ZrNx Films Research Articles

Effect of Nitrogen Partial Pressure on Structure, Mechanical Property, and Corrosion Behavior of ZrNx Films Prepared by Reactive DC Magnetron Sputtering.

ZrNx films were deposited by DC magnetron sputtering with pure Zr target in different nitrogen partial pressure atmospheres (r = N2/[Ar + N2]). The structure and composition of the thin films were characterized as a function of r using scanning electron microscope, glancing angle X-ray diffraction, and X-ray photoelectron spectroscopy. The hardness, adhesive strength, and corrosion behavior of the coatings were measured by nanoindentation, microscratch, and potentiodynamic measurements in 3.5 wt% NaCl solution. The results show that the structure of the ZrNx films changes from a nearly stoichiometric ZrN with a typical columnar structure to mixed phases composited of ZrN and α-ZrNx with a dense glass structure as r increases from 12% to 50%. The mechanical properties including hardness, elastic modulus, and adhesion decrease with increasing r due to nonstoichiometric compound and glass phase structure of the coatings, while the dense glass structure significantly improves the corrosion inhibition.

Emergence of superconducting dome in ZrNx films via variation of nitrogen concentration

Emergence of superconducting dome in ZrNx films via variation of nitrogen concentration

Effects of Nitrogen Flow Ratio on Structures, Bonding Characteristics, and Mechanical Properties of ZrNx Films

ZrNx (x = 0.67–1.38) films were fabricated through direct current magnetron sputtering by a varying nitrogen flow ratio [N2/(Ar + N2)] ranging from 0.4 to 1.0. The structural variation, bonding characteristics, and mechanical properties of the ZrNx films were investigated. The results indicated that the structure of the films prepared using a nitrogen flow ratio of 0.4 exhibited a crystalline cubic ZrN phase. The phase gradually changed to a mixture of crystalline ZrN and orthorhombic Zr3N4 followed by a Zr3N4 dominant phase as the N2 flow ratio increased up to >0.5 and >0.85, respectively. The bonding characteristics of the ZrNx films comprising Zr–N bonds of ZrN and Zr3N4 compounds were examined by X-ray photoelectron spectroscopy and were well correlated with the structural variation. With the formation of orthorhombic Zr3N4, the nanoindentation hardness and Young’s modulus levels of the ZrNx (x = 0.92–1.38) films exhibited insignificant variations ranging from 18.3 to 19.0 GPa and from 210 to 234 GPa, respectively.

XRD and EBSD analysis of Cu film on randomly oriented ZrNx film as the underlying materials

In order to further improve the EM resistance, the preferentially-oriented Cu(111) is strongly desired. In this study, we examine whether the preferentially-oriented Cu(111) can be obtained using the ZrNx film as an underlying material. As a result, it was found that the preferentially-oriented Cu(111) on the randomly oriented ZrNx film was obtained. We demonstrated that the obtained ZrNx film is one of the excellent materials as an underlying material.

Microstructure, properties and applications of Zr-carbide, Zr-nitride and Zr-carbonitride coatings: a review

Series of XRD spectra obtained for ZrNxfilms produced with RF DC magnetron sputtering with various nitrogen flux levels.

Effect of the varied nitrogen vacancy concentration on mechanical and electrical properties of ZrNx thin films

ZrNx films were deposited with reactive magnetron sputtering in different [Ar]/([Ar] + [N2]) atmospheres and analyzed using X-ray photoelectron spectroscopy, glancing incidence X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, nanoindentation techniques, and four-point probe meter. N vacancy concentration is defined as VN = 1- x, where x is N/Zr ratio in ZrNx. Results showed that the VN ranged from 0.02, through 0.08, 0.13, 0.24 to 0.30. The glancing incidence X-ray diffraction results showed a decrease in lattice parameter a0 from 4.582, through 4.578, 4.571, 4.564 to 4.548 Å with the increase of VN from 0 to 0.30. Berkovich nanoindentation results showed that the hardness of ZrNx films increased from 18 ± 1.3 GPa to 24 ± 1.2 GPa with the increase of VN from 0 to 0.24, which is due to vacancy-induced hardening. However, further increase of VN to 0.30, a drop-in hardness was observed, which was attributed to vacancy-induced softening. Both hardening and softening proved the existing of a turning point at VN around 0.24. In addition, the fracture toughness and sheet resistance of ZrNx films also presented the same tendency. The experimental results agreed with first principle predictions that the metal-N (d-p) bonds, ZrZr (d-d) σ bonds and the valance electron density around Zr atoms had changed greatly due to the varied VN.

Corrosion inhibition behaviors of ZrNx thin films with varied N vacancy concentration

Three sets of ZrNx films with varied N vacancy concentration (VN) were sputter-deposited onto 304 stainless steel sheets and Si substrates by physical vapor deposition. The thin films were characterized using scanning electron microscope, glancing angle X-ray diffraction and X-ray photoelectron spectroscopy. Their corrosion inhibition behaviors were studied by the potentiodynamic measurements and electrochemical impedance spectroscopy in 3.5 wt% NaCl solution. The experimental results indicated that the corrosion inhibition efficiency was relevant to VN. The samples with VN near 0.3 had the best corrosion inhibition efficiency. The quantum chemical parameters (EHOMO, ELUMO) were also calculated to evaluate the corrosion inhibition efficiency. The overall results showed that corrosion inhibition efficiency of ZrNx film was correlated to N vacancy concentration.

Oxygen-doped zirconium nitride based transparent resistive random access memory devices fabricated by radio frequency sputtering method

In this work, we present a feasibility of bipolar resistive switching (RS) characteristics for Oxygen-doped zirconium nitride (O-doped ZrNx) films, produced by sputtering method, which shows a high optical transmittance of approximately 78% in the visible region as well as near ultra-violet region. In addition, in a RS test, the device has a large current ratio of 5 × 103 in positive bias region and 5 × 105 in negative bias region. Then, to evaluate an ability of data storage for the proposed memory devices, we measured a retention time for 104 s at room temperature (RT) and 85 °C as well. As a result, the set and reset states were stably maintained with a current ratio of ∼102 at 85 °C to ∼103 at RT. This result means that the transparent memory by controlling the working pressure during sputtering process to deposit the ZrNx films could be a milestone for future see-through electronic devices.

Influence of ion–atom arrival ratio on structure and optical properties of ZrNx films

The influence of ion–atom arrival ratio on composition, micro-structure and optical properties of ZrNx films prepared by ion beam assisted deposition was studied by using XPS, XRD, and spectroscopic ellipsometry. The stoichiometric ZrN is prepared at ion–atom arrival ratio of 1.5. For ZrNx films deposited at ion–atom arrival ratio of 2.4 and 5.0, a strong (220) texture is formed in the ZrNx film. The refractive index of ZrNx films increased with the increase of ion–atom arrival ratio; whereas, a continuous decrease of the extinction coefficient was noticed.

Structural, mechanical, electrical and wetting properties of ZrNx films deposited by Ar/N2 vacuum arc discharge: Effect of nitrogen partial pressure

Non-stiochiometric zirconium nitride (ZrNx) thin films have been deposited on silicon substrates by vacuum arc discharge of (N2+Ar) gas mixtures at different N2 partial pressure ratio. The microstructure, mechanical, electrical and wetting properties of these films are studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy, Rutherford back scattering (RBS) technique, conventional micro-hardness testing, electrical resistivity, atomic force microscopy (AFM) and contact angle (CA) measurements. RBS results and analysis show that the (N/Zr) ratio in the film increases with increasing the N2 partial pressure. A ZrNx film with (Zr/N) ratio in the vicinity of stoichiometric ZrN is obtained at N2 partial pressure of 10%. XRD and Raman results indicate that all deposited films have strained cubic crystal phase of ZrN, regardless of the N2 partial pressure. On increasing the N2 partial pressure, the relative intensity of (111) orientation with respect to (200) orientation is seen to decrease. The effect of N2 partial pressure on micro-hardness and the resistivity of the deposited film is revealed and correlated to the alteration of grain size, crystallographic texture, stoichiometry and residual stress developed in the film. In particular, it is found that residual stress and nitrogen incorporation in the film play crucial role in the alteration of micro-hardness and resistivity respectively. In addition, CA and AFM results demonstrate that as N2 partial pressure increases, both the surface hydrophobicity and roughness of the deposited film increase, leading to a significant decrease in the film surface free energy (SFE).

Barrier Properties of Thin ZrNx Films Prepared by Radical-Assisted Surface Reaction

We have prepared thin ZrNx films at low temperatures without substrate heating. In the proposed process, radical species generated by the catalytic decomposition of NH3 molecules react on the sputtered Zr film to form ZrNx. The barrier performance of the obtained 5-nm-thick ZrNx film is as good as that prepared by reactive sputtering at 350 °C, indicating the usefulness of the proposed method in forming ZrNx films at low temperatures. We have also demonstrated the general effectiveness of the method for ZrNx preparation in addition to the previous result of TiNx.

Effect Analysis of Ar-N<sub>2</sub> Flow Rates on ZrN<sub>X</sub> Film by Pulsed Magnetron Sputtering Using Design of Experimental Method

The various nitrogen gas (N2) flows for depositing zirconium-nitride (ZrN) films on the substrate of a p-type (100) silicon wafer are investigated through reactive magnetron sputtering by a pulsed-DC power. The results, based on the design of experimental (DOE) method, indicate that the deposition effect of the ZrNx film is obviously affected by various flow rates of nitrogen gas at the specific pulsing duty cycles. The crystal orientation of the zirconium-nitride film has a less order microstructure which is similar to an amorphous microstructure. Although the composition ratio of chemical elements is not identical in Zr and N, the surface roughness, grain size, and resistivity are the better feature. The deposition rate is inversely proportional to the nitrogen flow rate and the chamber pressure is also an important factor. The basic effect of N2 flow rate on the surface roughness is rougher when more nitrogen gas is supplied. The resistivity of ZrNx thin film has a positive relationship to N2 flow rates at the reactive vacuum chamber.

Characterization of zirconium nitride films sputter deposited with an extensive range of nitrogen flow rates

Zr N x films are deposited by rf magnetron sputtering using a wide range of nitrogen flow rates to control film properties. Scanned probe microscope (SPM) oxidation is presented as a complimentary characterization tool to x-ray diffraction, colorimetric, and four point probe analyses. The SPM oxidation behavior of the ZrNx films is related to their structural, optical, and electrical properties. Whereas stoichiometric ZrN films have applications as protective and/or decorative coatings, ZrNx films sputtered with higher nitrogen flow rates have potential applications in devices where arrays of high aspect ratio nanostructures would be useful.

Effects of substrate bias and nitrogen flow ratio on the resistivity and crystal structure of reactively sputtered ZrNx films at elevated temperature

ZrNx films were sputtered in an Ar+N2 atmosphere, with different substrate biases (zero to −200V) at a 2% nitrogen flow ratio and various nitrogen flow ratios (%N2=0.5%–24%) under −200V of substrate bias. The resistivity, crystal structure, and compositional depth profiles of ZrNx films, before and after vacuum annealing at 500–900°C, were investigated. At 2% N2, the resistivity of ZrNx films decreases with increasing substrate bias due to reduction of incorporated oxygen and porosity. Additionally, the resistivity of −200V biased ZrNx films (%N2=2%) are about the same before and after annealing, but the resistivities of zero and −100V biased ZrNx films increase with increasing annealing temperature. In addition, the ZrO2 phases (monoclinic and tetragonal) are found in ZrNx films deposited with 2% N2 and no substrate bias after annealing at 900°C; however, ZrN and tetragonal ZrO2 phases are revealed in ZrNx films sputtered with a substrate bias at the same temperature. On the other hand, the resistivities...

Deposition and properties of ZrNx films produced by radio frequency reactive magnetron sputtering

Thin ZrNx films have been prepared by reactive radio frequency magnetron sputtering. The radio frequency power has been chosen as a sputtering parameter and the effect on the compositional and optical properties of the films was systematically studied. The films have been analyzed by X-ray photoelectron spectroscopy. The reflectance and transmittance of the samples have been recorded by a spectrophotometer in the UV–Vis–IR range. The effects of the different powers (in the range 100–400 W) on the stoichiometry of ZrNx films have been studied. The components revealed on N 1s photoelectron peaks were correlated with different bounding states for the zirconium nitride. The threshold power value between N-rich ZrNx films and Zr-rich ZrNx ones is 270 W. A correlation has been observed between the optical properties and the stoichiometry of the films. In fact, the samples catalogued as N-rich by X-ray photoelectron spectroscopy analyses are optically insulating and the Zr-rich ones show a metallic behaviour. A simple growth model has been set up in order to explain the different chemical states detected from the compositional measurements.

Properties of ZrNx films with x > 1 deposited by reactive radiofrequency magnetron sputtering

Thin ZrNx films have been prepared by reactive radiofrequency magnetron sputtering varying the nitrogen partial pressure in the range 0–3.26 Pa. The films have been analyzed by X-ray photoelectron spectroscopy (XPS) and by optical characterization in the UV–Vis–IR range. The cross-section and surface morphology of the samples were examined by means of field emission gun–scanning electron microscopy. The effects of the nitrogen partial pressure on the ZrNx films stoichiometry have been studied correlating the N 1s photoelectron peaks with different bounding states for the zirconium nitride. The XPS depth profile analysis has revealed the presence of metastable phases (ZrN2, Zr3N4) that vanishes when lowering the nitrogen partial pressure. The optical analysis has permitted to distinguish two different behaviours of the deposited samples in the visible range: semi-transparent and absorbent. Drude–Lorentz model fitted the behaviour of absorbent films, while the O'Leary model was applied to the semi-transparent ones. The semi-transparent films had a band gap varying between 2.36 and 2.42 eV, typical values of N-rich zirconium nitride films. Morphological analysis showed a compact and dense columnar structure for all the samples. A simple growth model explains the presence of the different nitride phases considering implantation and re-sputtering effects.

Effects of substrate bias and nitrogen flow ratio on the resistivity, density, stoichiometry, and crystal structure of reactively sputtered ZrNx thin films

Thin films of ZrNx were prepared by reactive rf magnetron sputtering from a Zr target in an Ar+N2 atmosphere, with different substrate biases (zero to −200V) and nitrogen flow ratios (0.5%–24%). The resistivity, density, stoichiometry, and crystal structure of ZrNx films were investigated. With 2% of nitrogen flow ratio, all ZrNx films exhibit the cubic ZrN crystal phase, regardless of the magnitude of substrate bias. The zero-biased ZrNx film contains substantial oxygen and shows high resistivity. Once a negative bias is applied to the substrate, the incorporated oxygen in ZrNx films can be reduced and the (111)ZrN preferred orientation is enhanced. Resistivity as low as 67μΩcm can be attained with −200V of substrate bias. At −200V of substrate bias, all films show the ZrN phase when the nitrogen flow ratio varies from 0.5% to 24%. However, the nitrogen content in ZrNx films increases continuously with the increasing nitrogen flow ratio. Resistivity of ZrNx films first decreases (0.5%–2%), and then increases with increasing nitrogen flow ratio (2%–24%). The best resistivity is obtained for the ZrNx film sputtered with 2% of nitrogen flow ratio and this sample exhibits the optimum grain size, (111)ZrN prefer orientation, density, and stoichiometry. The connection among the resistivity, density, stoichiometry, and crystal structure of ZrNx films and how they are influenced by the sputtering conditions (substrate bias, nitrogen flow ratio) are discussed.

Composition and Structure of Zirconium Nitride Films Produced by Ion Assisted Deposition

AbstractThe growth mechanism of ZrNx films produced by reactive ion beam sputtering with or without concurrent low energy ion bombardment of argon or nitrogen has been investigated. The effect of substrate temperature in the range of 300-680K, partial pressure of nitrogen and ion/atom arrival rate on the composition and microstructure of the films have been studied. RBS analysis has confirmed that the nitrogen content varies over wide range 0-60 at. %, depending on the nitrogen/zirconium arrival rate, and the ion assist flux but it is independent of the ion assist energy. TEM analysis shows that the films are non-columnar and polycrystalline with grain sizes l-15nm which depend on the nitrogen content and the deposition temperature.

Material properties of a ZrNx film on silicon prepared by ion-assisted deposition method

The resistivity, chemical composition, and crystalline quality of ZrNx films deposited on Si(100) substrates by an ion-assisted deposition (IAD) method were investigated as a function of deposition parameters. By this method, metallic Zr is deposited by electron-beam evaporation while simultaneously bombarding the film with nitrogen ions having energies of 400–700 eV. It was found that the crystalline quality of the film was improved by increasing the substrate temperature Ts to 820 °C and decreasing the ion energy. When Ts was 850 °C, zirconium silicide was formed easily near the interface between the film and the Si substrate. At Ts=820 °C, the chemical composition ratio of the film was hardly influenced by the arrival rate ratio N/Zr, Ra, in the range of 1.5 to 3.0 and the deposited ZrN film was almost stoichiometric. However, when Ra was more than 1.9, the film quality was degraded by radiation damage due to excess nitrogen ions in the growing film. When Ra was less than 1.5, the surface of the film was roughened and looked cloudy, probably because the nonstoichiometric film reacted with the Si substrate. Therefore, the optimum arrival rate ratio was found to be in the range of 1.5–1.9. With optimum fabrication conditions, a (100) oriented and almost stoichiometric ZrN film could be obtained with resistivity as low as 17.8 μΩ cm.

Epitaxial growth of ZrN on Si(100)

Epitaxial ZrNx (x=1.0±0.05) films have been grown on Si(100) substrates using reactive magnetron sputtering. The films were deposited from a Zr sputtering target in a pure N2 discharge with a growth rate of 700 nm/h and substrate temperatures Ts=750 and 900 °C. X-ray diffractometer results showed complete (100) preferred orientation for both temperatures. Transmission electron microscopy (TEM) observations for samples grown at Ts=750 °C indicated that the (100) grains were almost randomly oriented about the surface normal, but that a small fraction of epitaxial grains were present. Electron channeling and TEM showed that ZrN films were epitaxial for Ts=900 °C. The epitaxial relationships were found to be ZrN(100)//Si(100) and ZrN[011]//Si[011]. The resistivity of the films was 25–35 μΩ cm.