绿色环保化学机械抛光液的研究进展

原子级加工制造是实现半导体晶圆原子尺度超光滑表面的有效途径.作为大尺寸高精密功能材料的原子级表面制造的重要加工手段之一,化学机械抛光(chemical mechanical polishing,CMP)凭借化学腐蚀和机械磨削的耦合协同作用,成为实现先进材料或器件超光滑无损伤表面平坦化加工的关键技术,在航空、航天、微电子等众多领域得到了广泛应用.然而,为了实现原子层级超滑表面的制备,CMP工艺中常采用的化学腐蚀和机械磨削方法需要使用具有强烈腐蚀性和高毒性的危险化学品,对生态系统产生了不可逆转的危害.因此,本文以绿色环保高性能抛光液作为对象,对加工原子量级表面所采用的化学添加剂进行分类总结,详尽分析在CMP过程中化学添加剂对材料表面性质调制的作用机理,为在原子级尺度下改善表面性质提供可参考的依据.最后,提出了CMP抛光液在原子级加工研究中面临的挑战,并对未来抛光液发展方向作出了展望,这对原子尺度表面精度的进一步提升具有深远的现实意义.     

Uniformity investigation of MOCVD‐grown LED layers

Doped or undoped gallium nitride compounds (GaN/InGaN), usually grown by metal‐organic chemical vapor deposition (MOCVD) method, are at the heart of blue and green light emitting diodes (LEDs). Growth uniformities, such as the excited wavelength, luminous intensity and film thickness, critically influence their application in LED devices. In this paper, growth of GaN compounds in a MOCVD reactor, capable of a one‐time production of 36 × 2” wafers of nitrides, has been investigated. To examine growth uniformity across the wafer and from wafer to wafer, the reactor is divided into Zone A, Zone B and Zone C according to distance to the center of the graphite susceptor. Comparative analysis of each zone offers a straightforward view of the mean excitation wavelength, luminous intensity, film thickness and their standard deviations. Conformity of the growth uniformity in each zone is further checked comprehensively through averaging across‐wafer and wafer‐to‐wafer variables and their standard deviations. Zone B is found to retain excellent wavelength uniformity, since it is located at the middle of the susceptor with weaker effects of the susceptor edge and of the inlet gas flow. Zone A, at the center of the reactor, has the best mean intensity and thickness uniformities due to a well control of the infrared temperature measurement during the growth. And Zone C is worst in all uniformities and should be the main focus when optimizing the reactor. The above experimental analysis reveals the principles common to the MOCVD technique, and provides a basic for further optimization of the process window to improve the cycles with considerable reduction of the costs.     

Synthesis of 4‐Vinyl‐1H‐1,2,3‐triazoles on Solid Supports via Polystyrene‐Bound But‐3‐ynyl Selenide

A facile method for solid‐phase organic synthesis of 1‐substituted‐4‐vinyl‐1,2,3‐triazoles from polystyrene‐supported but‐3‐ynyl selenide has been developed. This sequential [3+2] cycloaddition and oxidation–elimination reactions could be carried out under mild reaction conditions with straightforward operation and good yield and purity of the products, and broad scope of substrates, and could be applied in this reaction system in generation of a small library of title compounds.     

Chemiluminescence immunoassay for cardiac troponin T by using silver nanoparticles functionalized with hemin/G-quadruplex DNAzyme on a glass chip array

The authors describe an array for chemiluminescence (CL) based determination of cardiac troponin T (cTnT), an important cardiovascular disease marker. The tracing tag consists of silver nanoparticles (AgNPs) loaded with guanine-rich DNA sequences and detection antibody in a high numerical ratio. The loaded AgNPs were then reacted with hemin to form a hemin/G-quadruplex DNAzyme. A disposable immunosensor array was fabricated by immobilizing capture antibody on corresponding sensing sites on a glass chip. Once a sandwich immunocomplex is formed on the array, the tracing tag catalyzes the CL reaction of the luminol-p-iodophenol and H₂O₂ system to produce a CL signal, which is collected by a CCD camera. An intuitive CL image is obtained containing all of the spots on the array. Under optimal conditions, the method shows a wide linear range over 4 orders of magnitude (from 0.003 to 270 ng·L^?1), a detection limit down to 84 fg·L^?1, and a throughput as high as 44 tests·h^?1. The results obtained with serum samples are in acceptable agreement with reference values. The AgNP-based tracing tag as well as the immunoassay method shows a promising potential for point-of-care testing for the early clinical diagnosis of cardiovascular disease.

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Graphical abstract Schematic presentation of silver nanoparticles (AgNPs) functionalized with hemin/G-quadruplex DNAzyme for highly sensitive chemiluminescence (CL) immunoassay of cardiac troponin T (cTnT) on a glass chip array.

     

Immobilization of silver nanoparticles into POEGMA polymer brushes as SERS‐active substrates

Surface‐enhanced Raman scattering (SERS) has attracted a great deal of interest during the past four decades and emerged as an ultrasensitive optical technique for chemical and biomedical analysis. It is widely accepted that the facile fabrication of SERS substrates with high activity and good reproducibility is of crucial importance for their applications. Herein, we report on a fast and robust method for the synthesis and immobilization of silver nanoparticles (AgNPs) into poly(oligo(ethylene glycol) methacrylate) (POEGMA) brushes under mild conditions without using any reducing agents. POEGMA brushes of different chain lengths were synthesized directly on silicon wafers by surface‐initiated atom transfer radical polymerization with various reaction time. X‐ray photoelectron spectroscopy and field emission scanning electron microscope measurements indicated that the AgNPs were firmly and homogeneously embedded into POEGMA brushes. The resulting POEGMA–AgNP hybrid films were employed as SERS substrates for the detection of 4‐aminothiophenol, giving rise to an enhancement factor of up to 1.9 × 10⁶. The influence of the POEGMA's chain length on SERS performance was also investigated. Copyright © 2016 John Wiley & Sons, Ltd.     

Chemical treatments on the cuticle layer enhancing the uranium(VI) uptake from aqueous solution by amidoximated wool fibers

Urea, sodium hydroxide and sodium sulfide were used to treat the cuticle layer of wool before graft copolymerization and amidoximation to enhance the uranium uptaking capacity of amidoximated wool fiber based adsorbent (Wool-g-AOs). The wool-g-AOs were used for recovery of U(VI) from aqueous solutions. The simulated nuclear industry effluent was used for investigating the selectivity and industrial applicability of Wool-g-AOs. The adsorption of uranium(VI) on Wool-g-AOs was pH dependent. The Langmuir model fitted well with the equilibrium data. Kinetic data were fitted well to pseudo second order model.

     

有序介孔Sn-SBA-15负载铂催化剂上丙烷脱氢性能的提高

丙烷脱氢制丙烯能够将低级烷烃转变成烯烃,是有效扩大丙烯来源的生产工艺.铂锡催化剂用于丙烷催化脱氢的主要缺点是稳定性差、选择性低,通过稳定锡的氧化态可以大大改善催化剂的脱氢性能及稳定性.本文采用一锅水热合成法制备了一系列高比表面积具有高度有序介孔结构的Sn掺杂的Sn-SBA-15材料,并作为载体负载铂催化剂用于丙烷脱氢反应.同时利用传统浸渍法(IM)合成了Sn/SBA-15-IM材料作为对比.结合X射线衍射(XRD)、BET比表面积和孔体积测试、红外光谱(FT-IR)、X射线光电子能谱、H2程序升温脱附(H2-TPD)、热重分析(TGA)、扫描电镜和透射电镜等多种物理化学表征手段研究了Sn-SBA-15材料和催化剂的结构性质及其丙烷脱氢反应性能.XRD和BET比表面积和孔体积测试结果表明,水热合成法原位引入助剂Sn不影响载体SBA-15的有序孔道结构,同时能够保持较大的比表面积.传统浸渍法引入Sn会堵塞载体孔道,载体比表面积及孔道有序度下降.Sn掺杂进入SBA-15骨架能够增强Sn物种与载体的相互作用,有利于Sn物种在反应过程中保持氧化态,提高催化剂丙烷脱氢反应的活性及选择性.当Sn掺杂量增至2.0 wt％时,Pt,Sn组分与载体之间的相互作用减弱,催化剂中Sn0物种所占比例增多,导致催化剂丙烷脱氢性能下降.在丙烷脱氢反应过程中,一锅法引入Sn的催化剂上反应活性和稳定性明显优于浸渍法引入Sn的催化剂.其中,Pt/0.5 Sn-SBA-15催化剂表现出最优的丙烷脱氢性能,丙烷转化率为43.8％,丙烯选择性为98.5％.     

Characterisation and effect of polymer network deformation in reverse-mode polymer-stabilised cholesteric texture

In reverse-mode polymer-stabilised cholesteric texture (PSCT), the dynamic response is derived from local director reorientation governed by dielectric coupling effect/self-assembly and polymer network deformation. A double exponential rise/decay model is proposed to investigate the underlying physical mechanisms. Through simulation of the transient rise and decay processes, the polymer network deformation in PSCT can be quantitatively evaluated. Less deformation and faster restoration speed of the polymer network can suppress hysteresis. These results provide useful guidelines for future PSCT fabrication and performance optimisation.     

Inelastic behavior of thick-walled cylinders subjected to nonproportionate loading

Inelastic behavior of thick-walled cylinders subjected to nonproportionate loading was studied by the testing of specimens made of C1045 steel and of annealed copper. Several theories were reviewed. A closed-form solution proposed by Mendelson¹² was used to predict external strains for open-end and closed-end thick-walled cylinders. An incremental theory proposed by Chu¹³ was used to provide incremental solutions for open-end thick-walled cylinders, and for cylinders subjected to nonproportionate loading. Test data for open-end and closed-end thick-walled cylinders made of C1045 steel and of annealed copper were in excellent agreement with the incremental theory. Larger values were predicted by use of the closed-form solution for circumferential strains than actual test data for open-end thick-walled cylinders at large depth of yielding. For cylinders subjected to nonproportionate loading, excellent agreement was indicated between the incremental theory and the experiments for the plot of axial load vs. circumferential strain for specimens made of both metals. Agreement between the incremental theory prediction of axial strains for the specimens made of annealed copper and test data is quite satisfactory. Larger values were predicted by the incremental theory for axial strain than experimental data for specimens made of C1045 steel. The error was conservative.     

泡沫流体的剪应力与法向应力差

本文在同时考虑表面张力与粘性力的情况下,以三维模型—长菱形十二面体及泡沫的应力张量表达式为基础,得出了泡沫的剪应力及法向应力差表达式,并通过计算机进行了求解,讨论了泡沫粘度、泡沫大小等因素对剪应力及法向应力差的影响。 实验使用了 RMS-605 大型流交仪、RV-2 流变仪及毛细管流变仪测定泡沫流变特性。消除了表面滑移影响后得到的剪应力与法向应力表数据与理论结果较接近,说明理论模型具有一定的实用价值。