Correlated diffusion of impurities and silicon in next-generation gate insulating film

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Understanding of silicon diffusion in the course of the advanced IC processing is becoming increasingly important in the era of nanoelectroics. For example, control of unwanted over diffusion of impurities in source and drain regions, formation mechanisms of silicon dioxide, etc. requires understanding of behaviors of silicon atoms. Up to know such details have been neglected in the research despite of its importance.In this project, we have employed two stable isotopes of silicon (^<28>Si and ^<30>Si) as markers for the secondary ion mass spectroscopy (SIMS) measurement to probe the diffusion and chemical reaction of silicon in the process of formation of source-drain regions and of thin film dioxide. We have concentrated especially on the diffusion of ion-implanted boron impurities whose diffusions are affected significantly by SiO defects that are generated at the interface of silicon dioxide and silicon, and diffuse to the region of silicon doped by boron impurities. As a result we have resolved the puzzle of the enhanced boron diffusion reported previously and succeeded in construction of a theoretical model to simulate and reproduce experiments. Such model will be useful for the development of nanosilicon process simulators.