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Influence of resist blur on resolution of hyper-NA immersion lithography beyond <inline-formula><math display="inline" overflow="scroll"><mrow><mn>45</mn><mtext>-</mtext><mi>nm</mi></mrow></math></inline-formula> half-pitch

2009; SPIE; Volume: 8; Issue: 1 Linguagem: Inglês

10.1117/1.3059551

1932-5134

Minoru Yoshii, Yasuhiro Kishikawa, Yuichi Iwasaki, Akinori Ohkubo, Miyoko Kawashima, Seiji Takeuchi, Tokuyuki Honda, Toyohiko Yatagai,

Integrated Circuits and Semiconductor Failure Analysis

For lithography of 45-nm half-pitch and beyond, the resist blur due to photoacid diffusion is a significant issue. On the other hand, it has been generally recognized that there is a trade-off between resist resolution and sensitivity. We study the influence of the resist blur on resolution in hypernumerical aperture ArF immersion lithography by utilizing a two-beam interferometric exposure tool. We evaluated the current photoresist performance for some of the latest commercial resists and estimated their acid diffusion lengths as 8 nm to 9 nm in sigma assuming Gaussian blur kernel. In addition, we found that the acid diffusion length, which is directly related to the resist resolution and is controllable by photoacid generator (PAG) anion size, polymer resin size, and post-exposure bake (PEB) temperature. We confirmed that there is a trade-off between resist resolution and sensitivity. Our results indicate that the resist blur is still a concern in order to extend lithography for 45 nm and beyond; however, it will not likely be a showstopper. We consider that total optimization of resists and exposure tools is important in order to achieve ultimate resolution in hyper-NA immersion lithography.