| AVS 61st International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Films Poster Session |
| Presenter: | Daniel Yates, University of Central Florida |
| Authors: | D.L. Yates, University of Central Florida X. Liu, Carnegie Mellon University D. Choi, Korea Railroad Research Institute, Republic of Korea P. Schelling, University of Central Florida K. Barmak, Columbia University K.R. Coffey, University of Central Florida |
| Correspondent: | Click to Email |
Previous work in copper thin films with thickness > 30nm demonstrated excellent agreement with the semiclassical models of the resistivity size effect. Using the same methodology developed for Cu, electron scattering at surfaces and grain boundaries in polycrystalline Ni, Ru, and W films was examined. 2-200 nm thick films were prepared via DC magnetron sputtering onto thermally oxidized silicon wafers. Films with thicknesses below 10nm were encapsulated in 0.5nm thick layers of Ta to improve film stability.
Films were annealed in the range of 200°C to 900°C in Ar+3% H2. They were characterized using X-ray reflectivity, Rutherford backscatter spectrometry, and transmission electron microscopy with precession electron diffraction techniques to measure thickness, grain size, and film continuity. Resistivity was measured using the Van Der Pauw method.
The contributions of surface and grain boundary scattering were assessed using the semiclassical models of Fuchs-Sondheimer and Mayadas-Shatzkes. Systematic deviations from model predictions were observed for films less than approximately 15nm thick in all three metals. The complex Fermi surfaces of these metals result in a variety of Fermi velocities, as several bands cross the Fermi level. This complexity may be a likely cause for the failure of the semiclassical models, which consider only an average mean free path value. The deviations are most pronounced in the thinnest films.