Optimization of copper CVD film properties using the precursor of Cu(hfac)(tmvs) with variations of additive content

Zhang, M.; Kobayashi, Akiko; Koide, Tomoaki; Sekiguchi, Atsushi; Okada, Osamu; Hosokawa, N.

doi:10.1109/iitc.1999.787112

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“…40 Secondly, there is one phenomenological report that adding 5 wt% VTMS to Cu(hfac)(VTMS) produced deposits with a particulate morphology on TiN surfaces, but relatively smooth films on a copper substrate. 22 However, those films were much thicker (about a micron thick), and no attempt was made to explain the origin of the results. Here, we show that VTMS modifies surface kinetics and can afford control of morphology.…”

Section: Selection Of Growth Inhibitormentioning

confidence: 99%

“…For example, addition of H 2 O to a flux of Cu(hfac)VTMS (hfac = hexafluoroacetylacetonate and VTMS = vinyltrimethylsilane) enhances the wettability of the surface and results in the deposition of smoother copper films. [21][22][23][24][25] Unfortunately, the addition of water tends to increase the resistivity of the film because copper oxides are also deposited. 21,22,26 Thus, this approach is not suitable for applications that require very thin (<10 nm) copper films with high electrical conductivities, although it can be useful for making thicker films by employing water only during the nucleation stage.…”

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confidence: 99%

“…[21][22][23][24][25] Unfortunately, the addition of water tends to increase the resistivity of the film because copper oxides are also deposited. 21,22,26 Thus, this approach is not suitable for applications that require very thin (<10 nm) copper films with high electrical conductivities, although it can be useful for making thicker films by employing water only during the nucleation stage. 27 Addition of iodine to a flux of Cu(hfac)VTMS enables bottom up filling of deep features due to the surface segregation and catalytic effects of iodine.…”

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confidence: 99%

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Chemical Vapor Deposition of Copper: Use of a Molecular Inhibitor to Afford Uniform Nanoislands or Smooth Films

Babar

Davis

Zhang

et al. 2014

ECS J. Solid State Sci. Technol.

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We report a method to control the surface morphology of thin copper films during growth by chemical vapor deposition from the precursor Cu(hfac)VTMS. A molecular inhibitor -an additive that modifies the surface attachment kinetics but does not decompose and contribute impurity atoms to the film -is added during the nucleation and/or growth stages of the film. Here we show that the reaction by-product VTMS can serve as such an inhibitor. If the inhibitor is added during the nucleation stage, when bare substrate surface is still exposed, the inhibitor greatly reduces the rate of coalescence and promotes the formation of a large density of uniformly-sized copper islands. Alternatively, if the film is allowed to nucleate in the absence of the inhibitor, subsequent addition of the inhibitor leads to a continuous copper film that is remarkably smooth on the nm scale. © 2014 The Electrochemical Society. [DOI: 10.1149/2.009405jss] All rights reserved.Manuscript submitted January 14, 2014; revised manuscript received February 27, 2014. Published March 11, 2014 Copper is used in many advanced nanoscale technologies due to its high electrical and thermal conductivity, and its strong surface plasmon resonance when in the form of nanoparticles.1-5 For continuous films, such as those used as the seed layer for electrodeposition in integrated circuits, the film must be less than 10 nm thick, pinholefree, and extremely smooth, with an rms roughness of less than 1 nm. For optical devices based on copper nanoparticles, it is important to control the nanoparticle size and morphology. 4,6 Rigorous control of copper growth can be difficult: the surface energy of copper is high and the atomic diffusion rate is significant, so that dewetting often occurs during growth or subsequent annealing. 7-12Thin films of copper can be deposited by a wide variety of techniques including wet chemical growth, physical vapor deposition, chemical vapor deposition (CVD) and atomic layer deposition (ALD). To deposit copper conformally in substrate architectures such as trenches and vias that have re-entrant or high aspect ratio features, ALD and CVD are preferred techniques because of the ability of the precursor molecules to diffuse throughout the structure.13-17 A general difficulty arises when the substrate is relatively unreactive, such as an oxide surface: the resulting films tend to be rough owing to a combination of sparse nucleation and the tendency of the deposited material to agglomerate. 18 Once surface roughness on the length scale of the island separation is formed, it cannot be eliminated by the overgrowth of more material. 18The use of additives to enhance film smoothness is well established in the electrochemical deposition of copper 19,20 but is not common in CVD. For CVD, the morphology of copper films can sometimes be improved by adding a second component to the growth gas. For example, addition of H 2 O to a flux of Cu(hfac)VTMS (hfac = hexafluoroacetylacetonate and VTMS = vinyltrimethylsilane) enhances the wettability of the surfac...

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Section: Selection Of Growth Inhibitormentioning

confidence: 99%