ULSI制造中铜化学机械抛光的腐蚀磨损机理分析

以超大规模集成电路(ULSI)芯片多层互连结构制造中的关键平坦化工艺——铜化学机械抛光(Cu—CMP)为研究对象，针对Cu—CMP中存在的抛光液的化学腐蚀作用和磨料的机械磨损现象，采用腐蚀磨损理论分析了Cu—CMP材料去除机理。提出铜CMP的材料去除中存在着机械增强的化学腐蚀和化学增强的机械磨损，并分析了Cu—CMP的静态腐蚀材料去除、机械增强的腐蚀去除与化学增强的机械去除机理。     

CMP过程芯片表面氧化膜生成速度影响因素的分析

根据理论和试验分析,将机械化学抛光(CMP)过程分成两个阶段:化学作用主导阶段和机械作用主导阶段,并从机械作用角度导出CMP过程两个阶段芯片表面材料去除率的数学模型,模型全面地考虑了抛光盘特性参数(弹性模量、硬度、表面粗糙度峰的尺寸分布)、CMP工作参数(压力和抛光速度)、抛光液中磨粒的机械作用和氧化剂种类、氧化剂浓度等化学作用的影响。然后根据这两个阶段的平衡点导出定量描述芯片表面氧化膜生成速度的数学模型。详细分析机械作用因素(磨粒的浓度、磨粒的粒度分布特性)、化学作用因素(抛光液中氧化剂种类、浓度)以及磨粒/芯片/抛光盘的材料特性参数对芯片表面氧化膜生成速度的影响规律。该CMP过程芯片表面氧化膜生成速度定量模型的导出,对进一步深入研究CMP材料去除机理和更加准确地控制CMP过程,具有一定的指导作用。     

化学机械抛光过程中抛光垫修整的研究

摘要：抛光垫是化学机械抛光（CMP）系统的重要组成部分，具有贮存、输送抛光液等作用，对晶片的去除率和平整度起着至关重要的作用。本文介绍和探讨了CMP过程中抛光垫修整对抛光垫表面结构以及对CMP过程影响规律。研究结果表明，抛光垫与晶片的接触面积、抛光速率、平坦化效果等都受到抛光垫修整的影响。大的修整深度能够获得较高的抛光去除率，而较小的修整深度则更有利于获得较好的平坦化效果。修整效果可以通过修整器的设计、修整工艺参数以及加工参数进行调整。     

芯片互连层化学机械平坦化过程中材料移除机理研究进展

化学机械平坦化(Chemical mechanical planarization,CMP)是芯片制造中的关键技术,用于实现多种结构表面纳米级别的超精细平坦化.互连层金属和芯片结构中的其他材料性质差异较大,其平坦化过程更加依赖于抛光浆料中的化学组分.协同机理适用于描述金属CMP的材料移除过程:抛光浆料中的化学组分对互连...     

超精密CMP电化学抛光试验台关键部件的设计

由于化学机械抛光(CMP)中机械和化学作用同时发生在芯片抛光过程中,因此,传统的电化学测试仪难以动态测试CMP中芯片表面成膜的过程。将传统CMP设备与电化学测试分析仪相结合,开发新型电化学CMP测设平台。研究关键部件抛光头和抛光盘的设计,采用ANSYS进行传感器弹性体的标定与设计,并进行电化学分析试验的验证。结果表明开发的测试平台数据采集稳定,工作平稳,基本达到设计目标。     

表面活性剂在集成电路多层布线CMP工艺中的应用研究

随着集成电路(IC)特征尺寸不断缩小,集成电路多层布线加工精度面临更高的要求,而化学机械抛光(CMP)凭借化学腐蚀和机械磨削的耦合协同作用,成为实现晶圆局部和全局平坦化的唯一可靠技术。抛光液作为CMP工艺中关键要素之一,其主要成分表面活性剂的选择以及含量会严重影响晶圆的表面质量。介绍表面活性剂的特性及其类型,回顾近年来国内外表面活性剂在集成电路多层布线相关材料CMP中的应用及作用机制,归纳总结得出表面活性剂在CMP过程中可以起到缓蚀保护、增强润湿、分散磨料、去除晶圆表面残留污染等多种作用,具有广泛的应用领域。同时,对表面活性剂在CMP中的应用前景进行了展望。     

蓝宝石衬底化学机械抛光中材料去除特性的研究

衬底基片的化学机械抛光(CMP)同时兼顾材料去除率及衬底表面质量,在抛光过程中,化学作用与机械作用相辅相成同时参与抛光,化学作用与机械作用的平衡对能否得到满意的衬底表面有重要有意义。针对蓝宝石衬底基片的CMP材料去除率进行了研究,分析了材料去除机理。使用单因素实验法测得:压力的增加会导致材料去除率的增加,但当压力增加到某一点后,材料去除率的增加反而减缓,与此同时衬底基片表面粗糙度达到最小。这一点附近的抛光参数可以达到机械与化学作用的平衡。在实验中,当抛光压力为6kg时材料去除率达到80nm/min,表面粗糙度达到0.2nm。     

超大规模集成电路制造中硅片平坦化技术的未来发展

在集成电路(IC)制造中,化学机械抛光(CMP)技术在单晶硅衬底和多层金属互连结构的层间全局平坦化方面得到了广泛应用,成为制造主流芯片的关键技术之一。然而,传统CMP技术还存在一定的缺点或局限性,人们在不断完善CMP技术的同时,也在不断探索和研究新的平坦化技术。在分析传统CMP技术的基础上,介绍了固结磨料CMP、无磨料CMP、电化学机械平坦化、无应力抛光、接触平坦化和等离子辅助化学蚀刻等几种硅片平坦化新技术的原理和特点以及国内外平坦化技术的未来发展。     

铜化学机械抛光中电化学理论的应用研究

概述了电位-pH图、极化曲线、交流阻抗谱和开路电压测试等电化学方法在铜化学机械抛光(Cu—CMP)中的应用，并分析了采用电化学方法进行CMP分析存在的问题，指出采用以上电化学方法进行Cu—CMP分析有利于对Cu—CMP的过程的理解，并可以为抛光液组分的选配提供依据。     

基于灰色模型的CMP过程免疫预测R2R控制

针对化学机械研磨(chemical mechanical polishing,CMP)过程非线性、时变、产品质量不能在线测量的特性,为了提高CMP过程R2R(Rum-to-Run)控制的精度,提出了一种基于灰色模型和克隆选择免疫算法的CMP过程R2R预测控制器GI-PR2R。通过离线测量获得历史批次少量数据,构建CMP过程的在线灰色GM(1,N)预测模型,解决了复杂CMP过程难以建立精确数学模型的难题提高了预测模型的精度。通过基于克隆选择免疫算法的CMP过程预测控制的滚动优化,避免了基于导数的优化技术易陷入局部最优的问题,进而提高了控制精度。仿真结果表明,CMP过程GIPR2R控制器的控制精度优于EWMA(exponentially weighted moving average)方法,有效抑制了过程漂移,减小了不同批次间产品的差异,材料去除率(material removalrate,MRR)的均方根误差在总批次与控制目标不同这2种情况下分别降低了18.09%和16.84%。     

考虑抛光垫特性的CMP流动性能

为了研究具有多孔结构抛光垫对化学机械抛光(Chemical mechanical polishing,CMP)性能所起的重要作用, 通过假定孔质层流体服从Darcy规律,即流动速度正比于压力梯度而反比于粘度,从而提出了CMP中考虑抛光垫特性的三维流体模型,并给出了流动方程。利用多重网格技术和线松驰技术求解上述所得的流动方程,用数值模拟方法探求了不同大小抛光垫孔径和不同孔质层厚度下承载能力和运行参数(包括节距高度、转角和倾角等)的关系。计算结果表明,当抛光垫的孔径尺寸较小和其孔质层较厚时有较大的承载能力(包括载荷与转矩),从而将提高CMP的材料去除率。孔隙直径较大的抛光垫由于允许较多的流体流过多孔层而导致其承载能力下降。研究结果有助于了解CMP的作用机理。     

Porosity model for flows in CMP

In an effort to explore the contribution of the pad, which is usually full of pores, to the performance of CMP (chemical mechanical polishing), a three-dimensional flow model of CMP is presented by assuming that the fluids in the porous layer comply with Darcy’s law, which states that the flow velocity is proportional to the pressure gradient and inverse proportional to the viscosity. The flow equation is deduced accordingly and, by taking advantage of the multi-level technique and line relaxation technique, numerical simulations are carried out to reveal the relationships between the load capacities and operational parameters (including pivot height, roll angle and pitch angle), under conditions with different porous parameters and different thicknesses of the porous layer. The little porous parameter will lead to a prominent increase of load capability (for instance, the load and the moment predicted), which is still augmented by the thicker layer parameter. This will result in a higher material removal ratio of CMP. A pad full of large pores will be used to deduce load capability, facilitating the free flow of the fluids through the pores. The research will add some insights on the mechanism of the CMP technique. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(4) (in Chinese)     

Applications of Taguchi and design of experiments methods in optimization of chemical mechanical polishing process parameters

This investigation applied the Taguchi method and designs of experiments (DOE) approach to optimize parameters for chemical mechanical polishing (CMP) processes in wafer manufacturing. Planning of experiments was based on a Taguchi orthogonal array table to determine an optimal setting. In this study, the material removal rate and non-uniformity of surface profiles were selected as the quality targets. This partial factorial experimental planning provided an efficient and systematic approach of determining an optimal parameter condition. Mathematical prediction models for the material removal rate and the non-uniformity of surface profiles were derived in terms of platen speeds, carrier speeds, back side pressure, slurry flow rates and head down forces by regression analysis. These parameters are found to be significant to both the removal rate and the non-uniformity of surface profiles for CMP processes.     

叶序结构抛光垫表面的抛光液流场分析

为了解决在化学机械抛光过程中抛光接触区域内抛光液的分布均匀性问题,基于生物学的叶序理论,设计葵花籽粒结构的仿生抛光垫,建市化学机械抛光抛光液流场的运动方程和边界条件,利用流体力学软件(Fluent)对抛光液的流动状态进行仿真,并获得叶序参数对抛光液流动状态的影响规律.结果表明:抛光液在基于葵花籽粒的仿生抛光垫的流动是均匀的,抛光液沿着逆时针和顺时针叶列斜线沟槽流动,有利于流体向四周发散.     

Analysis and Application of Grey Relation and ANOVA in Chemical–Mechanical Polishing Process Parameters

The parameters for chemical–mechanical polishing (CMP) in an ultra-large scale integrated (ULSI) planarisation process are explored. First, an analysis of variance (ANOVA) is conducted on the CMP process parameters derived from the Taguchi method. The objective is to understand the ranking of the effects of CMP parameters such as down force pressure, platen speed, carrier speed, oscillation, and flowrate on the removal rate. Findings are verified by grey relational analysis. The values of the sequencing results allow us to adjust the parameters to the required machining condition during the CMP experiment. This will reduce the number of experiments needed and the length of time required. This study also analyses the effect of data normalisation and data integrity in grey relational analysis on the degree of sensitivity. The results indicate that it is feasible to use grey relational analysis to predict the rank of the parameter effect in the case of insufficient data derived from the Taguchi method. ID="A1"Correspondance and offprint requests to: Professor Z.-C. Lin, Department of Mechanical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 10672, Taiwan. E-mail: zclin@mail.ntust.edu.tw     

一种基于非晶层粘性流动的机械化学抛光模型

通过分析单个微纳米磨粒滑动接触的分子动力学模拟的研究结果，提出了在典型的机械化学抛光（CMP）过程中芯片表面材料的去除应为表面非晶层物质粘性流动所致的新观点。基于这种机理，应用微观接触力学和磨粒粒度分布理论建立了一种新的表征CMP过程材料去除速率的数学模型。模型中引入了一个表征单个磨粒去除芯片表面非晶层能力的比例系数k，k综合反映了磨粒的机械作用、抛光液对芯片表面的化学作用和芯片的材料特性。通过实验验证发现该模型的理论预测值与实验测定值十分吻合。     

基于叶序仿生抛光垫化学机械抛光温度的研究与分析

为了解决在化学机械抛光过程中抛光温度分布不均匀问题,使用叶序仿生抛光垫进行研究,并建立了抛光温度场模型。利用有限元分析软件ANSYS,对抛光温度场进行了仿真分析,获得了抛光垫的叶序参量对抛光温度分布的影响规律。通过对仿真结果进行分析发现,合理选择仿生抛光垫的叶序参数,能够使抛光温度变得更均匀。     

Effect of wafer size on material removal rate and its distribution in chemical mechanical polishing of silicon dioxide film

Chemical mechanical polishing (CMP) is a semiconductor fabrication process. In this process, wafer surfaces are smoothed and planarized using a hybrid removal mechanism, which consists of a chemical reaction and mechanical removal. In this study, the effects of wafer size on the material removal rate (MRR) and its uniformity in the CMP process were investigated using experiments and a mathematical model proposed in our previous research; this model was used to understand the MRR and its uniformity with respect to wafer size. Under constant process conditions, the MRR of a silicon dioxide (SiO₂) film increased slightly along with an increase in wafer size. The increase in MRR may be attributed to the acceleration of the chemical reaction due to a rise in process temperature. Based on the results obtained, the k and α values in the mathematical model are useful parameters for understanding the effect of wafer size on the MRR and its distribution under a uniform, relative velocity. These parameters can facilitate the prediction of CMP results and the effective design of a CMP machine.     

A micro-contact and wear model for chemical–mechanical polishing of silicon wafers

A micro-contact and wear model for chemical–mechanical polishing (CMP) of silicon wafers is presented in this paper. The model is developed on the basis of elastic–plastic micro-contact mechanics and abrasive wear theory. The synergetic effects of mechanical and chemical actions are formulated into the model. A close-form equation of material removal rate from the wafer surface is derived relating to the material, geometric, chemical and operating parameters in a CMP process. The model is evaluated by comparing the theoretical removal rates with those experimentally determined. Good agreement is obtained for both chemically active and inactive polishing processes. The model reveals some insights into the micro-contact and wear mechanisms of the CMP process. It suggests that the removal rate is sensitive to the particle concentration in the slurry, more sensitive to the applied load and operating speed and most sensitive to the surface hardness and slurry particle size. The model may be used to study the effects of different materials, geometry, slurry chemistry and operating conditions on CMP processes.     

Preparation of La-doped colloidal SiO2 composite abrasives and their chemical mechanical polishing behavior on sapphire substrates

Chemical mechanical polishing (CMP) has become a widely accepted global planarization technology. Abrasive is one of the key elements in CMP process. In order to enhance removal rate and improve surface quality of sapphire substrate, a series of novel La-doped colloidal SiO₂ composite abrasives were prepared by seed-induced growth method. The CMP performance of the La-doped colloidal SiO₂ composite abrasives on sapphire substrate were investigated using UNIPOL-1502 polishing equipment. The analyses on the surface of polished sapphire substrate indicate that slurries containing the La-doped colloidal SiO₂ composite abrasives achieve lower surface roughness, higher material removal rate than that of pure colloidal SiO₂ abrasive under the same testing conditions. Furthermore, the acting mechanism of the La-doped colloidal silica in sapphire CMP was investigated. X-ray photoelectron spectroscopy analysis shows that solid-state chemical reactions between La-doped colloidal SiO₂ abrasive and sapphire surface occur during CMP process, which can promote the chemical effect in CMP and lead to the improvement of material removal rate.