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Proceedings Paper

Impact of deformed extreme-ultraviolet pellicle in terms of CD uniformity
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Paper Abstract

The usage of the extreme ultraviolet (EUV) pellicle is regarded as the solution for defect control since it can protect the mask from airborne debris. However some obstacles disrupt real-application of the pellicle such as structural weakness, thermal damage and so on. For these reasons, flawless fabrication of the pellicle is impossible. In this paper, we discuss the influence of deformed pellicle in terms of non-uniform intensity distribution and critical dimension (CD) uniformity. It was found that non-uniform intensity distribution is proportional to local tilt angle of pellicle and CD variation was linearly proportional to transmission difference. When we consider the 16 nm line and space pattern with dipole illumination (σc=0.8, σr=0.1, NA=0.33), the transmission difference (max-min) of 0.7 % causes 0.1 nm CD uniformity. Influence of gravity caused deflection to the aerial image is small enough to ignore. CD uniformity is less than 0.1 nm even for the current gap of 2 mm between mask and pellicle. However, heat caused EUV pellicle wrinkle might cause serious image distortion because a wrinkle of EUV pellicle causes a transmission loss variation as well as CD non-uniformity. In conclusion, local angle of a wrinkle, not a period or an amplitude of a wrinkle is a main factor to CD uniformity, and local angle of less than ~270 mrad is needed to achieve 0.1 nm CD uniformity with 16 nm L/S pattern.

Paper Details

Date Published: 9 July 2015
PDF: 14 pages
Proc. SPIE 9658, Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII, 96580K (9 July 2015); doi: 10.1117/12.2197752
Show Author Affiliations
In-Seon Kim, Hanyang Univ. (Korea, Republic of)
Michael Yeung, Fastlitho Inc. (United States)
Eytan Barouch, Boston Univ. (United States)
Hye-Keun Oh, Hanyang Univ. (Korea, Republic of)

Published in SPIE Proceedings Vol. 9658:
Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII
Nobuyuki Yoshioka, Editor(s)

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