Walter Scott, Jr. College of Engineering

Graduate Exam Abstract

Wei Li
Ph.D. Preliminary
Jul 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
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
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