Event
CHBE Seminar: Dr. Daniel Sunday, NIST
Friday, October 10, 2025
11:00 a.m.
Room 2108 Chemical and Nuclear Engineering Building
Patricia Lorenzana
301-405-1935
plorenza@umd.edu
"Characterizing Structure and Chemistry in High NA EUV Photoresists with Novel X-ray Methods"
Abstract: the transition to extreme ultraviolet (EUV) lithography for semiconductor manufacturing brings new challenges for lithographic materials including photoresists and underlayers. Chemically amplified resists (CARs), based on a polymer with a labile group, a photoacid generator and quencher, are the backbone of 193 nm processing and are still in use with EUV patterning. However, CARs are expected to reach limitations with future technology nodes unless there are improvements in the ability to control their compositional uniformity at the nanometer level. Furthermore, there are still questions about the mechanistic behavior of these resists, which makes them challenging to optimize. Metal oxides are a candidate for replacing CARs, as they have shown better ability to print features at smaller length scales with reduced roughness. Despite their promise, metal oxides have challenges including high doses, environmental sensitivity and stability during storage. Furthermore, while it is understood that cross-linking between metal oxide particles leads to the solubility switch, the chemical changes that occur are still not clearly understood, making development of new materials challenging.
X-rays offer an important characterization tool due to their sensitivity to electronic/chemical structure through atomic absorption edges. Combining this spectroscopy sensitivity with structural characterization through scattering or reflectivity measurements enables three-dimensional characterization of the chemical distribution. Measurements near the carbon edge can be particularly useful as the detailed fine structure can enable clear differentiation between different types of bonds, and how they are distributed in thin films. In this presentation we will demonstrate how these properties can be used in the characterization of both CARs and metal oxide photoresists. This will include resonant soft X-ray reflectivity for quantification of chemical depth profiles in photoresist stacks and absorption spectroscopy to provide insight into metal oxide chemistry.
Bio: Daniel Sunday is a staff scientist at NIST leading the Advanced Metrology to Enable Next Generation EUV Photoresist CHIPS project. He received his B.S. degree from Carnegie Mellon University and his Masters and Ph.D from the University of Virginia in chemical engineering. At NIST his work has focused on the development of X-ray scattering techniques for thin films of soft matter, including soft X-ray methods. He has used these methods to examine block copolymers, membranes and molecular glasses. He has also participated in the development of critical dimension small angle-Xray scattering as a semiconductor metrology. He has published over 40 manuscripts, 2 book chapters and has 1 patent.
