Surface and mechanical characterization of TaN-Ag nanocomposite thin films

TaN-Ag nanocomposite thin films with Ag nano-particles dispersed in TaN matrix and surface were prepared by reactive co-sputtering of Ta and Ag in the plasma of N₂ and Ar. After deposition, the films were annealed using RTA (Rapid Thermal Annealing) at 350 °C for 2, 4, 8 min respectively to induce the nucleation and growth of Ag particles. C-AFM (Conductive-atomic Force Microscopy) and SSPM (Surface Scanning Potential Microscopy) were applied to characterize the emergence of Ag nano-particles on the surface of TaN-Ag thin films in this study. It is seen that Ag nano-particles may emerge in the matrix and on the surface of TaN and, possibly, grow. The results are compared with that obtained by FE-SEM (field-emission scanning electron microscopy). After comparison, C-AFM and SSPM are seen to be useful in characterizing the emergence and distribution of Ag particles. The results also show that the films' hardness and Young's modulus values would increase or decrease with the increase of annealing time, depending on Ag content and annealing time. This behavior is similar to that of TaN-Cu nanocomposite film. In addition, the increase of wear resistance of these coatings is proved.     

Antibacterial and tribological properties of TaN–Cu,TaN–Ag,and TaN–(Ag,Cu) nanocomposite thin films

In this study, attempts were made to prepare and characterize TaN–(Cu,Ag) nanocomposite films by using a hybrid approach combining reactive co-sputtering and rapid thermal annealing at various temperatures to induce the formation of soft metal particles in the matrix or on the surface. The films’ properties and their antiwear and antibacteria behaviors were compared with those previously studied TaN–Cu and TaN–Ag films. All three types of TaN–(soft metal) films showed good tribological properties due to the lubricious Ag and/or Cu layers. It was also found that the antibacteria efficiency of TaN–(Ag,Cu) film against either Escherichia coli or Staphylococcus aureus could be much improved, comparing with that of TaN–Ag or TaN–Cu film. The synergistic effect due to the coexistence of Ag and Cu is obvious. The annealing temperature used to develop TaN–(Cu,Ag) films with good antibacterial and antiwear behaviors could be as low as 250 °C. The lowering of the annealing temperature made these films applicable onto low-melting-point materials, such as polymers.     

Study of Cu emergence on the surface of TaN-Cu nanocomposite thin films and its effects on tribological property

TaN-Cu nanocomposite films, were deposited by reactive co-sputtering on Si and tool steel substrates. The films were then annealed using RTA (Rapid Thermal Annealing) at 400 °C for 2, 4, 8 min respectively to induce the nucleation and growth of Cu particles in the TaN matrix and on the film surface. SSPM (Scanning Surface Potential Microscopy) and SEM (Scanning Electron Microscopy) were applied to examine the Cu nano-particles that emerged on the surface of TaN-Cu thin films. Pin-on-Disk tribometer was used to study the effect of annealing on the films' tribological properties. The results reveal that annealing by RTA can cause Cu nano-particles to emerge on the TaN surface. Consequently, hardness and friction coefficients will change depending on annealing conditions, Cu content, and/or Cu particle emergence.     

Diffusion barrier properties of ionized metal plasma deposited tantalum nitride thin films between copper and silicon dioxide

Tantalum nitride thin films with different thickness are sputtered deposited on silicon dioxide in the Cu/TaN/SiO₂/Si multiplayer structure. Using resistivity analyses, X-ray diffraction, scanning electron microscopy and Rutherford backscattering spectroscopy, this work examines the impact of varying layer thickness on the crystal structure, resistivity, intermixing and reactions at the interfaces before and after annealing. The thinner the film thickness of TaN, the severe the reactions at the interface of Cu/TaN and consumed more conductive Cu. All the structures shown similar degradation process, and were found to be stable up to 500°C for 35 min. Accelerated grain growth and agglomeration were also observed after annealing temperature higher than 550°C at all Cu surfaces of the samples.     

Preparation of Cr(N,O) thin films by RF reactive unbalanced magnetron sputtering

Chromium oxynitride thin films were deposited by radio-frequency (RF) reactive unbalanced magnetron sputtering at various O₂ flow rates onto Si(100) and glassy carbon substrates. The compositions of the thin films were analyzed by Rutherford backscattering spectroscopy. The thin films were found to contain up to 44 at.% oxygen. In Fourier-transform infrared spectra, a peak attributed to the Cr-N bond of CrN was observed, but no peak attributable to the Cr-O bond of Cr₂O₃ was found. The textures of the thin films were observed by transmission electron microscopy, which revealed that samples had a columnar structure. The hardness of the thin films was measured by nanoindentation. The hardness increased from 20 GPa to a maximum value of 31 GPa with increasing oxygen content.     

Microstructure of amorphous tantalum nitride thin films

The main purpose of the present microstructural analysis by transmission electron microscopy (TEM) and X-ray diffraction was to investigate whether amorphous TaN films are a potential candidate as diffusion barrier for Cu wiring used in Si devices. The TaN thin films were prepared by a sputter-deposition technique using Ar and N₂ mixed gas, and the film structure was found to be sensitive to the gas flow ratio of N₂ vs. Ar during sputtering. Polycrystalline TaN films were obtained when the N₂/(Ar+N₂) ratio was smaller than 0.10 and amorphous TaN films were obtained when the ratio was larger than 0.15. Cross-sectional TEM observations revealed that the amorphous films had columnar structure with fine grains and that nano-scaled voids segregated at the boundaries. In addition, two-layered structures were observed in the amorphous TaN films and high density of the grain boundaries was formed close to the substrate. The present results suggested that the amorphous TaN films would not have high resistance against interdiffusion between two different materials because the density of grain boundaries with small voids was extremely high.     

Microstructure and mechanical properties of polycrystalline NbN/TaN superlattice films

The polycrystalline NbN/TaN superlattice films have been grown on the substrates of 18-8 stainless steel by reactive magnetron sputtering. The microstructure and microhardness of the superlattice films have been studied with X-ray diffraction (XRD), high resolution transmission electron microscopy (HREM) and microhardness tester. The results showed that the NbN layers are of face cubic and the TaN layers are hexagonal crystal structure in the NbN/TaN superlattice films. The lattice plane (111) of NbN are coherent with the (110) of TaN and the lattice mismatch is 3.18%. The NbN/TaN superlattice film demonstrated superhardness effects. The maximum Knoop hardness value reached 5100 kgf/mm² with a modulation period from 2.3 nm to 17.0 nm. It was proved that even if NbN layers did not take the same crystal structure as TaN layers, hardness anomalous phenomenon still can be produced as long as the coherent strains exist.     

NbN/TaN纳米多层膜的微结构及超高硬度效应

用磁控反应溅射的方法在不锈钢基片上制备了NbN／TaN纳米多层薄膜,试验采用X射线衍射仪（XRD）、透射电子显微镜（TEM）及显微硬度仪对薄膜的微结构和硬度进行分析,结果表明：在NbN／TaN多层膜中,NbN层为面心晶体结构,TaN层为六方晶体结构;NbN／TaN纳米多层膜存在超硬效应,在调制周期2．3～170nm这一放宽的范围内保持超高硬度,硬度最大值HK达51.0GPa     

Preparation and antibacterial activities of Ag-doped SiO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript> composite films by liquid phase deposition (LPD) method

In the present study, Ag/SiO₂–TiO₂ thin films on ceramic tiles with glazed surface were successfully prepared by a liquid phase deposition method (LPD) at a low temperature. The Ag/SiO₂–TiO₂ thin films obtained were homogenous, well adhered and colored by interference of reflected light. The films were characterized by scanning electron microscopy and X-ray diffraction. From these analysis data, it was found that silver (Ag) nanoparticles were trapped in SiO₂–TiO₂ matrix. The antibacterial effects of Ag/SiO₂–TiO₂ thin films against S. aureus and E. coli were examined by the so-called antibacterial-drop test. The bactericidal activity for the above bacteria cells was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The Ag/SiO₂–TiO₂ thin films had an excellent antibacterial performance. Atomic absorption spectroscopy (AAS) was used for the quantitative determination of the Ag ion concentration releasing from the Ag/SiO₂–TiO₂ thin film. The releasing rate of Ag ions from the Ag/SiO₂–TiO₂ film is 0.123 μg/mL during 192 h. The antibacterial effect of Ag/SiO₂–TiO₂ thin film before and after aging in a weathering chamber for 48 h was compared and the results show that the antibacterial activity is not compromised after weathering.     

Deuterium post-metallization anneal of electrochemical-plated Cu film deposited on different barrier materials

In this paper, we report on electrochemical-plated (ECP) copper (Cu) film characterizations with different (Ta, TaN and TiN) barrier materials subjected to post-metallization-annealing (PMA) in deuterium (D₂) under various annealing conditions. For comparison, post-metallization-anneal of the ECP Cu film in pure nitrogen (N₂) and forming gas (20% hydrogen+80% nitrogen) were also performed. We used four-point probe to determine the sheet resistance. Scanning electron microscopy was used to examine the surface morphology of the after-annealed ECP Cu films. X-ray-diffraction (XRD) analysis was used to inspect the texture of the ECP Cu films before and after PMA. The deuterium distribution in the barrier layer was determined by using the secondary ion mass spectroscopy depth profile analysis. We found that under appropriate PMA conditions, the sheet resistance of ECP Cu films deposited on TaN barrier was the lowest after D₂ PMA when compared with those deposited on TiN and Ta barriers.     

Combinatorial investigation of Fe–B thin-film nanocomposites

Abstract

Combinatorial magnetron sputter deposition from elemental targets was used to create Fe–B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young's modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H₂ atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe₂B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films.     

Combinatorial investigation of Fe–B thin-film nanocomposites

Combinatorial magnetron sputter deposition from elemental targets was used to create Fe–B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young''s modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H₂ atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe₂B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films.     

Optoelectronic properties of sputter-deposited Cu2O-Ag-Cu2O treated with rapid thermal annealing

Cu₂O and two types of Cu₂O-Ag-Cu₂O (CAC) multilayered thin films were deposited on glass substrates using DC-magnetron sputtering. For CAC films, the mass thickness of Ag layer was controlled at 3 nm. After deposition, some of these films were annealed using a rapid thermal annealing (RTA) system at 650 °C, in order to create embedded Ag particles. AC films were used to study the clustering effect of Ag in Ar atmosphere, as well as for forming the 2nd type of CAC film by covering another Cu₂O layer on the annealed AC structure. A UV-VIS-NIR photometer, a Hall measurement system, and a I-V measurement system were used to characterize the optical and electrical properties of these films with and without RTA. The results show that 2-dimensional Ag layer can transform into many individual particles due to its high surface tension at annealing temperature, no matter when the annealing was carried out. For CAC films, without annealing, the optical transmission and the resistivity are decreased with the inserted Ag layer. After annealing, both the transmission and resistivity are increased, possibly due to the clustering effect of Ag layer. Most importantly, it is found that the embedded Ag particles can increase the light absorption in the NIR-IR region, which can increase photo-induced current.     

C-Ti nanocomposite thin films: Structure, mechanical and electrical properties

Carbon-titanium nanocomposite thin films were deposited by DC magnetron sputtering on oxidized silicon substrates in argon. The films were prepared at different deposition temperatures between 25 and 800 °C. Transmission electron microscopy was used to determine the structure of the films. All the C-Ti nanocomposites consisted of columnar TiC structure with average column width ∼10 and 20 nm and a thin carbon matrix. The thickness of the carbon matrix between adjacent TiC columns was ∼2-5 nm.Mechanical properties (hardness, reduced modulus) of C-Ti films showed a distinct variation depending on the deposition temperature. Films deposited at 200 °C had the highest hardness ∼18 GPa and the highest reduced modulus ∼205 GPa.Temperature dependence of the film resistance was measured between 80 and 330 K. C-Ti nanocomposites have a non-metallic conduction mechanism characterized by a negative temperature coefficient of resistivity (TCR). The most negative TCR was observed for films showing high hardness and reduced modulus of elasticity.     

Gamma-irradiation-induced Ag/SiO2 composite films and their optical absorption properties

Small Ag particles or clusters dispersed mesoporous SiO₂ composite films were prepared by a new method: First the matrix SiO₂ films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO₃ solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO₂ films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements.     

Hydrophilic properties of nano-TiO2 thin films deposited by RF magnetron sputtering

Microstructure and hydrophilicity of nano-titanium dioxide (TiO₂) thin films, deposited by radio frequency magnetron sputtering, annealed at different temperatures, were studied by field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle methods. It is found that the crystal phase transforms from amorphous to rutile structure with increase of annealing temperature from room temperature to 800 °C. It is also indicated that the organic contaminants on the surface of the films can be removed and the oxygen vacancies can be reduced by the annealing treatment. Annealed at the temperature below 300 °C, amorphous TiO₂ thin films show rather poor hydrophilicity, and annealed at the temperature range from 400 to 650 °C, the super hydrophilicity anatase of TiO₂ thin films can be observed. However, when the annealing temperature reaches 800 °C, the hydrophilicity of the films declines mainly derived from the appearance of rutile.     

Effect of oxygen on the surface morphology of CuGaS2 thin films

Since the effect of oxygen is very significant during the heat treatment of the thin films, we study the effect of this during the annealing of CuGaS₂ thin films by two different types. In this study, CuGaS₂ thin films were deposited by vacuum thermal evaporation of CuGaS₂ powder on heated glass substrates at 200 °C submitted to a thermal gradient. The films are annealed in air and under nitrogen atmosphere at 400 °C for 2 h. In order to improve our understanding of the influence of oxygen during two annealing types on device performance, we have investigated our CuGaS₂ material by X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) and spectrophotometry. A correlation was established between the surface roughness, growth morphology and optical properties, of the annealed CuGaS₂ thin films. It was found that annealing of CuGaS₂ film in nitrogen atmosphere leads to a decrease of the mean grain size and to an evolution of a (112) preferred film orientation. Annealing in air results in the growth of oxide phases such as CuO and modifies the films structure and their surface morphology.     

The effect of sputtering gas pressure on structure and photocatalytic properties of nanostructured titanium oxide self-cleaning thin film

Titanium oxide thin films were deposited by DC reactive magnetron sputtering on ZnO (80 nm thickness)/soda-lime glass and SiO₂ substrates at different gas pressures. The post annealing on the deposited films was performed at 400 °C in air atmosphere. The results of X-ray diffraction (XRD) showed that the films had anatase phase after annealing at 400 °C. The structure and morphology of deposited layers were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface grain size and roughness of TiO₂ thin films after annealing were around 10-15 nm and 2-8 nm, respectively. The optical transmittance of the films was measured using ultraviolet-visible light (UV-vis) spectrophotometer and photocatalytic activities of the samples were evaluated by the degradation of Methylene Blue (MB) dye. Using ZnO thin film as buffer layer, the photocatalytic properties of TiO₂ films were improved.     

Control of electrical resistivity of TaN thin films by reactive sputtering for embedded passive resistors

Tantalum nitride thin films were deposited by radio frequency (RF) reactive sputtering at various N₂/Ar gas flow ratios and working pressures to examine the change of their electrical resistivity. From the X-ray diffraction (XRD) and four-point probe sheet resistance measurements of the TaN_x films, it was found that the change of the crystalline structures of the TaN_x films as a function of the N₂ partial pressure caused an abrupt change of the electrical resistivity. When the hexagonal structure TaN thin films changed to an f.c.c. structure, the sheet resistance increased from 16 Ω/sq to 1396 Ω/sq. However, we were able to control the electrical resistivity of the TaN thin film in the range from 69 Ω/sq to 875 Ω/sq, with no change in crystalline structure, within a certain range of working pressures. The size of the grains in the scanning electron microscopy (SEM) images seemed to decrease with the increase of working pressure.     

Effect of annealing temperature on microstructure of microwave dielectric ceramic thin films fabricated by RF magnetron sputtering

Microwave dielectric ceramic thin films with perovskite structure were fabricated on SiO₂(110) substrates using radio frequency magnetron sputtering method and the as-grown samples were annealed at different temperature in oxygen ambient. The influence of annealing temperature on microstructure and surface morphology properties were investigated, which were examined by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The results show that the main phase of the film is Ba_0.5Sr_0.5Nb₂O₆ with tetragonal perovskite structure, which is different from the composition of target due to volatilization of ZnO during sputtering and annealing process. Surface morphology of samples is compact and uniform. These films are of excellent crystallization quality, with a polycrystalline and dense structure and the crystal quality can be improved by the increase of annealing temperature.