Recent status and future direction of EUV resist technology

The recent status of EUV resists is described based on experimental results using the small field exposure tool (SFET by EUVA/Canon) and full-field exposure tool (EUV1 by Nikon). Both exposure tools are linked to a coater/developer track system (Clean track ACT12 by Tokyo Electron) under a chemically controlled environment. The SFET, which was installed for the acceleration of the development of resist materials and processes, showed resist resolution limits of 25–26 nm half pitch (hp) lines-and-spaces (L/S). On the other hand, the EUV1, which is utilized to demonstrate that lithography integration, is a viable path to making EUV lithography a practical production technology, showed first static exposures with the resolution of 30 nm hp L/S and isolated lines and 30 nm holes. The potential resolution was found to be as good as 28 nm hp L/S. Based on these results; it was shown that progress was made regarding EUV resist resolution and sensitivity. However, accelerated improvement of line-width roughness (LWR) is still needed. The description of methods being developed to provide answers in the improvement of LWR is also discussed.