T. Satoh et al., OPTICAL LIMITATIONS TO CELL-SIZE REDUCTION IN IT-CCD IMAGE SENSORS, I.E.E.E. transactions on electron devices, 44(10), 1997, pp. 1599-1603
We have determined the practical limits of cell size reduction in inte
rline-transfer charge-coupled device (IT-CCD) image sensors, limits re
sulting from diffraction occurring at the aperture above the photodiod
e. We have found that image cell size cannot be reduced to a level for
which aperture width would fall below about 0.2 mu m. We have also fo
und, however, that image cells with greater than 0.2 mu m aperture siz
e are sensitive over the entire wavelength range of visible light, and
that sensitivity can be increased by thinning the photoshield film.