Evaluation of repair methods for native defects on EUV masks

摘要

Current densities of native defects on EUV mask blanks are still higher than required for high-volume production. In order to yield defect-free masks, repair capability is needed for the reduction of native defects. Inconsistent printing behavior of native defects due to loss of reflectivity and change of phase has affected and influenced the whole EUV mask repair strategies. We have investigated a method for reducing the number of native defects on LTEM substrate by local polishing and proved the feasibility of multilayer modification repair using a thermal probe. A more effective compensation method has been investigated to reduce the phase difference and minimize the loss of reflectivity between the defect-free and phase-defect regions.