Evaluation of Resist Capability for EUV Lithography

• Published in: Journal of Photopolymer Science and Technology Vol. 19; no. 4; pp. 507 - 514
• Main Authors: Oizumi, Hiroaki, Tanaka, Yusuke, Shiono, Daiji, Hirayama, Taku, Hada, Hideo, Onodera, Junichi, Yamaguchi, Atsuko, Nishiyama, Iwao
• Format: Journal Article
• Language: English
• Published: Hiratsuka The Society of Photopolymer Science and Technology(SPST) 01.01.2006; Japan Science and Technology Agency
• Subjects: cholate derivatives; Derivatives; EUV lithography; Floods; Illumination; Inspection; Lithography; molecular resists; polyphenol; Polyphenols; Resists
• ISSN: 0914-9244; 1349-6336; 1349-6336
• DOI: 10.2494/photopolymer.19.507

This study had three goals. One is an evaluation of the ultimate fine-pitch patterning performance of our high-numerical-aperture (NA = 0.3) small-field exposure system (HINA). Another is development of an EUV flood exposure tool for investigating the development characteristics of EUV resists. The third is an evaluation of the lithographic performance of molecular resists using HINA and the flood exposure tool. An investigation of the ultimate resolution of HINA using coherent illumination (σ = 0.0) revealed that the smallest patterns delineated were dense 27-nm-wide lines in a non-chemically-amplified resist, and the resolution obtained was nearly equal to the resolution limit of HINA for three-ray interference. A polymeric chemically-amplified (CA) resist based on acetal-protected poly(hydroxystyrene) provided the best performance, with 28-nm-wide lines and spaces being delineated at an exposure dose of 10 mJ/cm2. Two CA positive-tone molecular resists were also tested. One is based on a low-molecular-weight amorphous polyphenol, namely 4,4'-methylenebis[2-[di(2,5-dimehtyl-4-hydroxyphenyl)methyl] phenol (25X-MBSA-P), and the other is a cholate derivative, 1,4-bis(methyloxymethylcholate) cyrohexane (C2ChDM). CA polyphenol resist provided a high contrast, a resolution of 30 nm at an exposure dose of 10 mJ/cm2, and a low LER of 6.2 nm (3σ) at an inspection length of 2000 nm. Finally, the CA cholate-derivative resist provided a resolution of 50 nm at an exposure dose of 14 mJ/cm2. Unfortunately, both molecular resists exhibited severe pattern collapse in dense fine-pitch patterns.