Aberration Budget in Extreme Ultraviolet Lithography

摘要

It seems that the actual EUV lithography tools will have aberrations around ten times larger than those of the latest ArF lithography tools in wavelength normalized rms. We calculated the influence of aberrations on the size error and pattern shift error using Zernike sensitivity analysis. Mask-induced aberration restricts the specification of aberration. Without periodic additional pattern, the aberration to form 22 nm dual-gate patterns was below 8 mλ, rms. Arranging the periodic additional pattern relaxed the aberration tolerance. With periodic additional pattern, the aberration to form 22 nm patterns was below 37 mλ, rms. It is important to make pattern periodicity for the relaxation of the aberration specification.