DC Unbalanced Magnetron Sputtering Research Articles

Apatite Formation on Rutile TiO2 Film Deposited Using Dual Cathode DC Unbalanced Magnetron Sputtering

Rutile TiO 2 films were deposited on unheated stainless steel type 316L using dual cathode DC unbalanced magnetron sputtering. The effects of deposition time ranging 30, 60, 90, and 120 mins on the films structure were investigated. Moreover, all the samples were immersed in SBF for period times of 3 and 5 days also considered. The crystal structures were characterized by thin film X-ray diffraction (TF-XRD). The film’s thickness and surface morphology were evaluated using atomic force microscopy (AFM). The crystallinity, roughness, thickness, and grain size of rutile with only (110) plane increased with increased deposition time. After immersed samples in SBF for 3 day the highest and moderate crystallinity of apatite was observed on the 30 min and 90 min, respectively. However, the films deposited with 60 and 120 min cannot be observed the peak of apatite. An increase crystallinity of apatite clearly observed when after immersed in SBF for 5 day.

Influence of the Substrate Bias Voltage on the Structure of Rutile TiO<sub>2</sub> Films Prepared by Dual Cathode DC Unbalanced Magnetron Sputtering

Rutile TiO2 films are normally used as biomaterial that synthesized on unheated stainless steel type 316L and glass slide substrates by dual cathode DC unbalanced magnetron sputtering. The influence of the substrate bias voltages (Vsb), from 0 V to-150V, on the structure of the as-deposited films was investigated. The crystal structure was characterized by grazing-incidence X-ray diffraction (GIXRD) technique, the films thickness and surface morphology was evaluated by atomic force microscopy (AFM) technique, respectively. The results show that the as-deposited films were transparent and have high transmittance in visible regions. The crystal structure of as-deposited films show the XRD patterns of rutile (110) with Vsb at 0V and shifted to rutile (101) with increasing Vsb. The films roughness (Rrms) and the thickness were 3.0 nm to 5.7 nm and 420 nm to 442 nm, respectively.

Apatite Deposition on ZrO<sub>2</sub> Thin Films by DC Unbalanced Magnetron Sputtering

Zirconia thin films deposited on 316L stainless-steel substrate were prepared by DC unbalanced magnetron sputtering from a metallic zirconium target at low temperature with the target-to-substrate distance (dt-s) of 100 mm and sputtering power of 180 W. High purity gas of Ar as the working gas and O2 as the reactive gas were used. The depositions were performed for 120 min at a total pressure of 0.5 Pa. The effect of thermal treatment on the HA formation was investigated. The bioactivity was assessed by investigating the formation of hydroxyapatite (HA) on the surface soaked in simulated body fluids (SBF). Films structure, surface morphology and chemical composition of the ZrO2 films and HA formation were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR spectroscopy. The XRD results demonstrate the ZrO2 films are monoclinic phase. The annealed films show the higher film crystalline due to the rearrangement of film structure. After being immersed the samples in SBF, the bone-like apatite was observed on all ZrO2 films, but a denser and more continuous HA layer were observed on annealed films due to the crystallinity of ZrO2 films.

중간층 조건에 따른 Cr-Mo-N 막의 상형성 및 마찰마모 거동 연구

Phase evolution and tribological behavior of Cr-Mo-N multi compositional films with different interlayer were investigated. The films were deposited by hybrid PVD (Physical Vapor Deposition) system consisted of dc unbalanced magnetron (UBM) sputtering and arc ion plating (AIP) sources. A pure molybdenum (Mo) was used as sputtering target and also a pure Cr was used as AIP target to form the Cr-Mo-N films. Various growth planes were found, no textured surface, in all of the multi composition films. Maximum value of microhardness was measured in Cr-Mo-N film with Mo interlayer as 29 GPa. Composition film was mainly showed the aspect of the adhesive wear than CrN film. The friction coefficient was decreased from 0.6 for pure CrN coating to 0.35 for Cr-Mo-N film with Mo interlayer. This result may come from the formation of metal oxide tribo-layer which is known as solid lubricant during the wear test.

The role of target-to-substrate distance on the DC magnetron sputtered zirconia thin films’ bioactivity

Zirconium dioxide thin films were deposited on 316L-stainless steel type substrates using DC unbalanced magnetron sputtering. The process parameter of this work was the target-to-substrate distance (dt-s), which was varied from 60 to 120mm. The crystal structure and surface topography of zirconium dioxide thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The results demonstrate that all of the ZrO2 thin films are composed monoclinic phase. The film sputtered at short dt-s (60mm) shows a rather heterogeneous, uneven surface. The grain size, roughness, and thickness of thin films were decreased by increasing dt-s. The bioactivity was assessed by investigating the formation of hydroxyapatite (Ca10(PO4)6(OH)2) on the thin film surface soaked in simulated body fluids (SBF) for 7days. XRD and scanning electron microscopy (SEM) were used to verify the formation of apatite layers on the samples. Bone-like apatites were formed on the surface of the ZrO2 thin film in SBF immersion experiments. A nanocrystalline hydroxyapatite (HA) with a particle size of 2–4μm was deposited. Higher crystallinity of HA on the surface was observed when the distance dt-s increased to more than 80mm. Therefore, it seems that a dt-s greater than 80mm is an important sputtering condition for inducing HA on the zirconia film.

Piezoresistive properties and structure of hydrogen-free DLC films deposited by DC and pulsed-DC unbalanced magnetron sputtering

In the present research hydrogen-free DLC films were deposited by unbalanced DC and pulsed DC magnetron sputtering. Gauge factor, electrical properties and structure of the films were investigated versus technological conditions looking at the correlations between the gauge factor and other parameters relating to DLC films. Effects of the sputtering pulse frequency and substrate temperature were studied. The dependence of the gauge factor of DLC films on structure (parameters of the Raman scattering spectra) and resistivity was found to be in good accordance with a percolating metal and insulator composite model.

Effect of nitrogen content on nanostructure and mechanical properties of TiCxNy thin films

A series of TiCxNy thin films were deposited at 500°C on Si (100) substrates by way of incorporation of different amounts of nitrogen into TiC0·45 using reactive unbalanced dc magnetron sputtering method. Their phase configurations, microstructures and mechanical behaviours were subsequently investigated by X-ray diffraction, X-ray photoelectron spectroscopy and microindentation methods. The result indicated that TiC0·45 showed a fcc-like B-NaCl polycrystallite, and a solid solution nanocrystalline (nc-) TiCxNy with the same structure was formed by way of dissolution of nitrogen into TiC0·45 lattice when the atomic ratio of (C+N)/Ti was less than one unit. Both hardness and residual compressive stress values were increased with increasing N content. Their maximums were believed to be obtained at nc-Ti(C,N) solid solution with an atomic ratio of one unit. Enhancement of both of them was attributed to solid solution.

Mechanical behavior of TiN/CrN nano-multilayer thin film deposited by unbalanced magnetron sputter process

TiN and CrN single layer thin films along with TiN/CrN multilayer thin film, which has an average layer thickness of 4 nm were deposited on WC substrates by a commercially used unbalanced DC magnetron sputtering. The microstructure and mechanical properties of the as-deposited films were investigated. The TiN/CrN multilayer thin film has a single phase structure with the preferential orientation of (2 0 0), a finer surface morphology and a finer columnar crystal structure. Additionally, the TiN/CrN multilayer thin film also shows better adhesion on substrate and hardness than the single layer thin films. The hardness of the annealed multilayer thin film is slightly increased after annealed at temperatures of 600–800 °C. This is attributed to the increased intensity of (1 1 1) reflection during annealing.

Effect of oxidation temperature on microstructure, mechanical behaviors and surface morphology of nanocomposite Ti–Cx–Ny thin films

Two nanocomposite Ti–Cx–Ny thin films, TiC0.95N0.60 and TiC2.35N0.68, as well as one pure TiN, were deposited at 500°C on Si(100) substrate by reactive unbalanced dc-magnetron sputtering. Oxidation experiments of these films were carried out in air at fixed temperatures in a regime of 250–600°C with an interval of 50°C. As-deposited and oxidized films were characterized and analyzed using X-ray diffraction (XRD), microindentation, Newton's ring methods and atomic force microscopy (AFM). It was found that the starting oxidation temperature of nanocomposite Ti–Cx–Ny thin films was 300°C irrespective of the carbon content; however their oxidation rate strongly depended on their carbon content. Higher carbon content caused more serious oxidation. After oxidation, the film hardness value remained up to the starting oxidation temperature, followed by fast decrease with increasing heating temperature. The residual compressive stress did not show a similar trend with the hardness. Its value was first increased with increase of heating temperature, and got its maximum at the starting oxidation temperature. A decrease in residual stress was followed when heating temperature was further increased. The film surface roughness value was slightly increased with heating temperature till the starting oxidation temperature, a great decrease in surface roughness was followed with further increase of heating temperature.

Influences of annealing and hafnium concentration on the microstructures of sputter deposited β-NiAl coatings on superalloy substrates

This study was conducted to establish the influences of high hafnium concentrations and high temperature annealing on the microstructures of β–NiAl coatings. Binary NiAl and ternary NiAl-1.0at.% Hf coatings were deposited onto CMSX-4® superalloy substrates via unbalanced DC magnetron sputtering. Investigations were conducted using scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, X-ray diffraction, and three-dimensional atom probe tomography in an effort to determine the influences of annealing on the coating microstructures and coating/substrate interdiffusion. All as-deposited coatings were found to consist of a B2 structured solid solution consistent with the Ni-rich β–NiAl. Post-deposition annealing at 1000°C resulted in significant coating-substrate interdiffusion and in the formation of an interdiffusion zone, the extent/thickness of which decreased with the addition of Hf. Annealing additionally produced γ′–Ni3Al precipitates in the binary coatings and nanometer-sized Hf-rich precipitates in Hf-containing coatings. The majority of these precipitates were identified as the equilibrium Heusler (i.e., Ni2AlHf) phase; however, when Hf-containing specimens were annealed in a high carbon environment, significant concentrations of carbon were incorporated into the coatings. This sometimes resulted in the formation of HfC precipitates. The results have been analyzed and discussed relative to previous research on sputter deposited NiAl–Hf coatings.

Comparison of Nanocrystalline TiO2 Films Prepared on Unheated Substrates Using Single- and Dual-Cathode DC Unbalanced Magnetron Sputtering Systems

Titanium dioxide (TiO2) films were deposited on unheated Si(100) wafers by single- and dual-cathode dc unbalanced magnetron sputtering. Each cathode was specially designed with a high magnetic field strength. The effect of the radial distance from the center of the coating cathode on the film structures was investigated. For the substrate placed at the center of the coating cathode, it was found that the TiO2 films deposited by dual-cathode sputtering exhibit rutile with higher crystallinity than films deposited by single-cathode sputtering. At various radial distance from the center to 6 cm to the left and light of the center, mixed phases of rutile and anatase were observed on TiO2 films deposited using both single- and dual-cathode sputtering systems. Furthermore, in the case of using dual-cathode, crystalline TiO2 films were obtained for a longer range to the left of the center than to the right owing to the higher magnetic field strength.

Industrial-scale deposition of highly adherent CNx films on steel substrates

Highly adherent carbon nitride (CNx) films were deposited using a novel pretreatment with two high power impulse magnetron sputtering (HIPIMS) power supplies in a master–slave configuration: one to establish the discharge and one to produce a pulsed substrate bias. During the pretreatment, SKF3 (AISI 52100) steel substrates were pulse-biased in the environment of a HIPIMS Cr plasma in order to sputter clean the surface and to implant Cr metal ions. Subsequently, CNx films were prepared at room temperature by DC unbalanced magnetron sputtering from a high purity graphite target in a N2/Ar discharge at 3 mTorr. All processing was done in an industrial CemeCon CC800 system. A series of depositions were obtained with samples at different bias voltages (DC and pulsed) in the range of 0–800 V. Scanning transmission microscopy (STEM) and high resolution transmission electron microscopy (HRTEM) show the formation of an interface comprising a polycrystalline Cr layer of 100 nm and an amorphous transition layer of 5 nm. The adhesion of CNx films evaluated by the Daimler-Benz Rockwell-C reach strength quality HF1, and the scratch tests gives critical loads of 84 N. Adhesion results are correlated to the formation of an optimal interfacial mixing layer of Cr and steel.

Nanostructural C-Al-N thin films studied by x-ray photoelectron spectroscopy, Raman and high-resolution transmission electron microscopy

The effects of Al incorporation and post-deposition annealing on the structural properties of C-Al-N thin films prepared by reactive unbalanced dc-magnetron sputtering were investigated using x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). XPS studies demonstrated the presence of abundant Al-N bonds in addition to C-C and N-C bonds. At low incorporations of Al and N, the films were found to be essentially amorphous. By Raman and HRTEM, the formation of ∼5 nm fullerene-like carbon nitride (FL-CNx) nanostructures in an amorphous (C, CNx) matrix was evidenced with increasing Al content in the films. Crystalline improvement of FL-CNx nanostructures was seen, as well as the precipitation of ∼3–4 nm face centered cubic (fcc-) AlN nanograins by thermal annealing at 500 °C or above. Through these improvements, C-Al-N nanocomposite thin films were achieved. The effects of the incorporated Al and annealing on stabilizing fcc-AlN nanograins and FL-CNx nanostructures are elucidated and explained through the use of thermodynamic considerations.

Effect of nitrogen content on phase configuration, nanostructure and mechanical behaviors in magnetron sputtered SiC xN y thin films

SiC x N y thin films with different nitrogen contents were deposited by way of incorporation of different amounts of nitrogen into SiC 0.70 using unbalanced reactive dc magnetron sputtering method. Their phase configurations, nanostructures and mechanical behaviors were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM) and microindentation methods. The result indicated SiC 0.70 and all SiC x N y thin films exhibited amorphous irrespective of the nitrogen content. The phase configuration and mechanical behaviors of SiC x N y thin films strongly depended on nitrogen content. SiC 0.70 exhibited a mixture consisting of SiC, Si and a small amount of C. Incorporated nitrogen, on one hand linked to Si, forming SiN x , on the other hand produced CN x and C at the expense of SiC. As a result, an amorphous mixture consisting of SiC, SiN x , C and CN x were produced. Such effects were enhanced with increase of nitrogen content. A low hardness of about 16.5 GPa was obtained at nitrogen-free SiC 0.70. Incorporation of nitrogen or increase of nitrogen content increased the film hardness. A microhardness maximum of ∼29 GPa was obtained at a nitrogen content of 15.7 at.%. This value was decreased with further increase of N content, and finally a hardness value of ∼22 GPa was obtained at a N content of ∼25 at.%. The residual compressive stress was consistent with the hardness in the nitrogen content range of 8.6–25.3 at.%.

Mechanical and tribological properties of multicomponent Ti–B–C–N thin films with varied C contents

Multicomponent thin films of Ti–B–C–N with different C contents (C target current ranging from 0.0 to 4.0 A) were deposited onto unheated Si(100) wafers (for mechanical analyses) and M42 tool steels (for tribological measurements) by reactive close-field unbalanced dc-magnetron sputtering in an Ar–N 2 gas mixture. These films were characterized and analyzed in terms of their microstructure by X-ray diffraction, their hardness by microindentation measurements, their surface root-mean-square roughness by atomic force microscopy, and their friction and wear behaviors by Rockwell-C testing, microscratch testing, dynamic impact testing and pin-on-disc tribometer. It was found that the mechanical and tribological properties of multicomponent films (typically 1.6 ± 0.2 μm in thickness) were closely related to the C content (varied from 4.4 at.% to 42.0 at.%). For the best multicomponent film with 12.4 at.% C content, a high hardness of 27 GPa was achieved and the best cohesive and adhesive strength was evidenced in terms of critical load values of L C1 (~ 37 N), L C2 (>75 N), and the highest adhesive strength (HF1). Moreover, by dynamic impact testing the multicomponent film could endure impact cycles up to 2 × 10 5 without adhesive failure. However, when the C content was further increased up to 42.0 at.%, the hardness, cohesive and adhesive strength were decreased due to the formation of amorphous structure. It was also found that the pin-on-disc test under dry conditions showed that the frictional coefficients decreased with C content. The frictional coefficients obtained at a load of 2 N were kept at ∼0.57 without C incorporation and decreased to ~0.18 at C current of 4.0 A. The tribological properties of the Ti–B–C–N films with different C contents are also explained in terms of mechanical properties and wear mechanisms.

Composition design and properties of CoNbZr amorphous films deposited by unbalanced magnetron sputtering

Co87Nb10Zr3, Co76Nb19Zr5, Co64Nb26Zr10 and Co64Nb16Zr20 amorphous films were deposited on noncrystalline glass substrates by DC unbalanced magnetron sputtering. The compositions of amorphous films were tailored in the light of the individual deposition rate of Co, Nb and Zr. The amorphous films with the anticipated composition were prepared by means of co-sputtering Co, Nb and Zr targets simultaneously. It is indicated that there is interaction among three targets during co-sputtering. The morphology and composition of the films were observed by SEM, AFM and EDS. The structure and magnetic property were measured by XRD and physical property measurement system (PPMS). The coercivity changes with the composition, varying from 240 to 1 600 A/m. After vacuum isothermal annealing at temperatures of 475, 500, 525 and 550 °C for 15 and 30 min, respectively, it is found that high Nb content is beneficial to improving thermal stability of amorphous films. The crystallized films have the mean grain size of 2–19 nm.

Phase configuration, nanostructure, and mechanical behaviors in Ti-B-C-N thin films

A series of Ti-B-C-N thin films were deposited on Si (100) at 500 °C by incorporation of different amounts of N into Ti-B-C using reactive unbalanced dc magnetron sputtering in an Ar-N2 gas mixture. The effect of N content on phase configuration, nanostructure evolution, and mechanical behaviors was studied by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and microindentation. It was found that the pure Ti-B-C was two-phased quasi-amorphous thin films comprising TiCx and TiB2. Incorporation of a small amount of N not only dissolved into TiCx but also promoted growth of TiCx nano-grains. As a result, nanocomposite thin films of nanocrystalline (nc-) TiCx(Ny) (x + y < 1) embedded into amorphous (a-) TiB2 were observed until nitrogen fully filled all carbon vacancy lattice (at that time x + y = 1). Additional increase of N content promoted formation of a-BN at the cost of TiB2, which produced nanocomposite thin films of nc-Ti(Cx,N1-x) embedded into a-(TiB2, BN). Formation of BN also decreased nanocrystalline size. Both microhardness and elastic modulus values were increased with an increase of N content and got their maximums at nanocomposite thin films consisting of nc-Ti(Cx,N1-x) and a-TiB2. Both values were decreased after formation of BN. Residual compressive stress value was successively decreased with an increase of N content. Enhancement of hardness was attributed to formation of nanocomposite structure and solid solution hardening.

Low-temperature deposition of (1 1 0) and (1 0 1) rutile TiO 2 thin films using dual cathode DC unbalanced magnetron sputtering for inducing hydroxyapatite

Thin films of both (1 1 0) and (1 0 1) rutile titanium dioxide (TiO 2) were synthesized using a dual cathode DC unbalanced magnetron sputtering at low temperature with various substrate bias voltages ( V sb) ranging between 0 and −150 V. The TiO 2 film prepared with V sb = 0 underwent heat treatment after deposition. It was observed that the (1 1 0) rutile phase was deposited on the film with V sb below −50 V. Furthermore, the film showed high crystallinity after the heat treatment. However, when using V sb above −50 V, the phase of film shifted to (1 0 1) due to the formation of high-energy particles on the surface. For in vitro testing, the samples were immersed in simulated body fluid (SBF) for 7 days. The heat-treated (1 1 0) rutile shows a poor distribution of hydroxyapatite (HA) formation, generally causing the stress effect. The film was prepared with V sb = 50 V and observed to form higher crystallinity of HA.

Effect of N content on phase configuration, nanostructure and mechanical behaviors in Ti–C x–N y thin films

Ti–C x –N y thin films with different nitrogen contents were deposited by way of incorporation of different amounts of nitrogen into TiC 1.02 using unbalanced reactive unbalanced dc magnetron sputtering method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and microindentation methods were used to investigate their phase configurations, nanostructures and mechanical behaviors in order to investigate their dependences on nitrogen content. The result indicated that the nitrogen content had a significant effect on phase configuration, nanostructure and mechanical behaviors of Ti–C x –N y thin films. The nitrogen-free TiC 1.02 films exhibited a polycrystallite with nano-grains. On one hand, incorporated nitrogen substituted C in TiC 1.02, producing Ti(C,N), and subsequently linked to the substituted C, forming C–N. On the other hand, the substituted C lined to each other, forming C–C. As a result, nanocomposite thin films consisting of nanocrystalline Ti(C,N) and amorphous (C, C–N) were produced. With further incorporation of nitrogen more C was substituted, accompanying with formation of more amorphous matrices and decrease of size of nanocrystalline Ti(C,N). The trend was enhanced with further increase of nitrogen content. A microhardness maximum of ∼58 GPa was obtained in nitrogen-free TiC 1.02 thin films. This value was linearly decreased with incorporation of N or increase of N content, and finally a hardness value of about 28 GPa was followed at a N content of ∼25 at.%. Both elastic modulus and residual compressive stress values exhibited similar trends.

Magnetron sputtering deposition Ti–B–C–N films by Ti/B 4C compound target

Ti–B–C–N films were deposited by unbalanced DC magnetron sputtering with Ti/B 4C compound target. The sputtering zone in the surface of the target was adjusted by a magnetic coil. X-ray photoelectron spectrum, X-ray diffraction, nano-indentation and scratch tests were used to analyze the film composition, phase structure, hardness, modulus and scratch resistance. The results showed that the composition of the Ti–B–C–N films can be adjusted by changing deposition parameters, such as gas ratio of N 2 to Ar and the magnetron coil current. The main crystal phase in the films was TiB 2. The proportion of crystalline TiB 2 decreased with the increasing of N 2 partial pressure and reached a maximum value at 300 mA magnetic coil current, when the coil current changed from 200 mA to 500 mA. The films containing more TiB 2 proportion showed higher hardness and modulus. The scratch resistance of the films increased with the films hardness.