蓝宝石晶片飞秒激光辅助集群磁流变抛光试验研究

Experimental Study on Laser Assisted Cluster Magnetorheological Polishing of Sapphire Substrate

为了实现蓝宝石衬底材料高效高品质超光滑平坦化加工的目的,提出一种先利用飞秒激光对蓝宝石晶片表面材料进行预处理改性后再集群磁流变抛光新工艺,并且研究了飞秒激光扫描速度和集群磁流变抛光时间对激光预处理蓝宝石晶片表面抛光材料去除率和表面粗糙度的影响规律,同时借助X射线光电子能谱(XPS)和X射线衍射(XRD)分析了蓝宝石表面经过飞秒激光处理前后材料特性变化,深入研究了飞秒激光辅助集群磁流变抛光加工机理。研究结果表明,飞秒激光预处理对蓝宝石晶片集群磁流变抛光效果影响显著,蓝宝石晶片用飞秒激光预处理加工后的集群磁流变抛光材料去除率提高了1倍以上,并且飞秒激光扫描速度为100mm/s时,预处理的蓝宝石经过抛光后可以得到较好的表面质量和表面形貌;XPS和XRD检测结果表明蓝宝石衬底表面经过飞秒激光辐照后并未发生化学反应,而是飞秒激光使得蓝宝石表面层晶体结构发生了非晶化和微晶化有利于集群磁流变抛光过程中的材料去除。研究表明,飞秒激光可使蓝宝石表面层发生微晶化和非晶化进而有利于提升集群磁流变抛光蓝宝石的抛光效率和表面性能。

In order to achieve the purpose of high efficiency and high quality ultra-smooth and flat processing of sapphire substrate,a new process of pre-treatment and modification of sapphire wafer surface material by femtosecond laser and then cluster magnetorheological polishing is proposed in this paper.The effects of femtosecond laser scanning speed and cluster magnetorheological polishing time on the material removal rate and surface roughness of laser pretreated sapphire wafer were studied.At the same time,the material properties of sapphire surface before and after femtosecond laser treatment were analyzed by means of X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD),and the mechanism of femtosecond laser-assisted cluster magnetorheological polishing was studied.The results show that femtosecond laser pretreatment has a significant effect on cluster magnetorheological polishing of sapphire wafers.The material removal rate of cluster magnetorheological polishing of sapphire wafers pretreated with femtosecond laser is more than doubled,and when the scanning speed of femtosecond laser is 100mm/s,better surface roughness and surface morphology of sapphire can be obtained after polishing.The results of XPS and XRD show that there is no chemical reaction on the surface of sapphire substrate irradiated by femtosecond laser,but the amorphization and microcrystallization of the crystal structure of sapphire surface layer caused by femtosecond laser are beneficial to the material removal in the process of cluster magnetorheological polishing.It is concluded that femtosecond laser can microcrystallize and amorphize the surface layer of sapphire,which is beneficial to improve the polishing efficiency and surface performance of cluster magnetorheological polishing sapphire.