Defect inspection on rare-earth garnet surfaces

Equipment was identified and modified for use as a rare-earth garnet-film surface-inspection tool. Filters complementing the absorbtion spectrum of the garnet, which are normally transparent to white light, were obtained and inserted into the optical path of an existing wafer inspection tool. Backside effects normally seen with incident white light were eliminated. Several detergents for possible use in a bubble-memory Chip processing line were evaluated. Cleaning operations used in the existing cleaning process were also evaluated using the modified tool. The inspection procedure results made it possible to select the best detergent and eliminate cleaning steps which actually introduced contamination.