Bonding Structure of Ultrathin Oxides on Si(110) Surface
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1074-I03-50
Bonding Structure of Ultrathin Oxides on Si(110) Surface Yoshihisa Yamamoto1, Hideaki Togashi1, Atsushi Kato1, Maki Suemitsu1, Yuzuru Narita2, Yuden Teraoka3, and Akitaka Yoshigoe3 1 Tohoku University, 6-3 Aza-Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan 2 Kyusyu Institute of Technology, 1-1, Sensui-mach, Tobata-ku, Kitakyushu, 804-8550, Japan 3 Japan Atomic Energy Agency, 1-1-1, Kouto, Sayo-cho, 679-5148, Japan ABSTRACT The thermal oxidation kinetics of Si(110) surface up to oxide layer thickness of 1 ML has been investigated by real-time monitoring of chemical shift in the Si 2p core-level photoemission using synchrotron radiation. The uptake profiles of every Si oxidation states (Sin+: n = 1 − 4) indicate that the top surface Si(110) oxidation proceeds through a two-step oxidation pathway via Si2+ state, just like the Si(001) surface. In contrast to the Si(001) oxidation, however, Si3+ state is always more abundant than Si4+ state during oxidation. This is related to occurrence of imperfect oxidation of this surface, most probably due to accumulation of compressive strain during oxidation. INTRODUCTION Si(110) surface has a higher hole mobility than on Si(001) surface by a factor of 1.5-2.5 [1]. Moreover, the surface is inevitable in the forthcoming non-planer 3D-CMOS devices as an active channel layer [2]. There has been therefore increasing attention for Si(110) orientation. In order to establish the (110)-based COMS processing, it is of fundamental importance to clarify the initial oxidation process of the Si(110) surface. The importance survives even in the upcoming high-k era because formation of an ultrathin (
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