Tensile and high cycle fatigue test of copper thin film

This paper presents the results of tensile and high cycle fatigue tests for copper thin film. Copper films coated by Sn are often used in various electro devices. Especially, when the film is used in tape carrier package (TCP), the film is repeatedly exposed to mechanical or(and) thermal stresses which results often in the failure of the component. Therefore, to guarantee the reliability of the electrical devices using a film, tensile and fatigue characteristics of the film are important. In this study, to obtain the tensile and fatigue characteristics of the film, the specimen was fabricated by an etching process to make a smooth specimen of 2000 μm width, 8000 μm length and 15.26 μm thickness. The tensile and high cycle fatigue tests were performed with the specimen using the test machine developed by the authors. These specimens had measured values of Young's modulus (72 GPa) and a 0.2 % offset yield and an ultimate strength of 358 MPa and 462 MPa, respectively. A closed‐loop feedback control of the magnetic‐electric actuator allowed load‐controlled fatigue tests with 20 Hz frequency, in ambient environment and at two levels of mean stresses. The fatigue strength coefficient and exponent at 0.5 times of the ultimate tensile strength were 431 MPa and ‐0.0843, respectively. The fatigue strength coefficient and exponent at 0.6 times of the ultimate tensile strength were 371 MPa and ‐0.0923, respectively. The Goodman method is recommended when the fatigue life of thin film with mean stress will be estimated. The fatigue strength coefficient and exponent of copper thin film modified using Goodman method were 910 MPa and ‐0.0896, respectively.     

Synthesis and characterization of high surface area molybdenum nitride

The synthesis of high surface area γ-Mo₂N materials using the nitridation of oxide precursors MoO₃, H₂MoO₅, and H₂MoO₅·H₂O with ammonia at 650°C is described. H₂MoO₅ and its hydrated form were obtained from the reaction of MoO₃ and diluted H₂O₂. The materials were characterized by means of X-ray powder diffraction, thermal analysis and nitrogen physisorption. Directly after the preparation, the nitride materials were subjected to different processing conditions: (1) contact to air, (2) inert gas or (3) treated with 1% O₂(g)/N₂(g) gas mixture (Passivation). The synthesis and passivation conditions critically affect the specific surface area of the final product. By means of XRD a minor quantity of MoO₂ was detected in most of the products. The highest specific surface area of the nitrides was 158.4 m²/g for γ-Mo₂N materials using H₂MoO₅·H₂O as the precursor. The high specific surface area corresponds to an average particle diameter of 4 nm, assuming a cubic morphology of the nanocrystals (d_p = 6/ρS_BET, ρ = 9.5 g/cc). The nitrogen physisorption isotherms of γ-Mo₂N are of type IV, but pore sizes and diameters differ significantly depending on the synthesis conditions due to different defect structures of the intermediates generated in the course of the topotactic transformation of the oxides to nitrides.     

铜表面有机镀膜及薄膜性能研究

通过有机镀膜的方法,利用一种自设计合成的三嗪硫醇化合物(TTN)在铜表面制备有机薄膜.通过循环伏安法解释了TTN在纯铜表面的反应及有机薄膜(PTT)的生长过程,并在0.05mA/cm2的电流密度下进行恒电流有机镀膜.通过电化学方法对薄膜的性能进行了评价,测试结果显示有机镀膜方法能在铜表面获得均匀致密的有机膜,为有机介电薄膜的制备提供研究基础.     

Controlled surface modification of boron nitride nanotubes

Controlled surface modification of boron nitride nanotubes has been achieved by gentle plasma treatment. Firstly, it was shown that an amorphous surface layer found on the outside of the nanotubes can be removed without damaging the nanotube structure. Secondly, it was shown that an oxygen plasma creates nitrogen vacancies that then allow oxygen atoms to be successfully substituted onto the surface of BNNTs. The percentage of oxygen atoms can be controlled by changing the input plasma energy and by the Ar plasma pre-treatment time. Finally, it has been demonstrated that nitrogen functional groups can be introduced onto the surface of BNNTs using an N(2) + H(2) plasma. The N(2) + H(2) plasma also created nitrogen vacancies, some of which led to surface functionalization while some underwent oxygen healing.     

A study on the plasma polymer thin film surface modification for DNA alignment by using high energy electron beam irradiation

The plasma polymer thin films were deposited on Si(100) substrate by PECVD (plasma enhanced chemical vapor deposition) method. Liquid cyclohexene was used as single organic precursor. It was heated up to 60 °C and bubbled up by hydrogen gas, which flow rate was 50 sccm (standard cubic centimeters per min). Deposition temperature was room temperature. Plasma was ignited by a radio frequency (RF; 13.56 MHz) of 10 W.As-deposited plasma polymer thin films were treated by e-beam of 300 keV with various adsorption radiation doses. The plasma polymer films, which were treated by high energy e-beam (HEEB), were investigated by FT-IR (Fourier Transform Infrared), XPS (X-ray Photoelectron Spectroscopy), AFM (Atomic Force Microscopy), and the water contact angles.From IR spectra, the intensity of OH functional group is increased by increasing electron dose rate. XPS results also show that the intensity of O_1s peak is increased by increasing electron dose rate. C_1s peak shows that oxygen bonded at carbon site. The water contact angles are decreased by increasing electron dose rate. From the AFM analysis, we observed the formation of λ-DNA (deoxyribonucleic acid) array on plasma polymer film, which was treated by HEEB with 14 kGy of adsorption radiation dose.     

Synthesis of rose-like boron nitride particles with a high specific surface area

Novel rose-like BN nanostructures were synthesized on a large scale via a two-step procedure. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectrometer and nitrogen porosimetry. The results show that the obtained rose-like nanostructures are composed of a large amount of h-BN crystalline flakes and have a surface area of 90.31 m²/g. A mechanism was proposed to explain the formation process of the rose-like BN nanostructures.     

Electromigration in gold and copper thin film conductors

The electromigration behavior of gold thin film conductors with molybdenum, niobium, hafnium and zirconium adhesion layers and of copper thin film conductors with chromium and niobium adhesion layers was investigated under various fabrication and testing conditions. Niobium increases the electromigration lifetime of gold conductors by more than an order of magnitude, while hafnium and zirconium also improve it but by lesser amounts. Sputter-deposited gold conductors appear to be superior to vapor-deposited gold conductors. Pulse powering also increases the electromigration lifetime. In copper conductors chromium adhesion layers do not affect the electromigration lifetime, while niobium adhesion layers appear to reduce it.     

Swift heavy ion irradiation induced modification of structure and surface morphology of BiFeO3 thin film

BiFeO₃ (BFO) thin films of thickness about 800 nm deposited on Si (100) substrates by sol–gel spin coating method were irradiated by 200 MeV Ag ions. Modification of structure and surface morphology of the films under irradiation was studied using glancing incidence X-ray diffraction (GIXRD) and atomic force microscope (AFM). Fluence dependence of GIXRD peak intensity indicated formation of 10 nm diameter cylindrical amorphous columns in crystalline BFO due to 200 MeV Ag ion irradiation. AFM analysis indicated that the pristine film consists of agglomerated grains with diffuse grain boundary. Irradiation led to reduced agglomeration of the grains with the formation of sharper grain boundaries. The rms roughness (σ _rms) estimated from AFM analysis increased from 6·2 in pristine film to 12·7 nm when the film irradiated at a fluence of 1 × 10¹¹ ions cm ^???2 . Further irradiation led to decrease of σ _rms which finally saturated at a value of 7–8 nm at high ion fluences. The power spectral density analysis indicated that the evolution of surface morphology of the pristine film is governed by the combined effect of evaporation condensation and volume diffusion processes. Swift heavy ion irradiation seems to increase the dominance of volume diffusion in controlling surface morphology of the film at high ion fluences.     

Elaboration and surface modification of structured poly(l-lactic acid) thin film on various substrates

Biosourced or biodegradable polymers like poly(lactic acid) (PLA) are often base-material for tissue-engineered scaffolds. However, in most of the cases, their bioadhesion properties are not satisfactory. Since the adhesion is controlled both by roughness and surface chemistry, PLA films were textured by applying the breath figure procedure and, then, plasma-treated. Depending on physicochemical characteristics of the breath figure technique, nice hexagonal structures were obtained. Their surface properties, i.e. hydrophobic–hydrophilic balance were controlled by plasma modification. However, their surface decoration could be only preserved with some specific plasma parameters depending on the applied energy and also on the induced surface chemistry.     

电子封装材料表面化学制备高导电率聚吡咯薄膜的研究

研究了在环氧树脂塑料封装材料表面制备导电聚吡咯(PPy)薄膜的化学聚合方法,分析了影响聚吡咯薄膜微观形貌、附着力及电导率的因素.用四探针法测聚吡咯薄膜的电导率,并用扫描电子显微镜(SEM)、红外光谱(IR)、X射线光电子能谱(XPS)进行了表征.通过对电子封装材料的表面预处理与改性,制得了附着性好、均匀连续的聚吡咯薄膜,经掺杂电导率达到了45.10S/cm.     

Fatigue life and plastic deformation behavior of electrodeposited copper thin film under variable amplitude loading

As an exploratory study to investigate fatigue behavior of an elecrodeposited copper thin film under variable amplitude loading, repeated two-block loading tests were performed for various loading conditions. Plastic deformation behavior was continuously measured during the tests. Due to the load interaction effect under repeated two-block loading, fatigue life is significantly reduced. A concept is introduced to evaluate the load interaction effect and successfully utilized to predict fatigue life through simulation of the monotonic plastic strain (ratcheting strain) behavior under repeated two-block loading. Effects of load parameters of repeated two-block loading on fatigue life were also discussed.     

Synthesis of cubic boron nitride from rhombohedral form under high static pressure

The cubic, zincblende-type boron nitride (z-BN) has been synthesized from the rhombohedral form (r-BN) under high static pressures greater than 6 GPa without any planned addition of catalysts. The process of forming z-BN has been delineated from isobaric and isothermal series of data. At 6GPa, r-BN begins conversion to the graphite-type form (g-BN) upon heating to 600 °C. This conversion terminates at 1200 °C forming single-phase g-BN, which in turn transforms into z-BN at temperatures higher than 1300 °C. The appearance of z-BN occurs at lower temperatures when the pressure is raised to 7 or 8 GPa. At pressures beyond 10 GPa the wurtzite-type form (w-BN) is observed between 400 and 1200 °C, whereas z-BN is formed above 1000 °C. The boundary of pressure-temperature conditions for synthesizing z-BN from r-BN runs through 6GPa and 1300 °C, and is located near to the lowest bound hitherto known for non-catalytic z-BN synthesis from g-BN.     

应用性极薄铜薄膜电阻的自动测量

本文采用实时测量方法,测量了铜薄膜导电时的电阻.利用监测电阻状态可制作极薄的膜材.与接近块状薄膜相比较,导电性能有所不同.测量了真空下与常态下其随时间变化状况,观察到其形成后有波动的状态.使用光学干涉法测定了可作为常规电极极限态薄膜尺寸约为90 nm左右,其导通电流极限约为0.0290 A/mm,在大气中氧化过程极快,电阻也迅速增加,也更容易受到大电流的破坏.     

Parratt-based and model-independent X-ray reflectivity fitting procedure for nanoscale thin film characterization

A general-purpose fitting procedure is presented for X-ray reflectivity data. The Parratt formula was used to fit the low-angle region of the reflectivity data and the resulting electron density profile (continuous base EDP or cbEDP) was then divided into a series of electron density slabs of width 1 angstroms (discrete base EDP or dbEDP), which is then easily incorporated into the Distorted Wave Born Approximation (DWBA). An additional series of density slabs of resolution-limited width are overlapped to the dbEDP, and the density value of the each additional slab is allowed to vary to further fit the data model-independently using DWBA. Because this procedure combines the Parratt formula and the model-independent DWBA fitting, each fitting method can always be employed depending on the type of thin film. Moreover, it provides a way to overcome the difficulties when both fitting methods do not work well for certain types of thin films. Simulations show that this procedure is suitable for nanoscale thin film characterization.     

Structural features of boron nitride dense phase formation from rhombohedral modification under high static pressure

The real structure of boron nitride (BN) polycrystals after high-pressure treatment was investigated by X-ray and transmission electron microscopy methods. Different stages of boron nitride polycrystal evolution under high quasistatic pressure and high temperature were fixed, involving rhombohedral boron nitride twinning, one-dimensionally disordered structure, 2H, 4H, 3C dense phase formation and 3C-BN recrystallization. A new structural scheme of BN_r-BN_w transition is proposed.     

Influence of ambient air exposure on surface chemistry and electronic properties of thin copper phthalocyanine sensing layers

In this paper we present photoemission studies of the influence of 12-hour exposure to the ambient air on the chemical and electronic properties of thin 16-nm copper phthalocyanine (CuPc) sensing layers deposited on n- and p-type silicon Si(111) substrates covered with the native oxide. The surface chemistry and electronic parameters of organic thin film including surface band bending, work function, electron affinity and their variations upon the exposure have been monitored with X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy techniques. We found that after the exposure, the surface chemistry of CuPc remained unaffected, however the work function and surface band bending increased by 0.55 eV and 0.45 eV for the layers on n-Si and by 0.25 eV and 0.30 eV for those on p-Si. Additionally, we detected a slight surface dipole at CuPc on n-Si manifested by a small shift in electron affinity of 0.10 eV. In order to explain these changes we developed a model basing on the interaction of ionic species with the phthalocyanine surface.     

Piezoresponse force microscopy studies of nanoscale domain structures in ferroelectric thin film

Piezoresponse force microscopy was used to perform studies of nanoscale domain imaging, limit of ferroelectric nano-sized grains and electric field-induced displacement behavior of domain structures in ferroelectric PZT thin film. Nanoscale 180° and 90° domain configurations as small as 30 nm in size were clearly visualized in the individual grains. It was demonstrated that domain configuration was strongly dependent on the size of the grains. The limit of ferroelectric nano-sized grains was found to be smaller than 25 nm. Nanoscale displacement versus field hysteresis loops were obtained in ferroelectric domains of PZT thin film, and discussed in terms of phenomenological theory.     

Si3N4薄膜的表面微观特性

利用偏心静电单探针诊断了反应室内的等离子体密度的空间分布;在不同的工艺条件下制备了Si3N4薄膜,由STM和Telystep-Hobbso轮廓仪研究了ECR－PECVD制备的Si3N4薄膜的表面微观特性,分析了沉积温度对ECR－PECVD制备的Si3N4薄膜表面平整度特性影响的物理机理;结果表明ECR－PECVD制备的薄膜是一种表面均匀致密的纳米Si3N4薄膜。