GaN基LED衬底材料化学机械抛光研究进展

概述了化学机械抛光作用机制,着重阐述了3种常见衬底(α-Al2O3,SiC,Si)的化学机械抛光现状,主要从抛光工艺参数和抛光液组成(不同磨料、磨料粒径、氧化剂、络合剂、pH值等)对晶片抛光效果的影响展开研究,并指出了目前化学机械抛光存在的问题,进一步展望了LED衬底化学机械抛光的发展前景。     

硒化锌晶片抛光的研究

采用化学机械抛光（CMP）的方法,使用自主研发的氧化铝抛光液作为研磨介质,通过对硒化锌（ZnSe）晶片进行抛光实验,得出了氧化铝磨粒的粒度尺寸、抛光液的pH值、氧化剂种类及质量分数对ZnSe晶片表面状态和去除率的影响。实验结果表明:氧化铝抛光液适宜ZnSe晶片的抛光,采用质量分数15%的氧化铝抛光液（氧化铝粒度尺寸200 nm）,加入质量分数3%的次氯酸钠浸泡24 h,抛光液的pH值为8,试验结果较佳,此时去除率可达2 μm/min,晶片表面平整无划痕,表面质量较理想。      

GaN晶片芬顿反应化学机械抛光液组分优化

针对芬顿反应CMP抛光GaN晶片的抛光液,开展以表面质量为评价指标的参数优化试验,找出抛光液组分的最优配比。结果表明:当H₂O₂质量分数为7.5%时,GaN晶片加工表面效果最优,表面粗糙度达到3.2 nm;催化剂能有效调节芬顿反应的速率,对比液体催化剂FeSO₄溶液和固体催化剂Fe₃O₄粉末,固体催化剂Fe₃O₄粉末能在溶液中持续电离Fe2+,使芬顿反应能在整个加工过程中持续作用。当Fe₃O₄粉末粒径为20 nm时,抛光效果最佳,表面粗糙度达到3.0 nm;对比氧化铝、氧化铈、硅溶胶磨料,硅溶胶磨料抛光的表面效果最佳,晶片表面粗糙度达到3.3 nm;当硅溶胶磨料质量分数为20.0%,磨料粒径为60 nm时,抛光后晶片表面粗糙度达到1.5 nm。抛光液组分优化后,采用最优的抛光液组分参数抛光GaN晶片,其能获得表面粗糙度为0.9 nm的光滑表面。      

振动辅助固结磨料抛光氟化钙晶体

为了改善氟化钙晶体加工后的表面质量、提高加工时的材料去除率,提出了振动辅助固结磨料抛光氟化钙晶体的加工方法。利用振动与固结磨料抛光有效结合,采用正交实验研究加工工艺参数对材料去除率和表面质量的影响。结果表明:振动辅助固结磨料抛光氟化钙晶体的最优工艺参数为转速40 r/min,振动频率40 kHz,抛光液pH值9,转速比0.95;在最优参数下抛光氟化钙晶体的材料去除率为324 nm/min,表面粗糙度S_a值为1.92 nm;与无振动辅助的固结磨料抛光相比,材料去除率提高了57%,表面粗糙度降低了35%。研究表明:振动辅助能够利用空化作用及规律化间歇性接触,在固结磨料抛光中提高材料去除率及表面质量。      

用碱性抛光液化学机械抛光304不锈钢片研究

为提高化学机械抛光的加工效果,我们研究了pH值、氧化剂种类和氧化剂含量对材料去除率和表面粗糙度的影响。结果表明:不同氧化剂的抛光液在各自的最佳pH值时达到最大的材料去除率,分别为181 nm/min（H₂O₂抛光液,pH=9）,177 nm/min（Cr₂O₃抛光液,pH=11）,172 nm/min（Na₂Cr₂O₇抛光液,pH=11）和147 nm/min（NaClO抛光液,pH=13）;抛光液中氧化剂含量、pH值对抛光后不锈钢的表面粗糙度影响较小。其中,材料去除率较高的H₂O₂和Cr₂O₃可作为304不锈钢化学机械抛光碱性抛光液的氧化剂。      

抛光液pH值、温度和浓度对蓝宝石抛光效率的影响

目的研究抛光液pH值、温度和浓度对化学机械抛光蓝宝石去除率的影响,以提高抛光效率。方法采用CP4单面抛光试验机对直径为50.8 mm C向蓝宝石晶元进行化学机械抛光,通过电子分析天平对蓝宝石抛光过程中的材料去除率进行了分析,采用原子力显微镜(AFM)对蓝宝石晶元抛光前后的表面形貌和粗糙度(Ra)进行了评价。结果蓝宝石在化学机械抛光过程中的材料去除率均随抛光液pH值和温度的升高呈先增大后减小趋势。当抛光原液与去离子水按1:1的体积比混合配制抛光液,KOH调节pH值为12.2,水浴加热抛光液35℃时,蓝宝石抛光的材料去除率(MRR)达到1.119μm/h,Ra为0.101 nm。结论随着pH的增大,化学作用逐渐增强,而机械作用逐渐减弱,在pH为12.2的时候能达到平衡点,此时的MRR最佳;随着温度的升高,化学作用逐渐增强,而机械作用保持不变,抛光液温度为35~40℃时,化学作用与机械作用达到平衡,MRR最佳,当温度高于40℃后,抛光液浓度明显增大,而过高的浓度会导致MRR的减小。抛光液的相关性能优化后,化学机械抛光蓝宝石的MRR较优化前提高了71.4%。     

锇在磷酸体系抛光液中化学机械抛光研究

(锇有可能作为大规模集成电路铜互连扩散阻挡层新材料。)利用自制的抛光液对金属锇片进行抛光,研究在双氧水-磷酸体系抛光液中H2O2浓度和抛光液pH值对抛光速率的影响。结果表明,当抛光液中主要成分仅为氧化剂H2O2时,并不能在金属锇表面达到好的腐蚀效果。在磷酸体系抛光液中,H2O2能够通过促进阴极反应的进行从而增强抛光液对金属锇的化学作用;低浓度H2O2通过增强抛光液对金属锇的化学腐蚀能力,从而增加了抛光速率值;较高浓度H2O2的加入对抛光速率值影响较小。H3PO4能够在抛光液中起到抑制剂、pH调节剂和络合剂的作用。当抛光液pH值为4.0时,金属锇表面生成的钝化膜最致密。当pH值为4.0或5.0时,金属锇表面生成的钝化膜OCP值大于金属锇的OCP值,且此条件下的抛光速率值较高。     

纳米氧化铈抛光液对钌的化学机械抛光

采用液相沉淀法制备了纳米CeO2磨料,利用X射线衍射(XRD)表征其物相组成.通过纳米粒度仪研究了分散剂种类、热处理温度对CeO2磨料制备的悬浮液的粒径分布和Zeta电势的影响.用由CeO2磨料制备的抛光液对钌进行化学机械抛光,采用原子力显微镜观察钌片表面的微观形貌.结果表明:制备的粉体是具有立方萤石型结构的纳米CeO2,其晶粒尺寸随热处理温度的升高而增大;CeO2磨料在以六偏磷酸钠(SHMP)作为分散剂的悬浮液中分散效果最好;在抛光压力为6.9 kPa,抛光台转速为50 r/min,抛光液流量为50 mL/min,抛光液pH值为10.0,抛光液主要组成(质量分数)为1％ CeO2,1％(NH4)2S2O8,0.01％ SHMP的条件下,钌的抛光速率达到9.0 nm/min,表面粗糙度Ra值为2.2 nm.     

紫外光催化辅助Ga面GaN化学机械抛光试验研究

目的 探究在紫外光催化辅助抛光过程中,相关因素对氮化镓晶片Ga面去除率(MRR)及表面粗糙度(Ra)的影响规律,提高单晶氮化镓高效率低损伤的超光滑表面质量。方法 通过结合紫外光与化学机械进行抛光,采用单因素试验方案,对GaN晶片的Ga面进行紫外光催化辅助化学机械抛光试验,比较在无光照、光照抛光盘、光照抛光液3种抛光方式和不同TiO₂浓度、pH值、H₂O₂含量、抛光压力、抛光盘转速和抛光液流条件下的抛光效果。最后通过正交试验进行抛光工艺参数优化,通过测量不同条件下紫外光催化辅助化学机械抛光过程中的MRR值和Ra值,探究GaN晶片Ga面抛光效果。结果在紫外光催化辅助抛光条件下,通过对单因素试验和正交试验的抛光参数进行分析和优化,GaN晶片材料去除率可以达到698.864nm/h,通过白光干涉仪观测可以获得表面粗糙度Ra值为0.430nm的亚纳米级超光滑GaN晶体表面。结论 基于紫外光催化辅助GaN晶片Ga面化学机械抛光试验,紫外光辅助化学机械的复合抛光方式能够促进GaN表面生成物Ga₂O₃     

纳米CeO2的醇水法制备及其对GaAs晶片的抛光性能

在醇水体系中以HMT为缓释沉淀剂制备了纳米CeO2粉体,并用TEM、SAD、XRD对其进行了表征,将制备的不同粒径纳米CeO2粉体配制成抛光液,对GaAs晶片进行了化学机械抛光。研究了醇的引入及煅烧温度对粉体性能的影响,并就纳米CeO2磨料尺寸对GaAs晶片抛光后表面粗糙度的影响机理进行了探讨。结果表明:醇水体系中制备的纳米CeO2颗粒较水溶液中制备的颗粒粒径小,且分散性好;随着煅烧温度的升高,颗粒逐渐增大,不同尺寸的纳米颗粒具有不同的抛光效果;随着磨料粒径的增大,表面粗糙度值也随之升高。     

The polishing mechanism of electrochemical mechanical polishing technology

In this paper, the polishing mechanism of the electrochemical mechanical polishing (ECMP) technology for tooling steel SKD11 was investigated. Suitable electrochemical process parameters were evaluated. The electrochemical characteristics of a material such as active, passive and trans-passive (dissolution) can be revealed from its I–V curve. The characteristics of passive and trans-passive have great effects on the ECMP polishing mechanism. Experimental procedures included qualitative, quantitative and surface quality analyses. Qualitative analyses utilized potentiostat to study the I–V curves of a specific specimen in various electrolytes and electrolytic concentrations, and to find out the voltages at each electrochemical state. In quantitative analyses, the electrochemical polishing processes of the ECMP technology were conducted. From the measured and theoretical weight losses, each process state can be verified whether or not it followed the Faraday’s law. Finally, the surface roughness was measured by a surface profiler. The scanning electron microscopy (SEM) was used to observe the surface profile. The energy dispersive spectroscopy (EDS) analysis was employed to analyze the metallurgical compositions of the surface. In summary, the proposed mechanism and analyses were a good methodology in finding suitable electrochemical process parameters for ECMP technology.     

化学机械抛光中抛光垫修整的作用及规律研究

抛光垫修整是化学机械抛光的重要过程之一.修整后抛光垫的性能主要由修整器的性能和相关的工艺参数决定.本文介绍常用金刚石修整器的颗粒性能、胎体材料及相关工艺参数,总结金刚石修整器在不同条件下对修整性能的影响规律,发现:金刚石颗粒的类型影响修整效率,RAS越大,修整效率越高;颗粒尺寸的增大有利于提高修整效率;粘结力的增大,可以提高修整效率和使用寿命;颗粒的均匀排列有助于抛光垫表面沟槽的形成;使用陶瓷作为胎体材料,可以提高使用寿命;修整压力及转速的增大,可以提高修整效率;修整温度会对抛光垫的沟槽、微孔及硬度产生影响,温度的升高,可以改善修整质量;修整密度越大,抛光垫的磨损率越高.最后对金刚石修整器的发展趋势做出展望.     

The technology combined electrochemical mechanical polishing

Electrochemical mechanical polishing (ECMP) is a polishing process combining electrochemical and mechanical action. It has higher efficiency and better quality.

Mechanism, processing regulation and application are introduced in the paper.     

基于叶序仿生抛光垫的化学机械抛光的运动分析

为了改善化学机械抛光的接触状态和被加工工件的表面形态,基于生物学的叶序理论设计了仿生结构的抛光垫。从单颗磨粒切削理论出发,建立了抛光运动方程和材料去除率分布模型。利用所建立的运动方程和材料去除率分布模型进行了晶片表面材料去除率分布的计算分析,得到抛光机的运动参数及抛光垫的叶序参数对材料去除率的影响规律。结果表明:当抛光盘的转速较大、工件转速适中、摆臂摆动频率较小、摆臂中心角较小及叶序参数取值较小时可以获得更好的材料去除分布。     

化学机械抛光过程抛光液作用的研究进展

化学机械抛光(CMP)已成为公认的纳米级全局平坦化精密超精密加工技术。抛光液在CMP过程中发挥着重要作用。介绍了CMP过程中抛光液的作用的研究进展,综合归纳了抛光液中各组分的作用,为抛光液的研制和优化原则的制定提供了参考依据。     

Mechano-chemical polishing of silicon wafers

Rapid progress in recent IC fabrication industry has increased the demand of tight specification of non-uniformity (NU) and surface polishing in silicon wafer planarization. Chemical–mechanical polishing (CMP) is currently the most popular method for IC wafer planarization. However, the sub-surface damage problem caused by hard abrasives and chemical waste problem of CMP have decreased the throughput and increased the cost of IC fabrication. This study is to investigate the mechano-chemical polishing (MCP) of silicon wafers by slurry of soft abrasives, BaCO₃ and through experiments to verify that the solid phase chemical reaction (SPCR) is the main reaction process involved in MCP. A planarization mechanism with compliance has been designed and tested through MCP experiments. Experimental results of MCP of silicon wafers have achieved the average of surface roughness improvement ratio (SRIR) to 99% and the surface roughness R_a=0.633 nm measured by atomic force microscope (AFM). The material removal rate (MRR) has been calculated and the significant influence of slurry weight percent and polishing pressure have been found. The NU has also been estimated for evaluation of MCP parameters. The sub-surface damage of silicon wafer has not yet been found in experimental results and hence the MCP process of silicon wafers has been verified to become a green or environment-friendly technology of silicon wafer planarization.     

一种玻璃抛光用新型抛光盘的研究

研究了一种用于玻璃抛光的新型抛光盘。该抛光盘用不饱和聚酯树脂做结合剂,用环烷酸钴和过氧化甲乙酮组成促进引发体系,以氧化铝-氧化铈新型核壳复合磨粒作磨料,以硫酸镁做造孔剂,以铜粉、碳化硅作为导热填料,以钼酸铵作为活性抛光剂。其成品成本较低,磨削效率高,抛光面平整度好,没有裂纹、亮丝、划痕,可以达到稀土抛光盘的抛光效果。     

Ultra-precision machining by the cylindrical polishing process

A process planning method for removing an arbitrary and axially symmetric error profile by the cylindrical polishing process (abbreviated as the CPP process) is proposed in this study. This method is to plan the dwelling-time of the polishing tool so that the error profile can be accurately removed. The tool dwelling-time distribution is solved by a non-negative least square method. By using this method, the residual error between actual and desired removal depths may be induced. It is shown that the residual error is related to the width of the machining zone, the wavelength of the error profile, and the tool’s resolution. The computer simulations indicate that the residual error is always negligible when the wavelength of the error profile is larger than the width of the machining zone. If the wavelength of the error profile is large, a small size of the tool’s resolution is found effectively to reduce the residual error. The experimental study confirms that an arbitrary error profile can be accurately removed on the basis of the proposed method.     

固结磨料研磨与抛光的研究现状与展望

分析了传统游离磨料研磨抛光存在的缺点和固结磨料的研磨抛光的优点;阐述了固结磨料研磨抛光的材料去除机制以及固结磨料研磨盘抛光技术在氮化硅陶瓷加工、半导体制程中的应用;介绍了多种固结磨料研磨盘、抛光垫的制作方法;并展望了固结磨料的研磨抛光的发展趋势。     

A comparative study: polishing characteristics and its mechanisms of three vibration modes in vibration-assisted magnetic abrasive polishing

The automatic precision polishing technique of three-dimensional complicated micro-curved surfaces of components in extremely low surface roughness and high efficiency is greatly demanded by advanced industrial fields. The existing polishing methods have great difficulty in satisfying these demands. Therefore, three modes (horizontal vibration, vertical vibration and compound vibration) of vibration-assisted magnetic abrasive polishing processes have been developed. Previous research focused on each polishing characteristic. The aims of this paper are to characterize effects of vibration of workpiece on magnetic field, polishing pressure, in-process abrasive behavior and polishing performances in three vibration modes and to describe their machining mechanism. Furthermore, a realization of efficient polishing of a 3D micro-curved surface was confirmed to be possible by the process.