Study of corrosion phenomena of aluminium bond wire in integrated circuits using several surface- and microanalytical techniques

Summary The corrosion products were identified using laser microprobe mass analysis to be mainly Al oxides (hydroxides), Al sulphates and Al chlorides. Electron probe microanalysis showed the layered structure of the corroded wire and indicated the high chloride concentrations at the Ni contact side of the wire. Laboratory simulation tests with acceleration of the corrosion process, and variation of the critical parameters were performed. Auger and X-ray photoelectron spectroscopy, analytical electron microscopy and secondary ion mass spectrometry were used to study the observed corrosion phenomena. The use of these techniques showed that the Al corrosion and subsequent pitting formation are enhanced by the presence of water as a transport medium and surface electrolyte in an oxygenrich atmosphere, with chloride ions as stimulating and activating species. Using the analytical results, a proposal is made for the corrosion reactions. All critical and important parameters could be traced in the transistor systems by electron microscopy and residual gas (and moisture) analysis using mass spectrometry.

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Studium von Korrosionserscheinungen an Aluminium-Drahtverbindungen in integrierten Schaltkreisen mittels Oberflächen- und Mikroanalyse

Zusammenfassung Als hauptsächliche Korrosionsprodukte wurden mittels LAMMA Aluminium-Oxide bzw.-Hydroxide sowie Aluminium-Sulfate und -Chloride identifiziert. Mittels Elektronenstrahlmikroanalyse konnten das Vorhandensein einer Schichtstruktur auf dem korrodierten Draht und hohe Chlorid-Konzentrationen an der Seite des Nickel-Kontaktes am Draht nachgewiesen werden. Weiters wurden Modellversuche mit beschleunigtem Korrosionsprozeß und Variation der kritischen Parameter durchgeführt. Die auftretenden Korrosionsphänomene wurden mit AES, XPS, Elektronenmikroskopie und SIMS studiert. Der Einsatz dieses Methodenverbundes führte zu dem Ergebnis, daß die Korrosion von Aluminium und der nachfolgende Lochfraß in sauerstoffreicher Atmosphäre durch Wasser, welches als Transportmedium und Oberflächenelektrolyt wirkt, verstärkt wird. Chloridionen wirken korrosionserhöhend. Aufbauend auf den analytischen Ergebnissen, wird ein Vorschlag für die ablaufenden Korrosionsreaktionen gemacht. Alle wichtigen Einflußgrößen im Transistorsystem konnten mittels Elektronenmikroskopie und massenspektrometrischer Restgas-Feuchtigkeits-Analyse ermittelt werden.

     

The effects of a eutectic modifier on microstructure and surface corrosion behavior of Al-Si hypoeutectic alloys

Hypoeutectic aluminum–silicon alloys can have significant improvements in mechanical properties by inducing structural modification in the normally occurring eutectic. The eutectic modification may affect not only the mechanical properties but also the corrosion resistance of such alloys. It is well known that structural parameters such as grain size and interdendritic spacing can significantly affect corrosion resistance of alloys. However, to date, few researches have been performed to experimentally evaluate the effects of an effective modification of eutectic morphology on surface corrosion behavior of Al–Si alloys. In the present study, modified and unmodified samples of an Al 9 wt.% Si alloy were solidified under similar solidification conditions, and after metallographic procedures, the corrosion resistance was analyzed by both the electrochemical impedance spectroscopy technique and the Tafel extrapolation method carried out in a 0.5 M NaCl test solution at 25 °C. The impedance parameters and corrosion rate were obtained from an equivalent circuit analysis. It was found that the Al-9 wt.% Si alloy casting in the modified condition tends to have its corrosion resistance decreased when compared to the unmodified alloy.     

ATR-FTIR Investigation of Hydrogen-terminated Si(111) Surface in Various NH4F-Based Solutions

Wet chemical cleaning of silicon is a critical step in the semiconductor manufacturing. Particles, contaminants, metallic impurities, roughness and native oxide on silicon surface after wet chemical cleaning deteriorate the reliability of transistor performance in integrated circuits^[1]. Wet chemical etching of Si(111) and Si(100) in fluoride and alkaline solutions has been extensively studied in the past few years by using scanning tunneling microscopy (STM) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR)^[2-11]. In the present work, we extend our study to Si(111) surface after treating with NH₄F/HCl mixtures. STM, X-ray photo spectroscopy (XPS), and ATR-FTIR are used to determine surface roughness, contamination and bond information on Si(111) surface after wet chemical cleaning with various NH₄F/HCl mixtures. The results are discussed in details by comparison to those treated with RCA and HF solutions, indicating that ultra-clean and flat Si(111) surface is obtained by treatment with NH₄F/HCl mixture.     

Antihypertensive drugs as an inhibitors for corrosion of aluminum and aluminum silicon alloys in aqueous solutions

The corrosion behavior of aluminum and three aluminum–silicon alloys in different concentrations of HCl solutions and its inhibition by antihypertensive drugs was studied using potentiostatic polarization measurements. As the acid concentration increases, the rate of corrosion increases. Aluminum is less susceptible to corrosion than any of Al–Si alloys. The inhibition efficiency of the drug compounds increases with their concentration up to a critical value. At higher additive concentrations the inhibition efficiency starts to decrease. The inhibitive action of these compounds is due to their formation of insoluble complex adsorbed on the metal surface. The adsorption follows Langmuir adsorption isotherms. It was found that the drugs compounds provide protection to Al and Al–Si alloys against pitting corrosion by shifting the pitting potential to more positive direction until critical drug concentrations (250 ppm). After this critical concentration the inhibition against to pitting corrosion starts to decrease.     

LY12铝合金表面电化学沉积制备DTMS硅烷膜及其耐蚀性研究

采用电化学技术在LY12铝合金表面沉积制备了十二烷基三甲氧基硅烷(DTMS)膜. 反射吸收红外光谱表明, DTMS硅烷试剂与铝合金基体表面发生了化学键合作用, 生成—SiOAl键实现成膜. 通过对膜覆盖电极在质量分数为3.5%的NaCl溶液中的电化学阻抗谱(EIS)测试结果表明, 与开路电位下相比, 采用阴极电位沉积方法得到硅烷膜的耐蚀性能有明显提高, 且存在一个最佳“临界电位”, 在此电位下沉积得到的硅烷膜具有最高的耐蚀性. 扫描电镜观察结果表明, 在“临界电位”下制备得到的硅烷膜的结构最致密. 给出了硅烷膜覆盖电极的阻抗模型及相关参数的拟合结果.     

Decontamination of gaseous acetaldehyde over CoOx-loaded SiO2 xerogels under ambient, dark conditions

A series of CoO(x)-doped silica xerogels with various Co(2+) loadings (Co/Si = 0, 1, 2, 4, 6, and 10 mol %) has been prepared. All xerogels exhibit large (800-1050 m(2)/g) surface areas. Narrow pore size distributions with pore size maxima around 3 nm are characteristic for Co/Si = 1, 2, 4, 6, 10 samples. As-prepared CoO(x)/SiO(2) xerogels show high catalytic activity in the air oxidation of gaseous acetaldehyde at room temperature. Carbon dioxide and trace amounts of methane are the only products detected in the gas phase. Acetic acid, a less volatile product, resides on the surface of the xerogels but can slowly desorb. The formation of CO(2) begins after an induction period. The beginning of CO(2) production coincides with the conversion of Co(2+) incorporated in the SiO(2) framework into Co(3+). Thermogravimetry/gas chromatography/mass spectrometry analysis, UV-vis and FTIR spectroscopies, as well as kinetic measurements are employed for CoO(x)/SiO(2) catalyst characterization. A possible mechanism of the reaction is discussed.     

Spectroscopic and structural characterization of chlorine loading effects on Mo/Si:Ti catalysts in oxidative dehydrogenation of ethane

The structural changes induced in a silica-titania mixed-oxide support (1:1 molar ratio) by chlorine addition at different loading levels, their relation to the structural characteristics of supported MoOx species over the support, and their correlation with ethane oxidative dehydrogenation (ODH) activity have been examined. The molybdenum and chlorine precursors are incorporated into the Si/Ti support network as it forms during gelation by using a "one-pot" modified sol-gel/coprecipitation technique. In situ X-ray diffraction during calcination shows the Si/Ti 1:1 mixed-oxide support is in a state of nanodispersed anatase titania over amorphous silica. With the addition of molybdenum and chlorine modifier, this anatase feature becomes more pronounced, indicating a decreased dispersion of titania. The effective titania surface area on the chlorine-doped Si:Ti support obtained from 2-propanol temperature-programmed reaction supports this observation. Raman spectra of dehydrated samples point to an enhanced interaction of MoOx species with silica at the expense of titania. X-ray photoelectron spectroscopic results show that, without forming a molybdenum chloride, the presence of chlorine significantly alters the relative surface concentration of Si vs Ti, the electronic structure of the surface MoOx species, and the oxygen environment around supported MoOx species in the Si/Ti network. Secondary ion mass spectrometry detected the existence of SiCl fragments from the mass spectra, which provides molecular insight into the location of chlorine in Mo/Si:Ti catalysts. The observed increase in ethane ODH selectivity with chlorine modification may be ascribed to the MoOx species sharing more complex ligands with silica and titania with the indirect participation of chlorine. Steady-state isotopic transient kinetic analysis (SSITKA) is used to to examine the oxygen insertion and exchange mechanisms. The catalysts show very little oxygen exchange with the gas phase in the absence of a reaction medium. During the steady-state ODH reaction, lattice oxygen appears to be the primary source of oxygen in the formation of water and CO2.     

Multianalytical Study of Patina Formed on Archaeological Metal Objects from Bliesbruck-Reinheim

 Patinas naturally formed on archaeological bronze alloys were characterized using light microscopy (LM), micro energy dispersive X-ray fluorescence analysis (μ-EDXRF), time of flight secondary ion mass spectrometry (TOF-SIMS) and scanning electron microscopy in combination with energy dispersive X-ray microanalysis (SEM/EDX). The examinations carried out on cross-sections of samples have shown that in all samples the copper content in the corrosion layer is lower than in the bulk, while an increase of tin and lead could be observed. Two different types of corrosion were found: first type, a corrosion formation leading to a three layer structure was observed on lead bronze. The outer layer consists mainly of Cu(II) compounds and soil material, followed by a fragmented layer of cuprous oxide and the surface layer of the alloy, where a depletion of copper and an enrichment of tin and high amounts of Cl could be detected. The second type of corrosion is characterized by a two layer structure on the tin bronze sample consisting of an outer layer with copper containing corrosion products and a layer with cracks, which reveals a depletion of copper whereas tin and lead are enriched. Also high amounts of Si were detected in this surface layer.     

SIMS depth profiling of vertical p-channel Si-MOS transistor structures

SIMS depth profiling during O₂ ⁺ bombardment has been performed to analyse epitaxially grown Si p-n-p layers, which define the p-channel region in vertical Si-p MOS transistors, as well as to establish “on-chip” depth profiling of the functional vertical device. The SIMS detection limit of ³¹P in Si, phosphorus used as n-type dopant in the transistor, has been optimised as a function of the residual gas pressure in the SIMS analysis chamber and of the sputter erosion rate. We demonstrate that good vacuum during SIMS analysis combined with high erosion rates allows the simultaneous quantitative SIMS depth profiling of n- and p-type dopant concentrations in the vertical transistor. Small area “on-chip” SIMS depth profiling through the layered structure of Al-contact/TiSi₂/Si(p-n-p)/Si-substrate has been performed. Factors influencing the depth resolution during “on-chip” analysis of the transistor are discussed especially in terms of sputtering induced ripple formation at the erosion crater bottom, which has been imaged with atomic force microscopy. Received: 15 August 1996 / Revised: 17 January 1997 / Accepted: 21 January 1997     

药物莫西沙星对Q235钢在盐酸溶液中的缓蚀作用

为了探寻新的环境友好型缓蚀剂,采用电化学方法、失重法和量子化学计算研究了莫西沙星在1 mol/L HCl溶液中对Q235钢的缓蚀性能和缓蚀机理。结果表明,莫西沙星对Q235钢在盐酸溶液中是一种良好的以抑制阴极为主的混合抑制型缓蚀剂,缓蚀效率随其浓度的增加而增大,但随温度增加而减小,35℃下,在其浓度为200 mg/L时,缓蚀效率达90%;莫西沙星在Q235钢表面的吸附为自发过程,且符合Langmuir和El-Awady等温方程,同时,计算和讨论了相关的热力学和动力学参数。此外,采用量子化学计算对莫西沙星的缓蚀机理进行了进一步的分析,结果发现,莫西沙星的缓蚀作用由物理吸附和化学吸附共同产生。     

噻二唑型缓蚀剂对银片的缓蚀性能

采用增重法和金相显微技术,研究了不同浓度的沉降硫-石油醚溶液对银片的腐蚀作用,以及噻二唑型缓蚀剂TSJ-T6在不同浓度、不同温度下的缓蚀效率。 研究表明,TSJ-T6缓蚀剂对银片具有很好的缓蚀性能,且随着缓蚀剂浓度的增加,缓蚀效率也随之提高,当缓蚀剂浓度达到10.0 μg/g时,缓蚀效率达到94.37%。 经过吸附等温线拟合,得到缓蚀剂TSJ-T6在银片表面的缓蚀符合Langmuir吸附等温式,吸附过程为放热反应过程。     

Three-membered ring or open chain molecule - (F3C)F2SiONMe2 a model for the alpha-effect in silicon chemistry

(F3C)F2SiONMe2 was prepared from LiONMe2 and F3CSiF3. It was characterized by gas IR and multinuclear solution NMR spectroscopy and by mass spectrometry. Its structure was elucidated by single crystal X-ray crystallography and by gas electron diffraction. (It exists as a conformer mixture.) Important findings were extremely acute SiON angles [solid 74.1(1) degrees , gas anti 84.4(32) degrees and gauche 87.8(20) degrees] and short Si...N distances [solid 1.904(2) A]. The bending potential of the SiON unit was calculated at the MP2/6-311++G(3df,2dp) level of theory and appears very flat and highly asymmetric. The calculated atomic charges (NPA) are counterintuitive to the expected behavior for a classical Si-N dative bond, as upon formation of the Si...N bond electron density is transferred mainly from oxygen to nitrogen, while the silicon charge is almost unaffected. Despite the molecular topology of a three-membered ring, the topology of the electron density shows neither a bond critical point between Si and N atoms nor a ring critical point, but the electron density and Laplacian values are related to other hypercoordinate Si compounds. The electronic properties of (F3C)F2SiONMe2 were compared to those of the adduct (F3C)F2(MeO)Si-NMe3, whose properties and structure were also calculated. The charge distribution and Laplacian values along the Si-N vectors in both molecules are similar but not equivalent. (F3C)F2SiONMe2 contains thus a nonclassical Si...N bond, and its properties can be regarded as a new model for the explanation of the old postulate of an alpha-effect in silicon chemistry, explaining the behavior of compounds with geminal Si and N atoms.     

Molecular simulation of alkyl monolayers on the Si(111)surface

The structure of twelve-carbon monolayers on the H-terminated Si(111) surface is investigated by molecular simulation method. The best substitution percent on Si(111) surface obtained via molecular mechanics calculation is equal to 50%, and the (8×8) simulated cell can be used to depict the structure of alkyl monolayer on Si surface. After two-dimensional cell containing alkyl chains and four-layer Si(111) crystal at the substitution 50% is constructed, the densely packed and well-ordered monolayer on Si(111) surface can be shown through energy minimization in the suitable-size simulation cell. These simulation results are in good agreement with the experiments. These conclusions show that molecular simulation can provide otherwise inaccessible mesoscopic information at the molecular level, and can be considered as an adjunct to experiments.     

Molecular simulation of alkyl monolayers on the Si(111) surface YUAN

The preparation of monolayers on silicon surface is of growing interest for potential applica-tions in biosensor or semiconductor technology[1—5]. The alkyl modified Si(111) surfaces[6—10] can be obtained using the thermal, catalyzed, or photochemical reaction of hydrogen-terminated sili-con with alkenes, Grignard reagents, and so on. At the same time, the monolayer properties on Si(111) surface have been studied by a variety of experimental methods[8—10] such as X-ray photo-electron spect…     

Modification and chemical transformation of Si(1 1 1) surface

Modification of hydrogen-terminated Si(1 1 1) surfaces by hydrosilylation of activated alkenes and further chemical transformation of the modified surfaces is reported. A Si(1 1 1)-H surface was reacted with activated alkenes such as acrylate esters, acrylonitrile, and maleic anhydride under mild conditions to give modified surfaces with terminal functional groups. A modified surface with a terminal ester group was reduced by LiAlH₄ to give a hydroxy-terminated surface, and the hydroxy-terminated surface was transformed to a bromo-terminated surface. XPS analysis revealed that the brominated surface (Si(1 1 1)-CH₂CH₂CH₂Br) had 32% coverage with the 3-bromopropyl group. Ester and amide formation reactions were carried out on hydroxy- and carboxy-terminated Si surfaces by reaction with tert-butoxycarbonyl glycine, glycine tert-butyl ester, 2,2,2-trifluoroethanol and 4-trifluoromethylbenzyl alcohol in the presence of carbodiimide. XPS characterization indicated that the esters and amide were successfully formed with coverage ranging from 16% to 58%. Coverage ratios of octadecyl ester modified surfaces were also estimated by combination of surface reduction and gas chromatography analysis to be 25-35%.     

Fast determination of β-endosulfan, α-hexachlorocyclohexane and pentachlorobenzene in the river water from northeast of China

A magnetic solid-phase extraction method for the preconcentration of three organochlorine pesticides (OCPs) from water samples has been proposed, based on magnetic phosphatidylcholine (MPC) as adsorbents. The extraction procedure was carried out in a single step by stirring the mixture of MPC and water samples. Subsequently, the MPC was collected by an external magnetic field without additional centrifugation or filtration. The analytes were desorbed from the MPC and finally analysed by gas chromatography–tandem mass spectrometry. The influence of various parameters on OCPs recoveries was studied. Results show that phosphatidylcholine amount and extraction time were critical in enhancing extraction performance, and the presence of humic acid was shown to significantly reduce the extraction efficiency. The limits of detection obtained were in the range of 0.1–0.15 ng L^?1. Recoveries of spiked water samples ranged from 76.2% to 101.5% with relative standard deviations varying from 3.8% to 7.7%. The proposed method was employed for analysis of pentachlorobenzene, α-hexachlorocyclohexane and β-endosulfan in the surface water from two rivers in northeast China.     

Studies on the mechanical and friction properties of polyamide 6-Cu/Si nanocomposites

Polyamide 6 nanocomposites reinforced with Cu/Si nanoparticles (PA6-Cu/Si) were prepared by the in-situ ring-opening polymerization of ?-caprolactam. The in-situ polymerization was critical for preventing the aggregation of Cu/Si nanoparticles. The Cu/Si nanoparticles in the nanocomposite retained their nano characteristics and were not oxidized by the amino groups in PA6. The structure of the as-fabricated PA6-Cu/Si nanocomposite was evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), and ultraviolet-visible absorption spectroscopy (UV-vis). The friction and wear resistance, mechanical strength, and antistatic performance of PA6-Cu/Si were also evaluated. The PA6 polymer chains prevent the Cu/Si nanoparticles from aggregation by coating the surface of the Cu/Si nanoparticles via physical adsorption or an electrostatic effect. The mass fraction of the Cu/Si nanoparticles also had a significant effect on the crystalline form of PA6. The γ crystalline form of PA6 was predominant at a high mass fraction of Cu/Si to PA6. Moreover, PA6-Cu/Si with improved mechanical properties and wear resistance was generated by tuning the amount of nano-Cu/Si filler added during the polymerization. PA6-Cu/Si with a nano-Cu/Si content of 0.5% possesses the highest tensile strength and wear resistance and shows promise in applications as a functional polymer-matrix composite.     

Gas-Phase Silicon Alkoxide Reactivity vs. Na-Alginate Droplets for Conjugation of Alginate and Sol-Gel Technologies

Solutions with Na-alginate concentrations ranging from 0.5 to 2.5% w/v are processed to prepare Ca-alginate beads using a nozzle ejector under constant He-flow. Beads were spherical in shape and their size distributions were determined; in all samples the average diameter fell in the 120–140 μm interval. Volumetric yields were found to be linearly dependent of the original Na-alginate load whereas the bead diameters were almost constant, according to a constant hindrance of Ca-alginate macromolecular units in the final Ca-alginate gel. The rheology of Na-alginate solutions was studied, with determination of intrinsic viscosity; experimental evidence of microsphere formation, even at the lowest Na-alginate concentrations, indicated that ejection processing changes the rheological parameters controlling bead formation in ordinary dropping processing. Gaseous silicon alkoxides – Si(OEt)₄ and MeSi(OEt)₃ – carried by a He flow were deposited on Na-alginate droplets during ejection. The process was studied by continuous mass spectrometry analysis before and after Na-alginate ejection during the 5-min treatment; in all cases results indicated a deposition yield of 58%. Traces of alcohol in the mass spectrometry analysis of the out-flow gas excluded instantaneous formation of sol-gel silica on the Na-alginate droplets during their residence in the gas phase. For various Na-alginate concentrations, ethanol released by silica gel formation is constant as well as the amount of deposited SiO₂; a siliceous layer ranging from 0.08 to 0.17 μm thick on the surface of the Ca-alginate beads was calculated.     

甲基丙烯酸二甲氨基乙酯类离子液体 对Q235钢的缓蚀性能

以甲基丙烯酸二甲氨基乙酯为母体、 对氯甲基苯乙烯为季铵化试剂, 合成了一种具有疏水结构的甲基丙烯酸二甲氨基乙酯型离子液体(DEMA). 通过失重实验、 电化学分析、 原子力显微镜(AFM)、 接触角测试和量子化学计算等研究了DEMA在1 mol/L盐酸中对Q235钢的缓蚀性能, 并揭示了其在Q235钢表面的吸附行为和吸附机理. 失重实验结果表明, DEMA在盐酸中对Q235钢具有优异的缓蚀效果, 且在较高温度(60 ℃)下也能保持高效吸附; 电化学实验结果与失重测试结果一致; 接触角测试结果表明, DEMA可明显增强Q235钢表面的疏水性; 分析热力学参数可知, DEMA在Q235钢表面的吸附为自发、 放热过程, 符合Langmuir等温式, 且以化学吸附为主; 量子化学计算结果证实DEMA的结构中包含大量吸附活性位点.     

辛烷基二甲基苄基季铵盐离子液体对Q235钢的缓蚀性能

利用失重分析、 极化曲线、 电化学阻抗谱和扫描电子显微镜等研究了辛烷基二甲基苄基季铵盐离子液体(ODBA)对1 mol/L盐酸溶液中Q235钢的缓蚀性能, 并分析了其在Q235钢表面的吸附行为. 失重分析结果表明, 随着ODBA浓度的增加, 缓蚀效率逐渐提高, 在ODBA质量浓度为0.2 g/L、 温度为30 ℃时, 缓蚀效率可达95.53%; 电化学测试结果与失重分析结果一致; 热力学研究结果表明, ODBA在碳钢表面的吸附是放热过程, 且遵循Langmuir吸附等温线, 是以化学吸附为主的混合型吸附; 同步热分析测试表明ODBA具有良好的热稳定性.