Tungsten-carbon coatings have been deposited on stainless steel substrates by reactive magnetron sputtering from Ar–CH4 mixtures. The carbon concentration in the coatings measured by electron microprobe analyses was found to be proportional to the CH4 flow rate. Only the cubic α–W phase with a dilated lattice parameter was identified in W–C coatings having a carbon content lower than 25 at. %. Since the lattice parameter of the α–W phase in these W–C coatings increased with increasing carbon content, these coatings may be assumed to be W–C solid solutions. Only the nonstoichiometric β–WC1−x carbide (cubic phase) was detected in W–C coatings containing 30 to 70 at. % of carbon. The chemical state of the elements was investigated by x-ray photoelectron spectroscopy. The Vickers hardness of the W–C coatings was found to be considerably dependent on the carbon concentration. A maximum microhardness of 26 000 MPa was measured for W–C coatings containing either 14–15 at. % or 40–45 at. % of carbon. The correlation between crystallographic structure and microhardness is analyzed and discussed in this paper.
Tungsten and tungsten–carbon thin films have been produced from a W target sputtered in argon and argon–methane mixtures, respectively. The deposition rate of W films was measured as a function of the sputtering power and argon pressure varying in the range of 0.3–3 Pa. The crystallographic structure and composition of W films deposited on silicon and carbon substrates were investigated by x-ray diffraction and Rutherford backscattering spectroscopy. The electrical resistivity of the W films was minimum (12 μΩ cm) when the internal stresses in the films were negligible. The carbon concentration in the W–C films determined by nuclear reaction analyses and Rutherford backscattering spectroscopy was varied from 10 to 95 at. % with increasing CH4 content in the gas phase. The crystallographic structure of the W–C films was found to be dependent on the carbon concentration. Below 25 at. % of carbon, the structure of the W–C films was that of the cubic α-W phase with a dilated lattice parameter. For higher carbon concentrations, the bcc α-W phase disappeared and the structure was that of the nonstoichiometric cubic β-WC1−x phase. The structure of W–C films with a carbon content greater than 65 at. % was nearly amorphous. Internal stresses and electrical resistivity of W–C films were determined as functions of the carbon concentration. The experimental parameters suitable to produce W and W–C films with low resistivities and reduced internal stress level are reported in this article.
Copper-containing films were prepared at room temperature by microwave plasma-enhanced chemical vapor deposition from the Cu(C5H7O2)2-Ar-H2 system. The structure and composition of films as well as the concentration depth profiles of Cu, Si, C, and O atoms in the Cu/Si and Cu/Cr/Si contact structures were determined by x-ray-diffraction techniques, Auger electron spectroscopy, Rutherford backscattering spectroscopy, and nuclear reaction analyses. Carbon atoms were found as major impurities in the deposited material. The carbon content and resistivity of films were strongly dependent on the direct bias voltage of substrates and gas-phase composition. Pure copper films with a resistivity of 2–3 μΩ cm were deposited on Si substrates with a direct bias voltage of −50 V and a hydrogen-rich Cu(C5H7O2)2-Ar-H2 gas phase.
Integrated processes for IC manufacturing are today of prime importance for obtaining such high performance results as uniformity on large diameter wafers, reproducibility, throughput and reliability. Using an industrial integrated cluster reactor we have obtained selective epitaxial Si and selective TiSi2 deposition. This is a 200 mm reactor in which epitaxial silicon has been obtained with <1% (1σ) thickness uniformity and <2% over a 25 wafer batch. Full selectivity of Si on oxide has been obtained below a 20 Torr working pressure using the DCS/H2 gas system. No loading effect has been detected. The main characteristics of this system are described with the most relevant results like: sharp interfaces obtained in Si0.7Ge0.3/Si multilayer structures grown at 650°C, abruptly doped epitaxial layers and residual defect density.TiSi2 has been selectively obtained with minimum substrate consumption using the H2/SiH4 (or DCS)/TiC14 chemistry. The elevated source & drain has also been successfully tested by selective Si epitaxy followed by “in situ” selective TiSi2 deposition to compensate for substrate consumption.
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