Evaluation of novel EUV mask inspection technologies

EUV lithography is regarded as the leading technology solution for the post-ArF era. Significant progress was made in recent years in closing the gaps related to scanner technology. This progress rendered EUV mask defectivity and related infrastructure as the primary risk for EUV lithography. The smallness of mask features, the novel defectivity mechanisms associated with the multilayer reflecting coating, and the stringent constraints on both multilayer and pattern imposed by the EUV wavelength - present a major challenge to current inspection technology, which constitutes a predominant gap to EUVL production-worthiness. Here we present results from an evaluation of a DUV mask inspection system and e-beam mask inspection technology on EUV masks. On this 193nm DUV system, we studied sensitivity and contrast enhancements by resolution enhancement techniques. We studied both pattern and blank inspection. Next, we studied image formation and performance of e-beam mask inspection technology for patterned mask defects. We discuss the advantages and roadmap of DUV and EBI mask inspection solutions for blank and patterned masks.