HfO_2顶层多层介质膜脉宽压缩光栅的Piranha溶液清洗

Cleaning multilayer dielectric pulse compressor gratings with top layer of HfO_2 by Piranha solution

为了提高HfO2顶层多层介质膜脉宽压缩光栅(PCG)的抗激光损伤性能,使用Piranha溶液(浓硫酸和双氧水的混合液)清洗PCG去除其制作工艺和使用过程中残留在表面的污染物,包括CHF3作为工作气体对HfO2进行反应离子束刻蚀生成的碳氟化合物及金属氟化物。对Piranha溶液的清洗温度、组成成分、清洗时间、清洗遍数等参数进行了系统研究,用扫描电子显微镜(SEM)观察清洗前后的PCG表面形貌,用X射线光电子能谱仪(XPS)检测清洗前后PCG表面的元素成分及其原子分数的变化,并分析了各残留污染物的去除机理。实验结果表明:Piranha溶液能有效去除PCG表面污染物,而且清洗温度越高,清洗遍数越多,对PCG表面残留污染物的去除效果越显著。在90℃下60min有效活性时间内,使用浓硫酸和双氧水体积比为2∶1的Piranha溶液清洗3遍以上,PCG表面残留的F元素的原子分数接近0.1%(XPS的分辨极限),达到良好的清洗效果。

： In order to improve the resistance of multilayer dielectric pulse compressor gratings （PCGs） with top layer ,,）f HfO2 to laser damage, the residues including carbon fluorinated compounds and metal compounds containing fluorine, which are left on the surface of PCG during ion reactive etching of HfO2 with working gas of CHF3 , have been cleaned by Piranha solmion （the mixture of 98 % H2 SO4 and 30 % H2O2 ）. The parameters of Piranha solution cleaning, such as cleaning temperature, corn position, cleaning time, and times of cleaning, were studied systematically. Scanning electron microscope（SEM） was presented to observe the grooves of PCG and X-ray photoelectron spectroscopy（XPS） was employed to evaluate different elements on the sur face of PCG before and after cleaning. The removal mechanism of residual contaminants was analyzed. The experimental resuhs show that higher removal efficiency can be achieved with more times of cleaning and higher cleaning temperature. In the cleaning active time of 60 minutes at the temperature of 90℃, the atomic fraction of residual fluorine on the surface of pt;（; which were cleaned for three times or more was close to 0.1% （the resolution limitation of XPS）, when the volume ratio of H2SO4 to H2O4, was 2 ： 1.