A highly UV-light sensitive and sensitivity robust CMOS image sensor with a wide dynamic range (DR) was developed and evaluated. The developed CMOS image sensor includes a lateral overflow integration capacitor in each pixel in order to achieve a high sensitivity and a wide DR simultaneously. As in-pixel photodiodes (PDs), buried pinned PDs were formed on flattened Si surface. The PD has a thin surface p+ layer with a steep dopant concentration profile to form an electric field that drifts photoelectrons to the pinned n layer. This structure improves UV-light sensitivity and its stability. In addition, a buried channel source follower driver was introduced to achieve a low pixel noise. This CMOS image sensor was fabricated by a 0.18-μm 1-polycrystalline silicon 3-metal CMOS process technology with buried pinned PD. The fabricated image sensor has a high sensitivity for 200-1100nm light wave band, high robustness of sensitivity and dark current toward UV-light exposure and a wide DR of 97 dB. In this paper, the PD structures, the circuit, the operation sequence and the measurement results of this CMOS image sensor are discussed.
ASJC Scopus subject areas
- Physics and Astronomy(all)