碳化硅圆柱槽微结构表面的化学机械抛光

Chemical Mechanical Polishing of Micro-structures on SSiC

目前工业界对高精度微结构功能表面玻璃元件,比如作为高性能二极管激光器准直透镜关键元件的圆柱槽阵列微结构功能表面玻璃元件的需求日趋增加,而其微结构表面质量的优劣也会直接影响激光器输出功率的大小。该类元件能否很好的实现其特定的光学功能取决于玻璃模压用具有微结构表面的模具(如碳化硅陶瓷等)最终加工质量,但由于碳化硅等陶瓷的超硬材料属性导致其微结构表面在精密磨削后还需要进行后续的抛光加工以达到使用精度要求。因此针对精密磨削后的无压烧结碳化硅(SSi C)微结构表面展开原位化学机械抛光(CMP)试验,试验结果表明,微结构表面粗糙度Ra及面形精度PV由磨削后的71.8 nm和2.14μm降低到了抛光后的7.7 nm和0.46μm;抛光后微结构尖角处形貌完整无破损,但尖角圆弧半径R有所扩大,由磨削后的8.082μm增大到9.294μm;微结构亚表面裂纹深度经抛光后由磨削后的5μm左右降低至1μm左右,从而有效地提高了模具精度。

At present, the application of the micro-structured optical elements is continuously expanding, while the micro-structured surfaces should meet the required final quality to ensure the specific optical function. For example, collimation lenses for high performance diode lasers show an increasing industrial application with the requirement for micro-structured glass optical elements with cylindrical lens arrays, and the worse quality of cylindrical lens arrays may decrease the power output of the lasers. In essence, the optical properties of optical elements depend on the machined quality of the micro-structured mold used for the replication of the optical elements. However in consideration of the excellent property of pressureless sinter silicon carbide （SiC）, the ground micro-structured surface quality is hard to meet the requirement, therefore the in-situ abrasive polishing of micro-structures of molds is proposed. The experimental results show that the surface roughnessRa and profile accuracy PV of the micro-structured surface decrease from 71.8 nm and 2.14 μm through grinding to 7.7 nm and 0.46 μm through abrasive polishing. In addition, the morphology of the polished groove tip is more integrated, while the tip radiusR is expanded from 6.882 μm to 9.2936 μm after polishing. Moreover, although the sub-surface crack is not yet completely removed after polishing, the deepness of the crack is obviously shallow which effectively improve the service life of molds.