Fe基体上Ni膜和Cu基体上Ag膜的膜内应力

直流电沉积法在Fe基体上制备Ni膜和在Cu基体上制备Ag膜,利用悬臂梁法在线测量了膜中的平均应力,并计算了膜内分布应力,且对膜内平均应力的实验结果与Thomas?Feimi?Dirac?Cheng(TFDC)电子模型理论估算结果进行了对比。结果表明,Fe基体上Ni膜的平均应力和分布应力均为拉应力,而Cu基体上Ag膜的平均应力和分布应力均为压应力。两种膜的内应力均由界面应力引起。对于相同的基体和镀膜,膜内平均内应力的理论估算值与实验值较接近。     

Hydrogen induced microstructural variation in diamond and diamond like carbon thin films

Hydrogen plays a crucial role in the growth of micro-crystalline diamond (MCD) and diamond like carbon (DLC) thin films grown by plasma assisted chemical vapour deposition (PACVD) processes. It selectively etches graphite phase and helps in stabilizing the diamond phase. The presence of various hydrocarbon species in the plasma and their reaction with atomic, excited or molecular hydrogen on the substrate surface decide the mechanism of diamond nucleation and growth. Several mechanisms have been proposed but the process is still not well understood. Control of hydrogen and other deposition parameters in the PACVD process leads to deposition of yet another class of materials called diamond like carbon. By varying the concentration of hydrogen it is possible to produce purely amorphous carbon films on the one hand and amorphous hydrogenated carbon films (with as high as 60% hydrogen) on the other. Very hard, optically transparent and electrically insulating films characterize the diamond like behaviour. The proportion of hydrogen and its bonding with carbon or hydrogen in the film can be varied to obtain very hard to very soft films which could be optically transparent or opaque. The microstructure of these films have been investigated by a large number of techniques. The results show interesting situations. This paper reviews the work on the role of hydrogen on the growth, structure and properties of MCD and DLC thin films.     

沉积温度对等离子增强化学气相沉积TiN薄膜内应力的影响

实验表明,高速钢基体上的PECV-TiN薄膜处于压应力状态,其绝对值随沉积温度的升高而降低,反映微观组织状态及其不均匀性的衍射峰半高宽亦呈下降趋势,但晶体的择优取向受沉积温度影响较小。分析认为PECVD-TiN薄膜受离子轰击的影响较大,正常沉积温度下其内应力以本征应力为主,大小与薄膜的显微组织关系密切。较高温度下,热应力占主导地位,其大小主要决定于膜、基的热膨胀系数之差。     

Diamond films deposited on WC-Co substrates by use of barrier interlayers and nano-grained diamond seeds

Results on the structure, composition and properties of diamond films deposited onto WC-Co cemented carbides via special multilayer barrier interlayers preliminary seeded by nano-grained diamond particles are presented. The barrier interlayers comprise a layer adjacent to the substrate, which completely prevents substrate decarburization and Co diffusion from the substrate, and a diamond-bonding layer needed to obtain an enhanced adhesion of the PACVD diamond coating. Preliminary seeding the barrier interlayers with nano-grain diamond particles by use of a laser ablation technique allows a fine-grained, uniform and highly adherent diamond coating of high quality to be deposited by use of a conventional PACVD technique. Results on the nature of the interaction between the diamond nano-grained seeds and barrier interlayer are also presented.     

Plasticity and Interfacial Dislocation Mechanisms in Epitaxial and Polycrystalline Al Films Constrained by Substrates

Stresses in epitaxial and textured Al films were determined by substrate-curvature measurements.It was found that in both cases the flow stresses increase with decreasing film thickness.The flow stresses in the epitaxial Al films are in agreement with a dislocation-based model,while the same model strongly underestimates the flow stresses of textured Al films.In-situ transmission electron microscopy studies indicate that dislocations channeling through epitxial Al films on single-crytalline(0001)α-Al2O3 substrates frequently deposit dislocation segments adjacent to the interface.Furthermore,the Al/α-Al2O3 interface of textured Al films on oxidized sillicon substrates is between the crystalline Al and the amorphous SiOx interlayer.It is speculated that the different nature of the interfaces changes dislocation mechanisms and thus influences the flow stresses.     

沉积方式与基体材料对TiN薄膜内应力的影响

本文研究了TiN薄膜在化学气相沉积、物理气相沉积(包括热灯丝离子镀和多弧离子镀)以及等离子增强化学气相沉积等不同生成条件下的内应力变化。并通过改变钢及硬质合金基体的化学成份和表面状态。考察了基体材料对薄膜应力的影响。在此基础上,对薄膜内应力的形成机制进行了分析讨论。     

Internal stress and optical properties of Nb2O5 thin films deposited by ion-beam sputtering

The influence on the internal stress and optical properties of Nb2O5 thin films with ion-beam energy was investigated. Nb2O5 thin films were deposited on unheated glass substrates by means of ion-beam sputtering with different ion-beam voltage, Vb. The refractive index, extinction coefficient, and surface roughness were found to depend on the ion-beam energy. The stresses in thin films were measured by the phase-shifting interferometry technique. The film stress was also found to be related to Vb, and a high compressive stress of -0.467 GPa was measured at Vb = 850 V. The Nb2O5-SiO2 multilayer coatings had smaller average compressive stress as compared with single-layer Nb2O5 film.     

3.1 mechanical properties of PVD films

The mechanical properties of thin films are influenced by their structures, stability, internal stresses and thickness which makes the understanding of the mechanical behavior a complex problem. Thick films of metals and alloys seem to follow the same, well-established trends in structure and properties as bulk materials produced by more conventional wrought techniques. The state of understanding of the mechanical behavior of thick films of refractory compounds is still in its infancy and much work remains to be done for this very important class of materials.     

Mechanical properties of metal and compound films

Experimental results on internal stress, Young's modulus and adhesion of metal and compound films are presented and the correlation between these quantities is discussed. Internal stress and Young's modulus were determined by simultaneous in situ measurements during film deposition. In addition to the internal stress values of metal films, which have been given by many workers, we include results on compound films, some of which showed compressive stresses. The Young's moduli of films of such compounds as MgF₂ and TiC and of carbon, which have not previously been established, were determined. The strain energy density accumulated in a film during deposition was evaluated from the measured values of Young's modulus and internal stress. In some films, cracks or wrinkles were generated by strain energy, leading to the spontaneous peeling of the films from the substrates. The adhesion experiments were performed using the topple and pull test. The adhesive forces were directly measured and the adhesion energies were estimated. The effect of the substrate temperature and ion bombardment on the adhesion were investigated. The values of adhesion energies were compared with strain energies and the meaning of the adhesion test was considered.     

Properties of thin TiN films deposited onto stainless steel by an in-line dry coating process

A new coil-coating pilot plant, capable of utilizing ion plating, sputtering and plasma-assisted chemical vapor deposition (PACVD) processes, independently or in series, was developed and optimum conditions for TiN, TiC, Al_xO_y, SiO_x and Cr coating were established. This paper is mostly concerned with the results of characterization (conducted in parallel by the authors′ two institutions) of TiN films deposited by ion plating or sputtering onto type-304 stainless steel strips. In particular, the dependence of the basic properties such as chemical composition, structure, adhesion, and color on the coating process are discussed with respect to anti-corrosion, anti-wear, and decorative applications. TiN coatings with a very attractive gold coloration were obtained; they performed well in wear testing, but did not show satisfactory corrosion resistance. However, it was found that the latter can be improved significantly by depositing a SiO_x, top layer by PACVD above the TiN coating. Thus the in-line dry coating processes are capable of producing highly functional steel surfaces with decorative color and high corrosion resistance.     

Modeling of relaxation of viscoelastic stresses in multi-layered thin films/substrate systems due to thermal mismatch

Assume the ratio of the total axial rigidity of thin films to that of the substrate is smaller than 0.02, an approximate closed-form solution for viscoelastic stresses in multi-layered thin films/substrate systems due to thermal mismatch is derived. This is achieved by utilizing the analogy between the governing field equation of elasticity and the Laplace transform with respect to time of the viscoelastic field equation. Based on two solutions, simplified solutions for relaxation of residual stresses distributed in multiple layers of thin films deposited on a thick substrate are obtained. The effect of the thickness, thermal expansion coefficient, Young's modulus, and viscosity coefficient of the substrate and thin films on the relaxation of residual stresses is considered. This simplified solution can be applied to some special cases such as one layered or periodic multi-layered thin films on a thick substrate.     

Stresses in sputtered RUOx thin films

RuO_x thin films have been deposited by reactive sputtering in an O₂/Ar atmosphere. The films were characterized for their stress and resistivity as a function of deposition temperature (room temperature, 300°C) and the O₂ content (25–100%) in the sputtering gas. Additionally, the stresses in these films were determined as a function of annealing temperature (up to 600°C) using an in-situ curvature measurement technique. The as-deposited films were found to be under a state of compressive stress for all deposition conditions. The compressive stresses sharply increased with increasing deposition temperature from a value of around 200 MPa at 200°C to 1400 MPa at 300°C. This dramatic increase has been attributed to differences in microstructure at these deposition temperatures. The microstructural differences also led to the widely differing stress-temperature behavior during annealing of these films. For films deposited at temperatures lower than 200°C, the annealing process resulted in a decrease in the compressive stress and resistivity of the films. However, films deposited at a temperature of 300°C did not show any changes in the compressive stress or resistivity after annealing. The results of this study can be used to deposit RuO_x thin films with low resistivity and minimal stresses.     

Optical anisotropy,molecular orientations,and internal stresses in thin sulfonated poly(ether ether ketone) films

The thickness, the refractive index, and the optical anisotropy of thin sulfonated poly(ether ether ketone) films, prepared by spin-coating or solvent deposition, have been investigated with spectroscopic ellipsometry. For not too high polymer concentrations (≤5 wt%) and not too low spin speeds (≥2000 rpm), the thicknesses of the films agree well with the scaling predicted by the model of Meyerhofer, when methanol or ethanol are used as solvent. The films exhibit uniaxial optical anisotropy with a higher in-plane refractive index, indicating a preferred orientation of the polymer chains in this in-plane direction. The radial shear forces that occur during the spin-coating process do not affect the refractive index and the extent of anisotropy. The anisotropy is due to internal stresses within the thin confined polymer film that are associated with the preferred orientations of the polymer chains. The internal stresses are reduced in the presence of a plasticizer, such as water or an organic solvent, and increase to their original value upon removal of such a plasticizer.     

A computational study of the piezoelectric response due to the material effect in periodic, single island thin films and the geometric effect in periodic, bi-island thin films

The electromechanical response of a square-periodic array of circular piezoelectric (PE) thin films alternating with non-piezoelectric (NPE) films is studied in this paper. The material effects are studied for four film/substrate combinations in absence of NPE films for which it is found that if d_zxx ? d_zzz (z-axis being normal to the interfacial plane between the film and the substrate), it results in reduced substrate bending leading to reduced degradation in the electromechanical response of the thin film. The bi-island structure is studied for zinc oxide on strontium titanate, and, in general, it is seen that the NPE films not only reduce degradation of the electromechanical response of the PE films but also increase their internal stresses; the effect on the former is less than the latter. These effects are most prominent when the circular NPE thin films fill the space between the PE thin films and are elastically very stiff compared to the substrate.     

电子束反应蒸发氧化物薄膜的应力特性

研究了反应电子束蒸发氧化物光学薄膜在空气中的应力。为了找到能减小多层膜结构内应力的淀积工艺参数,测试了氧化物膜层TiO2,Ta2O5,SiO2,Al2O3,HfO2的应力,发现有些膜层为压应力,一些高折射率膜为张应力。实验表明,热处理可以有效地降低氧化物膜层光学吸收,并改变应力。     

A mass spectrometric investigation of the plasma polymerization of methyltrimethoxysilane in an r.f. discharge

Quadrupole mass spectrometry was used to determine the chemical species present during r.f. discharges in methyltrimethoxysilane (MTMOS) and in MTMOS-Ar and MTMOS-O₂ mixtures. Hydrogen, low molecular weight (C₁-C₃) hydrocarbons, aldehydes and alcohols and silicon-containing fragments arising from MTMOS decomposition were observed in discharges in MTMOS and in MTMOS-Ar mixtures. The major components of discharges in MTMOS-O₂ mixtures were found to be H₂, OH, H₂O, CO, CO₂ and residual oxygen.Discharges in MTMOS or in MTMOS-Ar mixtures deposited polyalkoxysiloxane films. Similar discharges in MTMOS-O₂ mixtures deposited oxygen-deficient vitreous silica films. All of these films had large internal stresses resulting from the plasma polymerization process. The use of argon as a carrier gas for MTMOS in the production of polyalkoxysiloxane coatings reduced this stress significantly.     

Flächeneinfluss bei der PACVD‐Beschichtung

Impact of the active surface on properties of DLC films in the PACVD coating chamber. In the automotive industry, economic and stable industrial processes to apply hard coatings for tribological applications are required. Hence detailed knowledge about the influence of coating parameters on the film characteristics is essential. the following paper deals with the process of plasma activated chemical vapor deposition with focus on the effect of the parameter “active area in the coating chamber“ on the properties of diamond‐like‐carbons (DLC). the coatings are deposited in an industrial coating chamber using reactive magnetron sputtering with a pulsed bias voltage (40 kHz) and at constant pressure. During the investigation of the influence of active area and current density on the mechanical and tribological properties of the DLC films, the expected correlation between active area and current density could be confirmed. By regulating the current density, consistent film properties could be achieved, independently of the active area in the chamber. Furthermore improved wear characteristics of the film – crucial for the endurance of heavily loaded automotive components – were achieved by adapting the load pattern of the chamber.     

Innovationen durch PACVD Duplex Schichtsysteme im Leichtmetall‐Druckguss

Innovative PACVD Duplex Layer Systems applied for the Light Metal Die Casting Process Duplex‐PACVD hard coatings are well‐known for increasing the tool performance in terms of adhesion, wear, fatigue, and corrosion resistance of the steel. The developments made in synthesizing duplex nanostructure and nanocomposite, mono and gradient layers based on borides are described. The aim of the investigation is to optimize the surface capability by plasma process combinations: duplex process, gradient‐layer. Within this work different types of duplex hard coatings produced by PACVD were investigated in terms of their tribological behavior and were tested in aluminum and magnesium die casting applications. Practical tests have been carried out by automobile producers and part suppliers. All coatings tested on die casting tools showed a significant increase of lifetime and a reduced metal adhesion tendency. The economic efficiency of coated die casting tools could be proved.     

Analytical modeling of residual stresses in multilayered superconductor systems

Residual stresses-induced damages in multilayered films grown on technical substrates present a reliability issue for the fabrication and applications of multilayered superconductor systems. Using closed-form solutions for residual stresses in multilayered systems, specific results were calculated for residual stresses induced by the lattice and the thermal mismatches in the system of YBCO/CeO₂/YSZ/Y₂O₃ films on a Ni-5 W substrate. It was concluded that lattice mismatch-induced residual stresses must be relaxed by forming interfacial defects. Studies of residual thermal stresses showed the following. When the thickness of a film is negligible compared to the substrate, the changes of its properties modify the residual stresses in this film layer but have negligible effects on the residual stresses in other layers in the system. On the other hand, when the thickness of certain film layer is not negligible compared to the substrate, residual stresses in each layer can be controlled by adjusting the properties and thickness of this film layer. Finally, the effects of buffer layers on thermal stresses in YBa₂Cu₃O_7–x (YBCO) were addressed by using YBCO/LaMnO₃/homo-epi MgO/IBAD MgO/Y₂O₃/Al₂O₃ films on Hastelloy substrate as an example.