OPTICAL-CONSTANTS OF ALUMINUM FILMS IN THE EXTREME-ULTRAVIOLET INTERVAL OF 82-77 NM

Measurements of the extreme ultraviolet (EUV) reflectance of unoxidize d aluminum films versus the angle of incidence in the interval of 82-7 7 nm, just below the aluminum plasma wavelength (83 nm), are presented . The continuum of helium was used as a radiation source for the first time in EUV reflectometry, to our knowledge. The surface roughness of substrates and samples was characterized by atomic force microscopy. The complex refractive index of unoxidized aluminum was obtained from reflectance measurements at each wavelength for the first time in this spectral range. Data on the refractive index, the dielectric constant , and the energy loss function in the above interval are shown togethe r with our previous data obtained in an interval of 82.6-113.5 nm. Cur rent results on the refractive index show a good match with the data i n the literature calculated through the Kramers-Kronig analysis, the l argest differences being in the imaginary part of the refractive index at the shortest wavelengths. (C) 1996 Optical Society of America