Techniques

A new heterogeneous integration technique has been developed and demonstrated to integrate vertical cavity surface emitting lasers (VCSELs) on silicon CMOS integrated circuits for optical interconnect applications. Individual oxide-apertured 850 nm Al-GaAs VCSEL micro-devices discs, 8 tm tall and 55 tm in diameter (pills), have been both bonded and electrically contacted within the dielectric stack of a commercially-fabricated silicon integrated circuit. To accomplish this, fully processed VCSEL de-vice pills are assembled within dielectric recesses using a vacuum pick up tool, and solder bonded in place using a method developed at M.I.T.. VCSELs device charac-teristic show threshold currents of 1 to 2.5 mA and thermal impedances as low as 1.6 *C/mW, similar to native substrate device impedances. This technique intimately connects devices within the dielectric stack, allowing for size independent, wafer scale monolithic processing of heterogeneous circuits. The size and placement of these de-vices prevent the stress build up that occurs in growth on non-native substrates due to thermal expansion mismatches. These same devices can be used in more paralle