In this paper, we demonstrate newly developed process technology to fabricate complementary metal-oxide-silicon field-effect transistors (CMOSFETs) having atomically flat gate insulator film/silicon interface on (100) orientated silicon surface. They include 1,200 C ultraclean argon ambient annealing technology for surface atomically flattening and radical oxidation technology for device isolation, flatness recovery after ion implantation, and gate insulator formation. The fabricated CMOSFET with atomically flat interface exhibit very high current drivability such as 923 and 538 mA/mm for n-channel MOSFET (nMOS) and p-channel MOSFET (pMOS) at gate length of 100 nm when combined with very low resistance source and drain contacts, four orders of magnitude lower 1= f noise characteristics when combined with damage free plasma processes, and one decade longer time dependent dielectric breakdown (TDDB) lifetime in comparison to devices with a conventional flatness. The developed technology effectively improves the performance of the silicon-based CMOS large-scale integrated circuits (LSI).

The angle-resolved Si 2p photoelectron spectra arising from a interfacial transition layer formed on a Si(100) were measured with a probing depth of nearly 2 nm. The novel analytical procedure of these spectra was developed by considering that one SiO2 monolayer, two compositional transition layers (CTLs), and one Si monolayer constituting the Si substrate surface are continuously connected with each other to maintain the areal density of Si atoms. It was found for thermally grown transition layers that two CTLs are formed on the oxide side of the CTL/Si interface and the chemical structures correlated with the residual stress appear on the Si substrate side of the interface. The effects of oxidation temperature in the range from 900 to 1050 °C, annealing in the forming gas, and oxidation using oxygen radicals on the chemical structures of transition layers formed on both sides of the interface were also clarified.

The chemical and electronic-band structures of SiO2/Si interfaces formed utilizing oxygen radicals were investigated by measuring angle-resolved photoelectron spectra arising from Si 2p and O 1s core levels and a valence band with the same probing depth. We clarified that (1) the SiO2/Si interfaces formed exhibited an almost abrupt compositional transition, (2) the valence band offsets at the Si(111)/Si, Si(110)/Si, and Si(551)/Si interfaces are almost the same and are 0.07 eV smaller than that at the SiO2/Si(100) interface.

The electrical and physical properties of ErSi x on n-type Si(100) and Si(551) surfaces are reported. The Schottky barrier heights (SBHs) depend on the Si substrate orientation. On a Si(100) surface, a low electron SBH around 0.3 eV is obtained and the obtained SBH is larger than 0.4 eV on a Si(551) surface, while this difference is caused by the quantity of Si atoms in ErSi x and on Si(100) this is less than on Si(551). These silicidation reactions are very important to develop the future high current drivability devices using any surface orientation.

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