Elasto-viscoplastic modeling for three-dimensional oxidation process simulation

With continued minimization of the device structure and the development of new semiconductor process, the characteristics of submicron transistors in ULSI or GSI technologies are strongly affected by multi-dimensional device structure. Process simulations have contributed to a better understanding of device physics and to the development of new processing techniques. Device isolation has been most commonly achieved through the use of LOCOS (LOCal Oxidation of Silicon) or LOCOS derivatives due to its process simplicity and excellent isolation characteristics. With device sizes shrinking, three-dimensional oxidation process simulations are required to predict the accurate shape of the oxide, the stress distribution and the three-dimensional effects, such as center effect and mask lifting effect. Therefore more accurate and robust oxidation model is needed in order to ensure optimal control of the technological oxidation process. In this paper, we developed the three-dimensional process simulator of oxidation with a newly proposed elastoviscoplastic model. In this model, the oxidant diffusion is solved by BEM (Boundary Element Method) which is suitable for moving boundary condition and surface mesh.