A low-noise wide dynamic range CMOS image sensor with low and high temperatures resistance

A temperature-resistant 1/3 inch SVGA (800×600 pixels) 5.6 μm pixel pitch wide-dynamic-range (WDR) CMOS image sensor has been developed using a lateral-over-flow-integration-capacitor (LOFIC) in a pixel. The sensor chips are fabricated through 0.18 μm 2P3M process with totally optimized front-end-of-line (FEOL) & back-end-of-line (BEOL) for a lower dark current. By implementing a low electrical field potential design for photodiodes, reducing damages, recovering crystal defects and terminating interface states in the FEOL+BEOL, the dark current is improved to 12 e^-/pixel-sec at 60 deg.C with 50 % reduction from the previous very-low-dark-current (VLDC) FEOL and its contribution to the temporal noise is improved. Furthermore, design optimizations of the readout circuits, especially a signal-and-noise-hold circuit and a programmable-gain-amplifier (PGA) are also implemented. The measured temporal noise is 2.4 e^-rms at 60 fps (:36 MHz operation). The dynamic-range (DR) is extended to 100 dB with 237 ke^- full well capacity. In order to secure the temperature-resistance, the sensor chip also receives both an inorganic cap onto micro lens and a metal hermetic seal package assembly. Image samples at low & high temperatures show significant improvement in image qualities.