Terabit/s-Class 24-Channel Bidirectional Optical Transceiver Module Based on TSV Si Carrier for Board-Level Interconnects

We report here on the design, fabrication and characterization of highly-integrated 3-D Optochips consisting of a Si carrier platform with 4 flip-chip attached components: two 24-channel 850-nm optoelectronic (OE) arrays (VCSELs and photodiodes) and two 24-channel CMOS ICs (receivers and laser drivers). The Si carrier incorporates three copper wiring levels for interconnection between the CMOS ICs and the OE arrays, and a dense array of electrical through-silicon-vias (TSVs) for the off-carrier dc and high-speed electrical connections. In addition, to allow optical transmission through the silicon carrier, 150-mu m diameter "optical vias" (holes) are etched through the carrier at the locations of the optoelectronic array elements. The ICs and OEs are designed for 10 - 15 Gb/s operation to provide 48-channel modules with bidirectional aggregate bandwidths of 240 to 360 Gb/s. Optochips based on TSV Si carriers with flip-chip bonded ICs and OEs have been assembled using AuSn solder. DC characterization verified electrically and optically operative Optochips with 24 VCSELs and 24 photodiodes (PDs). Assembly of the Optochips to a high-speed, high-density organic carrier to form the full optical modules has also been developed and demonstrated. The Si carrier TSV technology is key to enabling the bonding of the Optochip to the organic carrier using a C4 solder process. Initial high-speed characterization of the complete module showed receiver channels operating at 12.5 Gb/s and transmitter channels operating up to 15 Gb/s. This is the first demonstration of Terabus optical modules with dense 24 TX + 24 RX transceiver Optochips based on TSV Si carriers.