BLOOMING
When the maximum charge capacity of the CCD or photo-diode is exceeded, the excess charge will overflow into
adjacent CCD cells or photosites. This overflow of photogenerated charge is termed Blooming. The result of blooming
is a corrupted image near the blooming site. The extent of the image degradation is dependent on the level of excess
charge and on the architecture of the imager being used. The effects of blooming can be minimized by incorporating
an antiblooming structure near the charge collection site. Antiblooming structures are constructed so as to provide a
safe path for the excess photogenerated charge (i.e. blooming charge). Vertical antiblooming structures reside below
the charge collection site and allow excess charge to overflow directly into the substrate; whereas, lateral
antiblooming structures reside adjacent to the charge collection site and allow excess charge to overflow into a
reversed biased diode. Clocking schemes may be used to reduce blooming; however, these are less effective at higher
frame rates.