Repairing white and black defects in light phase displacement structured surfaces - by coating defect area with repair phases slide coating restoring the required phase displacement of the light

摘要

Method of repairing black defects (4) and white defects (7) in structural optical masks in which the area surrounding the black defect is coated with a repair phase slide layer (5) which is twice that of the phase slide layer (2) and in the case of the white defect is 3 times that of the phase slide layer (2). As the repair phase slide layer has the same refractory index as that of the phase slide layer the light passing through the repair phase slide layer including the black defect (4) is phase displaced by twice that of the light passing through the phase slide layer (2). In the case of a repair phase slide layer including a white defect (7) the light is displaced by 3 times. If the thickness of the phase slide layer is chosen so that it results in an 180 deg. phase displacement then the light through repair phase slide layer including black and white defects is respectively 360 and 540 deg.C. ADVANTAGE - Repairs defects in optical masks to restore their precise structural surface.