Optical diffraction-based methodology to measure on-product EUV exposure focus variations

Willem op 't Root; Jungwan Park; Youngsun Nam; Seho Kim; Hyunwoo Hwang; Jeong Heung Kong; Sang-Ho Yun; Youngseog Kang; Bram Klaassen; Karel van den Bos; Zhe Hou; Aileen Soco; Don Cheon; Jong-Hyuk Yim; Hong-seung Song; Mi-Yeon Baek

doi:10.1117/12.3010370

9 April 2024 Optical diffraction-based methodology to measure on-product EUV exposure focus variations

Willem op 't Root, Jungwan Park, Youngsun Nam, Seho Kim, Hyunwoo Hwang, Jeong Heung Kong, Sang-Ho Yun, Youngseog Kang, Bram Klaassen, Karel van den Bos, Zhe Hou, Aileen Soco, Don Cheon, Jong-Hyuk Yim, Hong-seung Song, Mi-Yeon Baek

Author Affiliations +

Proceedings Volume 12955, Metrology, Inspection, and Process Control XXXVIII; 129552Q (2024) https://doi.org/10.1117/12.3010370
Event: SPIE Advanced Lithography + Patterning, 2024, San Jose, California, United States

Conference Poster

Abstract

Stochastic printing variations are a challenge for EUV lithography and it is well known that these variations worsen if exposed out-of-focus because the EUV image contrast degrades. The introduction of 0.55NA will improve image contrast at a reduced depth-of-focus. This paper will describe how best focus planes differences between features can be used to design focus-sensitive metrology targets that can report EUV focus if used in combination with an optical metrology tool. Moreover, the developed target methodology ensures design rules compliance. The focus metrology target concept is experimentally demonstrated using a 24nm pitch line/spacer in combination with a low-n EUV mask absorber material, metal-oxide-resist (MOR), and a 0.33NA EUV scanner. The observed focus variation is modeled to quantify how much content is correctable using scanner feedback. This illustrates that on-product focus metrology can improve focus performance if combined with advanced process control.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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Willem op 't Root, Jungwan Park, Youngsun Nam, Seho Kim, Hyunwoo Hwang, Jeong Heung Kong, Sang-Ho Yun, Youngseog Kang, Bram Klaassen, Karel van den Bos, Zhe Hou, Aileen Soco, Don Cheon, Jong-Hyuk Yim, Hong-seung Song, and Mi-Yeon Baek "Optical diffraction-based methodology to measure on-product EUV exposure focus variations", Proc. SPIE 12955, Metrology, Inspection, and Process Control XXXVIII, 129552Q (9 April 2024); https://doi.org/10.1117/12.3010370

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