Precise control of Si[001] initial oxidation by translational kinetic energy of O/sub 2/ molecules

The precise control of Si oxidation is necessary for nano-fabrication of ultra-thin gate oxide layers at MOSFET??s in Si-based electronic devices. The translational kinetic energy (E,) of incident 0 2 molecules is a key to control surface reactions. Although the E, of incident 0 2 molecules has been known as an effective factor for both the passive and the active oxidation [ 1,2], the known data concerning the E, dependent oxidation are not enough to obtain the total understanding of incident energy roles. Therefore, the E, dependence of initial oxidation on the Si(OO1) surface has been investigated using a supersonic molecular beam (SSMB) technique and photoemission spectroscopy with high-resolution synchrotron radiation (SR) to make clear how the incident energy affected to the ultra-thin oxide layers formation. Although the saturated oxygen coverage on partially oxidized Si(O0 1) surfaces revealed two potential energy barriers [3], they have not been observed for clean Si(OO1) surfaces. The reason why such a deference appears is discussed on the basis of Si-2p photoemission spectra.