Methods are disclosed herein for determining the laser beam size and the scan pattern of laser annealing when fabricating backside illumination (BSI) CMOS image sensors to keep dark-mode stripe patterns corresponding to laser scan boundary effects from occurring within the sensor array regions of the image sensors. Each CMOS image sensor has a sensor array region and a periphery circuit. The methods determines a size of the laser beam from a length of the sensor array region and a length of the periphery circuit so that the laser beam covers an integer number of the sensor array region for at least one alignment of the laser beam on the array of BSI image sensors. The methods further determines a scan pattern so that the boundary of the laser beam does not overlap the sensor array regions during the laser annealing, but only overlaps the periphery circuits.