Titanium Nitride Surface Research Articles

Investigation of the TiN/photoresist interface degradation during a wet etch

In the context of titanium nitride (TiN) patterning in presence of photoresist, the formation of stains in large resist patterns during Standard Clean 1 (SC1) wet etches was investigated. These stains were found to be caused by surface modifications of the TiN layer below the photoresist, with the appearance of large bumps at its surface. XPS and ToF-SIMS characterization techniques were applied to study the TiN surface modification during the SC1 treatment. The TiN film was found to be globally etched by the SC1, with chemical modifications inside the bump area. It is hypothesized that the TiN was attacked after the penetration of wet etchants through the photoresist, but that the confined environment did not enable reaction products to be evacuated, resulting in bumps at the TiN surface.

Hydrothermal treatment for TiN as abrasion resistant dental implant coating and its fibroblast response.

Dental implant made of pure titanium (Ti) is prone to scratch and abrasion during routine oral hygiene procedures. This results an increase in surface roughness and therefore, facilitates the adhesion of bacteria. In severe cases, this could lead to peri-implantitis. To overcome this problem, surface modification of Ti is necessary to improve its abrasion resistance. Besides, a strong implant-gingiva interface should also be guaranteed to prevent the adhesion of bacteria. In this study, titanium nitride (TiN) coating was first prepared with gas nitriding to increase surface hardness of pure the substrate. Then, the TiN was hydrothermally treated in CaCl2 solution in order to improve its soft tissue biocompatibility. The effect of hydrothermal treatment temperature on surface properties of TiN was investigated and its biocompatibility was assessed in vitro using NIH3T3 fibroblast cell. It was determined that 120°C was the critical temperature for the hydrothermal treatment condition. Treatment below 120°C could incorporate Ca into TiN surface, oxidize TiN surface partially and then improve the wettability while preserving its morphology and hardness. Fibroblast cell attachment and proliferation were improved and cell spreading was enhanced on hydrothermally treated specimens compared with untreated ones. Improved wettability, Ca incorporation and negative surface due to interstitial N were believed to be the main reasons. Hydrothermal treatment is expected to make TiN a promising dental implant coating with excellent abrasion resistance and good soft tissue affinity.

Novel Mo/TiN composites for an alkali metal thermal-to-electric converter (AMTEC) electrode

Core–shell composite powders composed of molybdenum (Mo) coated on titanium nitride (TiN) were synthesized using a Pechini-type polymerizable complex method to improve the microstructural stability and electrochemical performance of alkali metal thermal-to-electric converter (AMTEC) electrodes. The coverage of porous Mo shells was controlled by adjusting the concentration of resin-embedded molybdenum sources around TiN particles. Each composite powder was characterized by microstructural analysis (SEM, TEM) and X-ray spectroscopy (XRD, EDX and XPS). During the synthesis process, thin oxide layers (i.e., TiOx, with x=1.0–2.0) were formed on the TiN surface. Each Mo and TiN phase shares a common intermediate oxide layer, and there are strong interactions between oxygen anions and Mo atoms at the interface. As a result, there are cohesive networks between Mo and TiN at the core–shell interface, and these networks control the grain growth of Mo at high temperatures (>700°C). A single cell composed of Mo/TiN powder (Mo 1.0mol%) was observed to perform well (180mW/cm2) and exhibit a low area specific resistance (ASR at 0.7V) of 0.4Ωcm2 at 700°C.

A charge optimized many-body potential for titanium nitride (TiN)

This work presents a new empirical, variable charge potential for TiN systems in the charge-optimized many-body potential framework. The potential parameters were determined by fitting them to experimental data for the enthalpy of formation, lattice parameters, and elastic constants of rocksalt structured TiN. The potential does a good job of describing the fundamental physical properties (defect formation and surface energies) of TiN relative to the predictions of first-principles calculations. This potential is used in classical molecular dynamics simulations to examine the interface of fcc-Ti(0 0 1)/TiN(0 0 1) and to characterize the adsorption of oxygen atoms and molecules on the TiN(0 0 1) surface. The results indicate that the potential is well suited to model TiN thin films and to explore the chemistry associated with their oxidation.

Grafting titanium nitride surfaces with sodium styrene sulfonate thin films.

The importance of titanium nitride lies in its high hardness and its remarkable resistance to wear and corrosion, which has led to its use as a coating for the heads of hip prostheses, dental implants and dental surgery tools. However, the usefulness of titanium nitride coatings for biomedical applications could be significantly enhanced by modifying their surface with a bioactive polymer film. The main focus of the present work was to graft a bioactive poly(sodium styrene sulfonate) (pNaSS) thin film from titanium nitride surfaces via a two-step procedure: first modifying the surface with 3-methacryloxypropyltrimethoxysilane (MPS) and then grafting the pNaSS film from the MPS modified titanium through free radical polymerization. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used after each step to characterize success and completeness of each reaction. The surface region of the titanium nitride prior to MPS functionalization and NaSS grafting contained a mixture of titanium nitride, oxy-nitride, oxide species as well as adventitious surface contaminants. After MPS functionalization, Si was detected by XPS, and characteristic MPS fragments were detected by ToF-SIMS. After NaSS grafting, Na and S were detected by XPS and characteristic NaSS fragments were detected by ToF-SIMS. The XPS determined thicknesses of the MPS and NaSS overlayers were ∼1.5 and ∼1.7 nm, respectively. The pNaSS film density was estimated by the toluidine blue colorimetric assay to be 260 ± 70 ng/cm(2).

Effect of zirconium nitride physical vapor deposition coating on preosteoblast cell adhesion and proliferation onto titanium screws

Titanium has long been used to produce dental implants. Problems related to its manufacturing, casting, welding, and ceramic application for dental prostheses still limit its use, which highlights the need for technologic improvements. The aim of this invitro study was to evaluate the biologic performance of titanium dental implants coated with zirconium nitride in a murine preosteoblast cellular model. The purpose of this study was to evaluate the chemical and morphologic characteristics of titanium implants coated with zirconium nitride by means of physical vapor deposition. Chemical and morphologic characterizations were performed by scanning electron microscopy and energy dispersive x-ray spectroscopy, and the bioactivity of the implants was evaluated by cell-counting experiments. Scanning electron microscopy and energy dispersive x-ray spectroscopy analysis found that physical vapor deposition was effective in covering titanium surfaces with zirconium nitride. Murine MC-3T3 preosteoblasts were seeded onto titanium-coated and zirconium nitride-coated screws to evaluate their adhesion and proliferation. These experiments found a significantly higher number of cells adhering and spreading onto zirconium nitride-coated surfaces (P<.05) after 24 hours; after 7 days, both titanium and zirconium nitride surfaces were completely covered with MC-3T3 cells. Analysis of these data indicates that the proposed zirconium nitride coating of titanium implants could make the surface of the titanium more bioactive than uncoated titanium surfaces.

Multi-scale modelling of the blood chamber of a left ventricular assist device

This paper examines the blood chamber of a left ventricular assist device (LVAD) under static loading conditions and standard operating temperatures. The LVAD's walls are made of a temperature-sensitive polymer (ChronoFlex C 55D) and are covered with a titanium nitride (TiN) nano-coating (deposited by laser ablation) to improve their haemocompatibility. A loss of cohesion may be observed near the coating-substrate boundary. Therefore, a micro-scale stress-strain analysis of the multilayered blood chamber was conducted with FE (finite element) code. The multi-scale model included a macro-model of the LVAD's blood chamber and a micro-model of the TiN coating. The theories of non-linear elasticity and elasto-plasticity were applied. The formulated problems were solved with a finite element method. The micro-scale problem was solved for a representative volume element (RVE). This micro-model accounted for the residual stress, a material model of the TiN coating, the stress results under loading pressures, the thickness of the TiN coating and the wave parameters of the TiN surface. The numerical results (displacements and strains) were experimentally validated using digital image correlation (DIC) during static blood pressure deformations. The maximum strain and stress were determined at static pressure steps in a macro-scale FE simulation. The strain and stress were also computed at the same loading conditions in a micro-scale FE simulation.

Effect of Nd:YAG laser-nitriding-treated titanium nitride surface over Ti6Al4V substrate on the activity of MC3T3-E1 cells

Ti6Al4V discs with a thickness of 2.5 mm and dimensions of 15 × 15 mm2 were fabricated. The titanium nitride (TiN) surface was formed via Nd:YAG laser-nitriding. A sandblast acid-etched (SA) surface was used as a control. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and surface roughness tests were conducted to study the surface and cross-section morphologies as well as the properties of TiN and SA surfaces. MC3T3-E1 osteoblast-like cells were cultured on the TiN and SA surfaces to evaluate the effect of TiN surface on cellular behaviors, including attachment, proliferation and differentiation. Morphological testing results revealed that the cross-section of TiN exhibited dendritic crystallization without cracking. The proliferation and differentiation of MC3T3-E1 cells on the laser-nitriding TiN surface were significantly increased compared to those cultured on SA surface. These findings suggested that the TiN surface generated from Nd:YAG laser-nitriding were favorable for the proliferation and differentiation of MC3T3-E1 cells, which is significant for implant surface modification.

Influence of Al/TiN/SiO2 structure on MOS capacitor, Schottky diode, and fin field effect transistors devices

Titanium nitride (TiN) films were tested for their suitability as upper electrodes in metal–oxide–semiconductor (MOS) capacitors and Schottky diodes and as metal gate electrodes in fin field effect transistor devices. TiOxNy formation on TiN surfaces was confirmed by x-ray photoelectron spectroscopy and appears to be associated with exposure of the metal electrodes to ambient air. In order to avoid the formation of TiOxNy and TiO2, a layer of aluminum (Al) was deposited in situ after the TiN deposition. TiN work function was calculated for the devices to study how dipole variation at the interface TiN/SiO2 influences TiN work function. TiOxNy and TiO2 formation at the film surface was found to affect the dipole variations at the TiN/SiO2 interface increasing the dipole influence on MOS structure. Furthermore, the estimated values TiN work function are suitable for complementary metal–oxide–semiconductor (CMOS) technology. Finally, this work had shown that Al/TiN structure can be used in CMOS technology, especially on n-type metal–oxide–semiconductor field effect transistor devices.

Bone Response to Surface-Modified Titanium Implants: Studies on the Early Tissue Response to Implants with Different Surface Characteristics

In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO2 surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO2, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography.

TiN surface modified SnO2 as an efficient anode material for lithium ion batteries

Tin dioxide (SnO2) attracts considerable attention as an anode material due to its high theoretical capacity compared with graphite. However, the practical use of a SnO2 anode is significantly hampered by its large volume changes during lithium insertion and extraction processes, which leads to poor cyclic performance. To overcome this problem, a simple and efficient method was employed to fabricate SnO2-based nanocomposites with controlled titanium nitride (TiN) modification. The as-prepared samples were characterized by XRD, Raman, XPS, TEM and electrochemical measurements. Compared with the pristine SnO2, the appropriate TiN modified SnO2 nanocomposite electrodes exhibited improved lithium storage performance. Particularly, the hybrid anode with 2 wt% TiN delivered a high first capacity of 1580.6 mA h g−1 and a stable capacity of 404 mA h g−1 after 50 cycles at a charge–discharge rate of 0.1 C. The improved lithium storage performance was attributed to the inactive TiN matrix, which significantly enhanced the structural stability and electronic conductivity of the SnO2–TiN nanocomposites.

Effects of Hydrothermal Treatment on Properties of Titanium Nitride Coating for Dental Implants

To improve surface hardness of dental implant made of pure titanium (Ti), titanium nitride (TiN) coating was introduced. However, studies revealed that TiN only showed osseointegration similar or inferior to that of Ti. Therefore it is necessary to improve the biocompatibility of TiN for dental implant coating. In the present study, TiN coating was prepared on pure Ti substrates and hydrothermal treatment was conducted to modify its surface properties. It was found that, TiN surface was partially oxidized after treatment and calcium (Ca) was successfully combined onto its surface. Surface morphology, roughness and hardness were not affected after treatments below 140°C and wettability was obviously improved.

Differences in proliferation, differentiation, and cytokine production by bone cells seeded on titanium–nitride and cobalt–chromium–molybdenum surfaces

Titanium-nitride coating is used to improve cobalt-chromium-molybdenum implant survival in total knee arthroplasty, but its effect on osteoconduction is unknown. Chromium and cobalt ions negatively affect the growth and metabolism of cultured osteoblasts while enhancing osteoclastogenic cytokine production. Therefore, it was hypothesized that a titanium-nitride surface would enhance osteoblast proliferation and/or differentiation and reduce osteoclastogenic cytokine production compared with a cobalt-chromium-molybdenum surface. MC3T3-E1 osteoblasts showed increased proliferation and decreased differentiation on titanium-nitride, while cytokine interleukin-6 production was higher on porous cobalt-chromium-molybdenum (p < 0.05), though interleukin-1β was occasionally detected on both surfaces. These findings suggest improved osteoconduction on titanium-nitride compared with cobalt-chromium-molybdenum surface.

Influence of crystallographic orientation on the early stages of oxidation of polycrystalline titanium nitride

Oxide islands are observed on polycrystalline titanium nitride surface after annealing at 1000°C for 10h under secondary vacuum (PO2 about 10−6mbars). EBSD orientation mapping revealed that the growth of these islands is affected by the orientation of the underlying substrate grain. Based on the size and population density of the islands, the following order was established for the reactivity at the early stages oxidation: TiN (100)>TiN (110)>TiN (111). Several possible explanations are proposed to understand the relative stability of TiN (111) surface. The results are not completely understood and further works are necessary to determine the oxidation rates as a function of the crystallographic orientation.

A Kinetic Model for Ammonia Adsorption on a Titanium Nitride Surface

Recent developments aiming to microsensors based on floating gate field effect transistors (FGFET) were investigated for application in a rodent cage monitoring. Given that these sensors were on the forefront of technology, a theoretical model was developed for the ammonia sensor to further understand the chemical reaction taking place on its surface. The sensors were tested in a controlled environment, where the air quality was known. The magnitude and time of the response to different levels of ammonia were determined in the 50-100 ppm range. The reaction mechanism selected for the model which was best supported by the literature and the experiments was molecular adsorption of ammonia on a titanium nitride surface. The experimental results were fitted to the model to obtain the adsorption and desorption rate constants, the equilibrium concentration constant, equilibrium constant, and Gibb's free energy, which were 6.28 L/mol · s, 6.43 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , 976.7 L/mol, 39.04, and -9.25 kJ/mol, respectively. Based on these values, it was determined that the forward reaction, or adsorption, occurs spontaneously. There was good correlation between the theoretical model and the experimental results, indicating that the theoretical model was sufficient for this application.

Investigations of laser-sustained plasma and its role in laser nitriding of titanium

Laser-sustained plasma (LSP) and CCD imaging of reactant species were employed to investigate the role of near-surface plasma in CO2 laser nitriding of titanium in open atmosphere. Insights were gained regarding the role of plasma processes and the role of reactive nitriding species in the nitriding process. Studies of single nitrided trails have identified the following regimes, as a function of LSP off-focal distance and beam translation speed, characterized by (1) the formation of heavily oxidized surfaces, (2) the formation of titanium nitride (TiN) nanoparticulate, (3) nitride formation in the absence of a surface-struck or LSP and (4) the formation of near-stoichiometric, oxide-free TiN surfaces with a LSP. For the first time it will be shown that the LSP can access nitriding conditions beyond those achieved with surface-struck plasma (or in the absence of plasma) to produce uniform, near-stoichiometric, titanium nitride coatings.

Non-equilibrium partial oxidation of TiN surface for efficient visible-light-driven hydrogen production

The non-equilibrium quick oxidation of titanium nitride (TiN) particles is found to be capable of kinetically controlling the partial oxidation on the surface and constructing a TiOxNy@TiN core–shell structure, in which the TiOxNy shell exhibits different components (x = 0.0–2.0). The TiOxNy@TiN structure can absorb visible light and display a high photocatalytic activity for hydrogen production, without any help from noble metal co-catalysts. A hydrogen generation rate of 506 μmol g−1 h−1 can be reached. The strong catalytic ability of TiOxNy@TiN can be attributed to the formation of heterojunction among the hybrid TiOxNy, which can facilitate the separation of light-induced electron–hole pairs. Furthermore, the non-equilibrium quick oxidation leads to the partial survival of electro-conductive TiN tiny crystals on the surface, which can act as co-catalysts to further improve the electron–hole separation and to catalyze hydrogen ion reduction.

Deposition of titanium nitride (TiN) on Co–Cr and their potential application as vascular stent

This study reports the effect of a TiN film on the mechanical properties and endothelial compatibility of a Co–Cr substrate. A dense, columnar TiN film with a preferential orientation of the (111) plane was deposited successfully on a Co–Cr substrate by reactive DC sputtering, particularly by applying a negative substrate bias during deposition. Good adhesion between the TiN film and Co–Cr substrate was achieved using a thin Ti film as an intermediate layer. The TiN film improved the mechanical properties of the Co–Cr significantly, such as the surface hardness and elastic modulus. In addition, the attachment and proliferation of endothelial cells were enhanced remarkably, which was attributed mainly to the favorable absorption of proteins on a biocompatible TiN surface.

Surface topography and physicochemistry of silver containing titanium nitride nanocomposite coatings

Titanium nitride (TiN) is a hard, wear-resistant coating material, which is widely applied to components operating in an abrasive wear environment. When codeposited with silver, the coating forms a nanocomposite structure consisting of nanoparticles of silver embedded in a TiN matrix. TiN/Ag coatings were deposited by cosputtering onto bright annealed stainless steel substrates. By control of the target powers, the silver content of the films was varied in the range of 0–16.7 at. %. The films were characterized using scanning electron microscopy (structure), energy dispersive x-ray spectroscopy (chemical composition), white light profilometry (roughness), atomic force microscopy (topography), and physicochemistry (ΔGiwi, γs, γsLW, γsAB, γs+, and γs−). Silver was heterogeneously distributed throughout the TiN matrix, and increasing the silver content in the TiN surfaces resulted in changes in surface nanotopographies with respect to surface features, grain sizes, and physicochemistry. In particular, a silver concentration of 16.7 at. % resulted in a distinct change in surface nanotopography and features, which were qualitatively demonstrated using visual images, linear profiles, and quantitatively using Rp, Rpm, Rz, and Rt roughness parameters. There were also some changes in γs− with increased silver content. When producing novel surfaces, changes in surface chemistry affect other surface parameters. A thorough analysis of surface parameters is essential since changes may affect the potential end use of the product.

Reversible Tuning of the Surface Chemical Reactivity of Titanium Nitride and Nitride−Carbide Diffusion Barrier Thin Films

The chemical properties of titanium nitride−carbide (TiNC) and titanium nitride (TiN) films deposited on silicon are investigated comparatively, showing that the surface reactivity of nitride-based films can be modified precisely and reversibly by controlling the surface elemental composition. These materials are used as diffusion barrier films, and therefore understanding their surface chemistry is key for controlling further deposition steps during interconnect metallization. Chemical vapor deposition (CVD) using Ti[N(CH3)2]4 leads to the formation of TiNC, and nitridation of this film through postannealing under NH3 decreases significantly the carbon content on the surface, leaving essentially a TiN surface, as characterized through the use of spectroscopic, depth-profiling, and microscopic techniques. As determined by the temperature-programmed desorption (TPD) studies of ethylene (carbidization reagent) and dimethylamine (decomposition product of the deposition precursor), the TiN surface is more rea...