Understanding and improving performance of 14-nm HP EUV lithography via rational design of materials

Abstract

Spin-on glass (SOG) underlayers to enhance extreme ultraviolet (EUV) lithography for patterning below 28nm pitch require an in-depth understanding of the required adhesion forces necessary for good lithography.Here, we proposed a fundamentally new SOG underlayer platform composed of polymer blends that can achieve superior uniformity to improve line fidelity and provide a design path for underlayer materials. The structure and property of elemental composition and surface energy can be controlled easily and precisely by varying the combination of polymer, and consequently understanding and tuning the lithographic performance. The lithographic performance of SOG blends was evaluated using NXE3400 EUV exposure system to print 13-nm and 14-nm HP line-space features and contact hole features with CD of 20 nm. The results show that the polymer blends expand the process window for EUV resist for line-space with printable CD >11 nm and biased LWR to 3.6 nm without impact on dose when compared to conventional copolymers. In the case of CH patterning, CDU and DOF improvements were observed when compared to conventional SOG copolymers. Systematic studies on polymer blends based on functional groups and formulation compositions are in progress to establish a better understanding of enhancement of EUV lithography.