超声波精细雾化抛光石英玻璃的抛光液研制*

为了配制适用于JGS1光学石英玻璃超声波精细雾化抛光的特种抛光液,以材料去除率和表面粗糙度为评价指标,设计正交试验探究抛光液中各组分含量对雾化抛光效果的影响,并对材料去除机制进行简要分析。结果表明：各因素对材料去除率的影响程度由大到小分别为SiO2、pH值、络合剂、助溶剂和表面活性剂,对表面粗糙度影响程度的顺序为SiO2、表面活性剂、pH值、助溶剂和络合剂;当磨料SiO2质量分数为19%,络合剂柠檬酸质量分数为1.4%,助溶剂碳酸胍质量分数为0.2%,表面活性剂聚乙烯吡咯烷酮质量分数为0.9%,pH值为11时,雾化抛光效果最好,材料去除率为169.5 nm/min,表面粗糙度为0.73 nm;去除过程中石英玻璃在碱性环境下与抛光液发生化学反应,生成低于本体硬度的软质层,易于通过磨粒机械作用去除。使用该抛光液进行传统化学机械抛光和雾化化学机械抛光,比较两者的抛光效果。结果表明：两者抛光效果接近,但超声雾化方式抛光液用量少,仅为传统抛光方式的1/7。     

精细雾化抛光TC4钛合金抛光液优化研究*

配制适用于TC4钛合金雾化施液抛光的特种抛光液,通过抛光实验获得纳米级的光滑钛合金表面。研究不同磨料、氧化剂和络合剂含量对钛合金材料去除率和表面粗糙度的影响,通过正交试验优化抛光液组成及配比。优化后的抛光液由质量分数20%的SiO2磨料、0.1%的柠檬酸、1%的聚乙二醇-400、2%的H2O2组成,pH值为4。抛光试验结果表明,优化后抛光液的抛光效果较好,材料去除率及试件表面质量均有所提升,其中材料去除率为549.87nm/min,表面粗糙度为0.678 nm。XPS分析表明,抛光过程中钛合金表层在酸性环境下与H2O2和柠檬酸反应,生成了易于通过机械作用去除的氧化层。     

纳米氧化硅在玻璃基片表面亚纳米级抛光中的应用

为满足先进电子产品对玻璃基片表面超光滑的要求,制备了一种纳米氧化硅抛光液,并研究了氧化硅粒子大小、抛光时间等参数对玻璃基片抛光后表面粗糙度、材料去除速率的影响。ZYGO形貌仪表明,采用纳米氧化硅抛光液,可以使玻璃表面粗糙度达到0.5 nm左右。AFM表明,抛光后的玻璃基片表面超光滑且无划痕等微观缺陷。     

磨料水射流抛光45钢工艺参数优化

对磨料水射流抛光45钢进行了研究,分析了材料的去除机理,在已有材料去除模型基础上,设计了正交实验,对不同参数组合下磨料水射流加工45钢的表面粗糙度、材料去除率进行了MATLAB数据分析,同时从材料去除机理方面对磨料粒度、射流压力、横向进给速度、靶距、喷嘴冲蚀角度等加工参数对于抛光表面质量和材料去除率的影响程度和影响趋势进行了分析。最终结合加工面表面粗糙度和材料去除率,选出45钢抛光加工最优加工参数组合。     

超细CeO2磨料对硅片的抛光性能研究

用均相沉淀法制备了不同形状和尺寸的CeO2超细粉体，并配制成不同pH值的抛光液对硅片进行化学机械抛光。研究了不同粒径CeO2磨料的抛光效果，结果表明，微米级的CeO2磨料粒径比较大，切削深度比较深，材料的去除是以机械作用为主。随着磨料粒径的减小，切削深度随之减小，材料以塑性流动的方式去除，最终在2μm的范围内得到了微观表面粗糙度Ra=0．120nm的超光滑表面。实验证明，CeO2磨料对硅片具有良好的抛光效果。     

单晶硅同质互抛实验研究

以材料的去除率和表面粗糙度为评价指标设计对比实验,验证了硬脆材料互抛抛光的可行性,得到了抛光盘转速对硬脆材料互抛的影响趋势和大小。实验结果表明：当抛光压力为48 265 Pa（7 psi）、抛光盘转速为70 r/min时,自配抛光液互抛的材料去除率为672.1 nm/min,表面粗糙度为4.9 nm,与传统化学机械抛光方式的抛光效果相近,验证了硬脆材料同质互抛方式是完全可行的;互抛抛光液中可不添加磨料,这改进了传统抛光液的成分;采用抛光液互抛时,材料去除率随着抛光盘转速的增大呈现先增大后减小的趋势,硅片的表面粗糙度随着抛光盘转速的增大呈先减小后增大的趋势。     

磁流变抛光表面粗糙度建模与仿真

为研究磁流变抛光表面粗糙度与工艺参数之间的关系,本文建立数学模型并进行了求解验证。通过分析磁流变抛光技术的原理以及磁流变抛光过程中的材料去除机理,结合Preston方程建立磁流变抛光力学模型。分析工件表面受到的正压力,依据磁流变抛光机理对氧化锆陶瓷工件理论模型的流体动压力和磁场产生的磁化压力进行求解分析,具体化磁流变抛光的力学模型,解得正压力。对磁流变抛光的表面粗糙度进行建模,依据单颗磨料的材料去除作用模型建立磁流变抛光的表面粗糙度数学模型,分析抛光过程中影响表面粗糙度的具体因素,并通过MATLAB软件对方程进行仿真求解,得到磁场强度和磨料粒径对表面粗糙度的影响规律。结果表明,表面粗糙度和工件的压入深度存在一阶线性关系;当磨料粒径固定不变时,表面粗糙度随着磁场强度的增大而增大;当磁场强度固定不变时,表面粗糙度值与磨料粒径之间呈现正比关系。通过实验证明了模型和仿真结果的准确性,仿真分析得到的磁场强度与磨料粒径的关系,磁场强度与表面粗糙度之间的关系与实验一致,确定的磁场强度合理范围为0.4T左右,磨料粒径在2.5μm左右。     

影响TA1钛合金电解质等离子抛光的关键因素研究

为了研究一种高效率、高质量的TA1钛合金植入物表面光整加工方法,在对TA1钛合金电解质等离子抛光过程中的电流-电压特性分析的基础上,研究工作电压、抛光液温度及抛光时间等关键因素对表面粗糙度和材料去除率的影响规律及作用机制,并对电解质等离子抛光前后试样表面的显微形貌、微观组织结构及硬度变化进行表征,验证该方法的有效性。研究结果表明,当工作电压为300和350 V时,采用电解质等离子抛光能够获得表面粗糙度值较小的表面,并且材料去除率随工作电压升高而降低;随抛光液温度升高,试样表面粗糙度增加,同时材料去除率降低;随抛光时间延长,试样表面粗糙度呈下降趋势;电解质等离子抛光后TA1钛合金结晶度提高,晶粒长大;电解质等离子抛光可去除TA1钛合金表面机械作用产生的加工硬化层,同时增强材料的塑性和韧性。     

应用纳米级金刚石抛光亚纳米级光滑表面

用爆炸法合成的纳米级金刚石是一种新型纳米材料,其物理机械特性与普通亚微米级金刚石微粉有很大差别。我们使用这种材料配制的抛光液对YVO4 晶体进行了超精密抛光的初步实验,获得了具有较低表面粗糙度(< 1 nm )的表面,发现了纳米金刚石作为抛光材料的独特之处。本文描述了实验结果,分析了抛光表面,并总结了纳米金刚石粉的抛光特性,提出了关于抛光中的材料去除过程的见解     

磁场作用下磁性抛光液体的抛光特性及实验研究

介绍了一种基于旋转磁性抛光液体的抛光技术。磁性抛光液体在磁力搅拌器的作用下产生旋转运动,利用外加强磁场作用增大磁性液体的粘度和剪切屈服应力,当加工工件放入磁性抛光液体中,磁性抛光液体与之相接触的工件表面发生磨削,从而达到对工件表面的光整加工。实验详细研究了磁性抛光液体抛光后工件的抛光区内表面粗糙度与抛光时间和位置之间的关系,实验结果表明:旋转磁性抛光液体抛光可以用于对工件进行超光滑加工,抛光时间越长,各处粗糙程度越接近,表面粗糙度越好,并且表面粗糙度比单独用研磨抛光膏的效果好。     

Pad surface and coefficient of friction correlation analysis during friction between felt pad and single-crystal silicon

In wafer polishing pad surface plays a crucial role in the polishing process. With the increase of friction time between pad and wafer, the pad becomes flattened or glazed with particles clogging the pores of the pad and forming a layer of slurry residue and wafer particles, leading to changes of COF, material removal rates and higher defects on the wafer surface. Thus, this study aims to determine the correlation between pad surface deformation, slurry adhesive rate and Coefficient of friction (COF) during friction between felt pad and single -crystal silicon, to analyze the relationship between pad condition and COF. The real-time COF between felt pad and single-crystal silicon wafer are tested which are sorted in groups depending on various loads and oscillation frequencies and surfaces of felt pads measuring by Scanning electron microscope (SEM) are compared. The correlation between pad surface deformation and abrasive adhesion and COF is evaluated through analyzing the experiment results.

     

新型环保抛光液的制备及其对软脆碲锌镉晶片的化学机械抛光

针对软脆碲锌镉晶片的传统加工工艺“游离磨料-抛光-化学机械抛光”存在的缺点,提出“固结磨料研磨-新型绿色环保抛光液化学机械抛光”新方法。固结磨料研磨工艺为：采用3000号刚玉防水砂纸,压力为17kPa,抛光盘与抛光垫转速均为80r/min,研磨时间为5min。新型绿色环保抛光液含有双氧水和硅溶胶,采用天然桔子汁作为pH值调节剂。化学机械抛光工艺为:采用自行研制的化学机械抛光液,绒毛抛光垫,抛光压力为28kPa,抛光盘与抛光垫转速均为60r/min,抛光时间为30min。试验结果表明,经过上述加工可获得超光滑的表面,表面粗糙度算术平均值、均方根值、峰谷值分别可以达到0.568nm、0.724nm、6.061nm。     

Investigation of increased removal rate during polishing of single-crystal silicon carbide

The application field of silicon carbide (SiC) as a next-generation compound semiconductor is expanding because of its significant advantages: high power, high frequency, low coefficient of thermal expansion, and high thermal conductivity. Many researchers have investigated SiC polishing for the manufacturing of semiconductor substrates using SiC. However, because SiC is a chemically and mechanically stable material, these researchers have faced difficulties due to its very low polishing rate (95–540 nm/h). Therefore, methods are required for increasing the material removal rate of SiC. The aim of this study was to investigate the increase in removal rate during the polishing of single-crystal SiC subjected to simultaneous polishing and dressing by using a diamond-impregnated polishing pad. Two types of pads—containing 1 and 5 wt% nanodiamond—were fabricated, and their performances were compared with that of a polyurethane polishing pad. A novel arrangement of conditioners was created in brazed diamond patterns, which were radially arranged in a cluster with 3–4 grits per cluster. Furthermore, a combined diamond disk was developed. The surface characteristics of the nanodiamond-impregnated pads, as well as the surface roughness, surface damage, and removal rate of the SiC polished with these pads and diamond disks, were investigated and compared with the corresponding attributes displayed by a polyurethane polishing pad and a conventional diamond disk. Experimental results showed that the removal rate of SiC with dressing was approximately 73 % higher than that of without dressing. The novel conditioner resulted in a dressing rate approximately two times higher and a removal rate approximately 38 % higher than those obtained by using the conventional diamond disk. In addition, SiC polishing tests revealed that the nanodiamond-impregnated polishing pads provided better surface roughness with no damage, as well as a removal rate approximately 2.5 times higher than that provided by the polyurethane polishing pad.     

Estimating the mechanical properties of polyurethane-impregnated felt pads

Chemical mechanical polishing (CMP) is an essential process in semiconductor fabrication. The results of CMP process are determined with the selection of consumables and process parameters. The polishing pad transports the slurry to the interface between the polishing pad and wafer and obtains material removal planarity. The mechanical properties of the polishing pad should be studied to analyze the material removal mechanism of CMP because polishing pad deformation is directly related to material removal rate and its uniformity. Various studies have investigated the stress distribution of the CMP process by using the elastic modulus and Poisson’s ratio of the polishing pad. However, these aspects of polishing pad have not been fully elucidated. In this study, we estimated the mechanical properties of commercial polyurethane-impregnated felt pads by comparing the experimentally measured compressive deformation amounts with finite element analysis results.     

TWO STEPS CHEMICAL-MECHANICAL POLISHING OF RIGID DISK SUBSTRATE TO GET ATOM-SCALE PLANARIZATION SURFACE

In order to get atomic smooth rigid disk substrate surface, ultra-fined alumina slurry and nanometer silica slurry are prepared, and two steps chemical-mechanical polishing (CMP) of rigid disk substrate in the two slurries are studied. The results show that, during the first step CMP in the alumina slurry, a high material removal rate is reached, and the average roughness (Ra) and the average waviness (Wa) of the polished surfaces can be decreased from previous 1.4 nm and 1.6 nm to about 0.6 nm and 0.7 nm, respectively. By using the nanometer silica slurry and optimized polishing process parameters in the second step CMP, the Ra and the Wa of the polished surfaces can be further reduced to 0.038 nm and 0.06 nm, respectively. Atom force microscopy (APM) analysis shows that the final polished surfaces are ultra-smooth without micro-defects.     

A study of material removal amount of sapphire wafer in application of chemical mechanical polishing with different polishing pads

The study mainly explores the fabrication mechanism for fabricating sapphire wafer substrate, by using chemical mechanical polishing (CMP) method. A slurry containing the abrasive particles of SiO₂ is used to contact with the sapphire substrate polish and to produce chemical reaction for removal of sapphire wafer substrate when CMP method is used. The study observes the changes of the removal amount of sapphire wafer substrate when the pattern-free polishing pad and hole-pattern polishing pad are used under different down forces, polishing velocities, abrasive particle sizes and slurry concentrations. Employing regression analysis theory, the study makes improvement of the equation of material removal rate (MRR) to be the material removal height per 30 minutes (MRRh), and develops a compensation parameter C_rv of the error caused by the volume concentration of slurry. The results of experimental analysis show that under a certain down force, if the polishing velocity is greater, the material removal amount will be greater. Generally speaking, the material removal amount of hole-pattern polishing pad is greater than that of pattern-free polishing pad. As to the relationship between abrasive particle size and slurry concentration, when particle size is smaller, the volume concentration of slurry will be higher, and the number of abrasives for polishing wafer will be greater. As a result, a better material removal depth can be acquired. Through the above analytical results, considerable help is offered to the polishing of sapphire wafer.     

Study on the effect of various machining speeds on the wafer polishing process

Silicon wafer polishing has an important role in semiconductor manufacturing; the general purpose of the polishing process is to produce a mirror-like surface. The wafer surface roughness is affected by many variables such as the carrier head unit characteristics, operation, platen and chuck speeds, pad and slurry ratios, and temperature. The optimum process conditions for the experimental temperature, down-force, slurry ratio, and processing time were determined in previous studies and used as fixed factors in this experiment. The main purpose of the present study was to determine how the different platen and chuck machining speeds influence the wafer surface roughness via the polishing process to obtain the optimum machining speed. In the results, the machining temperature appeared to differ at different machining speeds, which is a vital element with regard to wafer polishing.     

硅片边缘化学机械抛光的微小去除量测量

针对硅片化学机械抛光工艺的材料去除量非常微小并难以测量的问题,本文介绍一种采用表面粗糙度测量仪,对硅片边缘化学机械抛光的材料去除量进行一种简易、快速的测量方法,且该方法同时还可准确地测量硅片边缘抛光表面粗糙度值。检测结果表明,本方法较好地解决了硅片边缘化学机械抛光表面检测问题。     

MORPHOLOGY CONTROL OF ULTRAFINE CeO2 AND ITS POLISHING EFFICACY

Homogenous precipitation and subsequent calcination has been used to synthesize ultrafine ceria from cerium nitrate and urea solution. The ceria calcined from the precursor inherit the size and morphology of it. The size and morphology of the precursor are closely related to the preparation process. The morphology, size and distribution of the precursor could be tailored by changing the reaction condition and the ageing time. Monodispersed 200 run sized spherical particles is prepared by this method. The powder is used in the chemical-mechanical polishing of Si wafer. The average surface roughness of the polished Si wafer is 0.171 nm measured by AFM.