Parametric Research on the Deep-Junction Silicon SPADs for Wide Spectral Response and Low Dark Count Noise

A wide spectral single-photon avalanche diode (SPAD) with near-infrared (NIR) photosensitivity enhancement was implemented in 0.18-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m bipolar-CMOS-DMOS (BCD) technology. To enhance the NIR photon detection probability (PDP), a deep high-voltage P-well (HVPW)/high-voltage buried N<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> layer (HVBN) junction was proposed. Meanwhile, a lightly doped P-type epitaxial layer associated with a shallow P-well (PW) guard ring was devised to prevent premature edge breakdown (PEB) and reduce the dark count rate (DCR). Through technology computer-aided design (TCAD) simulations, we investigated the impacts of the variation in the device parameters such as guard ring width (GRW), shallow trench isolation (STI) position, the overlap distance between the P<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> anode and the PW, and active area radius (AR) sizes on the performance of the deep-junction SPADs. It is experimentally demonstrated that after the optimization of device parameters was determined, the SPAD achieves a wide spectral response, with a peak PDP of 45% at 600 nm and an NIR PDP of 8.7% at 905 nm at an excess bias (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {ex}}$ </tex-math></inline-formula>) of 5 V. At <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T} = 27 \; ^{\circ }$ </tex-math></inline-formula>C, the DCR is as low as ~0.08 Hz/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, and afterpulsing probability (AP) is lower than 0.45% under a 700-ns dead time. The full-width at half-maximum (FWHM) timing jitter at 905 nm is 223 ps under <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {ex}}$ </tex-math></inline-formula> of 5 V. The SPAD device with the best performance can be applied in low-noise SPAD arrays in NIR imaging applications.