Improving Etchability of Challenging Materials through the Ion Implantation Process

Abstract

Extreme ultraviolet lithography (EUVL) is employed in the mass production of advanced semiconductor devices, and the development of the high numerical aperture (NA) system for future 3 nm nodes is underway. However, the current tantalum (Ta)-based EUV masks face limitations in imaging performance for finer patterns, necessitating the exploration of alternative EUV mask absorbers. Furthermore, several promising absorber materials present challenges in etching during mask fabrication, leading to delays in their utilization. In this study, we propose a novel approach-the introduction of ion implantation processes in EUV mask fabrication to enhance the etching performance of absorber materials. We employed argon (Ar) ion implantation to enhance the etchability of platinum-tungsten (Pt-W) alloys. We not only acquired an implantation energy and dose condition that had negligible impact on film characteristics, but also confirmed that the etching rate of PtW increased by approximately 1.4 times after ion implantation, resulting in higher sidewall angles in patterns. In conclusion, the ion implantation process offers a practical solution for improving etchability without compromising film characteristics, demonstrating the potential for manufacturing EUV masks with absorbers featuring low etching performance.