Back-Illuminated U-Shape p-i-n SPAD with High PDE and Broad Spectral Response Fabricated in 110nm CIS Foundry Technology

We present a novel U-shape p-i-n SPAD (U-SPAD) and demonstrate the device performance using a back-illuminated (BI) 110 nm CIS foundry technology. The proposed SPAD is designed for outstanding broad spectral response, achieving photon detection efficiency (PDE) of 23.4 % at $940 \text{nm}, 73.8 {\%}$ at 700 nm, and 50 % at 475 nm, dark count rate (DCR) of about $21.6 \text{cps} / \mu \mathrm{m}^{2}$, about 210 ps timing jitter, and 0.3 % afterpulsing probability (APP) at 21.5 V breakdown voltage and 1.6 V excess voltage. While high-performance SPADs generally require an optimized custom process, the proposed U-SPAD achieves high performance in a standard foundry process without any process modification.