High-density and high-quality frame transfer CCD imager with very low smear, low dark current, and very high blue sensitivity

When the channel width of an FET becomes of the same order of magnitude as the depth of the gate depletion region, an increase of the threshold voltage is observed. This narrow channel effect has been applied successfully in creating an asymmetric potential well under an electrode for two-phase CCD operation. The feasibility of this structure has been confirmed in a 242-element analog delay line. The application is now extended to a 800 H/spl times/492 V frame transfer-type buried channel CCD imager with 14.31818 MHz frame shift, which results in a very low smear level of 0.01%, which is good enough for low-cost multimedia video camera applications.