Publication Date

Spring 2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical and Materials Engineering

Advisor

Dahyun Oh; Oleg Kostko; Richard Chung

Abstract

The next generation of computer processors, memory, and nano-scale technologies all rely on our ability to create patterns at the nanometer scale reliably. Extreme ultraviolet (EUV) lithography can create sub-10 nm features by exposing photoresist materials, typically polymers or organic networks, to 13.5 nm, 92 eV light. At these energies, absorption of photons by the photoresist leads to the emission of a primary electron around 80 eV which inelastically scatters throughout the material, initiating chemistry and creating secondary electrons. The resulting cascade of electrons and chemical reactions remains poorly understood for most photoresist materials systems. This work aims to characterize the physical and chemical interactions of electrons within polymer films. The EUV primary and secondary electrons are simulated by directly bombarding the film surface with an electron gun with set energies within 20-80 eV. Exposures were completed on three polymers (polytert- butyl-methacrylate, poly-methyl-methacrylate, and poly-4-hydroxystyrene), one copolymer (Chaucer), and a novel peptoid resist provided by collaborators. Outgassing from the films was characterized during exposure using a quadrupole residual gas analyzer. The thickness changes were measured using ellipsometry and chemical bond structure data were collected using Fourier-transform infrared spectroscopy (FTIR) after exposure. Outgassing, FTIR, and thickness data related linearly, and the induced chemistry was found to decay exponentially with dose. Significant thickness loss in some samples was observed and a simple model was developed and found to agree with experiment.

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Available for download on Monday, February 16, 2026

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