ZrN Thin Films Research Articles

Hydrogen permeation resistance of ZrN thin film deposited by ion-plating

Hydrogen absorption of Zircaloy nuclear fuel cladding, used in light water reactor at nuclear power plants, poses an increased risk of delayed hydride cracking during interim dry storage. Consequently, novel surface technologies aimed at reducing hydrogen absorption have become a critical area of research. Zirconium nitride coatings, renowned for their high hardness, corrosion resistance, and wear resistance, have seen widespread application in various industries, including medical devices, cutting tools, and decoration. This study explores the effectiveness of ZrN coating in suppressing hydride formation in Zircaloy-4, a material commonly used for nuclear fuel cladding. In this research, ZrN coatings were deposited onto recrystallized Zircaloy-4 substrates using a hollow cathode discharge ion-plating (HCD-IP) system. The coated and uncoated Zircaloy-4 samples were then subjected to electrochemical and gaseous hydriding processes. The study further investigates the differences in microstructure and hydrogen content of coated and uncoated Zircaloy-4. From these results, it is evident that the ZrN thin film deposited by HCD-IP exhibited great resistance to hydrogen permeation against both hydriding conditions. It is concluded that the ZrN thin films can serve as an excellent hydrogen barrier layer for Zircaloy-4.

300 mm CMOS-compatible superconducting HfN and ZrN thin films for quantum applications

The rising interest in increased manufacturing maturity of quantum processing units is pushing the development of alternative superconducting materials for semiconductor fab process technology. However, these are often facing CMOS process incompatibility. In contrast to common CMOS materials, such as Al, TiN, and TaN, reports on the superconductivity of other suitable transition-metal nitrides are scarce, despite potential superiority. Here, we demonstrate fully CMOS-compatible fabrication of HfN and ZrN thin films on state-of-the-art 300 mm semiconductor process equipment, utilizing reactive DC magnetron sputtering on silicon wafers. Measurement of mechanical stress and surface roughness of the thin films demonstrates process compatibility. We investigated the materials phase and stoichiometry by structural analysis. The HfN and ZrN samples exhibit superconducting phase transitions with critical temperatures up to 5.84 and 7.32 K, critical fields of 1.73 and 6.40 T, and coherence lengths of 14 and 7 nm, respectively. A decrease in the critical temperature with decreasing film thickness indicates mesoscopic behavior due to geometric and grain-size limitations. The results promise a scalable application of HfN and ZrN in quantum computing and related fields.

Chemical Interaction of Hydrogen Radicals (H*) with Transition Metal Nitrides.

Transition metal nitrides (TMNs) are reported as protective coatings in reactive hydrogen environments. Although the permeation of H2 through TMN coatings is well reported, their reducibility in H* environments is less investigated. In this work, we categorize the interaction of H* with ambient exposed TiN, ZrN, HfN, VN, NbN, and TaN thin films at 700 °C into three classes. We find that in TiN and VN samples, H*-induced reduction was limited to the surface (≈ top 2 nm). Significant denitridation was observed in ZrN and HfN samples beneath the surface, along with an increase in the transition metal oxide (TMOx) fraction. Denitridation was observed in NbN and TaN samples as well, but the increase in the TMOx content was less than for ZrN and HfN. We propose a model in three steps: hydrogenation, formation of volatile species, and diffusion of subsurface atoms to the surface. We show that the interaction of H* with TiN, ZrN, HfN, VN, NbN, and TaN with partially oxidized surfaces can be explained using the preferred hydrogenation pathway (based on the work functions) and the thermodynamic driver for forming volatile species (NH3 and H2O; based on the change in Gibbs free energy).

Structural, morphological, and electrochemical capacitive properties of sputtered ZrN thin films for supercapacitor

Structural, morphological, and electrochemical capacitive properties of sputtered ZrN thin films for supercapacitor

Residual Stress and Tribological Performance of ZrN Coatings Produced by Reactive Bipolar Pulsed Magnetron Sputtering.

In the past few decades, ZrN thin films have been identified as wear resistant coatings for tribological applications. The mechanical and tribological properties of ZrN thin layers depend on internal stress induced by the adopted deposition techniques and deposition parameters such as pressure, temperature, and growth rate. In sputtering deposition processes, the selected target voltage waveform and the plasma characteristics also play a crucial influence on physical properties of produced coatings. In present work, ZrN thin films, obtained setting different values of duty cycle in a reactive bipolar pulsed dual magnetron sputtering plant, were investigated to evaluate their residual stress through the substrate curvature method. A considerable progressive increase of residual stress values was measured at decreasing duty cycle, attesting the significant role of voltage waveform in stress development. An evident correlation was also highlighted between the values of the duty cycle and those of wear factor. The performed analysis attested an advantageous effect of internal stress, having the samples with high compressive stress, higher wear resistance. A downward trend for wear rate with the increase of internal residual stress was observed. The choice of suitable values of duty cycle allowed to produce ceramic coatings with improved tribological performance.

Effects of Nitrogen Content on the Structural, Mechanical, and Corrosion Properties of ZrN Thin Films Grown on AISI 316L by Radiofrequency Magnetron Sputtering

AbstractZirconium nitride films are deposited onto stainless steel AISI 316L and silicon (100) by radio frequency magnetron sputtering at different nitrogen flow ratios [N2/(Ar+N2)] varied between 0 and 0.25). Scanning electron microscope, atomic force microscopy, X‐ray diffraction (XRD), and Raman are used to investigate the surface morphology and microstructure of the thin films. The mechanical and electrochemical properties of all coatings are evaluated and compared with the uncoated AISI 316L to explore the efficiency of surface modification. The XRD and Raman analysis show that all the films are crystalline. This shows that the increased nitrogen content leads to a transformation from hexagonal α‐Zr phase to cubic c‐Zr and then to mixed α‐Zr and face centered cubic c‐ZrN phases. The films deposited with nitrogen flow ratio of 0.2 show the highest hardness of 32.2 GPa. Using the potentiodynamic polarization method, the corrosion behavior of the films is studied in Hank's solution. The comparison between uncoated and coated substrates shows a decrease in corrosion current density for all coated samples.

Characterizing the physicochemical and mechanical properties of ZrN thin films deposited on Zr substrates by pulsed laser technique

Due to their outstanding physical and mechanical features, ZrN thin films are increasingly used as coatings to protect materials intended for nuclear applications such as Zirconium. To our knowledge, there is no report of pulsed laser deposition (PLD) of ZrN thin films on a Zr substrate. In this work, we have successfully prepared ZrN thin films on Zr substrates using the PLD technique with a KrF excimer laser, in a N2 environment at 2 Pa pressure and a fixed substrate temperature of 500 °C. The deposited 200 nm ZrN thin films exhibited a homogeneous surface and showed a face-centered cubic polycrystalline structure. The surface roughness was 3.69 nm. X-ray diffraction, Raman and X-ray photoelectron spectroscopy measurements confirmed the presence of ZrN. The coated sample's mean value of hardness (11.6 GP) doubled that of the uncoated sample.

Improving stability of ALD ZrN thin film coatings over U-Mo dispersion fuel

Atomic layer deposition (ALD) of ZrN is a candidate technology for coating U-Mo dispersion fuel as a diffusion barrier coating. During the early development stages of the coating the ZrN deposition showed to be mechanically unstable and ultimately resulted in spalling. Based on experimental outcomes it was found that instabillity can be eliminated through the introduction of a thin amorphous (a) Al2O3 interlayer coating deposited in between the ~1-μm thick ZrN and the U-Mo. substrate. To elucidate these findings simulations were performed with density functional theory (DFT) to measure work of adhesions at different interfaces while finite element modeling (FEM) was performed to measure the residual stress distribution. DFT indicated that the ZrN coating deposited over (a)-Al2O3 is ~2.5 times stronger when compared to direct deposition over U or UO2 substrate. While calculations from FEM recognized; (1) large stress concentrations can originate from the irregularly distributed native surface oxides (UO2) over U-Mo and (2) stress concentrations can be reduced if those surface UO2 can be modified to a uniform layer (achieved after application of a 8 nm (a)-Al2O3 interlayer). These results provided explanations and confirmed the role played by interlayer in eliminating the original mechanical instability of the ZrN.

Study of columnar growth, texture development and wettability of reactively sputter-deposited TiN, ZrN and HfN thin films at glancing angle incidence

In this work, TiN, ZrN and HfN thin films fabricated using glancing angle deposition (GLAD) technique are studied both experimentally and by numerical simulations. The films (~1 μm thickness) were deposited by reactive magnetron sputtering at 0.3 Pa and 300 °C on Si substrates inclined at α = 85° with respect to the target. The film morphology and crystal structure were characterized by scanning electron microscopy, atomic force microscopy and X-ray diffraction (XRD), including pole figure measurements. The wettability of these coatings was investigated using the sessile drop method with three different liquids. It is shown that TiN, ZrN and HfN films have a cubic, NaCl-type crystal structure with a [111] out-of-plane orientation and exhibit a biaxial texture. XRD pole figures reveal that the crystal habit of the grains consists of {100} facets constituting triangular-base pyramids. The films develop columnar microstructures, with typical column widths of ~100 nm. The tilt angle β of the columns is found to increase from 24.5, 31.5 to 34° for TiN, ZrN and HfN films, respectively. Atomistic computations of the growth of these nitrides at glancing angle using a kinetic Monte Carlo model reveal that the growth morphology and variation in column tilt angle is well reproduced by considering the difference in the angular distribution of the sputtered particles. This study also shows that GLAD films are hydrophilic comparatively to the same films deposited at near-normal incidence, and among the three nitrides, TiN is the more wettable coating.

Effect of hafnium contaminant present in zirconium targets on sputter deposited ZrN thin films

Zirconium nitride thin films deposited by reactive magnetron sputtering recurrently present small amounts of hafnium (~1 at.%) in their composition derived from an inherent impurity existing in Zr targets. Hf presence in ZrN coatings is neglected by most of the researchers despite its known potential to modify properties of thin films. In this work, pure ZrN (0.9 at.% Hf contaminant) and ZrHfN thin films with intentional hafnium addition of 1.8, 3.7 and 5.5 at.% were deposited by reactive magnetron sputtering and characterized by RBS, GAXRD, SEM, nanohardness and high temperature oxidation tests. Based on the results, it is suggested that inherent hafnium presence in zirconium targets contributes for the good hardness values and oxidation resistance at 773 K registered for ZrN thin films.

The influence of substrate bias voltage on the electrochemical properties of ZrN thin films deposited by radio-frequency magnetron sputtering: Biomedical application

Abstract In order to study the influence of the substrate bias on the properties of ZrN thin films deposited by radio-frequency magnetron sputtering for biomedical application. Films of ZrN were grown onto 316L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure zirconium target in Ar - N2 gas mixture. The substrate bias voltage was varied from 0 to −100 V, which produces a variation in the structural and electrochemical properties of the obtained films. The deposited films were characterized by X-Rays Diffraction, Atomic Force Microscopy, scanning force microscopy and potentiodynamic polarization.

Microstructural investigations of 800 keV Ar ions irradiated nanocrystalline ZrN thin films

ABSTRACTThe effect of 800 keV Ar ion irradiation on the microstructure and composition of ZrN films grown by pulsed laser deposition technique was investigated. Grazing incidence and symmetrical X-ray diffraction showed films were nanostructured, with grain size around 13 nm and (111) textured. X-ray reflectivity investigations showed a 0.7% decrease of films density after irradiation with a fluence of 1 × 1014 cm−2 and no further decreased for a fluence of 1 × 1015 cm−2. An increase of the lattice parameter and a decrease of grain size after irradiation with a fluence of 1 × 1014 cm−2 was observed and almost no change after irradiation with a fluence of 1 × 1015 cm–2. X-ray photoelectron spectroscopy investigations did not detect changes in the composition of films after irradiation. Transmission electron microscopy studies confirmed that the films were nanocrystalline, compact, with columnar crystallites without pores or voids. After irradiation, the microstructure was not affected and no other phases appeared.

Microstructure and Young's modulus of ZrN thin film prepared by dual ion beam sputtering deposition

The ZrN film has drawn wide attentions as a protective material due to its attractive properties. In this study, ZrN films having thickness about 45 nm were prepared by dual ion beam sputtering deposition to investigate the influence of assisted ion beam (300 eV/25 mA ~ 800 eV/60 mA) and deposition temperature (unheated ~ 600 °C) on nano-film microstructure, grain size, density, and Young's modulus. A double layer structure, comprising an amorphous layer closed to the substrate and a crystalline layer above the amorphous layer was observed. The amorphous layer thickness decreases with the increase of atom mobility and the decrease of oxygen concentration. The assisted ion beam flux and energy influence the grain size, density, and Young's modulus. A porous structure and rough surface forms under high flux and energy assisted ion beam due to the severe damage and resputtering under high-energy nitrogen ion. Besides this, thickness of the amorphous layer decreases, increasing the grain size, density, and Young modulus due to deposition temperature. The Young's modulus shows some dispersion in the low (111) texture coefficient region indicates excellent linearity with the grain size and density. The Young modulus of nanofilm is strongly influenced by grain size or density. The nanofilm texture shows negligible impact on thin film Youngs Modulus.

Silicon influence on corrosion resistance of magnetron sputtered ZrN and ZrSiN thin films

ABSTRACTThis study compares the corrosion resistance of ZrN and ZrSiN films deposited on AISI 430 steel by the magnetron sputtering technique. Corrosion resistance was evaluated using electrochemical impedance spectroscopy (EIS) technique, in 3.5% (wt./v) NaCl solution. The chemical and morphological film characterisation was carried out by Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction and scanning electron microscopy (SEM). The RBS analysis showed that 51.5Zr–48.5N and 43.5Zr–7.6Si-48.9N (at.-%) coatings were deposited by using magnetron sputtering technique on AISI 430 ferritic stainless steel. According to the results of EIS and SEM, the ZrSiN thin film was more homogeneous and effective in protecting AISI 430 steel against corrosion than the ZrN thin film, in the studied solution. The corrosion mechanism showed a difference: the ZrN-coated steel showed a localised corrosion through pores in the coating and the ZrSiN showed uniform corrosion at the coating-steel interface.

Oxidation behavior and corrosion resistance of vacuum annealed ZrN-coated stainless steel

ZrN thin films were deposited on AISI 304 stainless steel (304SS) by unbalanced magnetron sputtering (UBMS). Afterwards, the specimens were annealed at 1000 °C in vacuum (4 × 10−6 Torr) for a duration ranging from 1 to 4 h. The purpose of this study was to investigate the oxidation behavior and corrosion resistance of the vacuum annealed ZrN-coated 304SS prepared by UBMS method. The results of X-ray diffraction indicated that ZrN remained as the major phase in the oxidized thin films even after heat treating at 1000 °C for 4 h in vacuum. The surface grain size of the oxidized film increased with heat treating duration. The oxidized ZrN thin film on 304SS formed two oxide layers, the outer layer on the film surface and the inner layer nearby the film/substrate interface, which could be attributed to the simultaneous diffusion of oxygen from film surface and the edge of film/substrate interface, respectively. The results of potentiodynamic polarization scan showed that the corrosion resistance of the oxidized ZrN-coated 304SS was excellent and increased by at least 100 times relative to that of bare 304SS, based on the decrease of corrosion current density. The oxidized ZrN-coated 304SS also showed excellent durability after 500-hr salt spray test with corrosion area less than 4% for all specimens, and the oxidized ZrN films showed better durability than the as-deposited ZrN film in salt spray test. The results suggested that the electrical conductivity of the film may be a significant factor on Icorr, and the relative corrosion resistance of ZrN and ZrO2 in NaCl solution may also play an important role in salt spray test. The fully oxidized ZrN thin film showed high corrosion resistance and remained intact on 304SS substrate after potentiodynamic polarization scan, which was associated with the enhanced adhesion by the interdiffusion layer due to heat treatment. The adhesive problem of ZrO2 on stainless steel could be solved either with or without ZrN interlayer, if the vacuum annealing could produce a large interdiffusion zone and thereby enhancing the adhesion.

First-principles study of fracture toughness enhancement in transition metal nitrides

Due to its superior thermophysical properties, ZrN thin film has been studied as a diffusion barrier for a variety of applications. However, cracks and delamination of ZrN coating takes place because of its brittleness. To identify new diffusion barrier materials with improved fracture toughness, we systematically studied the mechanical properties, surface energies and fracture toughness of IVB, VB and VIB transition metal mononitrides using first-principles calculations. TiN and HfN show slightly better toughness than ZrN. To improve the toughness of ZrN, we investigated the fracture toughness of ZrN alloyed with 25% IVB, VB and VIB transition metal nitrides. TiN, HfN and TaN was found to be able to increase the fracture toughness of ZrN through alloying. Meanwhile, we predicted the interfacial fracture toughness of ZrN/TiN and ZrN/HfN interfaces to evaluate the fracture toughness of ZrN/TiN and ZrN/HfN multilayer structures. Both ZrN/TiN and ZrN/HfN films exhibit higher interfacial fracture toughness than that of ZrN single film. Therefore, alloying and multilayer structures are promising approaches to enhance the toughness of brittle ZrN film.

Investigation of microstructure and properties of ultrathin graded ZrNx self-assembled diffusion barrier in deep nano-vias prepared by plasma ion immersion implantation

Ultrathin graded ZrNx self-assembled diffusion barriers with controllable stoichiometry was prepared in Cu/p-SiOC:H interfaces by plasma immersion ion implantation (PIII) with dynamic regulation of implantation fluence. The fundamental relationship between the implantation fluence of N+ and the stoichiometry and thereby the electrical properties of the ZrNx barrier was established. The optimized fluence of a graded ZrN thin film with gradually decreased Zr valence was obtained with the best electrical performance as well. The Cu/p-SiOC:H integration is thermally stable up to 500°C due to the synergistic effect of Cu3Ge and ZrNx layers. Accordingly, the PIII process was verified in a 100-nm-thick Cu dual-damascene interconnect, in which the ZrNx diffusion barrier of 1nm thick was successfully self-assembled on the sidewall without barrier layer on the via bottom. In this case, the via resistance was reduced by approximately 50% in comparison with Ta/TaN barrier. Considering the results in this study, ultrathin ZrNx conformal diffusion barrier can be adopted in the sub–14nm technology node.

Optical properties of Ar ions irradiated nanocrystalline ZrC and ZrN thin films

Employing wide spectral range (0.06–6 eV) optical reflectance measurements and high energy X-ray photoemission spectroscopy (HE-XPS), we studied the effect of 800 keV Ar ion irradiation on optical and electronic properties of nanocrystalline ZrC and ZrN thin films, which were obtain by the pulsed laser deposition technique. Both in ZrC and ZrN, we observed that irradiation affects the optical properties of the films mostly at low frequencies, which is dominated by the free carriers response. In both materials, we found a significant reduction in the free carriers scattering rate and an increase of the zero frequency conductivity, i.e. possible increase in mobility, at higher irradiation fluence. This is consistent with our previous findings that irradiation affects the crystallite size and the micro-strain, but it does not induce major changes in the chemical bonding. HE-XPS investigations further confirms the stability of the Zr-C and Zr-N bonds, despite a small increase in the surface region of the Zr-O bonds fraction with increasing irradiation fluence.

Effect of thickness on structural, corrosion and mechanical properties of a thin ZrN film deposited by medium frequency (MF) reactive sputtering

AbstractZirconium nitride (ZrN) thin films were prepared on stainless steel (SS) substrates by medium frequency (MF) reactive sputtering with gas ion source (GIS) by varying the deposition time and obtained thickness (tZrN) in the range of 1.25 to 3.24 μm. The effect of thickness on the structural and microstructural properties was studied using XRD and AFM. XRD characterization revealed that the texture of the ZrN thin films changes as a function of thickness. Both, the (111) and (200) peak, appear initially and (111) becomes more intense with increasing tZrN. AFM imaging revealed that the ZrN thin film coated with tZrN ≈ 3.24 μm shows larger grains that are uniformly distributed over the surface. An average hardness value of 19.79 GPa was observed for ZrN thin films having tZrN ≈ 3.24 μm. The ZrN thin films having tZrN ≈ 3.24 μm exhibits better adhesion strength up to 20 N. The electrochemical polarization studies indicated that the ZrN thin film having larger thickness shows improved corrosion resistance compared to SS in 3.5 % NaCl solution.

Characteristics of metal-gate metal-insulator-semiconductor capacitor with ZrN capping layer fabricated by high-power impulse magnetron sputtering

Metal-gate Al/TiN/ZrN/ZrO2/p-Si metal-insulator-semiconductor structures were fabricated. Epitaxial crystallization of a high-k ZrO2 thin-film was induced by conventional direct current magnetron sputtering (DCMS) or high-power impulse magnetron sputtering (HIPIMS) to enable the subsequent deposition of a ZrN capping layer on it. The HIPIMS-deposited ZrN samples have more favorable physicochemical and capacitance-voltage characteristics than DCMS- deposited ZrN samples. The insufficient power density and the ionization rate of the sputtered metallic atoms during ZrN thin film deposition may cause the (111) planes of t-ZrO2 to disappear in samples with DCMS-deposited ZrN thin films. The more crystalline texture and higher interface trap density arise from the formation of silicate in the ZrO2 films that is induced by the low pulse duration ratio under the applied target power of 500W, which corresponds to a high peak power density in the HIPIMS system. HIPIMS samples with a higher pulse duration exhibit greater hysteresis, strongly suggesting that the structural defects, such as oxygen vacancies in ZrO2 films, not only influence the crystallographic texture of ZrO2 films but also degrade the hysteretic characteristics.