Ultracompact 2.5-D Integration of RF Interfaces and Opto-Electronic Devices via Silicon Interposer

Abstract

This study presents a compact 2.5-D opto-electronic system-in-package solution based on a silicon interposer. This single package integrates opto-electronic chips, electrical chips, and directly soldered radio frequency (RF) interfaces (GPPO connector). This novel approach eliminates RF bond wires and enables direct connection between RF cables and optical chips, leading to a smaller form factor and improved signal integrity. Both single-ended and differential signal transmission lines are co-designed with the RF connector and patterned through wafer-level fabrication. The chips and connectors are connected via flip-chip bonding and solder reflow. Optical fiber is aligned through optical vias on the silicon interposer. In the demonstration, clear eye diagrams are achieved for both a vertical-cavity surface-emitting laser (VCSEL)-based optical transmitter and optical receiver. The directly modulated VCSEL exhibits a 106.25-Gb/s PAM4 eye diagram under a PRBS13Q pattern, while the receiver achieves a 25.78125-Gb/s NRZ.