We report on the development of 3D silicon sensors at the University of Science and Technology of China (USTC). The sensor involves columnar electrodes (5 um in diameter) of both doping types, etched from the same wafer side. The p+ electrodes pass through the epitaxial wafer, whereas the n+ electrodes stop at a short distance from the opposite side of the epitaxial wafer. With respect to previous generations of 3D sensors, they feature an ultra-thin active substrate (50 um) and a small pixel size of 50 um x 50 um or 25 um x 25 um. This R&D project aims to establish a sensor technology to simultaneously measure position and time information at the single-pixel level. The first run with one merged wafer layout has been completed. The design, fabrication, and characterization of the sensors are reported in this paper.
@article{arxiv.2605.13281,
title = {Development of Small-pitch, Ultra-thin 3D Silicon Sensors at USTC},
author = {Kuo Ma and De Zhang and Shengjia He and Tian-ao Wang and Han Li and Yu Nie and Xiuxia Wang and Jinlan Peng and Zheng Liang and Xiang Li and Wenhua Shi and Manwen Liu and Chuan Liao and Zheng Li and Zebo Tang and Yanwen Liu},
journal= {arXiv preprint arXiv:2605.13281},
year = {2026}
}