Yttrium oxide films are deposited on silicon using a new precursor, tris͑ethylcyclopentadienyl͒ yttrium with water vapor as the oxidizer, by means of atomic layer deposition ͑ALD͒. Film growth kinetics has been examined under different reactor conditions, and growth saturation is evident from precursor dosage dependence. The film thickness increases linearly with the number of deposition cycles, yielding a growth rate of 1.7 Ϯ 0.1 Å/cycle at optimal ALD conditions. Increasing the reactor temperature from 200 to 400°C shows gradual increase in growth rate, with a narrow temperature plateau in the range of 250-285°C. X-ray photoelectron spectral analysis of Y 2 O 3 films indicates the film to be stoichiometric with no evidence of carbon contamination, whereas glancing incidence X-ray diffraction data of as-deposited Y 2 O 3 suggests the film structure to be polycrystalline.

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Mo ∕ W – N bilayer thin film structures deposited on Si using sputtering have been studied as a copper diffusion barrier. The thermal stability of the barrier structure after annealing Cu∕Mo∕W–N∕⟨Si⟩ samples in N2 for 5min is studied using x-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy, and four point probe measurements. The failure of the barrier structure is indicated by the abrupt increase in sheet resistance value and the formation of Cu3Si phase as probed by XRD. Our results suggest that the Mo (5nm)∕W–N (5nm) barrier is stable and can prevent the formation of Cu3Si at least up to 775°C.

Hf O 2 and Y2O3 films, along with Y2O3-doped HfO2 composite films, have been deposited on Si by means of atomic layer deposition (ALD) using tetrakis(diethylamino)hafnium and tris(ethylcyclopentadienyl)yttrium with water vapor as the oxidizer. The growth rate and structural properties of these films have been investigated by spectral ellipsometry, grazing incidence x-ray diffraction, and x-ray photoelectron spectroscopy (XPS). The film growth temperature dependence of both HfO2 and Y2O3 films indicate overlapping ALD windows in the 250–285°C region, which is critical for ALD of Y2O3-doped HfO2 films. The composition of such films is controlled by altering precursor cycle ratios, and XPS analyses of the resulting films indicate strong correlation between the precursor cycle ratio and the film composition. From structural analyses, the as-deposited HfO2 was found to be amorphous but after annealing at 600°C or higher, it became monoclinic. In contrast, all Y2O3 films whether annealed or not had evidence of cubic crystallinity. Having a cycle ratio of at least 2.5% in a Y2O3-doped HfO2 composite film is observed to induce cubic phase crystallinity in the film after postdeposition annealing at 600°C or greater.

This work focuses on the barrier capabilities of sputter deposited Ti/Mo and Ti/MoN nanofilms against diffusion of Cu into Si substrates. The thermal stability of the corresponding bi-layer barrier structures is investigated after annealing Cu/barrier layer/Si samples at different temperatures in N(2) for 5 min. The drastic increase in sheet resistance of Cu and the probing of Cu(3)Si with x-ray diffraction after high temperature annealing indicate the failure of these barrier structures. The formation of Cu(3)Si at the barrier breakdown temperature is also confirmed by scanning electron microscopy and energy dispersive x-ray spectroscopy. Cu diffusion barrier performance analyses show that a Ti(5 nm)/MoN(5 nm) bi-layer nanostructure fails only after annealing at 800 °C; on the other hand, a Ti(5 nm)/Mo(5 nm) barrier stack is found to break down at 700 °C.