Recent Progress of Nonchemically-Amplified Resists for High-Resolution Lithography

Abstract

Advancements in high-volume manufacturing of semiconductors depend on the innovation of lithography technology to fabricate nanoscale features. As the key materials in lithographic processes, resists are of importance for high-resolution patterns. With the continuous shrinkage of critical dimensions, it is a great challenge for the traditional chemically-amplified resists (CARs) to resolve the sub-20 nm patterns due to their inherent acid diffusion blur. Nonchemically-amplified resists (n-CARs) started to attract renewed attention at about a decade ago, and have exhibited remarkable comprehensive performances on high-resolution lithography in recent years. They are considered as a promising candidate for next-generation lithography. In this review, recent progress of novel n-CARs is summarized, commented, and discussed according to the type of resist materials, which are classified as polymeric resists, organic molecular glass resists, and organic-inorganic hybrid resists. It focuses on the resist design strategy, the resist performance, and the relationship between the molecular structure and lithographic performance, providing our insights on the development of n-CARs for next-generation patterning materials. The outlook and trend of future resist studies are outlined and prospected as well.

Apropos high-resolution lithography for advanced device nodes, extreme ultraviolet lithography (EUVL) is one of the feasible technologies, also including e-beam lithography. Ekinci and co-workers have been dedicating to technologically developing the extreme ultraviolet (EUV) interference lithography tool since the 2010s, furnishing a credible platform to investigate the resolution limit of n-CARs. With the renewed emphasis of n-CARs and abundant discussions of high-absorption strategy, Ober's group pioneered the use of metal oxide nanoparticle resists in the 2010s. Brainard's group proposed the concept of molecular organometallic resists for EUVL, and started to establish novel platforms based on organic-inorganic hybrid materials in 2011. Then, Brouwer's group reported a substantial body of work on patterning and mechanism analysis of tin-oxo cage resists. In 2014, Gonsalves's group developed sulfonium-based n-CARs, providing a unique insight on photosensitive groups. In 2020s, Li and Yang et al. propelled deep explorations on polarity transition polymeric n-CARs and pursued pathfinding research on molecular n-CARs. Peng's group and Zhang's group respectively started to screen promising metal oxide clusters recently. Additionally, Xu et al. focus on comprehensive studies of zirconium-based resists. This review underscores the relationship between molecular structures and the lithographic performance of n-CARs for high-resolution lithography, which are divided into polymeric n-CARs, organic molecular glass n-CARs, and organic-inorganic hybrid n-CARs.

Keywords

Nonchemically-amplified resists / Polymers / Molecular glass / Organic-inorganic hybrid composites / E-beam lithography / Extreme ultraviolet lithography / High-resolution lithography / Nanotechnology

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