Corner roundness and contact area algorithms for reticle metrology through the use of region connectivity extraction
Roman Kris, Gidi Gottlib, Ovadya Menadeva, Ram Peltinov, Liraz Seagl, Naftali Shcolnik, Aviram Tam, Arcadiy Vilenkin · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2003
SEM Metrology becomes the standard metrology for the mask industry, as the precision and accuracy requirements tighten continuously. In this paper we consider the basic requirements for performing 2D measurements of the reticle, such as contact area and corner roundness as well as the algorithmic development to generalize a solution for these requirements. We consider three main requirements from such algorithm: a) To be generic and deal with general shape features. b) To measure new geometric metrics - such as contact area and corner roundness. c) TO measure new geometric patterns suhc as OPC features and small CDs. These challenges require the development of new algorithms for CD metrology. These algorithsm perform detection and measurement of new geoemtric objects, and provide the repeatability and robustness for reticle production process control. In the first part of the paper we will describe the novel algorithm for detection of general shape features - "Region Connectivity Extraction". In the second part of the paper, we will provide mathematical tools that we have implemented for analyzis of corner roundness of noisy contours and demonstrate the performance of these algorithms for synthetic contours of different shapes with different noise levels. We will conclude with the application of our algorithm and analysis of real SEM images of the reticle features.