Detection of Defects in EUVL Mask using Coherent EUV Source

Abstract

The detection and evaluation of printable defects in extreme ultraviolet lithography (EUV) masks are one of the most critical issues for high-volume manufacturing of next generation semiconductor. The coherent EUV scatterometry microscope is a strong candidate for high-precision inspection of defects. We have developed the high-order harmonics generation system to generate coherent EUV light using the commercial table-top laser system. The low beam divergence was measured to be 0.18mrad for 13.5nm (59th) high-order harmonics. The spatially coherent, 59th harmonics was improved the contrast ratio of diffraction images. Defect signals were observed from the 2-nm width line-defect in the 88-nm line-and-space (L/S) pattern and the 54-nm defect in the 360nm pitch pattern using coherent scatterometry microscope equipped with high-order harmonics generation system as a practical coherent EUV light source.