Mask pattern correction to compensate for the effect of off-axis incidence in EUV lithography

This study investigated the feasibility of individual mask-pattern corrections to compensate for the effects of off-axis incidence and optical proximity effects for a reflective mask in EUV lithography. Individual mask pattern corrections for the effects of off-axis incidence are made by biasing, and then merged with conventional optical proximity effect corrections (OPC). This method provides good pattern fidelity in printed images on a wafer. Three evaluation functions were used to determine the amount of bias; they are related to the energy of the light reflected from a mask surface, the energy of 0th-order diffracted light, and the energy of light passing through the pupil. Merging to obtain the final corrected mask pattern allows the use of conventional OPC algorithms and is a simple method that is applicable regardless of the relationship between the direction of the incident light and the orientation of the edges of mask patterns.