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、焦点和干涉测量点传感器由于衍射极限而在其横向分辨率能力方面受到限制。结果，光学测量的和真实的表面形貌数据之间出现系统偏差。为了满足对光学测量仪器精度不断提高的要求，需要考虑所有相关影响，对潜在效应进行更好的物理理解。对于入射光与表面结构的相互作用，精确的仿真模型是必不可少的。这些都必须纳入整体概念的光学轮廓的微米和纳米结构。目前的项目已经取得了很大的进展，正如许多出版物所记载的那样，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，模拟和测量的地形数据之间也达到了良好的一致性。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，其中包括基于模型的迭代逆方法的调查，从光学测量数据的精确轮廓重建，已经实施了示范性的个人边缘结构。然而，为了使开发的模型的有效使用的逆轮廓重建，仿真模型需要扩展到三维结构，在同一时间，仿真程序的运行时间必须显着减少。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提供了一个理想的补充方面的调查测量技术，理论基础的模拟模型和可用的测量系统。因此，协同效应的出现和模型可以通过直接比较来验证。光学模型将适用于上述不同的测量技术。这同样适用于为从测量数据进行迭代逆轮廓重建而开发的方法，由于计算时间的原因，这些方法将首先针对具有有限数量可变参数的表面结构进行开发。因此，我们预计项目第二阶段的研究将为虚拟测量仪器的开发提供实质性基础，其可用于测量不确定度的分析和用于确定相关的仪器特性，例如轮廓或形貌保真度。

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.