The Principle Of RCWA And Its Application In The Integrated Circuit Measuring

As Integrated Circuit (IC) feature size scaled down from ultra deep sub-microntoward nanometer, some technologies, such as sub-wavelength photolithography,copper interconnection, and novel materials bring more and more challenges to the ICmanufacturing. While Advanced Process Control (APC) is important for processstability and production yield, the control of Critical Dimension (CD) is especiallyimportant. For the CD measurement, Optical Critical Dimension (OCD), which hasbeen developed for several years, has obvious advantages compared to the conventionalelectron microscope measurement. The most effective electromagnetic field algorithmapplied to OCD equipment is Rigorous Coupled Wave Analysis (RCWA), so theresearch on RCWA is very important.This thesis has researched one dimension RCWA, and this method has beenapplied to the OCD equipment, mainly used to CD measurement of IC components. Themain research works are:Firstly, the theories about RCWA used in the periodic structure elements have beengeneralized in detail. The RCWA method used in the analysis the strict numericalsolution of reflectance of rectangular grating with different polarization for thesymmetric and asymmetric cases has been derived in detail firstly, and then introducedto solve the reflectance of multiple step structure grating.Secondly, according to the detailed derivation formula, through writing C++code,completed the one dimension RCWA realization process, and used the algorithm tosoftware development, integrated into the OCD equipment. The simulation platform hasfriendly interface, which can built model and inputted parameters of sample, measuredCD by clicking simple buttons and so on. By comparing with the GSOLVER simulationresults, verified the correctness and good convergence of the simulation platform.Thirdly, this part introduced the CD measurement technology of RCWA in theintegrated circuit. This part verified the stability of OCD, and analyzed the CD ofsilicon trenches and shallow trench isolation by using this simulation platform, bycompared with the analysis results of SEM and KLA company, we can concluded that the simulation platform is good at analyze CD of IC components.Finally, RCWA characteristics are used to research fast build database method.Firstly, the relationships between some grating parameters and the convergence layernumber have been obtained by simulation, then introduced the process and method ofbuild database in detail, at last the correctness and high efficient by using database toanalyze IC component CD can be verified by comparing the results between real-timesample analysis and database analysis.