TiN Films Research Articles

Deciphering the mechanical strengthening mechanism: Soft metal doping in ceramic matrices-A case study of TiN-Ag films

Soft metals have been widely added into ceramic-based films for fully meeting the demanding requirements of green tribological applications. However, the resulting considerable increase of the mechanical strength by adding a soft metal below 5 at.%, which reversed the rule-of-mixture, was still not fully revealed. In this paper, a case study of TiN-Ag films was carried out to investigate the strengthening mechanism induced by adding soft metal in TiN-Ag composite/multilayered films deposited by magnetron sputtering. The results showed that dual-phases of fcc-TiN and fcc-Ag co-existed in the composite films with the Ag particles embedded in the matrix. In some areas of the Ag particles, with a size below 4 nm, epitaxial growth with the TiN template was detected, which obliged the lattice to be distorted and shrunken. Consequently, both hardness and elastic modulus were enhanced from 21 and 236 GPa, for the reference TiN film, to 26 and 323 GPa for the TiN-Ag composite film with 2.4 at.% Ag. The possibility of having the epitaxial growth of Ag within TiN were also confirmed by designing a TiN/Ag multilayered film with an Ag layer thickness of ∼3 nm.

Microstructural and tribological properties of multilayered coatings developed through heat treatment on the surface of CP-Ti

It is well known that applying NiTi intermetallic coatings on the surface of different alloys can improve their tribological behavior. In this paper, various intermetallic phases of Ni3Ti, NiTi, and NiTi2 and a Ti-rich pearlite-like eutectoid structure were in situ synthesized on the surface of commercially pure (CP) titanium grade 2. Nickel electroplating was performed on titanium samples followed by heat treatment at a temperature of 800 °C for various times up to 8 h. The formation of various phases and structures along the depth were studied using SEM, EDS and XRD. Heat treatment at a temperature of 800 °C for 4 h resulted in the formation of a multi-layered composite of Ni3Ti, NiTi, and NiTi2 intermetallic films with a thickness of 5, 9, and 2 μm, respectively. A nickel diffusion layer (NDL) with a pearlitic structure containing nanolayers of αTi-NiTi2 was also formed beneath the NiTi2 layer even after 30 min of heating. Among the different layers formed on the surface of CP-Ti, the titanium-rich NiTi (51–52 at.% Ti) showed the highest hardness of more than 400 HV. Sliding wear tests were performed under a normal load of 10 N and the surfaces of wear tracks were studied using SEM. The results showed higher wear resistance of all intermetallic layers and NDL than the titanium substrate, with the highest wear resistance for Ni3Ti top layer.

Enhanced plasmonic performance of TiO2 derived TiN films via gas nitridation

This study demonstrates a cost-effective method for planar titanium nitride plasmonic film by nitriding spin-coated TiO2 in ammonia atmosphere. The effect of nitridation temperature on the structural, morphological, electrical and optical characteristics of the coated films were investigated. The films exhibited high carrier concentration of 1022/cc with significant reduction in resistivity of more than three order of magnitude, indicating the conversion to the nitride phase. Negative permittivity, crucial for plasmonic applications in the visible wavelength region, was verified for wavelengths > 463 nm using Drude-Lorentz model. A three-layer model was employed to verify the material’s plasmonic behaviour. The straightforward fabrication route, which combines spin-coating and ammonia nitridation at 950 °C, offers a new approach for titanium nitride films for plasmonic based gas and biosensing device applications in the visible region. In addition, for fabricating titanium nitride coatings for applications that require abrasion resistance, electrical conductivity, chemical stability, and biocompatibility.

A Fe3+-Doped TiO2 Superhydrophilic Coating with Transparent and Long-Lasting Antifogging Properties Constructed Based on Nanostructured Antireflective and Capillary Anchoring Effects.

Superhydrophilic surfaces have attracted great interest in antifogging applications. However, balancing long-lasting superhydrophilicity and high transparency on antifogging surfaces remains a serious problem to be solved. The objective of this work is to prepare superhydrophilic coatings with transparent and long-lasting antifogging properties. In the design, a three-step method was used to obtain the target coatings: (1) magnetron sputtering deposition of a TiN film to provide high intensity, (2) anodic oxidation of the TiN film to obtain TiO2 nanoparticles intended for nanostructured antireflective and capillary structures, and (3) the sol-gel method for the preparation of Fe3+-doped TiO2 coatings using spin-coating in order to achieve superhydrophilicity. The nanostructures, due to their subwavelength dimensions, not only provide high transparency but also recoverable superhydrophilicity owing to the presence of a capillary anchoring effect that prevents the coating from dissolving and peeling off after soaking. The doping of Fe3+ broadened the photoresponse range and maintained the long-lasting superhydrophilicity. Tests showed that the 2 mol % Fe3+-doped TiO2 coating with nanostructures exhibited the highest transparency, longest-lasting superhydrophilicity, and antifogging properties. Furthermore, the coating provided excellent self-cleaning properties, as well as mechanical and chemical stability.

Amorphous-like TiN Films as Barrier Layers for Copper

Amorphous-like TiN Films as Barrier Layers for Copper

Enhanced Oxidation Resistance and Interface Stability of Atomic-Layer-Deposited MoNx Electrodes via TiN Passivation for DRAM Cell Capacitor Applications.

The continuous miniaturization of dynamic random-access memory (DRAM) capacitors has amplified the demand for electrode materials featuring specific characteristics, such as low resistivity, high work function, chemical stability, excellent interface quality with high-k dielectrics, and superior mechanical properties. In this study, molybdenum nitride (MoNx) films were deposited using a plasma-enhanced atomic layer deposition (PEALD) employing bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and NH3 plasma for DRAM capacitor electrode applications. Depending on the deposition temperatures of the PEALD MoNx films ranging from 200 to 400 °C, the Mo/N ratio and crystal structure varied, transitioning from the cubic NaCl-B1-type MoN phase with Mo/N ratio of 1.4 to the cubic γ-Mo2N phase with Mo/N ratio of 1.9. Notably, MoNx films grown at 400 °C exhibited low resistivity (435 μΩ·cm), a high work function (5.28 eV), and superior mechanical hardness (11.3 GPa) compared to ALD TiN films. Despite these excellent properties, the PEALD MoNx electrode demonstrated insufficient chemical stability, particularly in terms of oxidation resistance and interface quality with ALD HfxZr1-xO2 (HZO) films. This resulted in poor morphology and the formation of significant oxygen-deficient HZO layers (such as HfO2-x), leading to considerable degradation in the electrical performance of metal-insulator-metal (MIM) capacitors. To mitigate this issue, a thin (2.5-14 nm) ALD TiN layer was introduced as a passivation layer between the MoNx bottom electrode and HZO dielectric. The TiN-passivated MoNx (TiN/MoNx) electrode showed substantially enhanced oxidation resistance and reduced interfacial reactions with the HZO dielectric. Consequently, MIM capacitors with TiN/MoNx bottom electrodes demonstrated outstanding electrical performance, including excellent dielectric properties, low leakage current density, and high mechanical strength. Hence, this study proposes a promising candidates for storage nodes in the next-generation DRAM capacitors.

XPS investigations of thin epitaxial and magnetron tin layers surface physico-chemical state

Thin layers of the tin-oxygen system with nanometer thicknesses and structures based on them are relevant objects of development for use in modern devices, for example in microelectronics. The general miniaturization of electronic devices, the achievement of energy efficiency in the operation of such devices, and the optimal modes of their operation determine the strategies for using the tin-oxygen system structures. First of all, the justification of the tin-oxygen system nanolayers formation technique. The dependence of the formed nanolayers properties on the state of their surface is significant. The article contains the results of direct experimental studies of the composition and physico-chemical state of the tinoxygen system thin nanolayers surface. To form the studied structures, the popular and in-demand methods of magnetron sputtering and molecular beam epitaxy were used. The X-ray photoelectron spectroscopy was applied with the use of the synchrotron radiation which has a high intensity and the possibility of spectrum excitation energy optimal selection, which is important for a small amount of the studied material. After formation, the research objects were stored in laboratory conditions for several weeks before synchrotron studies. Differences in the surface composition and physico-chemical state of the thin tin layers formed by magnetron sputtering or epitaxially, and then oxidized naturally, are shown. Five monolayers of tin formed by the molecular beam epitaxy make it possible to diffuse atmospheric oxygen, which oxidizes the Si buffer layer located under the Sn nanolayer on a silicon substrate. At the same time, the surface of the tin film obtained by magnetron sputtering is close to the natural oxide SnO2-x in its physico-chemical state. The results of the work can be useful for determining the optimal approaches to the formation and subsequent modification of thin and ultrathin layers of tin oxides for the tasks of creating active layers of modern electronic devices

Engineering Carrier Density and Effective Mass of Plasmonic TiN Films by Tailoring Nitrogen Vacancies.

The introduction of nitrogen vacancies has been shown to be an effective way to tune the plasmonic properties of refractory titanium nitrides. However, its underlying mechanism remains debated due to the lack of high-quality single-crystalline samples and a deep understanding of electronic properties. Here, a series of epitaxial titanium nitride films with varying nitrogen vacancy concentrations (TiNx) were synthesized. Spectroscopic ellipsometry measurements revealed that the plasmon energy could be tuned from 2.64 eV in stoichiometric TiN to 3.38 eV in substoichiometric TiNx. Our comprehensive analysis of electrical and plasmonic properties showed that both the increased electronic states around the Fermi level and the decreased carrier effective mass due to the modified electronic band structures are responsible for tuning the plasmonic properties of TiNx. Our findings offer a deeper understanding of the tunable plasmonic properties in epitaxial TiNx films and are beneficial for the development of nitride plasmonic devices.

Real‐Time Detection of Coherent Vibrational Dynamics in TiN Films

AbstractTitanium nitride (TiN) has recently gained considerable interest because of its remarkable plasmonic properties and for its strong electron–phonon (e–ph) coupling, leading to extremely fast (<100 fs) electron‐lattice cooling. Here, the generation of coherent phonons in TiN films is reported, along with their real‐time detection by means of broadband transient reflection spectroscopy with sub‐15‐fs temporal resolution. The measurements show damped oscillations, superimposed to excited state electronic decay. A coherent vibrational mode is revealed, with ≈10 THz frequency ascribed to defect‐activated normal modes, consistent with spontaneous Raman scattering data, and a dephasing time of ≈250 fs. Two π‐phase flips are also observed located at photon energies corresponding to interband optical transitions (at 3.2 and 2.5 eV), ascribed to selective coupling of the vibrational mode to these transitions; the energy modulation induced by the vibrational coherence is evaluated. It is shown that the displacive excitation of coherent phonons model describes the coherent response in terms of temporal behavior and of spectral amplitude profile. Overall, a comprehensive and detailed analysis of coherent phonons in TiN films, so far undected, is provided and relevant information on TiN photo‐physical properties, potentially useful for its applications, is given.

From weak to strong-coupling superconductivity tuned by substrate in TiN films

Abstract The interplay between substrates and superconducting thin films has attracted increasing attention. Here, we report an in-depth investigation on superconducting properties of the epitaxial TiN thin films grown on three different substrates by dc reactive magnetron sputtering. The TiN films grown on (0001) sapphire exhibit (111) crystal orientation, while that grown on (100) Si and MgO substrates exhibit (100) orientation. Moreover, the samples grown on Si reveal a relatively lower level of disorder, accompanied by the higher critical transition temperature Tc and smaller magnitude of upper critical field slope near Tc. Remarkably, we uncovered a rather high value of superconducting gap (with Δ0/kBTc = 3.05) in TiN film on Si indicating a very strong coupling superconductivity, in sharp contrast to the case using sapphires and MgO as the substrate which reveals a weak-coupling feature. The comprehensive analysis considering the scenarios of the three substrate shows that the grain size of the thin films may be an important factor influencing the superconductivity.

Evaluation of Corrosion Resistance of TiN and CrN Films Coated on SS304 Stainless Steel Using Cathodic Arc Deposition

Monolayer (TiN/Ti) and multilayer films (TiN/Ti; CrN/Ti, TiN/CrN/Ti) with an average thickness of 2300 nm were deposited on SS304 steel using the cathodic arc deposition method. Analysis revealed the presence of numerous macroparticles (peaks) and pinholes (valleys) uniformly distributed across the surface. The monolayer film exhibited superior surface quality compared to the multilayer films but demonstrated poor adhesion to the substrate. X-ray diffraction spectroscopy detected a noticeable shift in the preferred orientation of the deposited film, transitioning from (111) to (200) when employing a multilayer structure. Applying ceramic coatings onto stainless steel induced significant alterations in the potentiodynamic polarization curves of monolayer and multilayer films, resulting in a shift towards more noble potentials and lower corrosion currents than the substrate. Furthermore, the potential passive range expanded when employing multilayer structures based on TiN and CrN.

Fabrication of TiN metal hard masks via very-high-frequency-direct-current superimposed sputtering

In high-end logic devices, TiN films have attracted increasing attention as metal hard masks (MHMs) for scaling trenches and vias of Cu back-end of line. In this study, we investigated the application of very-high-frequency-direct-current (VHF)-DC superimposed magnetron sputtering for fabricating TiN MHM films and compared these films with TiN MHM films deposited via DC magnetron sputtering. The X-ray diffraction (XRD) pattern of deposited TiN MHs showed crystalline orientations corresponding to the (111), (200), and (220) orientations of NaCl TiN. The films deposited using DC magnetron sputtering exhibited high density (<5.2 g/cm³) and significant compressive stress (1.477 GPa) when the TiN film thickness ranged from 29 to 30 nm. The films deposited via VHF-DC superimposed sputtering exhibited a higher density (5.25 g/cm³) and tensile stress (0.928 GPa). As revealed by XRD, the films deposited via DC sputtering exhibited the (111) crystal orientation, whereas those deposited via VHF-DC superimposed sputtering exhibited the (200) crystal orientation. The film deposited by VHF-DC superimposed sputtering at a frequency of 60 MHz and a substrate temperature of 350 °C exhibited good resistivity (93.0–143.3 μΩ cm). Furthermore, the TiN films exhibited exceptional smoothness with a surface roughness of less than 0.5 nm. These results show that VHF-DC superimposed sputtering is a promising technique for fabricating TiN-based MHMs.

Investigation of laser-assisted micromachining of NiTi SMA bimorph based actuators toward developing optical shutters

Abstract This work explores laser-assisted micromachining for the precision cutting of NiTi shape memory alloy (SMA)-based bimorph in a single-pass laser scan. SMA thin film based optical shutters were developed with this method, which can generate the opening and closing via Joule’s heating rather than mechanical components. NiTi SMA bimorph was fabricated using the e-beam evaporation technique followed by micromachining using a 1064 nm fiber laser. The influence of laser power (LP), laser speed (LS), spot diameter (SP), and laser travel direction on kerf width and heat-affected zone after micromachining was studied using the design of experiments. The optimized parameter for micromachining was at LP 5 W with 5 mm s−1 LS and 50 μm SP. Various shapes were cut at the optimized parameter, including an optical shutter of a diameter of 30 mm. A LS of 6 mm s−1 has produced microchannels in the bimorph due to NiTi film removal only. The SEM analysis of the shutter reveals the formation of refined grains at micromachined edges compared to the center of the actuator. Fabricated optical shutter shows negligible optical transmittance in the 450–700 nm wavelength range.

Effect of bottom critical dimension (CD) size on TiN residual

Abstract The relationship between bottom critical dimension (CD) size and TiN residual in semiconductor manufacturing was elucidated. As an excellent electrode material, TiN needs to be cut from the continuous TiN film during the capacitor preparation process to achieve parallel connection of capacitors and increase capacitance. However, TiN film may only partially be removed under different process conditions. To illustrate the reason for TiN residual and its relationship with bottom CD size, the TiN and oxide thin films were deposited by atomic layer deposition (ALD) and plasma enhanced chemical vapor deposition (PECVD), respectively. The results show that the amount of TiN residual and bottom CD size was strongly coupled when the bottom CD size larger than 140 nm TiN can be fully removed. However, if the trench bottom CD size is smaller than 85 nm, there are different degrees (residual TiN thickness within the various of 1.8-11 nm) of TiN remain. Therefore, the results of this paper are of much importance as a reference for process design.

The formation process and mechanism of coaxial electrostatic atomization of nanofluid oil film droplets

Abstract In coaxial electrostatic atomization cutting, the atomization effect of nanofluid oil film droplets directly affects the cooling and lubrication performance. To further understand the formation process of tiny oil film water droplets in coaxial electrostatic atomization, this paper takes LB2000/water, LB2000/0.1 vol.% graphite water-based nanofluids, LB2000/0.3 vol.% graphite water-based nanofluids, LB2000/0.5 vol.% graphite water-based nanofluids as the research object. Coaxial electrostatic atomization simulation is carried out based on the determined common voltage of the conical jet (-6.5 kV). The formation process of nanofluid oil film water droplets was analyzed using electric field force, charge concentration, and volume force, and the droplet states under different fluid types were compared. The results show that when nanoparticles are added to the inner fluid, the charge concentration increases, the electric field force and volume increase, and the formation speed of the cone jet increases significantly.

Influence of topography on nano-mechanical properties of cylindrical magnetron sputtered TiN films

Numerous studies on Nano-mechanical behavior of the thin films explained primarily in terms of their film morphology and particle size rather than film topography. Therefore, the current study investigates the effect of film topography on the nano-mechanical characteristics of the film. Ti/TiN multilayer thin films were deposited at varying deposition pressures by using an indigenously developed Cylindrical Magnetron Sputtering (CMS) unit. Surface crystallographic information is characterized by synchrotron-based Grazing Incidence XRD analysis. Film growth follows self-assembled nano hill architecture as revealed by AFM and in situ Scanning Probe Microscopy images. The tribo-mechanical properties of the film is dependent on the height and spacing of its self-assembled structure, which experiences either crushing or buckling under the indenter load, thereby affecting film characteristics. Film deposited at moderate pressure exhibits superior wear behavior, attributed to the interplay between Plasticity Index (PI) and Depth Recovery Ratio (DRR). The study primarily focused on film growth phenomena by using cylindrical targets and their influence on nanomechanical properties of the film.

Cu enhances the photothermal effect of a TiN film for antibacterial applications

In recent years, diseases caused by the spread of hazardous microorganisms (e.g., bacteria) have become a growing global concern. Imparting antimicrobial properties to the surface of a material is critical for the prevention of bacterial disease transmission. In this study, titanium nitride/copper composite (TiN-CuX) films with excellent antibacterial properties were deposited on AISI 304 stainless steel (304ss) via magnetron sputtering. The TiN-CuX composite films exhibited excellent photothermal performance under near-infrared (NIR, 808 nm) irradiation: the temperature of a TiN-CuX composite film surface exposed to a bacterium-containing medium increased rapidly, resulting in the death of bacteria on the surface (∼100 %). The TiN–Cu600 film exhibited 70.8 % antibacterial activity owing to the release of Cu2+ in the absence of NIR irradiation. The TiN-CuX composite films prepared in this study demonstrated outstanding antibacterial capabilities owing to synergy between the photothermal effect and Cu2+ release. The TiN-CuX composite films prepared in this study are intended for use as photothermal antibacterial coatings and represent a new approach for the production of antibacterial coatings on material surfaces.

Sputter-deposited Ni-rich NiTi thin films: Mechanical behavior and composition sensitivity

In this study, we investigated the mechanical behavior of sputter-deposited Ni-rich NiTi thin films with various chemical compositions. Freestanding thin films were successfully produced by employing magnetron sputtering and microfabrication techniques. Notably, films containing Ni within the range of 52.6–57.6 at. % exhibited distinct stress-induced martensitic transformations. Among these, 53.3 at. % and 54.2 at. % Ni–Ti films demonstrated a remarkable combination of strength exceeding 1.5 GPa and elastic strain approaching 5%. Conversely, films with the highest Ni content displayed nearly linear elastic behavior, showcasing an exceptional tensile strength of 2.2 GPa. As the element composition deviated from the equiatomic ratio, the grain size of the deposited films underwent a transition from several micrometers to nano-scale. In addition, the critical stresses showed lower sensitivity to chemical composition compared to bulk alloys, indicating that superelastic behavior persists over a wider composition range in Ni-rich NiTi thin films. By comparing the NiTi matrix and precipitate morphology between bulk alloys and thin films, we discussed the variations in the mechanical behavior of thin films.

Duplex surface engineering of cold spray Ti coatings and physical vapor-deposited TiN and AlTiN thin films

The feasibility of a duplex coating based on cold spray technology and magnetron sputtering was evaluated for repair applications requiring a ‘thin-on-thick’ layered structure. Commercially pure angular-shaped Ti grade 4 particles are fed to a cold spray gun and accelerated toward a Ti alloy substrate to deposit thick coatings (∼4.5 mm). TiN and AlTiN thin films are deposited on polished cold spray coatings using a four-source closed-field unbalanced magnetron sputtering (CFUBMS) system. Microstructure was characterized using focused ion beam (FIB) lift-out, scanning electron microscopy (SEM), and electron channeling contrast imaging (ECCI). The nanoindentation technique was used to evaluate the mechanical properties of coatings. The H/E ratios and H3/E2 ratios for TiN films were found to be 0.098 and 0.26 GPa, respectively, while those for AlTiN films were measured at 0.066 and 0.052 GPa, respectively, suggesting higher capacity of TiN films to withstand both elastic and plastic deformation. Using scratch testing, the adhesion of TiN and AlTiN thin films to cold spray Ti was investigated, with TiN-Ti duplex coatings exhibiting better performance compared to AlTiN-Ti coatings. Tribological testing was performed on duplex coatings using a reciprocating tribometer equipped with an alumina ball counterface. The wear rate for AlTiN-Ti coatings after 2000 sliding cycles was found to be (1.0 × 10−3 ± 0.1 × 10−3 mm3/Nm), three orders of magnitudes higher than that for TiN-Ti (8 × 10−6 ± 2 × 10−6 mm3/Nm. SEM was used to reveal worn surface morphologies and cross-sectional analysis of the wear track. Subsurface microstructural changes due to wear were examined using focused ion beam cross-sectioning, revealing bending cracks and tribofilm formation.

Synthesis of high conformalty Ti-Six-N films using (CH3)3CCl and SiH4; density functional theory simulation and film characterization

The step coverage of the atomic layer deposition (ALD) of Ti-N thin films was improved by the addition of (CH3)3CCl, and Si atoms were added during the Ti-N deposition to form a Ti-Six-N thin film. By ALD, four to eight cycles of the gas (CH3)3CCl/TiCl4/NH3 formed the Ti-N layer and, subsequently, one to two cycles of the gas SiH4/NH3 added Si atoms to formed the Ti-Six-N layer. The ALD process was repeated to form a thin film Ti-Six-N 150 Å (bilayer of (Ti-N) 80 Å + (Six-N) 70 Å) while adjusting the amounts of (CH3)3CCl and SiH4. The crystallinity of Ti-N was studied by X-ray diffraction (XRD), and its composition was studied using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. The composition of the Ti-Six-N film was studied using electron energy loss spectroscopy and selected area electron diffraction, and its roughness was confirmed using atomic force microscopy. Transmission electron microscope was used to measures the thickness and composition of the Ti-Six-N film through location in a test pattern with an aspect ratio of 50:1. Step coverage improved to 99.9 % compared to conventional ALD Ti-N when using (CH3)3CCl. Additionally, (CH3)3CCl was more effective at lower temperatures (460 °C compared to 530 °C), and the effect of the (CH3)3CCl flow rate was saturated above 300 sccm.As the amount of (CH3)3CCl increased, the growth per cycle decreased from 0.29 Å/cycle to 0.15 Å/cycle. The addition of Si to the Ti-N film facilitated leakage gain by increasing the difference in the work function between the electrode and the capacitor, material but may have the side effect of pillar bending due to a decrease in crystallinity and hardness. We verified that the XRD (200)/(111) peak ratio decreased as the Si content increased. As a result, the optimal conditions for electrode Ti-Six-N were confirmed as follows: 300 sccm (CH3)3CCl Ti-N, SiH4 10 sccm Six-N combination.Furthermore, the Ti-Six-N layer can serve as the bottom electrode of a capacitor reduce the manufacturing process steps, and be a candidate for a solution for the electrode of the capacitor of a 5 nm node memory device.