Dr. Paul D. Ashby Profile

Dr. Paul D. Ashby

at Lawrence Berkeley National Lab

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Publications (6)

Proceedings Article | 1 December 2022 Presentation + Paper

Spatially resolved dissolution monitoring using AFM

Luke Long, Jiajun Chen, Andrew Neureuther, Patrick Naulleau, Paul Ashby

Proceedings Volume 12292, 1229206 (2022) https://doi.org/10.1117/12.2643273

KEYWORDS: Photoresist developing, Photoresist materials, Line edge roughness, Photoresist processing, Atomic force microscopy, Water, Raster graphics, Electronic filtering, Liquids, Image processing

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Proceedings Article | 16 October 2017 Presentation

A novel route to EUV resists design: Fundamental understanding of chemical processes (Conference Presentation)

Oleg Kostko, Bo Xu, Daniel Slaughter, Musahid Ahmed, D. Frank Ogletree, Kristi Closser, David Prendergast, Patrick Naulleau, Deirdre Olynick, Paul Ashby, Yi Liu, William Hinsberg, Gregory Wallraff

Proceedings Volume 10450, 104500J (2017) https://doi.org/10.1117/12.2281520

KEYWORDS: Electrons, Molecules, Extreme ultraviolet, Photons, Extreme ultraviolet lithography, Photoresist materials

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New resists are needed to advance EUV lithography. Tailored design of efficient photoresist is impossible without fundamental understanding of EUV induced chemistry. Resists incorporating high cross-section elements efficiently utilize EUV photons via radiation absorption by core-level electrons, resulting in emission of primary electrons. However, this is only an initial step in the process. Auger emission, molecular fragmentation, and subsequent electron-resist interactions are also critical. Understanding all these steps is crucial to harness all the deposited energy for improved patterning results. In this work, we present recent results of multimodal experimental approaches to study photoresist materials. To build our grasp of EUV photochemistry from the ground up we aim for understanding the whole variety of processes happening after absorption of an EUV photon by a single building block of resist material – a resist molecule. Model photoresist constituent molecules functionalized with halogen atoms, are isolated in the gas phase and exposed to tunable EUV radiation from the Advanced Light Source, Berkeley Lab and the direct processes are investigated by photoelectron spectroscopy and photoionization mass spectrometry. We quantify the performance of several candidate molecules in terms of photoemission cross-sections and electron yield per primary photoionization event. We demonstrate that some prototype resist molecules can emit several (photo- and Auger) electrons after single EUV photon absorption. Following the electron emission, the atomic relaxation leads to the molecule fragmentation, which also depends on the halogen functionalization. Secondary electron-driven reactions are studied by tunable electron impact ionization and dissociative electron attachment mass spectrometry. We demonstrate that even very low kinetic energy electrons may lead to the molecule dissociation. While gas-phase studies do provide insight into the primary EUV photon or electron induced events in the individual resist molecules, we seek to understand these processes in the condensed phase as this is where industrially relevant processes will occur. We discuss techniques allowing for generation of resist nanoparticles of different morphology, representing either condensed resist or a substrate coated by a resist film. The same techniques, as applied to investigate resist’s building blocks, are used to study the condensed resist material, connecting our understanding of the fundamental phenomena from each isolated molecule to the solid state system.

Proceedings Article | 20 March 2015 Paper

Revealing beam-induced chemistry using modulus mapping in negative-tone EUV/e-beam resists with and without cross-linker additives

Prashant Kulshreshtha, Ken Maruyama, Scott Dhuey, Dominik Ziegler, Weilun Chao, Paul Ashby, Deirdre Olynick

Proceedings Volume 9425, 94250I (2015) https://doi.org/10.1117/12.2086045

KEYWORDS: Electron beam lithography, Scanning electron microscopy, Scanning probe microscopy, Chemistry, Calibration, Line scan image sensors, Electron beams, Atomic force microscopy, Lithography, Line edge roughness

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Proceedings Article | 16 March 2015 Paper

Novel resist approaches to enable EUV lithography in high volume manufacturing and extensions to future nodes

Mark Neisser, Kevin Cummings, Sean Valente, Cecilia Montgomery, Yu-Jen Fan, Ken Matthews, JunSung Chun, Paul Ashby

Proceedings Volume 9422, 94220L (2015) https://doi.org/10.1117/12.2086307

KEYWORDS: Extreme ultraviolet, Extreme ultraviolet lithography, Absorbance, Chemically amplified resists, Line width roughness, Electrons, Photons, Molecules, Photoresist materials, Metals

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Proceedings Article | 18 April 2013 Paper

Nanoscale modulus and surface chemistry characterization for collapse free resists

Prashant Kulshreshtha, Ken Maruyama, Sara Kiani, Dominik Ziegler, James Blackwell, Deidre Olynick, Paul Ashby

Proceedings Volume 8681, 86810O (2013) https://doi.org/10.1117/12.2011657

KEYWORDS: Atomic force microscopy, Neodymium, Chemistry, Scanning probe microscopy, Ions, Silicon, Scanning electron microscopy, Calibration, Extreme ultraviolet lithography, Transmission electron microscopy

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Proceedings Article | 29 March 2013 Paper

Sub-20nm lithography negative tone chemically amplified resists using cross-linker additives

Prashant Kulshreshtha, Ken Maruyama, Sara Kiani, Scott Dhuey, Pradeep Perera, James Blackwell, Deirdre Olynick, Paul Ashby

Proceedings Volume 8682, 86820N (2013) https://doi.org/10.1117/12.2011640

KEYWORDS: Line edge roughness, Molecules, Extreme ultraviolet lithography, Scanning electron microscopy, Lithography, Image resolution, Electron beam lithography, Extreme ultraviolet, Chemically amplified resists, Image processing

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Showing 5 of 6 publications

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