Three-dimensional cliff analysis method for defining patterning resolution in EUV lithography

BackgroundAs the semiconductor industry pushes the boundaries of extreme ultraviolet lithography (EUVL) for advanced node semiconductor chips, the performance of extreme ultraviolet (EUV) photoresists (PRs) becomes increasingly critical in determining patterning resolution and overall chip quality. However, traditional evaluation methods for EUV PR patterning performance are struggling to keep pace with tightening scales, necessitating innovative approaches.AimTo this end, we propose a three-dimensional (3D) cliff analysis method that leverages after development inspection scanning electron microscopy images to visualize and quantify EUV PR resolution in three-dimensional ways.ApproachThis approach enables the precise characterization of stochastic failure defects such as bridge/break and missing/merging, offering unprecedented insights into PR performance based not only on the dose but also on the focus metrics.ResultsThis 3D cliff analysis method is applicable to both line/space and contact/hole patterns and can be used to assess not only defects but also other factors such as line width roughness and local critical dimension uniformity (LCDU).ConclusionsOur results demonstrate that the 3D cliff analysis method provides a comprehensive understanding of EUV PR behavior, enabling the optimization of patterning processes and improved chip yields. This approach has the potential to significantly enhance the development of EUVL and contribute to the advancement of high numerical aperture EUVL.