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26 May 2010 Effect of EUV exposure upon surface residual chemicals on EUV mask surface
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Proceedings Volume 7748, Photomask and Next-Generation Lithography Mask Technology XVII; 774804 (2010)
Event: Photomask and NGL Mask Technology XVII, 2010, Yokohama, Japan
Photo-induced defect for optic mask mainly depends on the surface residual ions coming from cleaning process, pellicle outgassing, or storage environments. Similar defect for EUV mask triggered by accumulated photon energy during photolithography process has drawn interest recently but this defect is somewhat different from normal photo-induced defect for optic mask. The photo-induced defect for EUV mask is known to be created by the chemical deposition of Carbon atoms originating from cracking of hydrocarbons by EUV light and secondary electrons on capping layer. It is very likely that Carbon contamination would be dominant under normal EUV exposure condition. On the other hand, it is expected that another kind of photo-induced defects would rise to surface under controlled environment where Carbon contamination growth is severely suppressed. We may have to understand the behavior of surface residual ions under EUV light in order to cope with another probable EUV photo-induced defect. In this paper, we will investigate whether surface ions remaining after cleaning process like sulfate or ammonium ions would create printable defects or decompose into evaporable species under EUV light. In case they create certain defects on mask surface, their effect on EUV reflectivity and absorber pattern CD variation will be also examined. Finally, improved cleaning process to impede photo-induced defect creation on EUV mask will be introduced.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Han-Shin Lee, Jaehyuck Choi, DonGun Lee, Hyungho Ko, SeongSu Kim, Chan-Uk Jeon, and HanKu Cho "Effect of EUV exposure upon surface residual chemicals on EUV mask surface", Proc. SPIE 7748, Photomask and Next-Generation Lithography Mask Technology XVII, 774804 (26 May 2010);

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