Substrate Defect Smoothing of EUVL mask blanks using TaSiN Films

摘要

Substrate or phase defects on EUVL masks are considered non-repairable because they lie underneath or are imbedded in the multi-layer mirror. One defect specification requires that no more than three defects greater than 80-nm can be present on a starting substrate. Finding and removing these small defects before multi-layer deposition can be very difficult tasks. It has been shown that very small defects can have an influence on the patterned absorber stack and the printed image from an EUVL system. Substrate defect mitigation using TaSiN smoothing layers has been investigated. Programmed Cr defects were formed using standard semiconductor processing techniques and subsequently buried by the defect mitigating film. Experimental results are presented showing that a sputtering process can be used to deposit very smooth and thick TaSiN films (i.e. less than 0.2-nm RMS surface roughness and greater than 1.5-microns thick) as a substrate defect mitigation layer.