A Near-Infrared Enhanced Silicon SPAD With Added P-Type Implant in High-Voltage PWell

A wide spectral response single-photon avalanche diode (SPAD) with near-infrared (NIR) enhancement is implemented in 0.18 μm Bipolar-CMOS-DMOS (BCD) technology. A deep multiplication region with a high-voltage p-well (HVPW)/buried n+ junction is devised to improve the responsiveness to NIR photons, meanwhile, a deep virtual guard ring by exploiting the less-doped epitaxial layer is employed to avoid the premature lateral breakdown. Especially, an added p-type implant in the HVPW is proposed for the significant enhancement in NIR photon detection probability (PDP) without process modifications. It is experimentally demonstrated that the improved structure achieves a peak PDP of 53 % at 600 nm and a NIR PDP of ~ 9.4 % at 905 nm with 5 V excess bias. Dark count rate (DCR) is as low as ~ 0.62 cps/μm ² and afterpulsing probability (AP) is lower than ~ 2.4 % at room temperature. The work provides a promising solution to realize NIR-sensitive silicon SPADs for time-of-flight measurement applications.