"Incorporating iodine as a sensitivity-boosting agent in polypeptoid photoresists for extreme ultraviolet lithography"

Cameron P. Adams^a, Chenyun Yuan^b, Qi Zhang^c, Oleg Kostko^c, Christopher K. Ober^b, Rachel A. Segalman^a

^aUniversity of California, Santa Barbara
^bCornell University
^cLawrence Berkeley National Laboratory

Polymers have long played a crucial role in patterning silicon to create microelectronic devices. However, as state-of-the-art “extreme ultraviolet” (EUV, 13.5 nanometer wavelength) photolithography tools now allow for the patterning of sub-10 nm features, polymeric photoresists are hindered by significant challenges with stochastics and sensitivity. To address these issues, we have developed polypeptoid-based photoresists as a platform to investigate the effects of polymer sequence and dispersity on patternability. In traditional polymeric systems, dispersities in molecular weight, composition, and sequence are unavoidable due to synthetic limitations. These are compounded by both material heterogeneities in photoresist formulations and poor EUV photon absorption which contribute to patterning defects that can cause chip failures. Sequence specificity of the peptoid system eliminates these variations between polymer chains, enabling precise study of the effects of sequence and dispersity on patternability. Additionally, incorporating halogens into peptoids allows us to probe the impacts of strongly EUV-absorbing elements on photoresist sensitivity at industrially relevant conditions.