Real Time Sputter Depth Measurement for In Situ Surface Microanalysis

用二次离子质谱仪(SIMS)和俄歇电子能谱对固体表面的元素组成进行深度分布分析，需要从表面对材料进行离子束溅射，以产生越来越深的陨石坑。只有在测量完成后，才能通过轮廓术测量陨石坑深度，平均溅射率，并完成成分与深度的校准。不幸的是，不同材料的溅射率差异很大，这会改变界面的表观位置。溅射率也与离子产额有关，离子产额影响用于量化SIMS中杂质数据的相对敏感系数。随着工业对更高水平的空间和成分精度的需求的增加，以及为了更快的分析周期，现场和实时测量陨石坑深度和溅射率是很重要的。干涉测量是这类测量的理想工具，因为它精确且非接触式。Charles Evans&amp；Associates建议开发一种可适应现有分析仪器的工具，可提供接近1纳米分辨率的动态深度测量。要做到这一点，必须解决这一独特应用程序特有的几个问题。在第一阶段，研究人员将在受现场应用限制的情况下建造一个演示干涉仪。他们将进行实验，以评估深度分辨率，并研究各种材料和近地表结构的影响。将在第二阶段设计将该装置并入现有的分析仪器。

Depth profile analysis of elemental composition at solid surfaces with secondary ion mass spectrometry (SIMS) and Auger electron spectrometry requires ion beam sputtering of material from the surface to create a crater of increasing depth. Only after the measurement is completed can the crater depth be measured by profilometry, the sputter rate averaged, and the calibration of composition versus depth completed. Unfortunately, sputter rates can vary widely in different materials, which shifts the apparent position of interfaces. Sputter rate has also been linked to ion yield, which affects the relative sensitivity factors used to quantify impurity data in SIMS. As industrial demands increase for higher levels of spatial and compositional accuracy, and for faster analytical turn around, it is important to measure crater depth and sputter rate in situ and in real time. Interferometry is an ideal tool for this type of measurement since it is precise and non-contacting Charles Evans & Associates proposes to develop a tool, adaptable to existing analytical instruments, that provides dynamic depth measurements to a resolution approaching one nanometer. To do this, several issues specific to this unique application must be addressed. During Phase I the researchers will build a demonstration interferometer subject to the constraints of in situ application. They will perform experiments to assess depth resolution and to study the influence of various materials and near-surface structures. A design will be laid out for incorporating this device into an existing analytical instrument in Phase II.