Interference lithography with extreme ultraviolet light

Abstract

In photolithography, increasing pattern density is a key issue for development of
semiconductor devices. Extreme ultraviolet (EUV) radiation is the next generation
light source for overcoming the resolution limit of conventional photolithography
in order to obtain nanostructures of higher density. In this thesis, we focus on
investigating resolution limits of interference patterns produced by EUV radiation.
Optical properties of interference fringes obtained using different types of
compact EUV sources are studied with regard to increasing pattern density.
Rigorous simulations of optical wave propagation of EUV radiation are performed
to investigate the resolution limits of interference fringes for the fractional Talbot
effect, the achromatic Talbot effect, and an image of Talbot carpet that has an
optical property of ever-decreasing size of interference fringes. In experiments,
interference lithography has been performed with three different types of compact
EUV sources including a gas discharge produced plasma, a plasma based EUV
laser, and a high-harmonic generation source. We analyze optical characteristics of
particular EUV sources resulting in different capabilities of patterning. Also
different optical system designs capable of overcoming the limitations of optical
properties of EUV radiation are investigated. We expect that the study of EUV
interference lithography can be helpful for understanding the upcoming
photolithography resolution and also can be useful as a technology for fabricating
very fine structures.

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Identifiers

ORCID for William Brocklesby: orcid.org/0000-0002-2123-6712

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