低损伤超精密磨削硬脆晶体的摩擦化学反应机理研究

Low-damage ultra-precision machining technology of hard brittle crystal components is needed in fields of optical elements, microelectronic and photo-electronic devices manufacture. Aiming at the needs, the mechanical chemical grinding process which introduces chemical action using soft abrasive grinding wheel is proposed to solve the damage problem caused by mechanical action in ultra-precision grinding using diamond super-hard abrasive grinding wheel. For the process, this research is focused on chemical reaction mechanism and material matching relation between abrasives and work-piece materials under the action of force and heat. The tribochemical reaction mechanism of work-piece surface and process conditions in the grinding process with soft abrasive grinding wheel, and the surface material removal mechanism of mechanical chemical grinding of hard brittle crystal are focused as well. Therefore, the simulation experiments methods are proposed that compound action of force and heat between abrasives and work-piece materials in chemical reaction is produced by high frequency mechanical vibration and microwave heating. The matching system of abrasives and work-piece materials in tribochemical reaction and grinding process conditions are determined through chemical reaction simulation experiments and soft abrasive grinding wheel grinding experiments. The frication/abrasion behavior, adhesion/adsorption behavior and micromechanics behavior on work-piece surface in mechanical chemical grinding are studied, together with micro morphology of work-piece surface and micro structure change of surface/subsurface. Through the studies, the removal mechanism of work-piece surface material is revealed and the material removal model is built. This research provides theoretical guidance for low-damage ultra-precision machining technology of hard brittle crystal.

面向光学元件、微电子和光电子器件制造等领域对硬脆晶体零件低损伤超精密加工技术的需要，为解决金刚石超硬磨料砂轮超精密磨削时机械作用导致的加工损伤问题，提出引入化学作用的软磨料砂轮机械化学磨削工艺。针对该工艺，主要研究力、热作用下磨料与工件材料间的化学反应机理与材料匹配关系，软磨料砂轮磨削环境下工件表面的摩擦化学反应机理与工艺条件，以及机械化学磨削硬脆晶体的表面材料去除机理。为此，提出利用高频机械振动和微波加热方式对磨料和工件材料混合物施加力、热复合作用的化学反应模拟试验方法，通过化学反应模拟试验和软磨料砂轮磨削试验，确定与工件材料发生摩擦化学反应的磨料匹配体系和工艺条件。通过研究机械化学磨削过程中工件表面的摩擦/磨损行为、粘结/吸附行为和微观力学行为，结合工件表面微观形貌和表面/亚表面微观组织的变化规律，揭示工件表面材料的去除本质，建立材料去除模型。为硬脆晶体的低损伤超精密加工提供理论指导。

面向微电子和光电子器件制造等领域对单晶硅、蓝宝石等硬脆晶体基片低损伤超精密加工技术的需求，本项目提出了采用软磨料引入化学作用、弱化机械作用的机械化学磨削新原理新技术，研究了软磨料砂轮机械化学磨削的基础理论、加工工具及其工艺。根据单晶硅和蓝宝石的材料特性以及机械化学磨削原理，建立了机械化学磨削单晶硅和蓝宝石的磨料体系，突破了软磨料砂轮的组织成分设计和制造工艺，研制出系列化软磨料砂轮。通过分析软磨料砂轮磨削硅片的表面微观形貌及其物相变化，揭示了软磨料砂轮利用机械和化学的交替复合作用实现硅片低损伤磨削加工的材料去除和表面形成机理，建立了软磨料砂轮机械化学磨削硅片的材料去除模型。通过系统的硅片磨削试验确定了软磨料机械化学磨削的加工条件和合理加工参数，加工硅片的表面粗糙度Ra≤0.5 nm，亚表面损伤深度≤15 nm，材料去除率≥1 μm/min，接近于化学机械抛光的加工效果，但材料去除率为化学机械抛光的1.5~2倍，实现了硅片高效超低损伤磨削。结合金刚石砂轮磨削和软磨料砂轮机械化学磨削的特点，提出硅片一次装夹定位下，依次采用金刚石砂轮粗磨、精磨和软磨料砂轮机械化学磨削的高效低损伤磨削新工艺，利用该工艺磨削减薄硅片的厚度可以达到40μm。