A dual backside-illuminated 800-cell multi-channel digital SiPM with 100 TDCs in 130nm 3D IC technology

We report on the world's first backside-illuminated silicon photomultiplier (SiPM) implemented in 3D integrated circuit technology. The SiPM was fabricated in a two-tier 130nm CMOS process; the top tier houses 1600 single-photon avalanche diodes (SPADs), organized in a dual 4×200 linear array; the bottom tier houses 2×100 time-to-digital converters (TDCs). Every 8 SPADs there is one shared TDC whose digital output is routed to a 1.04Gps readout interface that enables a total count rate of 80Mcps. Preliminary results show a photon detection probability of 11% at a wavelength of 725nm and a dark count rate of 1kHz at room temperature and nominal excess bias, which reduces to 80Hz if cooled to −40°C at 2V excess bias; the breakdown voltage, Vbd, was measured at 12.3V. The sensor is intended for time-of-flight vision, wide-field near-infrared imaging, and lifetime fluorescence spectroscopy used in medical, particle detection, and material analysis applications.