Articles you may be interested inAtomic layer deposition of ultrathin platinum films on tungsten atomic layer deposition adhesion layers: Application to high surface area substrates J. Vac. Sci. Technol. A 33, 01A130 (2015); 10.1116/1.4901459Low temperature hydrogen plasma-assisted atomic layer deposition of copper studied using in situ infrared reflection absorption spectroscopy Hot-wire-assisted atomic layer deposition (HW-ALD) has been identified as a successful method to form high quality metallic films using metallocene and NH 3 . A cobalt film formed by HW-ALD using cobaltocene and NH 3 was successfully demonstrated. The authors have elucidated the mechanism of HW-ALD during the precursor feed period and the reducing period. In the case of cobalt, a deposition temperature above 300 C is needed to avoid an inclusion of carbon impurities. This is because the physisorbed species are involved during the precursor feed period. NH 2 radical promotes the dissociation of the carbon-metal bond during the reducing period. This is examined by elucidation of the gas-phase kinetics, estimation of the surface reactions by quantum chemical calculations, and analysis of the exhaust gas using a quadrupole mass spectrometer.
Silicon carbide (SiC) films were prepared from methyltrichlorosilane (MTS) and H2 at temperatures ranging from 900 to 1000°C by low-pressure chemical vapor deposition (CVD). Multi-scale analysis was performed on the SiC film growth rate using a growth rate profile for a tubular reactor that was 300 mm long from the inlet to the outlet and a step coverage (SC) profile for micron-sized trenches. The precursor consumption ratio was estimated using a quadrupole mass spectrometer (QMS). These systematic analyses revealed that MTS was not the direct growth species for SiC deposition. We concluded that there were two major growth species controlling the SiC deposition rate. The partial pressures of these species were estimated by SC and growth rate analyses. An elementary reaction simulation was performed to predict the SiC film growth species. A comparison between the elementary reaction simulation results and the multi-scale analysis suggested several chemical species as candidates for the direct growth species. The candidates for the first species, with a low sticking probability of around 10−3, were CH4, C2H4, and C2H2, and candidates for the second species, with a high sticking probability of around 10−1, were CH3, C2H3, and C2H5.
This topical review deals with a multidimensional gravitational model containing dilatonic scalar fields and antisymmetric forms. The manifold is chosen in the form M = M 0 × M 1 × · · · × M n , where M i are Einstein spaces (i 1). The sigma-model approach and exact solutions in the model are reviewed and the solutions with p-branes (e.g. Majumdar-Papapetroutype, cosmological, spherically symmetric, black-brane and Freund-Rubintype ones) are considered.
Cobalt film with tungsten addition [Co(W)] has the potential to be an effective single-layered barrier/liner in interconnects awing to its good adhesion with Cu, a lower resistivity than TaN, and an improved barrier property with respect to cobalt films. Our previous study on chemical-vapor-deposited (CVD) Co(W) using carbonyl precursors clarified, however, that WO3 included in the films increased the resistivity. In this current study, to reduce the resistivity of Co(W), oxygen-free Co(W) films were fabricated from two oxygen-free precursors, bis(cyclopentadienyl)cobalt and bis(cyclopentadienyl)tungstendihydride, by atomic layer deposition (ALD) using NH2 radicals generated using a hot filament. Results revealed that (a) W concentration in ALD-Co(W) could be controlled by adjusting the gas-feed sequences, (b) W addition improved the barrier property of ALD-Co(W) against Cu diffusion, (c) diffusion of Cu into ALD-Co(W) had a high activation energy, 2.0 eV, indicating interstitial diffusion, and (d) ALD-Co(W) consisted mainly of an amorphous-like phase, which is consistent with the high activation energy of Cu diffusion.
Cobalt film with tungsten addition [Co(W)] has the potential to be an effective single-layered barrier/liner in Cu-interconnects owing to its good adhesion with Cu, a lower resistivity than TaN, and an improved barrier property with respect to cobalt films. Our previous study on chemical-vapor-deposited (CVD) Co(W) using carbonyl precursors clarified, however, that WO3 included in the films increased the resistivity. In this current study, to reduce the resistivity of Co(W), oxygen-free process for Co(W) films were designed using two oxygen-free amidinato precursors, bis(N-tert-butyl-N′-ethylpropionamidinato) cobalt and bis(tert-butylimino)bis(dimethylamino)tungsten, by chemical vapor deposition (CVD) and atomic layer deposition (ALD) at 350–400°C. Deposition process were designed by employing quantum chemical calculation, in which NH3 were chosen as a reducing reagent for the sake of the low activation energy of deposition. NH3 actually acted effective reducing reagent for Co or Co(W) deposition using amidinato precursors in our research. Co(W) films using amidinato precursors and NH3 contained no oxygen and a few amounts of nitrogen. Nitrogen, however, were easily eliminated by annealing at 400°C. Therefore, Co(W) films using amidinato precursors were so high quality to have lower resistivity than Co(W) films using carbonyl precursors or conventional PVD-TaN.
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