3.2 Megapixel 3D-Stacked Charge Focusing SPAD for Low-Light Imaging and Depth Sensing

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.