LARGE ARRAY OF GAAS MODULATORS AND DETECTORS FLIP-CHIP SOLDER BONDED TO SILICON CMOS USING INGAP AS THE SELECTIVE ETCH-STOP FOR GAAS SUBSTRATE REMOVAL

We demonstrate the integration of a large (64 x 68) p-i(MQW)-n GaAs di ode array to a silicon CMOS chip, using flip-chip solder bump bonding techniques together with concomitant GaAs substrate removal. The capab ility of removing a relatively large area of GaAs substrate cleanly an d uniformly is attributed to the introduction of a new selective etch stop with a smooth isotropic etchant for the GaAs substrate removal. T he presence of the lattice matched In0.49Ga0.51P selective etch stop l ayer has no detrimental effect on the performance of the GaAs/AlGaAs o ptical detector/modulator diodes, which gives the chip the large I/O c ount of 4352.