TiB_2含量对选区激光熔化TiB/Ti-6Al-4V复合材料组织及力学性能的影响

以球磨TiB_2和Ti-6Al-4V混合粉末为原料,采用选区激光熔化(SLM)技术制备了增强相为TiB的钛基复合材料,分析了B元素含量对SLM成形钛基复合材料显微组织和力学性能的影响。研究结果表明:在SLM过程中,TiB_2与Ti元素发生反应生成针状TiB增强相,B元素含量较高的试样中出现了针状增强相聚集的现象;由于B元素的存在,钛基复合材料中的α相明显细化;相比于传统的Ti-6Al-4V合金,TiB/Ti-6Al-4V复合材料的显微硬度、抗拉强度以及屈服强度均有明显改善。钛基复合材料优异的力学性能归因于TiB增强相的硬化、强化效应以及基体的晶粒细化。当B元素的质量分数为0.5%时,α片层的平均尺寸为0.49μm,钛基复合材料的抗拉强度和屈服强度相比于Ti-6Al-4V分别提高了25.7%和30.8%,抗拉强度为1396.4 MPa,屈服强度为1322.2 MPa。     

电子探针、离子探针和扫描电镜样品的制备方法

本文主要介绍电子探针、离子探针和扫描电镜样品的技术要求和几种制样方法。电子探针和离子探针制样方法包括:电炉加热压片法、铝或铜管灌铸导电胶粘结法、制光薄片法、粉末样品制样以及研磨和抛光技术等。扫描电镜样品制备着重介绍微粉样品的粘结。此外本文还介绍了各种方法有关的环墨导电胶的原料和配制方法。     

超薄硅双面抛光片加工效率的提升

用于5G通信芯片支撑层的超薄硅双面抛光片的生产是一个需要攻克的难题。该产品的技术难点在于,硅片厚度低至100μm,薄如纸张,采用传统粘蜡抛光工艺,加工效率极低且碎片率极高,同时硅片几何参数无法保证,成品率较低。由于磨削工艺可有效减少硅片表面的损伤层、改善几何参数,所以针对超薄硅片的加工,采用贴膜抛光工艺可以保证抛光的效率和成品率。在硅片腐蚀后采用磨削+贴膜抛光的工艺,解决了超薄硅双抛片加工效率低、碎片率高、几何参数难以保证、成品率低的问题。     

泥页岩样品自然断面与氩离子抛光扫描电镜 制样方法的比较与应用

根据不同的研究目的,泥页岩的扫描电镜实验常用自然断面和氩离子抛光两种制样方法.自然断面的样品一般利用二次电子(SE)信号成像,反映样品表面原始形貌,图像立体感强,是最常用的制样方法.自然断面方法适合观察较大的孔隙结构,矿物及有机质形态特征,有机显微组分等.氩离子抛光样品一般利用背散射(BSE)信号成像,反映样品原子序数差异,容易区分有机质与矿物质.氩离子抛光样品表面光滑平整,适合观察泥页岩中纳米级孔隙,能直观地观察到矿物及有机质的颗粒大小及分布情况,但经过切割、研磨和抛光等一系列复杂的处理过程,样品原始形貌受到一定的破坏,会损失掉一些有用信息.本文详细比较了自然断面与氩离子抛光两种制样方法的特点及适用条件,指出如何根据样品特征及研究目的选择合适的制样方法.     

TiN含量对激光选区熔化成形钛基复合材料微结构与耐磨性能的影响

采用激光选区熔化技术成功制备了TiN增强钛基复合材料,并研究了TiN含量对钛基复合材料微观结构、显微硬度和摩擦磨损行为的影响。结果表明:随着TiN含量的增加,α-Ti相衍射峰发生偏移,TiN衍射峰强度逐渐增强,复合材料的显微硬度从纯钛的(228±13) HV逐渐增大到(403±20) HV;当添加TiN的质量分数为7.5%时,复合材料的磨损性能比纯钛提高了29.2%。TiN颗粒的加入使钛基复合材料的硬度与磨损性能显著提升。     

化学机械抛光的钛宝石晶体低损伤加工

针对钛宝石晶体表面低损伤加工进行了系统研究,在CCOS数控小磨头抛光机上进行了正交实验,选用不同的抛光液对钛宝石进行化学机械抛光,有效去除精磨阶段的亚表面损伤,实验证明SiO2硅溶液作为磨料的抛光效果好,适合作为钛宝石加工的抛光液。研究了抛光盘种类、抛光盘压力、抛光盘速度、硅溶胶稀释浓度这四个因素和钛宝石晶体表面粗糙度和表面疵病的关系,并获得钛宝石低缺陷加工过程中工艺参数的影响规律。按照优化后的工艺参数进行实验,获得了低缺陷、高精度的钛宝石表面。运用灰色关联分析法对抛光参数进行优化,在最佳加工工艺组合条件下,得到钛宝石表面粗糙度为0.262 nm,表面疵病率为1.410-3 mm-1。     

钙钛矿太阳电池用NiO/石墨烯复合空穴传输材料北大核心

有机-无机杂化钙钛矿太阳电池（PSC）因其效率高、成本低及制备工艺简单等优点而得到广泛的关注。采用无机材料替代有机空穴传输材料可以进一步降低电池成本,拓宽钙钛矿太阳电池空穴传输材料的选择范围。采用水热合成法制备了NiO/石墨烯复合材料前驱体,经过高温处理,得到NiO/石墨烯复合材料,并将其应用于钙钛矿太阳电池空穴传输层。通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）和热重分析仪-差式扫描量热仪（TGA-DSC）等手段表征了复合材料组分及微观结构。同时,探索了复合材料质量浓度和制膜工艺对空穴传输层性能的影响。研究结果表明,当复合材料的氯苯溶液质量浓度为1.25 mg/mL时,采用喷涂工艺制膜得到的空穴传输层具有最优的性能,其相应钙钛矿太阳电池的光电转化效率为1.44%。NiO/石墨烯复合材料在钙钛矿太阳电池中表现出优于NiO和石墨烯的性能,体现了NiO和石墨烯在复合材料空穴输运过程中的协同作用。     

SiCp/6061Al金属基复合材料激光焊接研究

采用高能ＣＯ_２激光束对 ＳｉＣ颗粒增强 ６０６１铝基复合材料 ＳｉＣｐ／６０６１ＡＩＭＭＣ进行激光焊接、研究激光焊接工艺参数及填充材料对焊缝显微组织的影响。结果表明,对 ＳｉＣｐ／６０６１Ａｌ复合材料进行激光焊接,可以获得气孔很少、质量较高的焊接接头,但在激光直接熔化焊接焊缝中形成针状Ａｌ_４Ｃ_３脆性相,脆性相Ａｌ_４Ｃ_３的数量与尺寸随激光束功率密度增加而增大,随焊接速度增大而减少。激光焊接时加入０．３ｍｍ厚的金属钛片作为填充材料,在焊缝中形成ＴｉＣ增强相,从而抑制了脆性相Ａｌ_４Ｃ_３的形成。     

钛基多孔氧化锡纳米结构的制备

研究了采用电沉积和阳极氧化方法在钛基上制备多孔氧化锡纳米结构的技术.在3mm厚的钛片上,采用电沉积的方法首先预沉积镍层,然后沉积1μm厚高纯度锡膜作为阳极浸入0.5mol/L草酸溶液中,在直流恒压5V条件下,进行电化学氧化5min.电化学氧化处理后,分别采用扫描电镜和X射线衍射仪对样品进行了平面、横断面形貌观察和氧化产物分析.结果表明,在钛基上形成了一层厚约1μm、孔径70nm、孔间距80nm的多孔氧化亚锡薄膜,这种多孔结构薄膜可以进一步在空气中加热500℃处理2h,制成钛基氧化锡多孔材料,它也可作为制备钛基纳米复合材料的模板.     

钛基多孔氧化锡纳米结构的制备

研究了采用电沉积和阳极氧化方法在钛基上制备多孔氧化锡纳米结构的技术.在3mm厚的钛片上,采用电沉积的方法首先预沉积镍层,然后沉积1μm厚高纯度锡膜作为阳极浸入0.5mol/L草酸溶液中,在直流恒压5V条件下,进行电化学氧化5min.电化学氧化处理后,分别采用扫描电镜和X射线衍射仪对样品进行了平面、横断面形貌观察和氧化产物分析.结果表明,在钛基上形成了一层厚约1μm、孔径70nm、孔间距80nm的多孔氧化亚锡薄膜,这种多孔结构薄膜可以进一步在空气中加热500℃处理2h,制成钛基氧化锡多孔材料,它也可作为制备钛基纳米复合材料的模板.     

Cross-Section Preparation for Solder Joints and MEMS Device Using Argon Ion Beam Milling

Mechanical cross-section polishing has traditionally been the method of choice for preparing samples to be examined by scanning electron microscopy (SEM). Although mechanical polishing, allied to selective chemical etching can reveal the most important characteristics of solder joint microstructure, subtle details may be lost. A relatively new cross section polishing method has been developed using an argon ion beam to prepare a flat surface with potentially less sample damage. In this study we compare these two methods of cross section polishing for solder-substrate couples, and for delicate MEMS type structures. Four solder samples were prepared, consisting of SAC (Sn-Ag-Cu) solder, SAC solder on copper substrate, SAC solder on nickel substrate and In-Sn solder on niobium substrate. SEM was used to examine the polished samples and it was found that features such as the internal structure of intermetallic compounds (IMCs) was more readily identified using the new technique. The ion beam milling technique was also found to be more suitable for simultaneous observation of multiple aspects of microstructure (e.g., identification of IMCs in relation to grain boundaries, substrate crystal structure or the eutectic solder structure). The MEMS device cross-sections could only be prepared by the ion beam method as mechanical polishing caused too much damage.     

An analytical model of multiple ILD thickness variation induced byinteraction of layout pattern and CMP process

In this paper, an analytical model for chemical mechanical polishing (CMP) is described. This model relates the physical parameters of the CMP process to the in-die variation of interlayer dielectric (ILD) in multilevel metal processes. The physical parameters considered in this model include the deposited ILD profile, deformation of the polishing pad and the hydrodynamic pressure of slurry flow. Model parameters are adjusted based on the first ILD layer and then applied to the upper ILD layers. Comparison of simulated results with sample data is performed at the die level of a state-of-the-art microprocessor     

Preparation of silica/ceria nano composite abrasive and its CMP behavior on hard disk substrate

A novel silica/ceria nano composite abrasive was synthesized by homogeneous precipitation using carbamide, ammonium ceric nitrate and silica. The abrasive was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and scanning electron microscopy (SEM), respectively. Then, the chemical mechanical polishing performances of the composite abrasive on hard disk substrate with nickel-phosphorous plated were investigated. Atomic force microscopy images show that the prepared abrasive gives much lower topographical variations than before polishing. The average waviness (Wa) of the polished hard substrate surface can be reduced from 15.5 Å before polishing to 8.36 Å, and the average of roughness (Ra) can be reduced from 14 Å before polishing to 4.80 Å.     

Comparison of TEM specimen preparation of perovskite thin films by tripod polishing and conventional ion milling

In this article, the effects of the transmission electron microscopy (TEM) specimen preparation techniques, such as ion milling and tripod polishing on perovskite oxides for high-resolution TEM investigation, are compared. Conventional and liquid nitrogen cooled ion milling induce a new domain orientation in thin films of SrRuO(3) and LaFeO(3) grown on (001)-oriented SrTiO(3) substrates. This is not observed in tripod-polished specimens. Different ion milling rates for thin films and substrates in cross-section specimens lead to artefacts in the interface region, degrading the specimen quality. This is illustrated by SrRuO(3) and PbTiO(3) thin films grown on (001)-oriented SrTiO(3). By applying tripod polishing and gentle low-angle, low-energy ion milling while cooling the sample, the effects from specimen preparation are reduced resulting in higher quality of the TEM study. In the process of making face-to-face cross-section specimens by tripod polishing, it is crucial that the glue layer attaching the slabs of material is very thin (<50 nm).     

Mathematical modeling of CMP conditioning process

Up to now, the conditioning model with an oscillating conditioner wheel has not been studied. In this paper, kinematic analysis of the conditioning process and mathematical modeling of pad wear while the conditioner wheel oscillates is studied and the results show how the various parameters of the conditioning process influence the pad shape. The conditioning of the polishing pad is one of the most important processes associated with the CMP (Chemical Mechanical Polishing). As the wafer is polished, the surface of the pad can be deteriorated with a reduced polishing rate and reduced planarity due to wear and glazing of the pad. Thus, the polishing pad needs to be conditioned to maintain its effectiveness. In general, the conditioning process is used to regenerate the pad surface by breaking the glazed area of the pad and increase the MRR (Material Removal Rate) and give us longer pad life. However, as the conditioning process continues, the pad shape becomes more and more concave over the whole pad while the conditioner wheel oscillates (Y.Y. Zhou, E.C. Davis, Mat. Sci. Eng. B. 68 (1999), 91-98). It has been shown that the concavity of the polishing pad increases with conditioning time - longer conditioning induces a higher incidence of concavity of the polishing pad. Therefore, the conditioning process is related to the WIWNU (Within Wafer Non-Uniformity). Through this conditioning model, thickness variation of the polishing pad can be predicted.     

Cross-sectional nanoprobing sample preparation on sub-micron device with fast laser grooving technique

Cross-sectional sample preparation is one of the most important failure analysis (FA) techniques in the semiconductor industry. It was commonly used for film stack critical dimension measurement, defect identification, electrical fault isolation and etc. However, cross-sectional sample preparation to a specific target location on a sub-micron device is very challenging and time-consuming. This is because of mechanical polishing easily caused metal smear, delamination, film peel-off, micro-cracked and etc. This paper focused on cross-sectional nanoprobing (XNP) sample preparation improvement in quality and quantity. A laser blast to deprocess or create a groove at near to target location before conventional mechanical polishing and focus ion beam (FIB) fine milling. The proposed technique not only reduces the sample preparation time to the sub-micron target location but also prevent mechanical damages that caused by mechanical polishing technique.     

中高压阳极铝箔微观形貌的分析方法

为提高中高压阳极铝箔微观形貌参数测量分析的准确性,减少误差,提出一种结合计算机图像分析技术对中高压阳极铝箔微观形貌的分析方法。通过样品的表面处理,达到对其真实形貌的SEM观察,再运用计算机图像分析程序,统计反映蚀孔特征的参数,建立参数模拟图形,从而为阳极箔研究人员提供了系统、科学、快捷的分析依据。     

碲锌镉衬底的化学机械抛光液研究

作为碲锌镉衬底表面加工的重要工序，化学机械抛光（Chemical Mechanical Polishing, CMP）的加工效果决定了碲锌镉衬底的表面质量和生产效率。抛光液是CMP的关键影响因素之一，直接影响衬底抛光后的表面质量。对碲锌镉衬底CMP工艺使用的抛光液进行了研究，探究了以二氧化硅溶胶和过氧化氢为主体的抛光液体系在不同pH值、不同磨料浓度下对衬底抛光表面质量和去除速率的影响。结果表明，使用改进后的抛光液体系对碲锌镉衬底进行CMP，能够在获得超光滑表面的同时实现高效率加工，为批量化制备高表面质量的碲锌镉衬底奠定了良好基础。     

Sample preparation of GaN-based materials on a sapphire substrate for STEM analysis

In this work, a detailed TEM sample preparation recipe based on a wedge polishing technique for GaN-based materials is presented. The obtained samples have atomically flat surfaces without any obvious surface damages such as the formation of amorphous layers. A composition estimation of Al(x)Ga(1-x)N from Z-contrast STEM imaging is carried out using these samples. The results are in good accord with the nominal composition.     

Polishing of silicon by the cupric ion process

This paper describes a newly developed chem-mech polishing process for silicon wafers. This polishing process, without using any abrasives, can produce a silicon surface free of work damage. A solution composed of cupric nitrate, ammonium fluoride, and nitric acid is used on a conventional polishing wheel. The rate of stock removal is controlled primarily by the composition of the solution and the polishing wheel temperature. Highly polished surfaces have been obtained with stock removal rates as high as 20 mils per hour. At higher removal rates, the process is difficult to control and surface quality suffers.