Dependence of EUV Mask Printing Performanceon Blank Architecture

摘要

EUV lithography is the leading candidate for sub-32nm half-pitch device manufacturing. This paper deals with theinvestigation of the impact of the mask blank architecture on the wafer print by EUV lithography. Presently the materialstack on the mask is not fixed and different suppliers offer a range of variation. The purpose of the present paper is three-fold, as detailed hereafter. First it is shown that there are possibilities to make EUV masks less prone to reflectivity loss by carbon contamination.An estimate is given for the required limitations on mask contamination and fabrication tolerance to keep the imagingimpact below acceptable levels. These data can be used as preliminary error budgets for the individual and combinedcapping layer deterioration phenomena. Further-on, printing results on the Alpha Demo Tool (ADT) are reported, obtained with different reticles with identicallayout produced on blanks with different mask stacks. In preparation for this experimental work simulations have beenundertaken. The experimental results show good agreement in printing performance between the reticles tested. Finally, our work clearly shows the opportunity to reduce the absorber thickness without noticeable loss of contrast andwith the big advantage of shadowing effect reduction.