Electron scattering mechanisms in Cu-Mn films for interconnect applications

• Published in: Journal of applied physics 2014-08, Vol.116 (8)
• Main Authors: Misják, F., Nagy, K. H., Lobotka, P., Radnóczi, G.
• Format: Article
• Language: English
• Subjects: ALLOYS; Applied physics; Barrier layers; Binary systems; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Composition; Copper; Correlation analysis; DEPLETION LAYER; DEPOSITS; ELECTRIC CONDUCTIVITY; Electrical properties; Electrical resistivity; ELECTRONS; GRAIN BOUNDARIES; Magnetron sputtering; MAGNETRONS; Manganese base alloys; MATERIALS SCIENCE; Morphology; REFLECTIVITY; SCATTERING; SILICA; Silicon dioxide; SILICON OXIDES; SOLID SOLUTIONS; SPUTTERING; SUBSTRATES; Temperature; TEMPERATURE COEFFICIENT; TEMPERATURE RANGE 0273-0400 K; TRANSMISSION ELECTRON MICROSCOPY
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4893718

Electrical properties and corresponding structural features of Cu-Mn alloy films with potential application as barrier and interconnect layers were studied. Cu-Mn films were deposited by DC magnetron sputtering at room temperature on SiO2 substrates. Electrical resistivity measurements were made as a function of film composition and temperature. The specific resistivity varies linearly with the Mn content showing a maximum of 205 μΩcm at 80 at. % Mn. The temperature coefficient of resistance (TCR) of all alloy films is low, showing non-metallic conductivity for most compositions. Also a minimum TCR has been observed in the 40–80 at. % Mn range which was attributed to a magnetic transformation around 200–300 K. Electrical resistivity measurements are correlated with the film structure revealed by transmission electron microscopy to clarify the phase regions throughout the composition range. In the 20–40 at. % and 70–80 at. % Mn ranges, two-phase structures were identified, where Cu- or Mn-rich solid solution grains were surrounded by a thin amorphous covering layer. Based on the revealed phase regions and morphologies electron scattering mechanisms in the system were evaluated by combining the Matthiessen's rule and the Mayadas-Schatzkes theory. Grain boundary reflectivity coefficients (r = 0.6–0.8) were calculated from fitting the model to the measurements. The proposed model indicates that, in a binary system, the special arrangement of the two phases results in new scattering mechanisms. The results are of value in optimizing the various parameters needed to produce a suitable barrier layer.