3.2 Megapixel 3D-Stacked Charge Focusing SPAD for Low-Light Imaging and Depth Sensing
Kazuhiro Morimoto, J. Iwata, M. Shinohara, Hiroshi Sekine, A. Abdelghafar, Hiroyuki Tsuchiya, Yukihiro Kuroda, K. Tojima, W. Endo, Yu Maehashi, Y. Ota, T. Sasago, Shintaro Maekawa, Shingo Hikosaka, Taikan Kanou, Atsushi Kato, Tetsuo Tezuka, S. Yoshizaki, T. Ogawa, Kosei Uehira, A. Ehara, F. Inui, Yasushi Matsuno, Katsuhito Sakurai, T. Ichikawa
Abstract
We present a new generation of scalable photon counting image sensors, featuring zero read noise and 100ps temporal resolution. Newly proposed charge focusing single-photon avalanche diode (SPAD) is employed to resolve critical trade-offs in conventional SPAD pixels. A prototype 3.2 megapixel 3D-stacked backside-illuminated (BSI) image sensor with 1-inch format demonstrates the best-in-class photon detection efficiency (PDE), dark count rate (DCR) and timing jitter performance with the largest array size ever reported in avalanche photodiode (APD)-based image sensors. The proposed technology paves the way to compact and high-definition photon counting image sensors for low-light imaging and 3D time-of-flight sensing.