单晶碳化硅电化学机械平坦化的复合增效技术与摩擦磨损机理

We propose a novel technology of ultrasonic vibration assisted ectrochemical mechanical planarization (UVA-ECMP) featured by using catalyst metal pad in water-based electrolytes without abrasives. Based on a series of simulated UVA-ECMP tests for single crystal silicon carbide (SiC), aided with surface microscopic measuring and detecting means, the performances of SiC under tribochemical, catalysis, electrochemical and ultrosonic vibration states are investigated. The effects of various factors on friction and wear characteristics and on surface/subsurface quality are systematically studied, and the multi-parameter optimization model with material removal rate(MRR) as the objective is obtained and the mechanisms of compounded MRR-enhancement are explored.Through finite element /molecular dynamics simulation techniques coupled with chemical action dynamics theory and density function theory, the different etching rates of different cyrstalline faces of SiC, and the micro/nano- generation and removing process of its oxidation product under ultrosonic vibration and tribochemcal actions are simulated, and the tribological mechanisms of UVA-ECMP are further illuminated. The process optimazation measures of UVA-ECMP are proposed for SiC, and its evaluation bench tests are done to obtain an order higher MRR compared with that of traditional manufacturing technology, while maintaining the good surface/subsurface quality of SiC. This project has great practical significance and scientific value to enrich nano-tribology and tribo-electrochemistry, and to improve the level of ultro-precision manufacturing technology of SiC.

提出在无磨粒水基电解质中应用催化金属研抛盘、并辅以超声振动的电化学机械平坦化（ECMP）新技术。基于单晶SiC的超声振动辅助-ECMP模拟实验和表面微观检测手段，系统研究SiC研抛过程中摩擦化学、催化、电化学和超声振动作用下各因素对SiC摩擦磨损及表面/亚表面质量的影响规律和复合增效机理，获得以SiC磨损率为目标的多参量优化模型；结合化学反应动力学和密度泛函理论以及有限元和分子动力学仿真技术，模拟不同晶面SiC的各向异性腐蚀以及超声振动和摩擦化学反应条件下SiC表面氧化物的微纳加工去除过程，进一步揭示SiC超声振动辅助-ECMP的摩擦磨损机理；提出SiC超声振动辅助-ECMP的工艺优化措施并进行实验验证，在保证获得无损伤亚纳米光滑表面的基础上使材料去除率较传统工艺提高一个量级以上。项目研究对于丰富纳米摩擦学和摩擦电化学理论以及提高SiC超精密加工水平具有重要的科学价值和实际意义。

针对碳化硅材料，分别对磁场辅助电化学机械研抛（MA-ECMP）、超声振动辅助电化学机械研抛（USA-ECMP）进行了理论仿真分析和实验研究。针对单晶碳化硅，对其CMP的机械刻划作用及其在超声振动作用下的影响规律进行了分子动力学（MD）仿真。在CMP理论仿真方面，通过对MA-ECMP和USA-CMP过程分别进行了流场、温度场、磁场和电场以及反应介质质量传递过程的仿真分析；研究了超声振动的振幅、频率、流场膜厚与带孔抛光垫等对流场绝对压强、流速、气含率、磨损量等特征的影响规律。采用金刚石磨粒对立方碳化硅进行了机械刻划过程的MD仿真研究，分析刻划速度、刻划深度、磨粒大小对刻划过程中的材料形貌变化、晶体结构变化、温度、切削力、去除率和势能等相关宏观量的影响。并通过建立碳化硅表面的二氧化硅层模型，MD模拟抛光过程参数对SiC表层氧化膜刻划的影响规律。.在实验研究方面，分别研制了MA-ECMP试验机以及USA-ECMP实验机，研究了不同研抛液、外加电场、辅助磁场和磁流变液对SIC摩擦磨损性能的影响规律。分别应用铸铁抛光盘、聚氨酯抛光盘、半固定磨粒抛光盘三种抛光盘在自来水、KOH溶液、芬顿反应液三种研抛液中对SiC进行了超声-电化学机械研抛试验，获得了不同工艺参数对抛光参量的影响规律，研究对改进碳化硅的高效超精密加工工艺、抛光增效机理研究提供了重要依据和指导。