Graduate Exam Abstract

Wei Li

Ph.D. Preliminary
July 24, 2015, 2:00 pm - 4:00 pm
ERC Electronic Classroom A210
Coherent lithography using a table-top EUV laser

Abstract: Nanotechnology has drawn a wide variety of attention as interesting phenomena occurs when the dimension of the structures is in the nanometer scale. The particular characteristics of nanoscale structures had enabled new applications in different fields in science and technology. Our capability to fabricate these nanostructures routinely for sure will impcat the advancement of nanoscience. Apart from the high volume manufacturing in semiconductor industry, a small-scale but reliable nanofabrication tool can dramatically help the research in the field of nanotechnology. This dissertation describes alternative extreme ultraviolet (EUV) lithography techniques which combine table-top EUV laser and cost-effective imaging strategy. Several alternative techniques of EUV lithography is described in this dissertation. For each technique, numerical simulations, system design, experiment result and its analysis will be presented. In chapter II, a brief review of the main characteristics of table-top EUV lasers will be addressed concentrating on its high power and large coherence radius that enable the lithography application described herin. After that, the development of a Talbot EUV lithography system which is capable of printing 50nm half pitch nanopatterns will be illustrated in chapter III. A detailed discussion of its defect tolerance limitation, fabrication protocol for diffractive EUV mask, development of X-Y-Z positioning stage and pattern transfer using self- developed ion beam etching will be introduced. In addition, this dissertation discusses how to fabricate functional periodic nanostructures using Talbot EUV lithography. At the end of chapter III, experiments results for displacement Talbot EUV lithography together with fractional Talbot EUV lithography, which are capable of increasing spacial frequencies, will be demonstrated. Chapter IV will describe a hybrid EUV lithography which combines the Talbot imaging and interference rendering a high resolution interference pattern whose lattice is modified by a custom designed Talbot image. In other words, this method enables filling the arbitrary Talbot cell with ultra-fine interference nanofeatures. Detailed optics modeling, system design and experiment results using He-Ne laser and table top EUV laser are included. The last part of chapter IV will analyze its exclusive advantages over pure Talbot or interference lithography. In chapter V, a preliminary results using 18.9nm EUV laser are included and future anticipation for this research will be discussed.

Adviser: Mario Marconi
Co-Adviser: N/A
Non-ECE Member: Mingzhong Wu
Member 3: Diego Krapf
Addional Members: Carmen Menoni

“Defect-free periodic structures using extreme ultraviolet Talbot lithography in a tabletop system”, Wei Li, Victor Martinez Esquiroz, Lukasz Urbanski, Dinesh Patel, Carmen S. Menoni, Mario C. Marconi, Aaron Stein, Weilun Chao, and Erik H. Anderson, JVSTB 31, 06F604 (2013);

“Fractional Talbot lithography with extreme ultraviolet light”, Kim HS, Li W, Danylyuk S, Brocklesby WS, Marconi MC, Juschkin L, Optics Letters, Vol. 39, Issue 24, pp. 6969-6972 (2014).
“9x structure density multiplication of 2D arrays employing fractional EUV Talbot lithography”, Kim, Hyun-su; Li, Wei; Danylyuk, Serhiy; Brocklesby, William; Marconi, Mario; Juschkin, Larissa, Journal of Physics D: Applied Physics, Submitted, (2015)
“Hour-long continuous operation of a tabletop soft x-ray laser at 50-100 Hz repetition rate”, Brendan A. Reagan, Wei Li, Lukasz Urbanski, Keith A. Wernsing, Chase Salsbury, Cory Baumgarten, Mario C. Marconi, Carmen. S. Menoni, and Jorge J. Rocca, OPTICS EXPRESS, 21(23) 2013
“Defect tolerant EUV lithography technique”, Lukasz Urbanski, Wei Li, Jorge J. Rocca, Carmen S. Menoni, Mario C. Marconi, Artak Isoyan, and Aaron Stein, JVSTB 30(6), 06F502 (2012)

Program of Study:
ECE 642
PH 521
PH 641
ECE 641
ECE 673
ECE 795
ECE 799