Actinic inspection of EUVL mask blank defects by photoemission electron microscopy: Effect of inspection wavelength variation

Lin J, Neuhaeusler U, Slieh J, et al. Actinic inspection of EUVL mask blank defects by photoemission electron microscopy: Effect of inspection wavelength variation. In: Microelectronic Engineering. MICROELECTRONIC ENGINEERING. Vol 84. ELSEVIER SCIENCE BV; 2007: 1011-1014.Extreme ultraviolet (EUV) photoemission electron microscopy (PEEM), which employs standing wave field illumination of a sample, is a potential tool for at-wavelength inspection of phase defects on extreme ultraviolet lithography (EUVL) mask blank. In this paper, we will demonstrate that the contrast of an underneath multilayer programmed defect in EUV-PEEM image is strongly dependent on the inspection wavelength. The observed contrast variation at different inspection wavelengths is in good agreement with the simulation result of a standing wave field on surface of multilayer stack in the mask blank sample. We also observed some native defects on the programmed defect sample, and found that some of them reverse their contrast with varying inspection wavelengths while others do not. (c) 2007 Elsevier B.V. All rights reserved

High-resolution actinic defect inspection for extreme ultraviolet lithography multilayer mask blanks by photoemission electron microscopy

Neuhäusler U, Oelsner A, Slieh J, et al. High-resolution actinic defect inspection for extreme ultraviolet lithography multilayer mask blanks by photoemission electron microscopy. APPLIED PHYSICS LETTERS. 2006;88(5): 053113.We report on the development and first experimental results of a "at wavelength" full-field imaging technique for defect inspection of multilayer mask blanks for extreme ultraviolet (EUV) lithography. According to the International Semiconductor Roadmap by Sematech, less than 5x10(-3) defects per cm(2) should be present on such multilayer mask blank to enable mass production of microelectronics using EUV lithography, thus fast high-resolution methods for mask defect inspection and localization are needed. Our approach uses a photoemission electron microscope in a normal incidence illumination mode at 13 nm to image the photoelectron emission induced by the EUV wave field on the multilayer mask blank surface. We show that by these means, buried defects in the multilayer stack can be probed down to a lateral size of 50 nm. (c) 2006 American Institute of Physics