Pixel Scaling Technology in CMOS Image Sensors with a Lateral Overflow Integration Capacitor

The relationship between the resolution and pixel pitch considering the optical diffraction principally caused by the lens circle aperture is discussed for the image sensor required to secure a high SNR and full well capacity for each pixel. The light diffraction of some high luminance patterns was calculated. We discuss the results for the optimization methodology of pixel pitch scaling considering the influence of the light diffraction. The performance of a CMOS image sensor with shared and small pixels and lateral overflow integration capacitor was developed based on our results. A CMOS image sensor consisting of 1/3.3 inch optical format, 3-μm pixel pitch and 1280 (H) × 960 (V) pixels was fabricated Using a 0.18-μm 2P3M CMOS technology with a buried pinned photodiode process. The sensor achieved 84μV/e- photo-electric conversion gain, 6.9×104e- full well capacity and 90 dB dynamic range in one exposure.