The Influence of H sub(2) Plasma Treatment on LWR Mitigation: The Importance of EUV Photoresist Composition

To meet the demands for sub-20nm feature devices in the semiconductor industry, minimizing the line width roughness (LWR) is a critical concern for ultra-large scale integrated circuit manufacturing. Post-lithography treatments should reduce the LWR by at least 50% to meet the technology requirements, but the available post-lithography strategies come short. To support the delayed progress, an in depth understanding of the interaction of such post-lithography treatments with EUV-specific resist functionalities is required. In this article, we analyze the change in line widths and LWR's for 30-35nm lines using EUV photoresists. In addition we study the effect of the chemical composition on the reduction of LWR after hydrogen plasma treatment using "artificially" prepared reference resists. We highlight the effect of the fluorine unit, ester functionalities and photo acid generator/quencher loading on the LWR improvement and H sub(2) plasma induced reflow. The role of EUV photoresist chemistry and the importance of its additives, the fluorine group and ester functionalities, on line width roughness reduction after H2 plasma treatment is presented. Controlling the LWR has become a key challenge as the semiconductor industry pursues Moore's law towards smaller dimension. The effect of this treatment is evaluated and discussed for various line widths.