Reduction of lateral diffusion of photoelectrons in silicon photodiode imager arrays by internal gettering

The lateral diffusion of photoelectrons to adjacent picture elements in a silicon linear photodiode array is reduced in substrates with a high density of oxygen precipitates formed by internal gettering. The signal due to diffusion in adjacent pixels, normalized to the illuminated pixel signal, was reduced by a factor of 1.6 for pixels with centers 48 µm apart and by a factor of 10 for pixels farther apart; there was no significant decrease in sensor quantum efficiency. These results are interpreted with a numerical model that solves the three-dimensional diffusion equation for a substrate with different lifetimes in the surface and internal regions.