Single-photon avalanche diode fabricated in standard 55†nm bipolar-CMOS-DMOS technology with sub-20†V breakdown voltage.

This paper presents a single-photon avalanche diode (SPAD) in 55 nm bipolar-CMOS-DMOS (BCD) technology. In order to realize a SPAD having sub-20 V breakdown voltage for mobile applications while preventing high tunneling noise, a high-voltage N-well available in BCD is utilized to implement the avalanche multiplication region. The resulting SPAD has a breakdown voltage of 18.4 V while achieving an excellent dark count rate of 4.4 cps/µm2 at the excess bias voltage of 7 V in spite of the advanced technology node. At the same time, the device achieves a high peak photon detection probability (PDP) of 70.1% at 450 nm thanks to the high and uniform E-field. Its PDP values at 850 and 940 nm, wavelengths of interest for 3D ranging applications reach 7.2 and 3.1%, respectively, with the use of deep N-well. The timing jitter of the SPAD, full width at half maximum (FWHM), is 91 ps at 850 nm. It is expected that the presented SPAD enables cost-effective time-of-flight and LiDAR sensors with the advanced standard technology for many mobile applications.

Noise optimization of single-photon avalanche diodes fabricated in 110 nm CMOS image sensor technology.

This paper presents the effect of shallow trench isolation (STI) on the dark count rate (DCR) and after-pulsing probability (APP) of deep-junction-based single-photon avalanche diodes (SPADs). Two different SPADs were fabricated in 110 nm CMOS image sensor technology, one with STI and the other without STI between its anode and cathode. With TCAD simulations and measurements, we have clearly demonstrated that the SPAD without STI enables a dramatic decrease in DCR by more than three orders of magnitude without suffering from the lateral leakage current between the anode and cathode. By excluding the STI from the device, the proposed SPAD also achieves a negligible APP while the SPAD with STI shows a very high APP of 92%. Thanks to the low-noise performance, the proposed SPAD becomes operable with higher excess bias voltage so that it achieves good photon detection probability, 58.3% at 500 nm and 3% at 940 nm, and timing jitter, 71 ps full width at half maximum at 670 nm, when the reverse bias voltage is 17 V.