Measurement technique of nontelecentricity of pupil-fill and its application to 60 nm NAND flash memory patterns

Various pupil-fill measurement techniques are evaluated to monitor non-telecentricity of an illuminator as followings: transmission image sensor (TIS) of ASML, source metrology instrument (SMI) of Litel, Fresnel zone plate (FZP) of Philips, and non-telecentricity measurement technique using traditional overlay marks, which is based on an idea that pattern shift is proportional to the amount of defocus. Based on aerial image simulation with measured non-telecentricity, its effect on sub-70 nm device patterning is discussed. Experimental data shows that some of pupil-fills appear more than 70 milli-radian of source displacement error and it may cause serious pattern shift and/or asymmetry. Detailed descriptions of measurement techniques and experimental results are presented.