Interference lithography with extreme ultraviolet light

• Main Author: Kim, Hyunsu
• Other Authors: Brocklesby, William
• Published: University of Southampton 2016
• Subjects: 621.381
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.714558

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.