Segregation and transport coefficients of impurities at the Si/SiO2 interface have been studied. A brief model has been proposed which relates the two coefficients to the oxidation rate and the impurity concentrations at both sides of a Si/SiO2 interface. The model enables us to obtain the transport coefficients from the measured impurity profiles for the first time. The transport coefficients of arsenic and phosphorus are, for example, 0.12 and 5.0 μm/min at 1100 °C, respectively. The segregation coefficients can be also calculated from this model. They are more than 1000 for arsenic and phosphorus, and less than 1 for boron at 1000–1100 °C.

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A new one‐dimensional process simulator, ASPREM or advanced SUPREM, has been developed. ASPREM features the capability for multilayer structures and the incorporation of many up‐to‐date models. In this paper, general features of ASPREM are first described. Then details of many up‐to‐date models, such as oxidation‐enhanced diffusion with or without polysilicon, impurity diffusion in polysilicon and SiO2 , and stress effects to phosphorus diffusion after high dose ion implantation are reported with experimental results. Finally, applications to base‐emitter self‐aligned technology (BEST) transistors are described, followed by brief concluding remarks.

X-ray photoelectron spectroscopy (XPS) has been applied to characterize the damage introduced into SiO2 by ion implantation. By measuring the peak width of Si2p from SiO2 which corresponds to perturbation of the SiO2 network, good depth profiles of the damage have been obtained for implanted samples and subsequently annealed samples. The results show that the damage distributed more widely than that calculated from energy deposition and that the perturbation of the network is caused not only by radiation damage but also by the existence of impurities in the network. It has been found that the XPS method is effective to understand the atomic structure, and thus, electrical properties of SiO2.

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