A Novel Anti-ESD-Enhanced Single Photon Avalanche Diode for Industry-Level Fluorescence Detection

The application environment of industry-level fluorescence temperature sensors is harsh, posing a significant threat to the reliability of the detectors. To address this issue, this article proposes a novel anti-ESD-enhanced single photon avalanche diode (AESPAD) that directly couples photoelectric conversion and electrostatic discharge (ESD) protection at the structural level. Technology Computer Aided Design (TCAD) simulation is used to verify the working mechanism of the device. AESPAD is achieved through a $0.18 \mu \text{m}$ bipolar-CMOS-DMOS (BCD) process. Photoelectric characterization and transmission line pulse (TLP) test results show that the normal operating voltage range of the device is between 12.2 and 15.2 V, the threshold voltage for ESD protection is greater than 19.2 V. When the excess bias voltage is 3 V (15.2 V), the dark count rate (DCR) of AESPAD is 29.67 Hz/ $\mu \text{m}^{{2}}$ . The photon detection probability (PDP) reaches 48.3% at a wavelength of 480 nm. ESD protection remains off during normal device operation. When the electrostatic pulse comes, the silicon-controlled rectifier (SCR) inside the device turns on and quickly forms a low-resistance path to discharge the ESD current. The trigger voltage ( ${V}_{\text {t1}}$ : 20.55 V) and the holding voltage ( ${V}_{\text {h}}$ : 18.36 V) of the SCR both meet the ON-chip protection requirements of SPAD, and its equivalent Human-Body-Model (HBM) level exceeds 12 kV.