Optimization And Analysis For The Microelectronic Critical Dimensions Measuring System And Visualization Technology

With the rapid development of semiconductor technology, the technology nodes in the critical dimension(CD) measurements and fabrication process such as the oxidation of various materials and structures, doping, etching, deposition, are also got their great development. However, microelectronic measuring and analyzing techniques have encountered a great challenge due to the increasing complexity of new materials and new structures. Online measurement of critical dimensions is a key link in IC manufacturing.As a result, measuring and analyzing methods, which are more practical and can meet the demanding requirements better, need immediate researches and applications.In contrast with the measuring methods such as scanning electron microscopy(SEM), atomic force microscopy(AFM) and scanning probe microscopy(SPM), advantages of the optical critical dimension(OCD) measuring and analyzing system are classified as lower cost and lower requirements on the measuring environment. Besides, it can provide online and real-time measurement and analysis without any damages to the structures of the samples under test. Therefore, it is well worth detailed study and widely applied in many fields.Critical dimension measurement is an inverse problem of OCD system. In order to solve this problem, various optimization methods for nonlinear problems such as the steepest descent method, Newton method, Gauss- Newton method and LevenbergMarquardt algorithm(referred to as the LM algorithm), are presented in this paper. All these methods are based on the least squares methods. Then examples are given to show optimization and analysis of the critical dimensions of the film/grating structures basing on the LM algorithm. In addiction, another two methods such as searching for the critical dimensions in a database built by the users and a hybrid method combining database with LM algorithm are presented to implement optimization of the critical dimensions in the purpose of achieving global optimization.In addition, as one of the most famous visualizing technologies, Open Graphics Library(OpenGL) is added to the software platform of the OCD system mainly relying on the Microsoft Foundation Classes(MFC). As a result, three-dimensional visualization of the film / grating structures is realized with the use of functions in OpenGL.