Yu.Ya. Platonov

Enhancement of reflectivity of multilayer mirrors for soft x-ray projection lithography by temperature optimization and ion bombardment

Abstract In this paper we discuss two techniques to optimize the quality of multilayer x-ray mirrors, namely optimization of the temperature of the substrates during deposition and ion-bombardment of the layers. We produced Mo/Si multilayers applying both methods and present the effect on the near normal incidence reflectivity for λ = 13–14 nm radiation. Furthermore an analysis of the homogeneity of the deposited layers is given.

Determination of layered synthetic microstructure parameters

Abstract A method for determining the parameters of real layered synthetic microstructures (LSMs) of superthin films (the layer thickness is about 1–10 nm) is discussed. This method is based on the analysis of small angle X-ray diffraction spectra (λ≈0.1 nm). The following LSM parameters have been determined: (1) concentration of atoms in the layers; (2) thickness of the layers and thickness of the interface between the LSM constituent layers; (3) characteristics of the layer thickness fluctuations. The Ni-C and Ni-Ti structures serve to illustrate the method. The potentialities of this technique in superthin film growth and diffusion investigation are demonstrated.

Multilayer X-ray optics for synchrotron radiation

Abstract Layered synthetic nanostructures are considered both as normal incidence imaging and dispersive optical elements in the soft X-ray range and as filters of γ-radiation for Mossbauer spectroscopy.

Multilayer coated reflective optics for Extreme UV lithography

In this paper we present normal incidence reflectivity measurements of EUV reflective multilayer coatings for @l=13-14 nm, the wavelength of interest for EUV projection lithography. The multilayer coatings are produced by e-beam evaporation in combination with ionbombardment of the layers and by magnetron sputtering. These techniques are used for coating the mirrors of our Schwarzschild telescope. We show measurements of absolute EUV reflectivity and homogeneity of the layer thickness over the mirrors. Furthermore we discuss the matching of the centre wavelength of the reflectivity curves for each of the components of our projection system.

New modification of X-ray standing waves above the surface of layered substrates under total external reflection conditions for structural characterization of organic layers

Abstract Information about the structure of organic monolayers of fatty acid salts and phospholipids deposited by the Langmuir-Blodgett technique on layered substrates has been obtained for the first time with the help of amplitude-modulated X-ray standing waves formed under total external reflection conditions. The detailed E field intensity distribution as well as the advantages of such a new modification of X-ray standing waves are discussed.

Extreme UV lithography: a new laser plasma target concept and fabrication of multilayer reflection masks

Results are reported on the development of a laser plasma source and the fabrication of multilayer reflection masks for extreme ultra-violet lithography (EUVL). A new concept of a target for a laser plasma source is presented including experimental evidence of elimination of macro debris particles from the source. Concerning the fabrication of reflection masks, a new method is described involving a two-layer absorber system protecting the Mo-Si structure against etching damage.

Diffusion in multilayer structures of metal-carbon superthin films

Abstract The effect of annealing on the X-ray optical characteristics of artificial multilayer structures of superthin films (1–3 nm thicknesses) composed of metal (chromium, iron, nickel, molybdenum, rhodium, tungsten, platinum and others) and carbon is studied. The diffusion kinetics in multilayers is determined by analysing the variations in angular spectra of reflected “hard” (λ≈0.1 nm) and soft (λ≈1–10 nm) X-rays. It is shown experimentally that, for all investigated metallic materials, there is an annealing temperature range in which the X-ray reflectivity increases. The observed effect is explained by the carbon atom displacement into the metal region through the interface.

Multilayer X-ray mirrors for the wavelength range 25–44 Å

Abstract A pair of materials was chosen and multilayer mirrors using NiTi and NiSc were fabricated for the wavelength range 25–44 A which had not previously been provided with dispersive elements. The influence of thermal annealing on the mirror properties was studied.

Issues of laser plasma sources for soft x-ray projection lithography

Abstract Results of optimization of an excimer laser-induced plasma x-ray source for projection lithography in the range λ = 13–15 nm are reported. A conversion efficiency of >0.7% in 2% BW has been achieved with high-Z target materials. Two methods of reducing contamination of optical elements by target debris have been tested: usage of a thin target layer (for Ta 1 μm was found to be optimal) and of a heavy buffer gas. The effect of the use of Ta-tape target and Kr buffer gas has been measured by determining the reflectivity of a Mo-Si multilayer sample after 10 5 shots.

Spectral selective plasma imaging in the wavelength range 2.4 - 4.5 nm in SPEED 2 device

X-ray images of the compression phase of a deuterium-embedded argon pinch plasma generated with the SPEED 2 driver in a plasma focus configuration were obtained. To record spectral selective images, an x-ray microscope based on cylindrically bent multilayer mirrors (MLMs) mounted in a parallel configuration was developed. The plasma images were taken at different wavelengths in the interval from 2.4 to 4.5 nm with a spectral resolution of and a spatial resolution of approximately 80 m within a 30 mm diameter field of view. A strong wavelength dependence of the shape and the size of the emitting regions of the plasma was found. Images of bright spots with a size of about 0.5 mm identified as being early stages of micropinches were obtained.