Alternative EUVL resist processes for stochastic defect reduction

Abstract

Investigations on the application of aqueous ethyltrimethylammonium hydroxide (ETMAH) as an alternative developer solution for extreme ultraviolet lithography (EUVL) were carried out. Utilizing a widely-used chemically amplified resist, it was found that the ETMAH developer solution has no negative impact on lithographic performance; resolution, line width / line edge roughness, and sensitivity (compared to the de facto standard aqueous tetramethylammonium hydroxide or TMAH). Stochastic defectivity analysis was performed by considering the effect of line-break (in the overdose region) and line-bridge defects (in the underdose region), on exposure latitude (ELX) and critical dimension or CD margin (CDMX). Results show that the ETMAH improves ELX and CDMX by around 10% and 5%, respectively at a lower developer solution concentration of 0.20N. These results confirmed the capability of the ETMAH in reducing resist-based stochastic defects, demonstrating its potential as an alternative developer solution for EUVL.