HfO_2顶层多层介质膜脉宽压缩光栅的离子束刻蚀  

Ion beam etching for multilayer dielectric pulse compressor gratings with top layers of HfO_2

作　　者：徐向东[1] 刘颖[1] 邱克强[1] 刘正坤[1] 洪义麟[1] 付绍军[1] 

机构地区：[1]中国科学技术大学国家同步辐射实验室,合肥230029

出　　处：《物理学报》2013年第23期165-172,共8页Acta Physica Sinica

基　　金：国家高技术研究发展计划资助的课题~~

摘　　要：多层介质膜光栅是高功率激光系统的关键光学元件.为了满足国内强激光系统的迫切需求,首先利用考夫曼型离子束刻蚀机开展了HfO2顶层多层介质膜脉宽压缩光栅的离子束刻蚀实验研究.采用纯Ar及Ar和CHF3混合气体作为工作气体进行离子束刻蚀实验,获得了优化的离子源工作参数.结果表明,与纯Ar离子束刻蚀相比,Ar和CHF3混合气体离子束刻蚀时的HfO2/光刻胶的选择比大.HfO2的离子束刻蚀过程中再沉积效应明显,导致刻蚀光栅占宽比变大.根据刻蚀速率分布制作的掩模遮挡板可以提高刻蚀速率均匀性,及时清洗离子源和更换灯丝,可保证刻蚀工艺的重复性.利用上述技术已成功研制出多块最大尺寸为80 mm×150 mm、线密度1480线/mm、平均衍射效率大于95%的HfO2顶层多层介质膜脉宽压缩光栅.实验结果与理论设计一致,为大口径多层介质膜脉宽压缩光栅的离子束刻蚀提供了有益参考.Multilayer dielectric grating （MDG） is one of the key optical elements of high-power laser systems. To meet the need of MDGs for high-power laser systems, experimental investigation on MDG with a top layer of HfO2 has been carried out using Kaufman-type ion beam etcher. The optimal ion source conditions have been obtained by etching of HfO2 in pure Ar and Ar/CHF3 mixture plasmas. Compared with pure Ar plasma etching, better selectivity was achieved with Ar/CHF3. The redeposition of sidewalls effects are quite obvious during etching, which results in the increase in duty cycle of etched grating. As there is a distribution of etch rate along the direction normal to the scan movement, a special-shaped mask was made to be used as a substrate holder, which increases uniformity of the etched profile. In order to process repeatability, the ion source should be cleaned up, the cathode and neutralizer filament should be changed after etching process to full completion. Based on the above techniques, a number of MDGs have been achieved, each of which has a mean diffraction efficiency greater than 95%, a line density 1480 lines/mm, and on aperture up to 80 mm×150 mm. Experimental results agree fairly well with the designed, which provides a good reference for the large aperture MDGs ion beam etching.

关 键 词：光栅 多层介质膜 离子束刻蚀 

分 类 号：TN248[电子电信—物理电子学]