化学机械抛光垫沟槽形状的研究及展望

在化学机械抛光过程中,沟槽形状是抛光垫性能的重要影响因素之一,它会直接影响抛光效果。本文介绍了化学机械抛光垫上沟槽的基本形状及其对抛光效果的影响,以及不同复合形状的抛光垫沟槽及其对抛光效果的影响,并就研究中现存的主要问题提出展望。     

抛光垫特性对氧化镓CMP影响的实验研究

对比分析了不同抛光垫的表面形貌、表面粗糙度、硬度以及涵养量对氧化镓晶片化学机械抛光过程中表面质量和材料去除率的影响规律,结果表明:在同一抛光参数条件下,Suba600无纺布抛光垫的材料去除率最大,为30.8nm/min,但抛光后氧化镓表面有明显的凹坑;Politex阻尼布、LP57聚氨酯抛光垫抛光后晶片表面形貌都较好,获得了镜面无损伤晶片表面,但LP57聚氨酯抛光垫的材料去除率为22.6nm/min,大于Politex阻尼布抛光垫16.4nm/min的材料去除率;LP57聚氨酯抛光垫更适合对单晶氧化镓晶片进行化学机械抛光。该研究为氧化镓化学机械抛光(CMP)提供了参考依据。     

化学机械抛光工艺中的抛光垫

抛光垫是晶片化学机械抛光中决定表面质量的重要辅料。研究了抛光垫对光电子晶体材料抛光质量的影响：硬的抛光垫可提高晶片的平面度;软的抛光垫可改善晶片的表面粗糙度;表面开槽和表面粗糙的抛光垫可提高抛光效率;对抛光垫进行适当的修整可使抛光垫表面粗糙。     

KDP无磨粒抛光微机械作用力学模型建立与仿真

无磨粒化学机械抛光是一种柔和的表面处理方法,可以有效去除磷酸二氢钾(KDP)晶体表面的小尺度飞切刀纹。在抛光过程中不使用磨粒,KDP晶体与抛光垫粗糙峰直接接触,两者之间相对运动,在表面接触应力的作用下,抛光垫对KDP晶体表面产生微机械作用,在实现材料去除和改善表面质量方面具有重要的作用。为了深入了解无磨粒化学机械抛光中微机械去除作用,文章通过研究表面接触应力分布和变化规律,对抛光过程中的微机械作用进行定量分析,建立了KDP晶体与抛光垫粗糙峰接触力学的数学模型并开展系统研究。根据Hertz理论对抛光过程中KDP晶体表面接触应力进行了计算与分析,研究了抛光压力、摩擦系数、抛光垫杨氏模量和抛光垫粗糙峰半径等抛光参数对微机械作用的影响规律,获得了不同抛光条件下最大许用抛光压力。结合实验结果,对KDP晶体与抛光垫之间的微机械作用进行了实验验证,进一步揭示了KDP晶体无磨粒化学机械抛光去除机理。     

化学机械抛光技术研究现状及进展

通过回顾化学机械抛光技术的发展历史,概述化学机械抛光技术的实际应用情况,着重阐述了化学机械抛光技术的作用机理、主要构件(抛光机、抛光垫、抛光液)以及抛光工艺参数对加工过程的影响,进一步展望了化学机械抛光技术的发展前景与研究方向。     

CMP过程中抛光垫表面沟槽对液膜厚度影响研究

抛光垫表面沟槽结构是决定抛光液抛光效果的重要因素之一。为了研究抛光垫表面沟槽对化学机械抛光过程的影响,设计并搭建了高速摄影仪在线检测平台,检测并研究了有无沟槽及不同类型沟槽结构对液膜厚度的影响。实验结果表明:抛光垫开槽可以增加抛光液液膜厚度分布均匀性;在同心圆型、放射型、网格型、复合型4种类型抛光垫结构中复合型沟槽具有最优抛光效果。     

抛光垫特性对抛光中流体运动的影响分析

抛光垫表面特性能可大大改变抛光液的流动情况,从而影响化学机械抛光的抛光性能。考虑抛光垫粗糙度和孔隙等对抛光液流动的影响,提出了一个初步的晶片级流动模型,并用数值模拟方法研究了不同参数条件(载荷和速度的变化等)下抛光液的流动特征。计算结果表明增加外载荷将导致粗糙峰的磨损概率增加,增加剪切速率则提高了剪切应力,均可导致高材料去除率。模型能较好理解材料去除机制和输运,从而有助于对化学机械抛光机制的了解。     

无抛光垫化学机械抛光技术研究

应用双电层理论分析了SiO2磨粒与聚苯乙烯粒子在溶液中的ζ电位及粒子间的相互作用机制,观察到SiO2磨粒吸附在聚苯乙烯粒子表面的现象.分析了基于复合粒子抛光液的无抛光垫化学机械抛光技术特点及其材料去除机理.比较试验表明,基于复合粒子抛光液的硅片无抛光垫化学机械抛光具有与传统化学机械抛光相接近的材料去除率和硅片表面粗糙度值,并可避免工件塌边现象的产生.     

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。     

集成电路制造中的固结磨料化学机械抛光技术研究

经过对传统化学机械抛光技术的研究与分析，指出了目前ULSI制造中使用的传统化学机械抛光技术的缺点，通过对固结磨料化学机械抛光中的抛光垫结构、抛光机原理及抛光液的分析，得出了固结磨料化学饥械抛光技术的优点，同时还对硅片固结磨料化学机械抛光的缺陷进行了研究。     

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.     

Effects of particle size, polishing pad and contact pressure in free abrasive polishing

The objective of this research is to better understand the mechanisms of material removal in the free abrasive polishing process. Experiments were carried out to understand the effects of particle size, polishing pad and nominal contact pressure on the wear rate and surface roughness of the polished surface. A theoretical model was developed to predict the relationship between the polishing parameters and the wear rate for the case of hard abrasive particles sandwiched between a soft pad and a workpiece (softer than the abrasive particles). Experimental results and theoretical predictions indicate that the wear rate increases with an increase in particle size, hardness of polishing pad and nominal contact pressure, and with a decrease in elastic modulus of the polishing pad. Surface roughness increases with an increase in particle size and hardness of polishing pad, and nominal contact pressure has little effect on the roughness. A dimensionless parameter, wear index which combines all of the preceding parameters, was introduced to give a semi-quantitative prediction for the wear rate in free abrasive polishing. It is also suggested that when polishing hard material, in order to achieve a high materials removal rate and a smooth surface, it is preferable to use diamond as the polishing particles because of their high deformation resistance.     

Dependence of pad performance on its texture in polishing mono-crystalline silicon wafers

Mono-crystalline silicon wafers are important materials in the semiconductor industry for fabricating integrated circuits and micro-electro-mechanical systems. To ensure high surface integrity of polished wafers, the effect of pad texture and its variation on the pad performance needs to be understood. This paper studies experimentally the dependence of pad performance on its texture deterioration by investigating its correlation with polishing time, polishing pressure, and material removal rate. The study concludes that material removal rate decreases as the cylindrical cell structure of a pad is gradually deteriorated, that there is a pad life limit beyond which polishing quality can no longer be maintained, and that the workable pad life can be extended to a certain degree by applying higher polishing pressure.     

数控抛光中不同运动方式下小抛光盘抛光特性之比较

阐述行星运动与平转动两种运动方式下数控抛光中小抛光盘的工作函数,论述了抛光盘本身在不同运动方式下的材料磨损情况。通过采用计算机对抛光盘工作函数及磨损曲线的模拟将抛光盘的两种运动方式进行了分析与比较。     

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。     

A review on the progress towards improvement in surface integrity of Inconel 718 under high pressure and flood cooling conditions

Self-conditioning performance of polishing pad is an important characteristic to influence processing efficiency and service life in chemical mechanical polishing (CMP). The slurry can react with the pad surface, which affects its self-conditioning performance in fixed abrasive polishing process. Wear ratio of wafer material removal rate (MRR) and pad wear rate is introduced to evaluate self-conditioning performance of fixed abrasive pad (FAP). To clear the effect of chemical additive on FAP self-conditioning, wear ratio, FAP surface topography, friction coefficient, and acoustic emission signal of polishing process were investigated in fixed abrasive polishing of quartz glass with ferric nitrate, ethylenediamine (EDA), and triethanolamine (TEA) slurry, respectively. Results indicate that TEA slurry can provide excellent self-conditioning of FAP in fixed abrasive polishing of quartz glass. MRR and wear ratio maintain high levels during the whole polishing process. Friction coefficient and acoustic emission signal are more stable than that of the other two chemical additives. An appropriate amount of TEA, which is beneficial to enhance MRR and extends service life of FAP, is added in the polishing slurry to improve FAP self-conditioning in fixed abrasive polishing process.     

Factors influencing the dressing rate of chemical mechanical polishing pad conditioning

The primary consumables in the chemical mechanical polishing (CMP) process are the polishing pad and the slurry. Among those consumables, the polishing pad significantly influences the stability of the process and the cost of consumables (CoC). Furthermore, the small holes on the pad surface will be filled by the reactant from the CMP process, and the surface of the pad will deposit hard glazing gradually. The glazing not only reduces the ability of absorbing slurry of the pad, but it also causes scratching on the work piece. In order to maintain the stability of the CMP process and return to an ideal pad surface status, we must condition the pad according to a regular time schedule. At the same time, if we use different pad conditioning factors, the dressing rate of the CMP pad will be different. Most important of all, we have to decrease the pad material abrasion due to the pad conditioning process. In conclusion, if we can understand the influence of the dressing rate and conditioning factors effectively, it will be useful for maintaining CMP process stability, extending pad life, and reducing CoC and non-processing time.     

软性粒子抛光石英玻璃的材料去除机理

基于阿伦尼乌斯原理和分子振动理论,分析了软性抛光粒子、石英玻璃和抛光垫之间的弹性与超弹性接触,研究了用软性粒子抛光石英玻璃的材料去除机理。基于理论研究进行了大量的抛光试验,建立了软性粒子抛光石英玻璃的材料去除率模型。理论计算与试验结果表明:在石英玻璃化学机械抛光中,材料的去除主要由抛光粒子与石英玻璃的界面摩擦化学腐蚀作用来实现;单个抛光粒子压入石英玻璃的深度约为0.05nm,且材料去除为分子量级;石英玻璃表层的分子更易获得足够振动能量而发生化学反应实现材料的去除;抛光压力、抛光液中化学试剂种类和浓度以及石英玻璃试件与抛光盘的相对运动速度决定了软性粒子抛光石英玻璃的材料去除率大小。     

Estimating chemical mechanical polishing pad wear with compressibility

A polishing pad is an important component in a chemical mechanical polishing (CMP) system. Few investigations have specialized in the variation of the characteristics of the pad as it undergoes wear. All of the information concerning a pad, such as compressibility and pad life, comes from the manufacturer. No acknowledged standard or instrument exists for determining a pad’s quality. This study obtained the variation of the compressibility (K) of major types of pad (single-layer pad and composite pad) with polishing time (pad wearing) by theoretical modeling and real experiments. The K of single-layer or composite pads changes due to wear, and the trends in the K values of the two types of pads are exactly opposite. A finite element method (FEM) is used here to show that the variation in K strongly affects the polishing process. Theoretically, the compressibility of a pad can be used to judge whether the pad is good for polishing or not.