The contentious issue in ArF lithography is to reduce cost with multi-patterning process. To achieve low defectivity is required at high speed scanner for increasing throughput. Especially, demand of applying topcoat (TC) less process is being increasing recent year at using high speed scanner. The hydrophobic film surface is preferred because less immersion defect is caused without remaining water droplet in exposure. For positive-tone development (PTD) by using alkaline developer, the polarity-change property function of film surface from hydrophobic to hydrophilic after alkaline development process is key to reduce defectivity. High alkaline-responsive materials which were not only polymer additives but also copolymers as main component of resist have good potential to defectivity reducing. Additionally, to suppress swelling is one of very impotent factor to improve bridge type defect mode.

In 2019, finally, extreme ultraviolet (EUV) lithography has been applied to high volume manufacturing (HVM). However, the performance of EUV resist materials are still not enough for the expected HVM requirements, even by using the latest qualifying EUV resist materials. The critical issues are the stochastic issues, which will become ‘defectivity’. The analyzing summary of the stochastic factors in EUV lithography was reported, which described 2 (two) major stochastic issues, which are ‘Photon stochastic’ and ‘Chemical stochastic’. In the past, speaking of the stochastic issue was basically considered from low photon number from EUV light source, which means ‘photon shot noise’. It was still critical concerning point, even with recent progress on source power improvement. However, the stochastic issue is not only from them but also from EUV materials and processes, called ‘Chemical stochastic’. The ‘Chemical stochastic’ means caused from resist materials and processes for lithography, materials uniformity in the film, reactive uniformity in the film, and dissolving behavior with the developer. In this paper, we will focus on ‘Chemical stochastic’ improvement, especially, the dissolving behavior by using negative-tone imaging (NTI, using organic solvent-based developer) with EUV exposure (EUV-NTI). EUV-NTI had a potential for improving ‘Chemical stochastic’ because of their properties, which were low swelling and smooth dissolving behavior. However, the pattern collapse was easily observed for preparing fine patterns with the standard developer. Newly proposed novel formulated organic solvent-based developer will be expected to improve the patter collapse issue and ‘Chemical stochastic’. Lithographic performance will also be reported.

The main challenge in ArF lithography is to reduce cost of ownership (CoO) because increase in multi-patterning process is generally required to obtain a fine pattern. As a consequence, industry strongly requires ArF lithography process with a fast scan speed scanner and low defectivity material for CoO. The breakthrough technology to improve defectivity and resolution simultaneously was the polarity-change property of film surface from hydrophobic to hydrophilic after alkaline development process because a property after development process should be only associated with defectivity, not with fast scan speed. The materials with high polarity change function were explored to EUV process to achieve low defectivity with good lithography performances.

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