Electrical transport, optical properties, and structure of TiN films synthesized by low-energy ion assisted deposition

Savvides, N.; Window, B.

doi:10.1063/1.341468

Cited by 104 publications

(34 citation statements)

References 49 publications

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“…In single-crystalline TiN the electrical resistivity at room temperature is 18 µΩ cm [55]. Resistivities of polycrystalline films are typ- ically in the range of 25-1000 µΩ cm [75,[83][84][85]. Such an increase in resistivity from a single-crystal to a polycrystalline film is due to scattering from the grain boundaries, vacancies and possibly also oxynitrides associated with the polycrystalline TiN [83,86].…”

Section: Electronic and Optical Propertiesmentioning

confidence: 93%

“…However, the color and spectral reflectivity of TiN films can also depend on surface roughness and near-surface defects, arising from the columnar growth in polycrystalline TiN. Comparisons with the electrical properties point toward an inverse correlation of reflectivity and resistivity, with the highest reflectivity and lowest resistivity observed for higher deposition temperatures and moderate ion energies [85].…”

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

“…Typical TiN layers with resistivities below 100 µΩ cm have a golden yellow color, while films with increasing resistivities appear bronze to brown. A reflection edge in the visible region with a characteristic reflectivity minimum at about 450 nm is responsible for the golden yellow color of the pure, stoichiometric TiN, making it a popular choice for decorative coatings [85,87]. The location of the reflection edge can be affected by changes in the carrier concentration.…”

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

“…TiN containing excess nitrogen appears bronze to brown in color while substoichiometric TiN is reported to be bright yellow. Other reasons for a shift of the reflection edge include lattice defects, and oxygen and carbon impurities [85,88]. However, the color and spectral reflectivity of TiN films can also depend on surface roughness and near-surface defects, arising from the columnar growth in polycrystalline TiN.…”

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

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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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Section: Electronic and Optical Propertiesmentioning

confidence: 93%

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

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High-resolution characterization of TiN diffusion barrier layers

Mühlbacher¹

2015

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“…Such plasmas are of paramount interest for the deposition of nitride [1] and oxide [2] films and complex composite structures [3] on the surfaces of chosen substrates. Gas-metal plasmas for technological applications are routinely produced using arc discharges with added gas flow, or a magnetron discharge in selfsputtering mode.…”

mentioning

confidence: 99%

Gas-metal e-beam-produced plasma for oxide coating deposition at fore-vacuum pressures

Борисович¹,

Alexeevich²,

Michailovitch³

et al. 2016

Proceedings of TUSUR

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This article describes an experiment on the deposition of oxide coatings on silicon and metal substrates from a gasmetal plasma. The plasma was produced by e-beam evaporation of metals (Mg, Al) with subsequent ionization of gas (oxygen) and evaporated material particles at fore-vacuum (1-10 Pa) pressures. We studied the ion composition and species fraction in the gas-metal plasma (using quadruple mass-spectrometry), as well as the thickness and surface resistivity of the coatings. Keywords: fore-vacuum, plasma-cathode electron source, coating deposition. doi: 10.21293/1818-0442-2016-19-4-10-12 A gas-metal plasma is a plasma containing ions of both gaseous and metallic species with controlled relative content. Such plasmas are of paramount interest for the deposition of nitride [1] and oxide [2] films and complex composite structures [3] on the surfaces of chosen substrates. Gas-metal plasmas for technological applications are routinely produced using arc discharges with added gas flow, or a magnetron discharge in selfsputtering mode. In recent work we have demonstrated the advantages of using a fore-vacuum pressure, plasma-cathode, electron beam source [4][5][6][7] for various applications including the generation of gas-metal plasmas by electron beam evaporation of metals in oxygen for the deposition of oxide coatings [8]. Here we describe our further research on the features of gas-metal plasmas at fore-vacuum pressures and the properties of deposited coatings.

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TiN as an Anode Material for Organic Light-Emitting Diodes

Adamovich

Shoustikov

Thompson³

1999

Adv. Mater.

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Organic light-emitting diodes (OLEDs) are currently receiving a great deal of attention, both academically and commercially. These devices have promise in applications ranging from low information content alphanumeric displays, to high resolution, large area flat panel displays. The most common OLED structure consists of a substrate coated with a transparent conductor (indium tin oxide, ITO) coated with a thin film of organic material(s), followed by a vapor deposited metal cathode. When a potential is applied to the device, holes are injected into the organic material(s) from the ITO electrode and electrons from the metal cathode. The holes and electrons recombine in the organic material, giving excitons, which radiatively relax to give off light. The efficiency of the device is best if multiple organic layers are used, i.e. separate hole and electron transporting layers.The choice of anode material for OLEDs is based on several criteria. The anode in a conventional OLED must have good optical transparency, good electrical conductivity and chemical stability, and a work function that lies near the HOMO levels of the organic materials to which it will inject holes. ITO fits these criteria and is the most widely used anode material in OLEDs. ITO films combine high transparency (» 90 %) with low resistivity (1´10 ±3 ±71 0 ±5 W cm). [1,2] Thin films of ITO can be prepared by a variety of methods, including sputtering, chemical vapor deposition (CVD) and sol-gel techniques.[2] The work function of ITO (4.4±4.7 eV based on ultraviolet photoemission spectroscopy measurements) [3±4] lies near the HOMO levels of typical OLED hole transporting or injecting material, which leads to a small barrier for hole injection into the organic material. It has been found that the ITO electrode can be treated to reduce this energy barrier. For example, devices with lower drive voltage and higher brightness have been prepared by treating the ITO surface with an oxygen plasma [5] or aqua regia. [6] The authors stressed the relationship between the surface morphology of the ITO and the device behavior. The device stability and efficiency strongly depend on the nature of the anode/organic interface. [7] One of the causes of long term OLED degradation involves the diffusion of metal ions or oxygen from the ITO into the organic film.[8±10]By introducing an ultra-thin interlayer of different organic materials at the interface, the efficiency of the devices could be improved.[11] Application of ITO covered with polyaniline film in the same type of devices also gives better results in terms of carrier injection and electroluminescence efficiency. [12,13] Polyaniline film serves as a barrier that prevents oxygen from diffusing out of the ITO and thus stabilizes the electrode±organic interface. In addition to polymers, copper phthalocyanine (CuPc) [3] and aluminum oxide [14] have been used as hole-injecting buffer layers between the ITO electrode and hole-transporting materials in OLEDs. Although the ITO electrode can be used efficiently with m...

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Electrical transport, optical properties, and structure of TiN films synthesized by low-energy ion assisted deposition

Cited by 104 publications

References 49 publications

High-resolution characterization of TiN diffusion barrier layers

High-resolution characterization of TiN diffusion barrier layers

Gas-metal e-beam-produced plasma for oxide coating deposition at fore-vacuum pressures

TiN as an Anode Material for Organic Light-Emitting Diodes

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