been developed and prototypes have been fabricated.; The prototype hybrid optical receiver consisting of 2 x 2 microlens array, a 2 x 2 photodiode array, transimpedance amplifiers, and the associated passive circuitry is designed, fabricated and demonstrated. The photodiode array is bonded and aligned to the microlens array using self aligning flip-chip bonding technology. Also, the developed flip-chip bonding is utilized to study the interaction of the solder bond geometric parameters on the self-alignment accuracy. Furthermore, the PROM technique for microlens fabrication is developed and the effect of the manufacturing parameters on the optical parameters of the lens is studied experimentally.