Observation of oxide/Si(001)-interface during layer-by-layer oxidation by scanning reflection electron microscopy

Abstract

We have found that terrace contrast of oxidized Si(001) substrate observed with a scanning reflection electron microscopy (SREM) is reversed by progress in thermal oxidation by one atomic layer of Si. The cause for such terrace contrast reversion is that reflection electron intensity depends on Si-bond direction at oxide/Si interface. This fact was confirmed by calculations based on a multiple scattering theory. The motion of oxide/Si-bulk interface can be, thus, observed by SREM. The reversion and continuous change of the terrace contrast indicate that oxidation occurs monolayer by monolayer on Si(001) substrate.

Water-saturated Si(100)-(2×1): Kinetic Monte Carlo simulations of thermal oxygen incorporation

“…Thus, in most cases the theoretical approaches have provided static equilibrium configurations, from which the growth kinetics could only be extracted in some specific cases. 5,6,8 So far, therefore, complications in the oxidation process have prevented quantitative understanding of silicon oxide formation.…”

“…In both cases there is a need to control the very first interfacial layer of SiO x . Recognizing the limitation of highly successful continuum approaches such as the Deal-Grove model 2 in describing the growth of ultrathin films, researchers over the past decade have devoted considerable effort towards developing experimental techniques [2][3][4][5][6][7][8][9] and first principles calculations [10][11][12][13][14][15][16][17][18][19] in order to arrive at an atomic scale understanding of the initial oxide growth mechanism. Ab initio electronic structure calculations have proven very useful in determining the local initial oxidation configurations and associated energies, [10][11][12][13][14] while ab initio molecular dynamics simulations have been used to depict the interface structure starting from known crystalline structures and interface bonding.…”

Direct observation of two-dimensional growth at SiO2/Si(111) interface

“…However, at the atomic level, the oxidation mechanism is not yet completely understood. Recently, the layer-by-layer process model, where oxidation is modeled as a layer-by-layer process at the SiO 2 /Si interface, was proposed from the measurements of high-resolution transmission electron microscopy (TEM), scanning reflection electron microscopy (SREM), reflection high-energy electron diffraction, and X-ray photoelectron spectroscopy (XPS) [6][7][8][9][10][11][12][13][14][15][16]. In this study, we directly observed the morphology change of the SiO 2 /Si(111) interfaces of oxide films grown at different temperatures, 1050 and 900°C, with various thickness from 4 to 14 nm under near normal conditions where metal-oxidesemiconductor devices are fabricated.…”

Kinetics of Initial Layer-by-Layer Oxidation of Si(001) Surfaces

“…Oxidation of the surfaces was carried out by introducing molecular oxygen into the analysis chamber. Since the electron gun and the energy analyzer were independently evacuated, the AES measurement could be performed under oxygen pressure on the order of 10 26 Torr.As we previously reported, since SREM images of SiO 2 ͞Si systems are obtained by recording the intensity change in reflection spots from a crystal Si substrate covered with an amorphous oxide layer, the interfacial structure can be observed without the need to remove the SiO 2 overlayer [12][13][14]. Figures 1(a)-1(d) show SREM images of Si(001) surfaces before and after oxidation.…”