Engineering Breakdown Probability Profile for PDP and DCR Optimization in a SPAD Fabricated in a Standard 55nm BCD Process

Abstract

CMOS single-photon avalanche diodes (SPADs) have broken into the mainstream by enabling the adoption of imaging, timing, and security technologies in a variety of applications within the consumer, medical and industrial domains. The continued scaling of technology nodes creates many benefits but also obstacles for SPAD-based systems. Maintaining and/or improving upon the high-sensitivity, low-noise, and timing performance of demonstrated SPADs in custom technologies or well-established CMOS image sensor processes remains a challenge. In this paper, we present SPADs based on DPW/BNW junctions in a standard Bipolar-CMOS-DMOS (BCD) technology with results comparable to the state-of-the-art in terms of sensitivity and noise in a deep sub-micron process. Technology CAD (TCAD) simulations demonstrate the improved PDP with the simple addition of a single existing implant, which allows for an engineered performance without modifications to the process. The result is an 8.8 &#x03BC;m diameter SPAD exhibiting ~2.6 cps/&#x03BC;m<formula> <tex>$^{2}$</tex> </formula> DCR at 20&#x00B0;C with 7 V excess bias. The improved structure obtains a PDP of 62 % and ~4.2 % at 530 nm and 940 nm, respectively. Afterpulsing probability is ~0.97 % and the timing response is 52 ps FWHM when measured with integrated passive quench/active recharge circuitry at 3V excess bias. Author