Optomodule Optocard Lens Array SLC CMOS IC OE’s Optomodule Optocard Lens Array Optocard Lens Array Lens Array SLC CMOS IC OE’s SLC CMOS IC OE’s CMOS IC OE’s OE’s 160-Gb/s Bidirectional Parallel Optical Transceiver Module for Board-Level Interconnects Using a Single-Chip CMOS IC Fuad E. Doany, Clint L. Schow, Christian Baks, Russell Budd, Yin-Jung Chang 1 , Petar Pepeljugoski, Laurent Schares, Daniel Kuchta, Richard John, Jeffrey A. Kash, Frank Libsch IBM T. J. Watson Research Center 1101 Kitchawan Road, Yorktown Heights, New York 10598 Email: doany@us.ibm.com, Tel: 914-945-2831, Fax: 914-945-4219 1 Present Address: Dept. of Elec. Eng., Georgia Institute of Technology, Atlanta, GA Roger Dangel, Folkert Horst, and Bert J. Offrein IBM Research GmbH, Säumerstrasse 4, 8803 Rüschlikon, Switzerland Abstract We report here on the design, fabrication and high-speed performance of a novel parallel optical module with sixteen 10-Gb/s transmitter and receiver channels for a 160-Gb/s bidirectional aggregate data rate. The module utilizes a single-chip CMOS optical transceiver containing both transmitter and receiver circuits. 16-channel high-speed photodiode (PD) and VCSEL arrays are flip-chip attached to the low-power CMOS IC. The substrate emitting/illuminated VCSEL and PD arrays operate at 985 nm and include collimating lenses integrated into the backside of the substrate. The IC-OE assembly is then flip-chip attached to a high density organic package forming the transceiver optical module. The exclusive use of flip-chip packaging for both the IC-to-optoelectronic (OE) devices and for the IC-to- organic package minimizes the module footprint and associated packaging parasitics. The OE-on-IC assembly achieves a high area efficiency of 9.4 Gb/s/mm 2 [1]. The complete organic carrier transceiver package provides a low- cost, low-profile module similar to a conventional chip-carrier that can be directly surface mounted to a circuit board using a conventional BGA solder process. SLC transceiver modules with transmitter and receiver OE-IC arrays were assembled and characterized. Operation of all 16 transmitters in the transceiver module was demonstrated at data rates >10 Gb/s. Similarly, all 16 receiver channels operated error-free at >10 Gb/s. The receiver eye-diagrams were generated using a second transceiver source and therefore constitute a full transceiver optical link. Introduction Advances in high performance computing and switch/router applications continue to drive the requirements for wider and higher-speed data buses. High performance chips and multi-chip modules are increasingly limited by off- chip or off-module bandwidth. Parallel optical interconnects offer the potential to meet the increasing interconnect bandwidth requirements of systems with higher speeds and multiple processors. Key challenges, such as power consumption, density, throughput and cost must first be met for the adoption of optical interconnects between processor modules on a single circuit board or boards interconnected through a backplane. Optical interconnects provide the additional benefit of supporting longer link lengths than electrical links. In the Terabus program, we are developing technologies for chip-to-chip (module-to-module) board-level interconnects that fulfill the speed, density, and power requirements that are capable of providing terabit/sec-class data transfer. Earlier, we reported the development of a chip- like optoelectronic packaging structure based on a silicon carrier that is assembled directly onto an organic circuit board with integrated waveguides (Optocard) [2]. The Si carrier provides a platform for heterogeneous integration of 48- channel CMOS chips and 48-channel optoelectronic (OE) devices using flip-chip bonding, and provides electrical through vias, high speed wiring and a cavity for the OE devices [3]. The Optocard incorporates 48-channel polymer waveguides on a 62.5-µm pitch with core dimensions 35 µm x 35 µm. In this paper, we describe the design and fabrication of a novel optical transceiver module that explores application of the Terabus OE-on-IC and on-card waveguiding technology to more conventional chip attachment processes. A single CMOS IC with flip-chip attached optoelectronic devices is mounted directly onto an organic chip carrier forming the transceiver optical module (Optomodule). The transceiver Optomodule provides a low-cost, low-profile module that utilizes key aspects of the Terabus technology: 1) high-speed, low-power CMOS analog amplifier circuits, 2) efficient, high- speed substrate illuminated/emitting photodiode (PD) and VCSEL arrays that operate at 985 nm, 3) exclusive use of flip-chip packaging to minimize both the module footprint and associated packaging parasitics. Transceiver: Design and Fabrication Figure 1. Transceiver Optomodule concept. The concept of the Terabus transceiver Optomodule is depicted in Fig. 1. OE arrays are flip-chip attached to the CMOS IC, which is then flip-chip attached to the organic 1-4244-0985-3/07/$25.00 ©2007 IEEE 1256 2007 Electronic Components and Technology Conference