Dr. Slavomir Nemsak Profile

Dr. Slavomir Nemsak

at Lawrence Berkeley National Lab

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Author

Publications (2)

SPIE Journal Paper | 21 July 2021

Chemical and structural characterization of EUV photoresists as a function of depth by standing-wave x-ray photoelectron spectroscopy

Giuseppina Conti, Henrique Martins, Isvar Cordova, Jonathan Ma, Rudy Wojtecki, Patrick Naulleau, Slavomír Nemšák

JM3, Vol. 20, Issue 03, 034603, (July 2021) https://doi.org/10.1117/12.10.1117/1.JMM.20.3.034603

KEYWORDS: Extreme ultraviolet lithography, Interfaces, X-rays, Photoresist materials, Mirrors, Aluminum, Multilayers, Self-assembled monolayers, Photoemission spectroscopy, X-ray characterization

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The success in the miniaturization of the electronic device constituents depends mostly on the photolithographic techniques. Recently, to achieve patterning at the sub-10-nm node, extreme ultraviolet (EUV) lithography has been introduced into high volume production. Continued scaling of EUV via increased numerical aperture to achieve nodes at 3-nm and below requires the development of fundamentally new patterning materials and new characterization methods. Current EUV-resist film thicknesses are in the 20- to 40-nm range, and further thickness reduction is required for the next generation. Therefore, interfaces become exceedingly important, and the properties of the resist film would be dominated by top and bottom interfacial effects. X-ray photoelectron spectroscopy (XPS) combined with standing-wave excitation (SW-XPS), a fairly new method in the EUV lithography field, previously had been largely applied in multilayers and superlattices for characterizing the composition and electronic structure of buried layers and interfaces as a function of depth. We applied the SW-XPS method to organic/inorganic photoresists to provide depth-selective information on their structural and chemical conditions of as a function of temperature, EUV exposure, different underlayers, and other fundamental parameters. As a first attempt, we perform an SW-XPS feasibility study on self-assembled monolayer (SAM) films after exposure to an electron beam. By SW-XPS, we determined that the interface between the Al2O3 underlayer and the SAMs is smooth, with a mean roughness of about 0.2 nm. Moreover, we determined that the SAM chains are, on average, tilted by ∼30 deg off the sample normal. The SW-XPS results also suggest that the SAM is not a perfectly aligned and uniform monolayer, with some areas having thickness higher than a single monolayer. We demonstrated that SW-XPS can provide useful information on ultrathin materials with high potential for being used as a characterization method of organic/inorganic photoresists.

Proceedings Article | 10 November 2020 Presentation + Paper

Sub-nm depth characterization of EUV nanoscale photoresist films by standing-wave photoemission spectroscopy

G. Conti, H. Perin Martins, I. Cordova, J. Ma, R. Wojtecki, P. Naulleau, S. Nemsak

Proceedings Volume 11517, 115170I (2020) https://doi.org/10.1117/12.2575463

KEYWORDS: Photoresist materials, Extreme ultraviolet lithography, Nondestructive evaluation, Photoemission spectroscopy, Interfaces, Nanolithography, Photoresist developing, Transistors, Extreme ultraviolet, Optical properties

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