360×360 element three-phase very high frame rate burst image sensor: design, operation and performance

Design, fabrication, operation and performance are described for a 360×360 element very high frame rate (VHFR) image sensor that can capture images at a frame rate of up to 10⁶ frames/s. This VHFR imager has 50×50 μm macropixels, each consisting of a high-speed zero-lag photodetector with a 13.5% fill factor and 30 stages of serial-parallel type buried-channel CCD registers for storage and readout of the last 30 image frames acquired. Readout of this imager is similar to a frame transfer CCD consisting of four quadrants. Each quadrant contains one million pixels, readout at a relatively slow rate compatible with low readout noise, and PC class microcomputer-based data acquisition and storage. This imager is designed using SiO₂/Si₃N₄ gate dielectric, four levels of polysilicon, three levels of metal, eight implants, 21 photo masks using 1.5-μm design rules, and it has four output ports. The high-speed photodetector is designed in the form of a graded three-potential-level pinned-buried BCCD structure. This 33-μm long photodetector can achieve complete readout of photogenerated electrons in less than 0.1 μs