Thin Film Nucleation, Growth, and Microstructural Evolution

Greene, J. E.

doi:10.1016/b978-0-8155-2031-3.00012-0

Cited by 65 publications

(75 citation statements)

References 137 publications

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“…1,8,9,10 However, the balance is delicate and at higher ion energies, a steep price is extracted in the form of residual ion-induced compressive stress resulting from both recoil implantation of surface atoms and trapping of rare-gas ions in the lattice. 11,12,13 We recently demonstrated that high-power pulsed magnetron sputtering (HIPIMS) provides an alternative route for ion-assisted TM nitride film growth via the use of substrate bias synchronized to the metal-rich portion of the plasma pulse. Stresses can be dramatically reduced, or even eliminated, since metal (as opposed to inert-gas) ions are components of the film.…”

Section: Introductionmentioning

confidence: 99%

Control of Ti1−xSixN nanostructure via tunable metal-ion momentum transfer during HIPIMS/DCMS co-deposition

Greczyński

Patscheider

et al. 2015

Surface and Coatings Technology

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Section: Introductionmentioning

confidence: 99%

Control of Ti1−xSixN nanostructure via tunable metal-ion momentum transfer during HIPIMS/DCMS co-deposition

Greczyński

Patscheider

et al. 2015

Surface and Coatings Technology

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“…In conventional dc magnetron sputtering (DCMS), reported AlN kinetic solubility limits in cubic alloys are typically xmax ≃ 0.50 at film growth temperatures Ts = 500 °C, 1,2 while xmax values up to 0.66 have been reported using cathodic arc evaporation 3 with a substrate bias of -100 V. 4 However, both sets of films exhibit extremely high compressive stresses ranging up to -5 GPa for DCMS 5 and -9.1 GPa for arc-deposited films. 6 There is a large literature on the use of rare-gas ion bombardment of the growing film during low-temperature sputter deposition in order to increase film density, 7,8,9 improve film/substrate adhesion via interfacial mixing, 10,11,12,13 enhance crystallinity and control texture through collisionally-enhanced adatom mean free paths, 14,15,16 form metastable phases through ion-irradiation-induced near-surface mixing, 17,18,19 etc. However, at high ion energies, a steep price is extracted in the form of residual ion-induced compressive stress.…”

Section: Introductionmentioning

confidence: 99%

A review of metal-ion-flux-controlled growth of metastable TiAlN by HIPIMS/DCMS co-sputtering

Greczyński

Jensen

et al. 2014

Surface and Coatings Technology

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We review results on the growth of metastable Ti1-xAlxN alloy films by hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS/DCMS) using the time domain to apply substrate bias either in synchronous with the entire HIPIMS pulse or just the metal-rich portion of the pulse in mixed Ar/N2 discharges. Depending upon which elemental target, Ti or Al, is powered by HIPIMS, distinctly different film-growth kinetic pathways are observed due to charge and mass differences in the metal-ion fluxes incident at the growth surface. Al + ion irradiation during Al-HIPIMS/Ti-DCMS at 500 C, with a negative substrate bias Vs = 60 V synchronized to the HIPIMS pulse (thus suppressing Ar + ion irradiation due to DCMS), leads to single-phase NaCl-structure Ti1-xAlxN films (x ≤ 0.60) with high hardness (> 30 GPa with x > 0.55) and low stress (0.2-0.8 GPa compressive). Ar + ion bombardment can be further suppressed in favor of predominantly Al + ion irradiation by synchronizing the substrate bias to only the metal-ion-rich portion of the Al-HIPIMS pulse. In distinct contrast, Ti-HIPIMS/Al-DCMS Ti1-xAlxN layers grown with Ti + /Ti 2+ metal ion irradiation and the same HIPIMS-synchronized Vs value, are two-phase mixtures, NaCl-structure Ti1-xAlxN plus wurtzite AlN, exhibiting low hardness (≃18 GPa) with high compressive stresses, up to -3.5 GPa. In both cases, film

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“…Once a nucleus exceeds a critical size determined by the trade-off between volume free energy and surface energy, it is said to be stable. Stable nuclei continue to grow by the incorporation of further adatoms and subcritical clusters, forming distinct islands [17,36]. Eventually, these islands coalesce with their neighbors, thus gradually decreasing the overall island density.…”

Section: Nucleation and Early Stages Of Growthmentioning

confidence: 99%

High-resolution characterization of TiN diffusion barrier layers

Mühlbacher¹

2015

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Titanium nitride (TiN) films are widely applied as diffusion barrier layers in microelectronic devices. The continued miniaturization of such devices not only poses new challenges to material systems design, but also puts high demands on characterization techniques. To gain understanding of diffusion processes that can eventually lead to failure of the barrier layer and thus of the whole device, it is essential to develop routines to chemically and structurally investigate these layers down to the atomic scale. In the present study, model TiN diffusion barriers with a Cu overlayer acting as the diffusion source were grown by reactive magnetron sputtering on MgO(001) and thermally oxidized Si(001) substrates. Cross-sectional transmission electron microscopy (XTEM) of the pristine samples revealed epitaxial, single-crystalline growth of TiN on MgO(001), while the polycrystalline TiN grown on Si(001) exhibited a [001]-oriented columnar microstructure. Various annealing treatments were carried out to induce diffusion of Cu into the TiN layer. Subsequently, XTEM images were recorded with a high-angle annular dark field detector, which provides strong elemental contrast, to illuminate the correlation between the structure and the barrier efficiency of the single- and polycrystalline TiN layers. Particular regions of interest were investigated more closely by energy dispersive X-ray (EDX) mapping. These investigations are completed by atom probe tomography (APT) studies, which provide a three-dimensional insight into the elemental distribution at the near-interface region with atomic chemical resolution and high sensitivity. In case of the single-crystalline barrier, a uniform Cu-enriched diffusion layer of 12 nm could be detected at the interface after an annealing treatment at 1000 °C for 12 h. This excellent barrier performance can be attributed to the lack of fast diffusion paths such as grain boundaries. Moreover, density-functional theory calculations predict a stoichiometry-dependent atomic diffusion mechanism of Cu in bulk TiN, with Cu diffusing on the N-sublattice for the experimental N/Ti ratio. In comparison, the polycrystalline TiN layers exhibited grain boundaries reaching from the Cu-TiN interface to the substrate, thus providing direct diffusion paths for Cu. However, the microstructure of these columnar layers was still dense without open porosity or voids, so that the onset of grain boundary diffusion could only be found after annealing at 900 °C for 1 h. The present study shows how to combine two high resolution state-of-the-art methods, TEM and APT, to characterize model TiN diffusion barriers. It is shown how to correlate the microstructure with the performance of the barrier layer by two-dimensional EDX mapping and three-dimensional APT. Highly effective Cu-diffusion barrier function is thus demonstrated for single-crystal TiN(001) (up to 1000 °C) and dense polycrystalline TiN (900 °C)

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Thin Film Nucleation, Growth, and Microstructural Evolution

Cited by 65 publications

References 137 publications

Control of Ti1−xSixN nanostructure via tunable metal-ion momentum transfer during HIPIMS/DCMS co-deposition

Control of Ti1−xSixN nanostructure via tunable metal-ion momentum transfer during HIPIMS/DCMS co-deposition

A review of metal-ion-flux-controlled growth of metastable TiAlN by HIPIMS/DCMS co-sputtering

High-resolution characterization of TiN diffusion barrier layers

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