Surface damage thresholds of polished calcite crystals were measured with a pulsed ruby laser at the wavelength of 694.3 nm. Three grades of calcite used for laser polarizers were tested: Grade A, Schlieren-Free, and Scatter-Free, as characterized by the manufacturer, Karl Lambrecht Corporation of Chicago. The test samples were cut and polished with the surfaces parallel to the optic axis. Sample dimensions were 1 cm X 1 cm and 2 to 3 mm thick. The ruby laser oscillator was passively Q-switched to produce 12-ns pulses in a single-transverse and longitudinal mode. Samples were irradiated at near-normal incidence to the 1-cm2 surfaces with a laser 1/e2 spot diameter of approximately 0.12 mm. Tests were conducted with a single shot per site, and photoelectric detection of a laser- induced surface spark was used as a sensitive method for detecting the onset of damage. Damage threshold of 30, 60, and 50 mJ/cm2, were determined for the three grades, respectively. No significant threshold differences were observed between test with the laser polarization parallel and perpendicular to the optic axis. Laser-induced damage, visible by scattering of a collinear He-Ne laser beam, was most frequently observed at the rear surfaces, although it sometimes occurred at the front surface alone or in the interior. On the basis of standing wave electric-field analysis, the predicted energy density at the rear surface was more than twice that at the front surface, and laser damage at the rear surface was expected to occur at a correspondingly lower fluence. Early damage at randomly distributed surface imperfections appeared to preclude such a consistent correlation.
The development of a capability to infer wind velocities simultaneously at a number of ranges along one direction in real time is described. The elastic backscatter lidar data used was obtained using the XM94 lidar, developed by Los Alamos National Laboratory for the US Army Chemical and Biological Detection Command. In some respects this problem is simpler than measuring wind velocities on meso- meteorological scales. Other requirements, particularly high temporal fidelity, have driven the development of faster software algorithms and suggested opportunities for the evolution of the hardware.
We report results of an extensive set of oxide and carbon film contamination experiments with Al, Si, Rh, and Ag films and surfaces to quantify the film growth rates and parameter dependencies. These four materials were selected initially because they exhibit total external reflectance at moderate angles of incidence, e.g., > 45 degree(s), as needed for high- reflectance multifacet mirrors. In addition, these materials are candidate films for single- surface and multilayer mirrors at normal incidence as well as transmission filters in XUV projection lithography optical systems. (Abstract only)
We review the degradation susceptibility of the various optical components proposed for use in XUV projection lithography systems at 13 - 20 nm. Contamination by laser plasma target debris and carbonaceous films are two primary hazards that must be essentially nullified. Pertinent experimental results of a number of researchers illustrate the present status.
The rationale, design, component properties, and potential capabilities of extreme-ultraviolet (XUV) projection lithography systems using 60 - 80 nm illumination and single-surface reflectors are described. These systems are evaluated for potential application to high-volume production of future generations of gigabit chips.
Brian Newnam, Roger Warren, Steven Conradson, John Goldstein, Brian McVey, Mark Schmitt, C. James Elliott, Michael Burns, Bruce Carlsten, Kwok-Chi Chan, W. Johnson, Tai-San Wang, Richard Sheffield, Karl Meier, R. Olsher, Marion Scott, J. Griggs
Los Alamos has designed and proposes to establish an XUV-IR free-electron laser (FEL) user facility for scientific research and industrial applications based on coherent radiation ranging from soft x rays as short as 1 nm to far-infrared wavelengths as long as 100 micrometers . As the next-generation light source beyond low-emittance storage rings with undulator insertion devices, this proposed national FEL user facility should make available to researchers broadly tunable, picosecond-pulse, coherent radiation with 104 to 107 greater spectral flux and brightness. The facility design is based on two series of FEL oscillators including one regenerative amplifier. The primary series of seven FEL oscillators, driven by a single, 1-GeV rf linac, spans the short-wavelength range from 1 to 600 nm. A second 60-MeV rf linac, synchronized with the first, drives a series of three Vis/IR FEL oscillators to cover the 0.5 to 100-micrometers range. This paper presents the motivation for such a facility arising from its inherently high power per unit bandwidth and its potential use for an array of scientific and industrial applications, describes the facility design, output parameters, and user laboratories, makes comparisons with synchrotron radiation sources, and summarizes recent technical progress that supports the technical feasibility.
Free-electron laser (FEL) sources, driven by rf linear accelerators, have the potential to operate in the extreme ultraviolet (XUV) spectral range with more than sufficient average power for high-volume projection lithography. For XUV wavelengths from 100 to 4 nm, such sources will enable the resolution limit of optical projection lithography to be extended from 0.25 to 0.05 μm with an adequate total depth of focus (1 to 2 μpm). Recent developments of a photoinjector of very bright electron beams, high-precision magnetic undulators, and ring-resonator cavities raise our confidence that FEL operation below 100 nm is ready for prototype demonstration. We address the motivation for an XUV FEL source for commercial microcircuit production and its integration into a lithographic system, including reflecting reduction masks, reflecting XUV projection optics and alignment systems, and surface-imaging photoresists.
xUv (10 nm -100 nm) free-electron lasers (EELs) are potentially important light sources for advanced lithography and materials applications. The average power of an XUV EEL oscillator may be urnited by thermal loading of the resonator mirrors. We analyze the requirements for the thennal performance of the mirrors of a metal multifacet-mirror ring resonator for use at 12 nm. We use analytical methods and numerical approaches which include simulations with the 3-D EEL code FELEX. Thermal distortion of mirror surfaces leads to optical wavefront aberrations which reduce the focusability of the light beam in the gain medium (wiggler/electron beam) and limit the laser performance.
Free-electron laser sources, driven by ri-linear accelerators, have the potential to operate in the extreme
ultraviolet (XUV) spectral range with more thansutficient average power for high-volume projection lithography.
For XUV wavelengths from 100 nm to 4 nm, such sources will enable the resolution limit of optical projection
lithography to be extended from 0.25 pm to 0.05 im and with an adequate total depth of focus (1 to 2 jtm).
Recent developments of a photoinjector of very bright electron beams, high-precision magnetic undulators,
and ring-resonator cavities raise our confidence that FEL operation below I 00 nm is ready for prototype
demonstration. We address the motivation for an XUV FEL source for commercial microcircuit production and
its integration into a lithographic system, including reflecting reduction masks, reflecting XUV projection optics
and alignment systems, and surface-imaging photoresists.
Future ti-linac-driven FELs, operating in the range from 4 nm to 100 nm, could be excellent exposure
tools for extending the resolution limit of projection optical lithography to □O.1 m and with adequate total
depth of focus (1 to 2 Rm). When operated at a moderate duty rate of □1%, XUV EELs should be able to
supply sufficient average power to support high-volume chip production. Recent developments of the
electron beam, magnetic undulator, and resonator mirrors are described which raise our expectation that FEL
operation below 1 00 nm is almost ready for demonstration. Included as a supplement is a review of initial
design studies of the reflecting XUV projection optics, fabrication of reflection masks, characterization of
photoresists, and the first experimental demonstrations of the capability of projection lithography with 14-nm
radiation to produce lines and spaces as small as 0.05 m.
Within the last several years a number of meetings and conferences have addressed the
unique scientific opportunities which would result from the development of an RF-linac FEL user
facilty accessing the XUV and mid-JR spectral regions. The capabilities of a number of linear
and nonlinear spectroscopies would be enhanced by one or more features of the FEL output, e.g.,
its free tunability in these regions, transform-limited linewidth, high peak power and brightness,
time structure, and the possibility of multi-color pump-probe experiments utilizing the coordinated
output from more than one FEL oscillator. These advances would in turn benefit a variety
of scientific areas. In the realm of basic science, experiments or measurements which either require
an FEL or where increased sensitivity would be advantangeous can be found in quantum,
atomic, cluster, molecular, and condensed matter physics, magnetic materials, surface science and
catalysis, non-linear spectroscopy, and biophysics and -chemistry. Potential technological applications
at such a facility include analytical chemistry and physics, advanced fabrication processes,
medical applications, and others. These applications form the basis for the specifications of the
FEL and for the design of the laboratories for the proposed FEL user facility at Los Alamos.
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