| AVS 58th Annual International Symposium and Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Thursday Sessions |
| Session EL-ThP |
| Session: | Spectroscopic Ellipsometry Poster Session |
| Presenter: | Victor Atuchin, Institute of Semiconductor Physics, Russian Federation |
| Authors: | V.V. Atuchin, Institute of Semiconductor Physics, Russian Federation T.I. Grigorieva, Institute of Semiconductor Physics, Russian Federation A.S. Kozhukhov, Institute of Semiconductor Physics, Russian Federation V.N. Kruchinin, Institute of Semiconductor Physics, Russian Federation L.D. Pokrovsky, Institute of Semiconductor Physics, Russian Federation R.S. Vemuri, Pacific Northwest National Laboratory C.V. Ramana, University of Texas at El Paso |
| Correspondent: | Click to Email |
Tungsten (W) and titanium (Ti) films are widely used in electrochemistry, microelectronics, energy conversion and nanotechnology. In integrated optics, the nanometric Ti films are used as a source for doping LiNbO3 and LiTaO3 substrate and optical waveguide fabrication by thermal diffusion. Because effective refractive indices of the waveguide modes are strongly dependent on the optical profiles in doped layer, precise control of Ti film thickness (h) is needed in the range h~10-50 nm. Ellipsometry can be successfully applied for nondestructive determination of the thickness of a dielectric and semi-transparent metal film when optical constants of the material are known. Regrettably, noticeable scattering was found for optical constants reported earlier in literature for W and Ti films and crystals. As it seems, this scattering appeared due to different film quality and surface state. The focus of the present work is centered on W, Ti and W-Ti film fabrication and evaluation of their optical parameters with spectroscopic ellipsometry. Tungsten and tungsten-titanium films were prepared by magnetron sputtering deposition in vacuum below 10-5 Torr. Titanium films were fabricated by thermal evaporation method in vacuum below 10-5 Torr. The substrate temperature was T=100 °C. For precise determination of optical parameters, thick metal films (h~100 nm by as determined from optical interferometry) were prepared on silica substrate. To increase the metal adhesion, the substrate was subjected to RCA chemical cleaning just before insertion into vacuum chamber. Structural parameters of metal films were studied with reflection high-energy electron diffraction (RHEED). Surface micromorphology was controlled with atomic force microscopy (AFM). Spectral dependencies of refractive index n(λ) and extinction coefficient k(λ) were determined with the help of spectroscopic ellipsometry in the spectral range, λ~250-1030 nm. A relation between optical constants of pure metal W and Ti and mixed metal W-Ti films is discussed.