熔石英再沉积层结构的纳米级表征和杂质分析

利用原子力显微镜观察熔石英不同蚀刻时间的表面形貌,结合二次离子质谱分析,研究了熔石英的再沉积层结构和杂质分布。结果表明,熔石英表面深度10nm的再沉积层内存在大量微裂纹和杂质,经蚀刻展开形成nm级划痕和坑点,其分布随着深度增加呈指数衰减。根据nm级划痕密度、宽深比随蚀刻深度变化的规律,估算出再沉积层厚度,估算结果与二次离子质谱测得的杂质嵌入深度基本一致。杂质元素嵌入深度与抛光微裂纹分布特征的关联性表明,杂质很有可能藏匿在抛光微裂纹中。

Structure characterization of fused silica redeposition layer in nanoscale and analysis of impurities

Polishing-induced redeposition layer of fused silica optics seriously limits the laser damage resistance, and currently the focus of research lies in absorbing impurities. This article focuses on structure characterization of fused silica redeposition layer in nanoscale and analysis of impurities. With atomic force microscopy to observe surface morphology of fused silica at different etching time and using secondary ion mass spectroscopy, such redeposition layer structure and impurity distribution are investigated. The results indicate that a large number of microcracks and impurities existing in redeposition layer within 10 nm deep are formed into nanoscale scratches and pits after etching, which decay exponentially with depth. The thickness of the redeposition layer is estimated based on the evolution of nanoscale scratches density and aspect ratio with etching depth, which is basically consistent with the depth of embedded impurities measured by secondary ion mass spectroscopy. Correlation between depth of embedded impurities and distribution of polishing microcracks shows that impurities are more likely to hide in the polishing microcracks.