超薄激光晶片的超精密加工工艺及几何精度和表面质量协调控制方法

To meet the demand for YAG and GGG ultra-thin crystal substrate used in high power thin-disk laser, aiming at the problem of difficult to achieve ultra-thin crystal substrate with high accuracy and surface quality by using traditional lapping and polishing technology, a new ultra-precision processing technology combining the fixed abrasive lapping and chemical mechanical polishing is proposed. Through theoretical simulation and experimental investigation on the interaction between particles and crystal substrate, the mechanic-chemistry action between slurry, polishing pad and crystal substrate, the machining stress and particle trajectories distribution during processing, the stress and deformation of crystal substrate in the machining process and the bonding process of crystal substrate and carrier, reveal the mechanism of material removal, the formation mechanism of surface/subsurface damage and the formation mechanism of high-precision and ultra-smooth surface in fixed abrasive lapping and chemical mechanical polishing of ultra-thin crystal substrate. Furthermore, establish the theoretical modeling of surface quality and geometric accuracy of ultra-thin crystal substrate, research key technologies such as controllable loading of lapping and polishing load, and online measurement of crystal substrate thickness, high precision and reliability bonding of crystal substrate, in accordance with theoretical model and by use of key technologies, realize the cooperative control of the geometric accuracy and surface quality of ultra-thin crystal substrate. Finally, develop a new ultra-precision machining technology of ultra-thin crystal substrate with independent intellectual property right.

面向高功率盘片激光器制造对超薄激光晶片的需求，针对传统研磨和抛光工艺难以保证超薄激光晶片加工精度的问题，以YAG和GGG激光晶片为加工对象，提出固结磨料研磨和化学机械抛光相组合的超精密加工工艺，通过对加工过程中磨粒与激光晶片表面相互作用、抛光液和抛光垫与激光晶片表面机械化学作用、加工应力和磨粒轨迹分布仿真和试验研究，揭示激光晶体加工过程中材料去除机理、加工表面损伤形成和演变机理、超薄激光晶片加工应力和变形规律、超薄激光晶片固持过程中力热行为和超薄激光晶片变形规律以及超薄激光晶片高精度超光滑表面形成机制，建立超薄激光晶片表面质量和几何精度的理论建模，突破超薄激光晶片加工过程中可控加载、超薄激光晶片厚度在线检测、超薄激光晶片高精度高可靠固持等关键技术，实现超薄激光晶片几何精度与表面质量的协调控制，开发具有自主知识产权的超薄激光晶片的超精密加工技术。

针对高性能激光晶体基片的硬脆难加工材料特性、超薄低刚度结构特点和高精度高表面质量加工要求，研究了激光晶体超精密抛光中的材料去除机理和微观形貌演化规律、低刚度晶体基片高精度低应力固持方法及固持变形规律、超薄激光晶体基片的加工变形规律及研磨抛光中的面形精度和表面粗糙度变化规律，以及激光晶体基片的抛光中的面形精度和表面质量协调控制方法；研发了超精密固结磨料双面抛光和化学机械抛光装备及其集成工艺，实现了高性能超薄激光晶体的高效超精密加工，研究结果表明:（1）新型激光晶体CMP高效抛光液，与传统硅溶胶抛光液相比材料去除率提高240%；（2）提出的基于切槽上盘粘接的超薄晶片高精度低应力固持方法，与传统整面上盘粘接固持方法相比固持变形量可降低75%。（3）提出的单面抛光面形预测模型精度能达到12%，实现了面形的有效预测；（4）提出的双面行星研磨工件上下表面平面度预测方法可实现研磨面形的有效预测；（5）提出“双面研磨-双面抛光-单面化学机械抛光”的超薄石英晶片超精密加工工艺，可获得表面粗糙度0.58 nm，平面度1.3 μm的石英晶片；（6）抛光压力为90 N，抛光时间为105 rpm，抛光转速为6 rpm时，超薄石英晶片的面形精度和表面粗糙度能达到最优。