Novel silicon photomultiplier with high fill factor

We report the successful fabrication of a new silicon photomultiplier (SiPM) with the highest fill factor achieved to date. By utilizing a novel trench structure, a SiPM of 0.5 × 0.5 mm2 was designed and fabricated. The device consisted of 1024 micropixels, and a 70% fill factor was achieved for each of the 15 × 15 µm2 micropixels. The fabricated SiPM showed the desired characteristics for a fast photomultiplying device, namely, a rise time of ∼2 ns, a gain of 1 × 105-5 × 105, and a photon detection efficiency of ∼10% at the 470 nm wavelength. The details of the design, fabrication, and performance characteristics are presented together with the implications for the future development of SiPM-based imaging sensors.