As the semiconductor industry continues to push the limits of integrated circuit fabrication, reliance on extreme ultraviolet lithography (EUVL) has increased. Additionally, it has become clear that new techniques and methods are needed to mitigate pattern defectivity and roughness at lithography and etch process and eliminate film-related defects. These approaches require improvements to the process chemicals and the lithography process equipment to achieve finer patterns. ESPERTTM (Enhanced Sensitivity develoPER TechnologyTM) technique has been developed and optimized to fulfil this novel development need. ESPERTTM has demonstrated a capability that can enhance the developing contrast between the EUV exposed and unexposed areas. This paper reviews 23 nm pitch line and space and sub-40 nm pitch pillars which were realized by optimized illuminators with 0.33 NA single exposure, and we will show how ESPERTTM helped improve the minimum critical dimension size, defectivity, roughness and electrical yield at the finer patterns.
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