Technology Intimate Integration of VLSI circuits with Active Optical Elements: an Opto-Electronic VLSI Technology AraLight uses flip-chip bonding technology, which requires the placement of conductive solder "microbumps" on pads formed in the upper layers of metallization of a silicon VLSI circuit. This layer is typically already present in VLSI, and can be fabricated above active circuitry. Once these microbumps are formed, the chip can be attached to another wafer. The formation of these conductive microbumps creates an interface that enables the connection of the silicon VLSI circuit to another wafer. The microbumps not only serve the purpose of creating physical contact between the two wafers, but form a two-dimensional array of parallel electrical connections as well. AraLight's Enabling Photonic Flip-Chip Bonding Technology A number of challenges had to be overcome in order for flip-chip techniques to be used effectively with photonic circuits. While at Lucent Technologies Bell Laboratories, AraLight founders developed key processes to successfully integrate silicon VLSI and photonic circuitry using flip-chip bonding. Microbump Fabrication AraLight has developed a proprietary fabrication process that enables it to reduce the average size of its connection bumps by a factor of 25 to 100 relative to standard solder bumps. The company uses this process, which employs standard lithography techniques on standard equipment, to create a weld between transistor circuits and arrays of active optical devices that is smaller and more reliable than connections achieved by conventional techniques. Back Surface Substrate Removal AraLight has developed a back surface substrate removal process to enable flip-chip bonded VCSELs to transmit 850nm light freely. Using this patented technology, AraLight produces a photonic overlay, which allows optical interconnection without modification of the VLSI circuit. Integrated Opto-Electronic Solutions AraLight's key technologies and processes, covered by U.S. patents - microbump fabrication, flip-chip bonding and back surface substrate removal - combine the speed of optics with the processing power of silicon integrated circuits to form high-performance integrated opto-electronic subsystems.