Laser-produced plasmas (LPPs) are being studied as potential extreme ultraviolet (EUV) and soft x-ray (SXR) sources for a wide variety of applications in commercial, defense, and medical research. For radiation sources to be of practical use in these systems, they must very efficiently emit light at the desired wavelength. EUV lithography, a viable approach in the manufacture of next-generation semiconductor chips, requires radiation sources that efficiently emit light at a wavelength of 13.5 nm, while producing relatively little radiation at other wavelengths in order to avoid damaging the wafer. Developing highly efficient plasma radiation sources requires a good understanding of critical physics issues that influence the plasma emission, including laser heating, plasma hydrodynamics, radiation transport, and atomic physics. We have developed a suite of well-tested plasma hydrodynamics, atomic physics, and plasma radiation simulation tools that are being used to simulate in detail the key physical processes in LPPs, and guide the development of higher efficiency plasma radiation sources. These tools include: 1-D and 2-D radiation-hydrodynamics codes, multidimensional spectral analysis tools, and a suite of atomic physics codes used to generate accurate atomic databases for radiation source simulations. Here, we discuss results from 2-D simulations of tin spherical droplets irradiated on one side by 0.35 μm laser beams. In particular, we examine the angular dependence of the 13.5 nm flux from the Sn plasma, and the sensitivity of the 13.5 nm conversion efficiency (CE) to the laser spot size and laser pulse width.
[1]
P. R. Woodruff,et al.
HELIOS-CR – A 1-D radiation-magnetohydrodynamics code with inline atomic kinetics modeling
,
2006
.
[2]
I E Golovkin,et al.
Dopant radiative cooling effects in indirect-drive Ar-doped capsule implosion experiments.
,
2005,
Physical review. E, Statistical, nonlinear, and soft matter physics.
[3]
Shinsuke Fujioka,et al.
Characterization of extreme ultraviolet emission from laser-produced spherical tin plasma generated with multiple laser beams
,
2005
.
[4]
J. Macfarlane,et al.
Radiation-Hydrodynamics , Spectral , and Atomic Physics Modeling of Laser-Produced Plasma EUV Lithography Light Sources
,
2005
.
[5]
Martin Richardson,et al.
High conversion efficiency mass-limited Sn-based laser plasma source for extreme ultraviolet lithography
,
2004
.
[6]
Uwe Stamm,et al.
High-power EUV sources for lithography: a comparison of laser-produced plasma and gas-discharge-produced plasma
,
2002,
SPIE Advanced Lithography.
[7]
J. Kilkenny,et al.
Dynamic hohlraum radiation hydrodynamics
,
2006
.
[8]
James E. Bailey,et al.
NLTE Radiative Cooling Effects in ICF Capsule Implosions with Mid-Z Dopants
,
2004
.
[9]
Dimitri Mihalas,et al.
The equation of state for stellar envelopes. I - An occupation probability formalism for the truncation of internal partition functions
,
1988
.