Development of holistic measurement concepts for highly resolved measurement of micro structures based on scanning and imaging optical techniques

光学轮廓仪，如相干扫描干涉仪、共焦扫描显微镜以及共焦、焦点和干涉点传感器，由于衍射限制，其横向分辨率能力受到限制。因此，光学测量数据和真实表面形貌数据之间会出现系统性偏差。为了满足不断增长的对光学测量仪器精度的要求，需要改进对潜在影响的物理理解，并考虑所有相关的影响。对于入射光与表面结构的相互作用，精确的模拟模型是必不可少的。这些必须包括在微米和纳米结构光学轮廓术的整体概念中。通过本项目，已经取得了很大的进展，正如它在许多出版物中所记录的那样，所产生的传感器模型在严格模拟的基础上考虑了与测量对象的光学相互作用，即使对于复杂的结构，模拟的地形数据和测量的地形数据也达到了很好的一致性。特别是，三维光传播(锥形照明和衍射)的考虑已被证明是至关重要的。由此产生的新的方法学方法，包括研究基于模型的迭代逆方法，从光学测量数据中精确地重建轮廓，已经针对单个边缘结构进行了示范实施。然而，为了能够有效地使用所开发的模型进行逆轮廓重建，需要将模拟模型扩展到三维结构，同时必须显著减少模拟程序的运行时间。除了更有效的计算方法外，还需要研究通过使用数据库来减少参数空间。两个参与机构的合作在所调查的测量技术、模拟模型的理论基础和现有的测量系统方面提供了一个理想的补充。因此，协同效应产生了，模型可以通过直接比较来验证。光学模型将适应上述不同的测量技术。这同样适用于根据测量数据迭代反轮廓重建的方法，该方法将首先针对受计算时间限制的可变参数数量有限的表面结构而开发。因此，我们预计第二个项目期的研究将为虚拟测量仪器的开发提供实质性的基础，该仪器可用于测量不确定度分析和相关仪器属性的确定，如轮廓或地形保真度。

Optical profilometers such as coherence scanning interferometers, confocal scanning microscopes as well as confocal, focal and interferometric point-sensors are restricted in their lateral resolution capabilities due to the diffraction limit. As a consequence, systematic deviations between optically measured and real surface topography data appear. In order to meet the continuously increasing demands on accuracy of optical measuring instruments, an improved physical understanding of the underlying effects considering all relevant influences is needed. With respect to the interaction of incident light with surface structures, accurate simulation models are essential. These must be included into holistic concepts for optical profilometry of micro- and nanostructures. With the present project, great progress has already been made, as it is documented in numerous publications.The resulting sensor models consider the optical interaction with the measurement object on the basis of rigorous simulations and achieve good agreement between simulated and measured topography data even for complex structures. In particular, the consideration of three-dimensional light propagation (conical illumination and diffraction) has proven to be crucial. The resulting new methodological approach, which consists of the investigation of model-based iterative inverse methods for exact profile reconstruction from the optical measurement data, has already been implemented exemplarily for individual edge structures. However, in order to enable an effective usage of the developed models for inverse profile reconstruction, the simulation models need to be extended to three-dimensional structures and, at the same time, the runtime of the simulation programs must be significantly reduced. Besides more efficient computation methods, the reduction of the parameter space by use of a data base needs to be examined. The cooperation of the two participating institutes provides an ideal complementation with respect to the investigated measurement techniques, the theoretical basics of the simulation models and the available measurement systems. Consequently, synergy effects arise and the models can be validated by direct comparison. The optical models will be adapted to the different measurement techniques mentioned above. The same applies to the methods developed for iterative inverse profile reconstruction from measurement data, which will be developed first for surface structures with a limited number of variable parameters due to computation time.Therefore, we expect that the investigations of the second project period will provide a substantial basis for the development of virtual measurement instruments, which can be used for the analysis of measurement uncertainty and for the determination of related instrumental properties such as profile or topography fidelity.