【作者】 王彩玲；

【导师】 康仁科；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2010， 博士

【摘要】 化学机械抛光(Chemical Mechanical Polishing, CMP)技术是集成电路(IC)制造中,可以有效兼顾加工硅片表面局部与全局平坦度的一项重要技术。随着集成电路制造技术的飞速发展,为增加芯片产量并降低制造成本,硅片直径不断增大,特征线宽不断减小,对CMP技术及设备提出越来越高的要求。由于硅片直径增加,抛光头及抛光盘的驱动力成指数倍增长,对抛光机的动力系统提出了较高要求；硅片表面的压力分布不均问题更加突出,尤其是硅片边缘区域压力分布不均更加明显,这对硅片的加压系统及压力控制技术提出了更高要求。本文在深入研究CMP材料去除率(MRR)及硅片表面压力分布等理论问题的基础上,对CMP设备中的关键技术进行了研究,主要研究内容和结论如下：建立了基于单点速度向量积分方法的CMP材料去除率模型。分析了转速、摆幅、摆速等工艺参数对MRR及材料去除非均匀性(NUMR)的影响规律。理论分析结果表明抛光盘转速是影响MRR的主因,抛光头转速对MRR的影响很小；摆动幅度对MRR、NUMR也有较大影响,而摆动速度对MRR、NUMR几乎没有影响。利用建立的理论模型,分析了具有三种不同抛光头运动形式的化学机械抛光机床的MRR、NUMR。理论分析及实验结果表明直线轨道式抛光机与弧形轨道式抛光机的MRR、NUMR相差不大；两种轨道式抛光机比定偏心旋转式抛光机具有更高的MRR,更低的NUMR。对三种运动形式的抛光机进行结构方案对比,综合考虑理论分析结果、各自的结构特点,确定了直线轨道式CMP抛光单元设计方案。采用有限元模拟方法,分析了300mm硅片CMP过程中保持环对硅片表面压力分布的影响,发现保持环对硅片边缘的压力分布有很大影响；保持环压力与硅片压力存在一定的匹配关系,合理调整和控制保持环压力,可以大大改善硅片边缘的压力分布。针对硅片表面压力分布均匀性对抛光头加压系统的要求,采用对硅片及保持环分别进行加压和调整的方法设计了CMP加压系统。分别采用气腔及高精度比例调压阀对硅片进行加压及压力调整；提出了一种双弹簧组合弹性元件加压方式用于对保持环进行加压及压力调整,并对弹性元件的加压精度进行了理论分析及实验验证。进行了直线轨道式CMP单元的结构设计,对其主要零部件进行结构分析、动力学分析及结构改进和优化。在此基础上,提出了一种由三个CMP单元集成的多工位、柔性化、全自动CMP设备的设计方案,开发了基于PC的CMP设备监控系统及软件。更多还原

【Abstract】 Chemical mechanical polishing (CMP) is the important technology, to satisfy the local and golobal planarization, in the process of the intergrated circuit (IC) manufacturing. With the development of the IC processing technology, wafer size is increasing, the device feature size is scaling down for the need of the high chip yield and the low manufacturing cost, and the requirement for the CMP technology and equipment becomes higher and higher. The drive system of the large-scale wafer polisher requires high performance because the drive power rises to the second power of the proportion of the wafer scale. The nonunifomity of the pressure distribution on the wafer surface, especially on the edge, make higher demands on the pressure system and the control technology. On the basis of the deep research on the material removal rate (MRR) and the pressure distribution of wafer, the key technology of the CMP equipment is studied, the main contents and conclusions are as follows:The model of the MRR of a point on the wafer is established by velocity vector integral. The effects of the process parameters, such as the rotation speed, reciprocation range and the reciprocation speed, on MRR and the nonuniformity of the material removal (NUMR) are analyzed. The results of the theoretical analysis show that the speed of the polishing plate is the major factor to affect the MRR, but the speed of the carrier has little effect on it. The reciprocation range has some influence on MRR and NUMR, but the reciprocation speed seldom impacts MRR and NUMR.Based on the model, the effects of the three kinematic forms on MRR and NUMR are analyzed. The results of the theoretical analysis and the experiment show that the reciprocation polisher and the oscillation polisher have little difference on MRR NUMR, but the both have higher MRR and less NUMR than the eccentric polisher.Comparing the structure design of three types of polisher, the scheme of the reciprocating polisher is determinated taking into account the structure and the theory results.The effects of the retaining ring on the pressure distribution on 300mm wafer surface are analyzed by finite element model. The results show that the retaining ring has great influence on the pressure distribution on the wafer edge, and there exists the matching relationship between the pressure on the ring and that on the wafer. Reasonable adjustment of the ring pressure will improve the pressure distribution on the wafer edge.Aiming at the requirement of the pressure distribution uniformity on the wafer surface for the polishing-head press system, the press system is designed in manner of the separate pressure regulation on the retaining ring and the wafer. The downforce on the wafer is applied by the air chamber and regulated by the high-accuracy proportional dump valve. A manner to apply the downforce by compound springs is brought forward to press and regulate the pressure on the retaining ring, and the accuracy of the device is analyzed in theory and by experiment.The structure design of the reciprocating polisher is completed, and the static and dynamic analysis of the important parts is carried out in order to perfect the design. And then scheme of the multi-station, flexibility and automatic polishing system has been put forward, also the control system of the equipment is completed on Personal Computer (PC).更多还原