Nanoimaging with a compact extreme-ultraviolet laser.

Images with a spatial resolution of 120-150 nm were obtained with 46.9 nm light from a compact capillary-discharge laser by use of the combination of a Sc-Si multilayer-coated Schwarzschild condenser and a free-standing imaging zone plate. The results are relevant to the development of compact extreme-ultraviolet laser-based imaging tools for nanoscience and nanotechnology.

Effects of a near-surface transition layer on x-ray reflection and scattering.

The influence of smooth (not step-like) variation of the dielectric function near a surface on the reflectivity and scattering of x rays is investigated theoretically with the model function ε(z) = 1 - 0.5(1 - ε+)(l + tanh(z/(2L))) taken as an example. It is shown that the presence of the transition layer can essentially change the shape of the differential scattering intensity diagram, especially when the incidence angle of the x-ray beam is greater than the critical angle of the total external reflection (TER). The results of measurements of the x-ray reflection coefficient and the differential scattered intensity are discussed. The model of the near-surface transition layer is shown to describe quantitatively the specific features of experimental curves for the incident beam beyond the TER region, whereas these experimental data cannot be explained in the framework of a step-like model of the dielectric function, taking into account the scattering from surface roughness.

Optimum collimator for proximity X-ray lithography - Theoretical analysis.

The paper deals with the application of soft X-ray optics to the enhancement of the efficiency of X-ray proximity lithography based on a point X-ray source. The grazing incidence X-ray collimators are shown to increase the efficiency coefficient in several hundreds times. The design of the optimum X-ray collimator is proposed and analysed for the scheme of X-ray proximity lithography with spatial resolution 0.05 µm. The collimator transforms the divergent radiation of an X-ray point source into high collimated beam that illuminates uniformly the mask at normal incidence.

Focusing of a tabletop soft-x-ray laser beam and laser ablation.

We focused the beam of a high-repetition-rate capillary-discharge tabletop laser operating at a wavelength of 46.9 nm, using a spherical Si/Sc multilayer mirror. The energy densities significantly exceeded the thresholds for the ablation of metals. Single-shot laser ablation patterns were used in combination with ray-tracing computations to characterize the focused beam. The radiation intensity within the 2-mum -diameter central region of the focal spot was estimated to be approximately 10(11)W/cm(2), with a corresponding energy density of ~100 J/cm(2).

Damage to extreme-ultraviolet Sc/Si multilayer mirrors exposed to intense 46.9-nm laser pulses.

The damage threshold and damage mechanism of extreme-ultraviolet Sc/Si multilayer mirror coatings are investigated with focused nanosecond pulses at 46.9-nm radiation from a compact capillary-discharge laser. Damage threshold fluences of approximately 0.08 J/cm2 are measured for coatings deposited on both borosilicate glass and Si substrates. The use of scanning and transmission electron microscopy and small-angle x-ray diffraction techniques reveals the thermal nature of the damage mechanism. The results are relevant to the use of newly developed high-flux extreme-ultraviolet sources in applications.