Physical Properties of Highly Conformal TiN Thin films Grown by Atomic Layer Deposition

Kim, Jaebum; Hong, Hyunseok; Ghosh, Sumana; Oh, Ki–Young; Lee, Chongmu

doi:10.1143/jjap.42.1375

Cited by 31 publications

(26 citation statements)

References 3 publications

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“…Such an increase in growth rate with deposition temperature was also reported by others for similar ALD processes. 33,34 Ex situ XRR measurements were carried out to measure the film thickness for TiN films deposited at H-terminated c-Si substrates; however, the films were deposited with a different number of cycles compared to the films listed in Table II. Therefore, the growth rate obtained from both techniques will be compared.…”

Section: Physical Properties Tin Filmsmentioning

confidence: 99%

In situ spectroscopic ellipsometry study on the growth of ultrathin TiN films by plasma-assisted atomic layer deposition

Langereis

Heil

Sanden

et al. 2006

Journal of Applied Physics

102

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The growth of ultrathin TiN films by plasma-assisted atomic layer deposition (PA-ALD) was studied by in situ spectroscopic ellipsometry (SE). In between the growth cycles consisting of TiCl4 precursor dosing and H2–N2 plasma exposure, ellipsometry data were acquired in the photon energy range of 0.75–5.0eV. The dielectric function of the TiN films was modeled by a Drude-Lorentz oscillator parametrization, and the film thickness and the TiN material properties, such as conduction electron density, electron mean free path, electrical resistivity, and mass density, were determined. Ex situ analysis was used to validate the results obtained by in situ SE. From the in situ spectroscopic ellipsometry data several aspects related to thin film growth by ALD were addressed. A decrease in film resistivity with deposition temperature between 100 and 400°C was attributed to the increase in electron mean free path due to a lower level of impurities incorporated into the films at higher temperatures. A change in resistivity and electron mean free path was observed as a function of film thickness (2–65nm) and was related to an increase in electron-sidewall scattering for decreasing film thickness. The TiN film nucleation was studied on thermal oxide covered c-Si substrates. A difference in nucleation delay was observed on these substrates and was related to the varying surface hydroxyl density. For PA-ALD on H-terminated c-Si substrates, the formation of an interfacial SiNx film was observed, which facilitated the TiN film nucleation.

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Section: Physical Properties Tin Filmsmentioning

confidence: 99%

In situ spectroscopic ellipsometry study on the growth of ultrathin TiN films by plasma-assisted atomic layer deposition

Langereis

Heil

Sanden

et al. 2006

Journal of Applied Physics

102

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“…However, these films become dielectric below 5 nm and may not be useful for nanophotonic applications . This is because TiN thin films grown using ALD with a TiCl 4 precursor are more prone to Cl impurities, which could result in a degradation of the metallic properties in thinner films …”

Section: Introductionmentioning

confidence: 99%

Optical Properties of Plasmonic Ultrathin TiN Films

Shah

Reddy

Kinsey

et al. 2017

Advanced Optical Materials

100

101

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Theoretical studies have been conducted to comprehend these characteristics in ultrathin gold films. [6,7] However, the fabrication of such thin films is generally quite difficult. For conventional plasmonic metals, such as silver and gold, continuous, smooth films with thicknesses lower than 10 nm are challenging to produce because of island formation and large defect concentrations which result from their high surface energy. [8][9][10] On the other hand, transition metal nitrides (TiN, ZrN, etc.) can be grown epitaxially on substrates such as c-sapphire and MgO, [11] enabling the formation of continuous ultrathin films down to 2 nm while maintaining high quality. [12] These materials have gained much interest for plasmonic applications for the visible and near-infrared region due to their tailorable optical properties and refractory quality. [13] TiN has already been shown to have potential applications in photovoltaics, [14,15] waveguiding, [16] modulators, [17,18] and nonlinear optical devices. [3,19] Although some of these devices use films of ≈10 nm, there is additional interest in the formation of ultrathin metallic films (<10 nm) which may facilitate additional applications. To support this, there have been efforts to grow ultrathin TiN films using atomic layer deposition (ALD). However, these films become dielectric below 5 nm and may not be useful for nanophotonic applications. [20] This is because TiN thin films grown using ALD with a TiCl 4 precursor are more prone to Cl impurities, which could result in a degradation of the metallic properties in thinner films. [21][22][23] In the present study, we have grown continuous, epitaxial, ultrathin TiN films that remain plasmonic in the optical range via DC reactive magnetron sputtering. Using sputtering to grow the film decreases the chance of contamination since only Ti, N, and Ar are introduced into the system, which helps maintain the metallic properties in ultrathin films. The dielectric permittivity of these films was extracted using spectroscopic ellipsometry, while Hall measurements give further insight into the optical behavior of the films. Results and DiscussionUltrathin TiN films with thicknesses of 2, 4, 6, 8, and 10 nm were grown on MgO using DC reactive magnetron sputtering. Due to the lattice matching between TiN (4.24 Å) and substrates such as MgO (4.21 Å) and sapphire (4.76 Å), high quality,Overcoming the challenge of growing ultrathin metallic films is of great importance for practical applications of nanoplasmonic structures. In the present work, epitaxial, ultrathin (<10 nm) films of plasmonic TiN are grown on MgO using DC reactive magnetron sputtering. The optical properties of the films are studied through variable angle spectroscopic ellipsometry and Hall measurements. As the film thickness decreases, they become less metallic and exhibit higher loss while still remaining plasmonic in the optical range. These trends are related to the decreasing carrier concentration in the thinner films and increased scattering, respectively. Howev...

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“…In order to deposit thin films of TiN on various substrates, it is common to use processes such as physical vapor deposition (PVD) [ 8 ], chemical vapor deposition (CVD) [ 9 ], atomic layer deposition (ALD) [ 10 ], and hallow cathode ionic plating (HCIP). Among those processes, the PVD process is known to be easy and to present a good adhesion between the film and the substrates of metals and ceramics [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Heteroepitaxial growth of TiN film on MgO (100) by reactive magnetron sputtering

2014

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TiN thin films were deposited on MgO (100) substrates at different substrate temperatures using rf sputtering with Ar/N2 ratio of about 10. At 700°C, the growth rate of TiN was approximately 0.05 μm/h. The structural and electrical properties of TiN thin films were characterized with x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall measurements. For all deposition conditions, XRD results show that the TiN films can be in an epitaxy with MgO with cube-on-cube orientation relationship of (001)TiN // (001)MgO and [100]TiN // [100]MgO. TEM with selected-area electron diffraction pattern verifies the epitaxial growth of the TiN films on MgO. SEM and AFM show that the surface of the TiN film is very smooth with roughness approximately 0.26 nm. The minimum resistivity of the films can be as low as 45 μΩ cm.

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Physical Properties of Highly Conformal TiN Thin films Grown by Atomic Layer Deposition

Cited by 31 publications

References 3 publications

In situ spectroscopic ellipsometry study on the growth of ultrathin TiN films by plasma-assisted atomic layer deposition

In situ spectroscopic ellipsometry study on the growth of ultrathin TiN films by plasma-assisted atomic layer deposition

Optical Properties of Plasmonic Ultrathin TiN Films

Heteroepitaxial growth of TiN film on MgO (100) by reactive magnetron sputtering

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