Reflectance anisotropy spectroscopy (RAS) for III/V semiconductor crystal dry-etching (RIE) for in-situ identification of self-organized roughness (roughness-RIE-RAS)

在某些参数范围内，例如半导体表面的无掩膜（可能是反应性）离子（束）干蚀刻（IE， IBE， RIE， RIBE）可以产生锥体或波状特征，典型特征长度为10- 100nm。这些发现的原因是自组织。特征结构在表面上排列不规则，但在平面上分布密集。在短暂的蚀刻时间后，形貌保持稳定，并且在表面上进一步蚀刻只是作为一个整体。反射各向异性光谱（RAS）已经发展成为一种强大的表面敏感光学测量技术，用于外延半导体生长的原位监测。但在申请人的研究小组中，也已经进行了许多成功的尝试，使用RAS来监测干式蚀刻过程，到目前为止，主要是用于蚀刻参数，这导致了光滑的蚀刻前沿（到目前为止，可以精确地控制蚀刻深度），但初步也已经在参数范围内，其中某些自组织的表面粗糙度形态演变。根据器件应用的不同，自组织表面结构是有利还是不利的。理想情况下，在蚀刻过程中可以实时抑制或促进其发生。RAS可以提供对表面的现场监测和控制，允许进行适当的蚀刻参数更改。这是本提案的主要思想。要进行的特别调查是，RAS是否以及如何适合作为识别和分类这些自组织表面粗糙度形态的原位工具。

In certain parameter ranges maskless (maybe reactive) ion (beam) dry-etching (IE, IBE, RIE, RIBE) e.g. of semiconductor surfaces can result in characteristic morphologies like cones or wavelike features with typical characteristic lengths of 10-100 nm. The reason for these findings is self-organization. The characteristic structures are irregularly arranged on the surface, but lie dense in the plane. After a short etch time the morphologies stay stable and further on the surface is only etched as a whole.Reflection anisotropy spectroscopy (RAS) has already been developed to a powerful surface-sensitive optical measurement technique for the in-situ monitoring of epitaxial semiconductor growth. But in the applicant’s research group also already many successful attempts have been pursued to use RAS for the monitoring of dry-etch processes, so far mainly for etch parameters, which result in smooth etch fronts (so far to control etch-depth precisely), but rudimentarily also already in parameter ranges, where certain self-organized surface roughness morphologies evolve.Depending on device applications self-organized surface-structuring is disadvantageous or advantageous. Ideally its occurrence can be suppressed or promoted in real time during the etch process. RAS could provide for in-situ monitoring and control of the surface, allowing to make appropriate etch parameter changes. This is the main idea of this proposal.In particular investigations on the question are to be performed, whether and how RAS is suitable as an in-situ tool for identification and classification of these self-organized surface roughness morphologies.