High density optical and electrical interfaces for chip-scale silicon photonic receiver

For use in a chip-scale-packaged parallel optical receiver module, a 125-μm-pitch oblique cone-shaped optical pin array has been developed as an input/output (I/O) interface, and a glass interposer with regularly-arranged 250-μm-pitch through-glass-vias has been developed as an electrical I/O interface. An 8°-tilted cone-shaped optical pin was fabricated by oblique illuminated photolithography. It successfully acts as a spot-size converter for the incident light from a GI 50 multimode fiber to an integrated Ge surface-illuminated photodiode. The glass interposer provides 100 electrical I/O pads, which are sufficient for 12-channel operation. Silicon photonic receiver chips with 1.8-μm-thick Ge photodiodes and Cu/polyimide redistribution layers have also been developed at a 300-mm wafer line. A 5 mm × 5mm optical I/O core receiver with these developed technologies demonstrated 25 Gbps/ch O-band multimode transmission.