A Back-Illuminated 10 μm-Pitch SPAD Depth Sensor with 42.5% PDE at 940 nm using an Optimized Doping Design

We present a novel single-photon avalanche diode (SPAD) pixel array designed for accurate distance measurement with a high photon detection efficiency (PDE). This study was conducted with a SPAD depth sensor of 10 μm-pitch with the back-illuminated (BI) structure on a 300 mm CMOS platform. To enhance PDE, we optimized the multiplication region design to increase the triggering probability for the Geiger mode, achieving a 92.9% with 3 V excess bias. Additionally, by introducing new doping, enabling a more efficient charge collection, we have achieved a 98.8% charge collection efficiency. Consequently, in the Si-type SPAD technology, we achieve the world's highest PDE of 42.5% at 940 nm.