XUV Metrology: Surface Analysis with Extreme
Ultraviolet Radiation
M. Banyay
1
, L. Juschkin
1
, T. Bücker, P. Loosen
RWTH-TOS, Steinbachstraße 15, D-52074 Aachen, Germany
A. Bayer
1
, F. Barkusky, S. Döring, C. Peth, and K. Mann
Laser-Laboratorium Goettingen e.V., Hans-Adolf-Krebs-Weg 1,
D-37077 Goettingen, Germany
H. Blaschke
1
, I. Balasa
1
, D. Ristau
Laser-Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany
ABSTRACT
The utilization of nanostructured materials for modern applications gained more and more importance during the last few
years. As examples super-fluorescent quantum dots, the use of carbon nano tubes (CNTs) in microelectronics,
electrospun fibers in filter membranes, thin film coatings for solar cells, mirrors or LEDs, semiconductor electronics, and
functionalized surfaces may be named to address only a few topics. To optimize the systems and enable the full range of
capabilities of nanostructures a thorough characterization of the surface-near topography (e.g. roughness, thickness,
lateral dimension) as well as of the chemical composition is essential.
As a versatile tool for spatial and chemical characterization XUV reflectometry, scatterometry and diffractometry is
proposed. Three different experimental setups have been realized evaluating spectral resolved reflectance under constant
incidence angle, angular resolved reflectance at a constant wavelength, or a combined approach using laboratory scaled
XUV sources to gain insight into chemical composition, film thickness and surface/interface roughness. Experiments on
near-edge X-ray absorption fine structure spectroscopy (NEXAFS) at the carbon K-edge have been performed. The
investigated systems range from synthetic polymers (PMMA, PI) over organic substances (humic acids) to biological
matter (lipids), delivering unique spectra for each compound. Thus NEXAFS spectroscopy using a table-top XUV source
could be established as a highly surface sensitive fingerprint method for chemical analysis. Future extended experiments
will investigate the silicon L-edge where e.g. silicon oxide interlayers below high-k or other nano-layered material on Si-
substrates depict a technological important group of composite systems.
Keywords: EUV/XUV, Lithography, 13.5nm, Water Window, Material Analysis, NEXAFS, Carbon K-Edge, Silicon L-
Edge, Surface Analysis, Thin films, Interface Roughness, Soft X-Rays
1. INTRODUCTION
Methods to investigate thin film systems or surfaces utilizing electromagnetic radiation can be traced back many
decades. Some methods are even more than a hundred years old, such as ellipsometry or reflectometry
[1]
. As light
sources evolved over time these techniques became two of the most common characterization tools for industrial use.
Also with the invention of the laser in the 60s even more metrology methods became available
[2]
and known techniques
as e.g. ellipsometry could be improved. As the downsizing and complexity of electronic devices continues a combination
of characterization techniques rather than one ultimate tool needs to be deployed to gain insight into the physical and
chemical composition of material surfaces. Thus it is of great advantage to apply a non-destructive technique that is
capable of gathering as much information as possible at once.
1
Corresponding Authors: matus.banyay@ilt.fraunhofer.de , larissa.juschkin@ilt.fraunhofer.de , armin.bayer@llg-ev.de ,
i.balasa@lzh.de , h.blaschke@lzh.de
Damage to VUV, EUV, and X-Ray Optics II, edited by Libor Juha, Saša Bajt, Ryszard Sobierajski
Proc. of SPIE Vol. 7361, 736113 · © 2009 SPIE · CCC code: 0277-786X/09/$18 · doi: 10.1117/12.833648
Proc. of SPIE Vol. 7361 736113-1