Subresolution assist features in extreme ultraviolet lithography

Abstract

Lithographic critical dimension (CD) printing variability can be easily captured with a CD uniformity measurement; however, minimizing the variability is a challenging task that requires manipulation of many variables. Contact hole variability has a direct impact on device performance, while via variability affects metal area scaling and design. Subresolution assist features (SRAFs) have been used in the past to improve lithographic printing variability. SRAFs enhance the image log slope of nearby features but are not intended to print themselves. The role of SRAFs in extreme ultraviolet is explored here.