STM study of thermal oxide/Si(001) interface morphology

M. Gotoh, K. Sudoh and H. Iwasaki

The Institute of Scientific and Industrial Research (ISIR), Osaka University
8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

We have developed a novel method to observe the Si/SiO2 interface morphology with subnanometer resolution by an ultrahigh vacuum scanning tunneling microscope (UHV-STM) [1]. The silicon-oxide-overlay is removed selectively by a low-energy electron stimulated reaction (LEESR), irradiating an electron beam from the STM tip at a temperature of 300 イ. Now we applied this method to observe the interface between a Si(001) substrate and the oxide formed by introducing oxygen at 600 イ (thermal oxide) and at room temperature (RT-oxide). We found that the thermal oxide/Si interface exhibits terrace-step structure but the RT-oxide/Si interface does not.

[1] M. Gotoh, K. Sudoh and H. Iwasaki, J. Vac. Sci. Technol. B 18(4) (2000) 2165.