A 70-dB SNR High-Speed Global Shutter CMOS Image Sensor for in Situ Fluid Concentration Distribution Measurements

This article presents a global shutter (GS) high signal-to-noise ratio (SNR) and a high-frame-rate CMOS image sensor (CIS) for in situ fluid concentration distribution measurements using absorption imaging. The pixel consists of a ultraviolet (UV)-visible-near infrared (NIR) waveband pinned photodiode (PD) with high robustness against UV light irradiation for various measurement objects, two-stage lateral overflow integration capacitors (LOFIC) for high dynamic range and high SNR, and a voltage-domain memory bank for GS. The developed prototype CIS with 22.4- $\mu \text{m}$ pitch pixels exhibited 69.7-dB maximum SNR, 123-dB dynamic range, and 1000-frames/s maximum frame rate under single exposure GS and successfully captured images of dynamic movement of NO ₂ gas concentration distribution in the vacuum chamber for 300-mm-diameter wafers.