Bias sputtered Ta modified diffusion barrier in Cu/Ta(Vb)/Si(111) structures

In this investigation, we have fabricated Ta(V_b)/Si(111) and Cu/Ta(V_b)/Si(111) systems using a DC bias sputtering technique at high Ar pressure (100 mTorr). For Ta/Si(111) system, tantalum layer was formed under various bias voltages ranging from 0 to −150 V. The films were characterized by Rutherford backscattering spectrometry (RBS), scanning electron microscopy (SEM) and four-point probe sheet resistance measurements (R_s). From electrical resistivity and SEM data, a minimum resistivity (99 μΩ cm) and well surface morphology at an optimum bias voltage (V_b=−50 V) was obtained for the Ta(V_b)/Si(111) system. The Ta films deposited under these conditions with 50 nm thickness are then used as a diffusion barrier in the Cu/Ta(V_b)/Si(111) multilayer structure. According to our RBS, SEM and R_s analysis, the Ta barrier layer formed under the controlled bias sputtering at high Ar pressure has demonstrated an improved Ta structure with excellent thermal stability up to 650°C for the Cu/Ta(V_b)/Si(111) system annealed in N₂ environment for 30 min. Formation of TaSi₂ was observed at 700°C after the barrier failure using RBS spectra.     

Effect of substrate temperature on the texture and structure of polycrystalline Si0.7Ge0.3 films deposited on SiO2 by molecular beam deposition

The evolution of microstructure and texture of molecular beam deposited Si_0.7Ge_0.3 films on SiO₂ at the deposition temperature range of 400–700°C was investigated by X-ray diffraction and transmission electron microscopy. At deposition temperatures between 400 and below 500°C, the films were directly deposited as a mixed-phase on SiO₂ and have a inversely cone-shaped structure. In this temperature range deposited as a mixed-phase, the grain size increases as the temperature increases, so that the grains not only grow up by deposition, but also laterally grow by the solid phase crystallization, furthermore, the texture is changed from a {110} texture to mixed {311} and {110} textures. At 500°C, the film was deposited as only a crystalline phase and has a columnar structure with a strong {110} texture. In the temperature range of 500–700°C, as the temperature increases, the {311} and {111} textures develop whereas the {110} texture reduces. The film deposited at 700°C has a random orientation and structure.     

An analysis of macroparticle-related defects on CrCN and CrN coatings in dependence of the substrate bias voltage

Chromium nitride coatings with and without a carbon content being assigned as CrCN and CrN were prepared by cathodic arc evaporation. The effect of negative substrate bias voltages (10-300 V) on the microstructure, phase composition and morphology of the coating surface was studied. X-ray diffraction data show that almost all coatings crystallized in the cubic structure with (111) and (200) diffraction lines appearing only for low negative bias voltage and a (220) diffraction line being present for the coatings deposited at higher negative bias voltages. For CrN coatings obtained at −300 V a hexagonal structure was also observed. In case of CrCN coatings the (220) diffraction line shows much higher intensity than in case of CrN coatings and was significantly broadened. On the surface of the coatings a large number of macroparticles of different size was observed. An increase of bias voltage causes a reduction of the areal density of macroparticles and a decrease of the mean surface roughness Ra.     

Heteroepitaxy of CuInSe2 on {111}-oriented germanium

Thin films of CuInSe₂ were deposited onto {111}-oriented germanium substrates by flash evaporation and were investigated by reflection high energy electron diffraction. Epitaxial growth was found in the substrate temperature range 720–820 K. In all cases the epitaxial layers had the chalcopyrite structure except at growth temperatures higher than 795 K where the layers were cubic. Deposition of CuInSe₂ onto {111}-oriented germanium is characterized by one-dimensional epitaxy, and the epitaxial relationship for the chalcopyrite phase is given by {111}_Ge{112}_CuInSe2     

Effect of bias voltage on microstructure and mechanical properties of arc evaporated (Ti, Al)N hard coatings

In the present study, authors report on the effect that substrate bias voltage has on the microstructure and mechanical properties of (Ti, Al)N hard coatings deposited with cathodic arc evaporation (CAE) technique. The coatings were deposited from a Ti _{0· 5}Al _{0· 5} powder metallurgical target in a reactive nitrogen atmosphere at three different bias voltages: U _B ?=??? 25, ?50 and ?100 V. The coatings were characterized in terms of compositional, microstructural and mechanical properties. Microstructure of the coatings was investigated with the aid of X-ray diffraction in glancing angle mode, which revealed information on phase composition, crystallite size, stress-free lattice parameter and residual stress. Mechanical properties were deduced from nano-indentation measurements. The residual stress in all the coatings was compressive and increased with increasing bias voltage in a manner similar to that reported in literature for Ti–Al–N coatings deposited with CAE. The bias voltage was also found to significantly influence the phase composition and crystallite size. At ?25 V bias voltage the coating was found in single phase fcc-(Ti, Al)N and with relatively large crystallites of ~ 9 nm. At higher bias voltages (?50 and ?100 V), the coatings were found in dual phase fcc-(Ti, Al)N and fcc-AlN and the size of crystallites reduced to approximately 5 nm. The reduction of crystallite size and the increase of compressive residual stress with increasing bias voltage both contributed to an increase in hardness of the coatings.     

Reactive magnetron sputtering of indium tin oxide films on acrylics – morphology and bonding state

Indium tin oxide (ITO) films were deposited on acrylics by low temperature reactive magnetron sputtering. The effects of oxygen flow and bias voltage on the microstructure, surface morphology and bonding state of films were evaluated. In this investigation, X-ray photoelectron spectroscopy, X-ray diffraction, Atomic force microscope were used. It was found that the grain size of ITO films increased and surface roughness decreased with the increase of oxygen flow rate. The XPS spectra of In 3d and Sn 3d indicated that the oxygen flow had little effect on the binding energy of ITO films. The relative strength of O²⁻_II increased, while that of O²⁻_I decreased with increasing oxygen flow rate. The grain size increased with the bias voltage. However, at a maximum voltage of −90 V fine grains were detected due to the formation of numerous nuclei resulting from bombardment of high energy particles. The bias voltage had little effect on the bonding state of In, Sn and O ions.     

电解液组分对TiCP/Ti6Al4V复合材料微弧氧化膜耐蚀性及耐磨性影响

采用微弧氧化技术在 TiC_P/Ti6Al4V 复合材料表面制备陶瓷膜。在NaAlO₂和NaH₂PO₂两种溶液体系中通过添加不同添加剂 NaOH、C₁₀H₁₂CaNa₂N₂O₈·4H₂O和Na₂SiO₃, 研究电解液组分对陶瓷膜组织、耐蚀性和耐磨性的影响。结果表明: 在NaH₂PO₂电解液体系中生成的膜层由金红石型和锐钛矿型TiO₂相组成, 而在NaAlO₂体系中除了生成TiO₂外, 还生成了Al₂TiO₅和γ-Al₂O₃。添加NaOH可以加快微弧氧化反应速率, 添加NaAlO₂和Na₂SiO₃有利于提高膜层的硬度, NaH₂PO₂溶液体系中形成的膜层厚度是NaAlO₂溶液体系的2~3倍。 在NaAlO₂和NaH₂PO₂电解液体系中生成的膜层, 其耐腐蚀性能排序均为: Na₂SiO₃>C₁₀H₁₂CaNa₂N₂O₈·4H₂O>NaOH。在NaAlO₂电解液体系中生成的膜层的耐磨性能排序为: Na₂SiO₃>NaOH>C₁₀H₁₂CaNa₂N₂O₈·4H₂O, 而在NaH₂PO₂电解液体系中生成的膜层的耐磨性能排序为: Na₂SiO₃>C₁₀H₁₂CaNa₂N₂O₈·4H₂O>NaOH。TiC_P/Ti6Al4V复合材料经过微弧氧化处理后, 耐磨性和耐蚀性均优于基体, 在NaH₂PO₂+Na₂SiO₃电解液中生成的微弧氧化膜的耐蚀性最好, 耐磨性也较好, 其腐蚀电流密度较钛基复合材料基体降低约2个数量级, 因此综合性能最好。     

Influence of Substrate Negative Bias on Structure and Properties of TiN Coatings Prepared by Hybrid HIPIMS Method

TiN coatings were deposited using a hybrid home-made high power impulse magnetron sputtering(HIPIMS)technique at room temperature.The effects of substrate negative bias voltage on the deposition rate,composition,crystal structure,surface morphology,microstructure and mechanical properties were investigated.The results revealed that with the increase in bias voltage from-50 to-400 V,TiN coatings exhibited a trend of densification and the crystal structure gradually evolved from(111) orientation to(200)orientation.The growth rate decreased from about 12.2 nm to 7.8 nm per minute with the coating densification.When the bias voltage was-300 V,the minimum surface roughness value of 10.1 nm was obtained,and the hardness and Young's modulus of TiN coatings reached the maximum value of 17.4 GPa and 263.8 GPa,respectively.Meanwhile,the highest adhesion of 59 N was obtained between coating and substrate.     

Texture comparison of an ordinary IF steel and a high-strength IF steel under ferritic rolling and high-temperature coiling

The present work was performed to investigate the texture difference of an ordinary Ti-IF steel and a high-strength Ti-IF steel under ferritic hot rolling and high-temperature coiling. Comparing with the completely recrystallized textures of the ordinary IF steel, the textures of the high-strength IF steel were still deformed textures. The texture difference for the two steels is related to high P content in the high-strength IF steel which prevents the recrystallization during the coiling process. For the ordinary IF steel, the texture components were mainly very weak {001}110 orientation at the surface, and partial 110//RD (rolling direction) textures focused on {223}110 orientation and 111/ND (normal direction) texture at the mid-section and 1/4-section. For the high-strength IF steel, the texture components were mainly of {110}001 orientation at the surface and of a sharp 110//RD texture from {001}110 to {223}110 and weak 111/ND texture at the mid-section and 1/4-section.     

The Dislocation Structure of a Single-Crystal γ + γ′ Two-Phase Alloy After Tensile Deformation

The dislocation structures of an industrial single-crystal γ + γ′ two-phase alloy DD3 after tensile deformation from room temperature to 1273K were studied by transmission electron microscopy. The strength of this alloy decreased with an increase in the temperature, and showed a strength peak at 1033K. At room temperature, the dislocations shearing the γ′ particles were found to be 1/3<112> partial dislocations on the dodecahedral slip system <112>{111}. Some dislocation pairs on the cubic <110>{100} system that blocked the glide of dislocations were found at a medium temperature of 873K. As a result, dislocation bands were formed. Shearing of γ′ particles by 1/3<112> partial dislocations on the dodecahedral slip system <112>{111} was also found at this temperature. At the peak temperature of 1033K, because of the strong interaction between dislocations on the {111} and {100} planes, the extent of dislocation bands with high dislocation densities was extensive. The 1/3<112> partial dislocations on the dodecahedral slip system <112>{111} also existed. When the temperature reached the high temperature of 1133K, the range of dislocation bands was limited. The γ′ particles were sheared by <110> dislocation pairs on the octagonal <110>{111} system and the cubic <110>{100} system. At 1273K, the regular hexagonal dislocation networks were formed in the γ matrix and at the γ/γ′ interface. The Burgers vectors of the network were found to be b₁ = 1/2[110], b₂ = 1/2[1–10], b₃ = [100], and the last one was formed by the reaction of b₁ + b₂ → b₃. Dislocations shearing the γ′ particles were found to be <110> dislocation pairs on the octagonal system <110>{111} and cubic slip system <110>{100} at 1273K.     

Microstructure and mechanical properties of CrAlN coatings deposited by modified ion beam enhanced magnetron sputtering on AISI H13 steel

CrAlN coatings were deposited on silicon and AISI H13 steel substrates using a modified ion beam enhanced magnetron sputtering system. At the modified ion beam bombardment, the effects of bias voltage and Al/(Cr + Al) ratio on microstructure and mechanical properties of the coatings were studied. The X-ray diffraction data showed that all CrAlN coatings were crystallized in the cubic NaCl B1 structure, showing the (111), (200), and (220) preferential orientation. It is noted that the (111) diffraction peak intensity decreased and the peaks broadened as the bias voltage increased at the same ratio of Al/Cr targets power, which is attributed to the variation in the grain size and microstrain. The microstructure observation of the coatings by field emission scanning electron microscopy cross-section morphology shows that the columnar grain became more compact and dense with increasing substrate bias voltage and Al concentration. At a substrate bias voltage of −120 V and a Al/(Cr + Al) ratio of 40%, the coating had the highest hardness (33.8 GPa) and excellent adhesion to the substrate.     

反应溅射TiN纳米晶薄膜的结构特征和耐蚀性

利用直流反应溅射技术在不锈钢和硅基体上沉积了TiN纳米晶薄膜,采用场发射扫描电镜(FESEM)、X射线衍射(XRD)和电化学阻抗谱(EIS)技术研究了薄膜的表面形貌、相结构和耐蚀性与偏压的关系。结果表明,TiN薄膜的表面结构明显取决于所施加的偏压,适当提高偏压有利于获得细小、均匀、致密和光滑的膜层。XRD分析发现,TiN薄膜为面心立方结构,其择优取向为(111)面。实验显示,对应0V和-35V偏压的薄膜为欠化学计量比的,而偏压增加至-70V和-105V时的薄膜为化学计量比的TiN。EIS结果表明,较高偏压下的TiN薄膜几乎在整个频率范围内均表现为容抗特征,其阻抗模值明显高于低偏压下的膜层,这主要与较高偏压下的薄膜具有相对致密的微结构有关。较低偏压的TiN薄膜因结构缺陷较多其耐蚀性低于基体不锈钢。EIS所揭示的薄膜结构特征与FESEM观测结果一致。可见,减少穿膜针孔等结构缺陷有利于改善反应溅射TiN纳米晶薄膜耐蚀性。     

2024铝合金表面扫描式微弧氧化工艺研究

本研究利用小功率微弧氧化电源, 通过内充液式管状阴极的逐行扫描, 在2024铝合金样件表面生成微弧氧化陶瓷膜层, 对样件的局部受损部位进行了成功的修复, 从而突破了传统微弧氧化技术不能用于铝合金构件现场局部防护与修复的限制; 利用XRD、SEM、EDS等分析方法对陶瓷膜层的相组成与微观组织形貌进行了研究。利用纳米压痕仪测试了陶瓷膜层的纳米压痕硬度和弹性模量, 用动电位极化曲线测试陶瓷膜层的耐腐蚀性能。结果表明: 在恒电流模式下, 扫描式微弧氧化电压快速升高, 直接进入微弧放电阶段。其一次扫描成膜层厚度17 μm, 相对于传统微弧氧化具有很高的成膜效率。铝合金扫描式微弧氧化陶瓷膜层主要由α-Al₂O₃和γ-Al₂O₃组成, 膜层分为致密层和疏松层, 表面多微孔, 且有微裂纹; 纳米压痕测试结果表明, 陶瓷膜层纳米压痕硬度和弹性模量沿界面向外呈现先增加后减小的变化趋势。动电位极化曲线表明, 扫描式和传统微弧氧化陶瓷膜层都能够对基体起到有效的腐蚀防护作用, 传统微弧氧化陶瓷膜层的腐蚀防护作用高于扫描式。     

Bias effects on the tribological behavior of cathodic arc evaporated CrTiAlN coatings on AISI 304 stainless steel

In this study, CrTiAlN coatings were deposited on AISI 304 stainless steel by cathodic arc evaporation under a systematic variation of the substrate bias voltage. The coating morphology and properties including surface roughness, adhesion, hardness/elastic modulus (H/E) ratio, and friction behavior were analyzed to evaluate the impact of the substrate bias voltage on the coating microstructure and properties. The results suggest that for an optimized value of the substrate bias voltage, i.e. − 150 V, the CrTiAlN coatings showed increased Cr content and improved properties, such as higher adhesion strength, hardness, and elastic modulus in comparison to the coatings deposited by other substrate bias voltage. Moreover, the optimum coatings achieved a remarkable reduction in the steel friction coefficient from 0.65 to 0.45.     

Effect of substrate bias voltage on structural and mechanical properties of pulsed DC magnetron sputtered TiN-MoSx composite coatings

TiN-MoS_x composite coatings were deposited by pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) using separate Ti and MoS₂ targets in an Ar and N₂ gas environment. The effect of substrate bias voltage on the structure and mechanical properties of TiN-MoS_x composite coating has been studied. The structure and composition of the coating were evaluated using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) by X-ray and grazing incidence X-ray diffraction (GIXRD). Scratch adhesion tests, Vickers microhardness tests and ball-on-disc tests with a cemented carbide (WC-6%Co) ball were carried out to investigate mechanical properties of the coating. Application of substrate bias was found to transform the structure of TiN-MoS_x composite coating from open columnar to a dense columnar structure. The changes in grain size and texture coefficient appear to be associated with variation in substrate bias voltage. The mechanical properties of the coating such as adhesion and composite microhardness were also observed to be related to the change in bias voltage. A maximum hardness of 22 GPa was obtained for a coating deposited at substrate bias voltage of −40 V. The improved structural and mechanical properties of the coating deposited at −40 V were also reflected in its excellent wear resistance property.     

Intrinsic stress and preferred orientation in TiN coatings deposited on Al using plasma immersion ion implantation assisted deposition

TiN coatings were deposited on Al substrates using the plasma immersion ion implantation and deposition (PIIIAD) technique, employing a filtered Ti cathodic arc in a nitrogen atmosphere. Negative pulsed bias voltages between 0 to −4.0 kV were applied with varying duty cycles, at a constant time-averaged bias. Stress measurements using X-ray diffraction reveal an increase and then a decrease in the intrinsic compressive stress at increasing on-time bias. A bias-dependent preferred orientation of TiN is observed, i.e. {111}, {200} and {220} at low bias and predominantly {200} at higher bias. The hardness reduces from 29 GPa at lower bias to 20 GPa at higher bias. Thus, the time averaged energy of ion bombardment does not uniquely determine the properties of the growing coating, which can be adjusted by the on-time substrate bias applied for very short durations. A simplified subplantation model of stress development is formulated for the case of pulsed bias, the predictions of which are in reasonable agreement with the experimental data.     

Doping and electrical characteristics of in-situ heavily B-doped Si1−x−yGexCy films epitaxially grown using ultraclean LPCVD

Doping and electrical characteristics of in-situ heavily B-doped Si_1−x−yGe_xC_y (0.22<x<0.6, 0<y<0.02) films epitaxially grown on Si(100) were investigated. The epitaxial growth was carried out at 550°C in a SiH₄–GeH₄–CH₃SiH₃–B₂H₆–H₂ gas mixture using an ultraclean hot-wall low-pressure chemical vapor deposition (LPCVD) system. It was found that the deposition rate increased with increasing GeH₄ partial pressure, and only at high GeH₄ partial pressure did it decrease with increasing B₂H₆ as well as CH₃SiH₃ partial pressures. With the B₂H₆ addition, the Ge and C fractions scarcely changed and the B concentration (C_B) increased proportionally. The C fraction increased proportionally with increasing CH₃SiH₃ partial pressures. These results can be explained by the modified Langmuir-type adsorption and reaction scheme. In B-doped Si_1−x−yGe_xC_y with y=0.0054 or below, the carrier concentration was nearly equal to C_B up to approximately 2×10²⁰ cm⁻³ and was saturated at approximately 5×10²⁰ cm⁻³, regardless of the Ge fraction. The B-doped Si_1−x−yGe_xC_y with high Ge and C fractions contained some electrically inactive B even at the lower C_B region. Resistivity measurements show that the existence of C in the film enhances alloy scattering. The discrepancy between the observed lattice constant and the calculated value at the higher Ge and C fraction suggests that the B and C atoms exist at the interstitial site more preferentially.     

Residual stress, Young''s modulus and fracture stress of hot flame deposited diamond

Chemical vapour deposition (CVD) diamond coatings deposited on various substrates usually contain residual stresses. Since the residual stress affects the adhesion of the coating to the substrate, as well as the performance of the coating/substrate composite in many technical applications it is of importance to study the magnitude of these stresses.

In the present study the hot flame method was used to deposit diamond coatings on cemented carbide inserts by scanning the surface with a nine flame nozzle. By varying the oxygen to acetylene flow ratio and the deposition time coatings of different qualities and thicknesses were obtained. The residual strain/stress of the coatings was measured by three different methods: X-ray diffraction using the sin² (Ψ) method, Raman spectroscopy and disc deflection measurements. To extract the residual stress from the strain data the Young's modulus was obtained from bending tests of diamond cantilever beams manufactured from free standing diamond films. The latter technique was also used to determine the fracture stress of the diamond films.

All deposited coatings displayed a residual compressive strain/stress state. The residual strain in the diamond coatings did not vary with coating thickness (1.5 μm to 20 μm) but was found to increase from −1.8 × 10⁻³ to −2.2 × 10⁻³ with decreasing diamond quality. The compressive residual stress was found to decrease from −2 GPa to −1.3 GPa with decreasing diamond quality. This is mainly due to a decrease in Young's modulus (from 1.1 TPa to 0.6 TPa) with decreasing diamond quality. Also the fracture stress was found to decrease (from 1.8 GPa to 0.8 GPa) with decreasing diamond quality. The three methods used for measuring the stress state in the coatings, X-ray diffraction, Raman spectroscopy and deflection measurement, all give the same result. The deflection technique has the advantage that no information about the elastic properties of the coating is needed, whereas Raman spectroscopy has the best lateral resolution (≈5 μm) and is the fastest method (≈5 min).     

Effect of nitrogen on diamond growth using unconventional gas mixtures

The influence of nitrogen on the growth of diamond using unconventional gas mixtures of CH₄---CO₂ by microwave plasma chemical vapor deposition was investigated. A clear improvement in the surface morphology and quality of the diamond films indicates the beneficial effect of adding nitrogen to CH₄-CO₂ gas mixtures. However, most interestingly, for lower methane concentration, the addition of small amounts of nitrogen resulted in the formation of isolated diamond particles possessing a vacant “cage-like” structure with completed {100} facets This result indicates that the continued addition of nitrogen gives rise to the deterioration of {111} facets and the retention of {100} facets. Analysis using Auger electron spectroscopy and secondary ion mass spectroscopy shows very low and uniform levels of nitrogen in the diamond films. Although the amount of atomic hydrogen in the ground state decreased and CN radicals increased with increasing amounts of added nitrogen, good-quality diamond films were deposited resulting from a larger amount of atomic oxygen and the decrease in the C₂ emissions in the gas phase under optimum conditions.     

Effect of negative bias voltage on mechanical and electrochemical nature in Ti–W–N coatings

Mechanical and electrochemical surface properties of Si (100) and AISI D3 steel substrates-coated Ti–W–N, deposited by r.f. magnetron sputtering process from a binary (50% Ti, 50% W) target in an Ar/N₂ (90%/10%) mixture, have been studied using nanoindentation, Tafel polarization curves and electrochemical impedance spectroscopy (EIS). The crystallinity of the coatings was analyzed via X-ray diffraction (XRD) and the presence of TiN(111), TiN(200), WN₂(107), and W₂N(220) phases were determined. Depth sensing nanoindentation measurements were used to investigate the elasto-plastic behavior of Ti–W–N coatings. Each group of samples was deposited under the same experimental conditions (power supply, Ar/N₂ gas mixture and substrate temperature), except the d.c. negative bias voltage that varied (0, ?50, and ?100 V) in order to study its effect on the mechanical and electrochemical properties of AISI D3 steel coated with Ti–W–N coatings. The measurements showed that the hardness and elastic modulus increase from 19 to 30 GPa and from 320 to 390 GPa, respectively, as a function of the increasing negative bias voltage. Coating track and coating-substrate debonding have been observed with atomic force microscopy (Asylum Research MFP-3D^®) on the indentation sites. Finally, the corrosion resistance of Ti–W–N coatings in 3.5 wt% NaCl solution was obtained from electrochemical measurements in relation to the increase of the negative bias voltage. The obtained results have shown that at the higher negative bias voltage (?100 V), the steel coated with Ti–W–N coatings presented the lower corrosion resistance. The corrosion resistance of Ti–W–N in 3.5 wt% NaCl solution was studied in relation to the increase of the bias voltage.