Silicon oxidation model

Oxide Thickness Versus Time. Silicon oxidation has been modeled by using the linear-parabolic macroscopic formulation of Deal and Grove (69). As a starting point for the study of this model, the kinetics of oxidation... 

Analysis of a vast amount of data by Reisman et al. (72) has shown that silicon oxide thickness versus time can be modeled by a general power law of the form... 

In coating technology, surfaces are coated to protect them from corrosion. This is usually done by a layer containing polymer, pigment, etc.. As a model system, thin polystyrene films on silicon oxide have been studied [150,151]. Does polystyrene form a stable layer or would you expect it to dewet the surfaces assuming that van der Waals forces dominate ... 

The sedimentation diffusion model, when applied to the silicon oxide system, gave solid settling velocities several times higher than predicted hy theory. Solid dispersion coefficients, however, did mostly agree with the Kato correlation. 

Infrared spectra were recorded on a Perkin-Elmer Model 983G double-beam spectrophotometer in the transmission mode using 3500 A thick PBTMSS films spin-coated and processed on polished NaCl plates. Spectral subtraction and absorbance correction to account for the decreased film thickness were used to isolate the silicon oxide absorption band at about... 

It is known that the presence of oxygen in silicon microelectronic elements can considerably affect their electrophysical properties. Concentration of oxygen can decrease due to reaction between oxygen and silicon (oxidation of silicon). Let us consider a possible influence of the size on above-mentioned chemical reaction in a spherical silicon nanoparticle. We accept the model used in [2]. In this model it is supposed that oxidation of silicon by molecular oxygen takes place over the whole volume of silicon. Under this assumption the concentration of oxygen in the particle can be found from the following equation ... 

A New Model. The results of the studies on anodic oxide films (see section 5.9 and chapter 3 on passive film and anodic oxides) show that anodic oxide properties (oxidation state, degree of hydration, 0/Si ratio, degree of crystallinity, electronic and ionic conductivities, and etch rate) are a function of the formation field (the applied potential). Also, they vary from the surface to the oxide/silicon interface, which means that they change with time as the layer of oxide near the oxide/silicon interface moves to the surface during the formation and dissolution process. The oxide near the silicon/oxide interface is more disordered in composition and structure than that in the bulk of the oxide film. Also, the degree of disorder depends on the formation field which is a function of thickness and potential. The range of disorder in the oxide stmcture is thus responsible for the variation in the etch rate of the oxide formed at different times during a period of the oscillation. The etch rate of silicon oxides is very sensitive to the stmcture and composition (see Chapter 4). 

Passivation Models. The models based on surface passivation suggest that a passive layer, similar to the silicon oxide formed under an anodic potential, exists on... 

In a slightly different angle, Kendall reasoned that beeause the 111 surfaee is oxidized thermally more rapidly than other low-index surfaees, the silicon surface ean be covered with a silicon oxide (or a hydrated silieon oxide) during etehing in aqueous solution, mueh faster than other planes. The formation of the oxide film passivates the (111) plane and blocks the dissolution reaetions. This model implies that the etch rate of a (111) surface should be similar to that of silieon oxide in KOH solu-... 

The models based on surface passivation suggest that a passive layer, similar to the silicon oxide formed under an anodic potential, exists on (111) silicon at OCP but not on other planes [82, 126, 156]. Instead of oxide, formation of inactive hydration complexes of K+ and OH-has been proposed to block the (111) surface [49, 134]. The fact that the relative etch rates of the different planes vary with the type of solution was attributed to the orientation-dependent adsorption of solvation complexes on the surface. 

Among the SAMs suitable for coating silicon, the OTS based variety is the most widely used. Some of the properties for the OTS SAM, of relevance to MEMS, are listed in Table 1. Although there is much debate concerning the true structure of the OTS monolayer on silicon oxide. Fig. 5 illustrates a simplified conceptual model of the film. 

Membrane structures that contain the visual receptor protein rhodopsin were formed by detergent dialysis on platinum, silicon oxide, titanium oxide, and indium—tin oxide electrodes. Electrochemical impedance spectroscopy was used to evaluate the biomembrane structures and their electrical properties. A model equivalent circuit is proposed to describe the membrane-electrode interface. The data suggest that the surface structure is a relatively complete single-membrane bilayer with a coverage of 0.97 and with long-term stability/... 

In 1990, Canham observed intense visible photoluminescence (PL) from PSi at room temperature. Visible luminescence ranging from green to red in color was soon reported for other PSi samples and ascribed to quantum size effects in wires of width 3 nm (Ossicini et al, 2003). Several models of the origin of PL have been developed, from which we chose two. In the first (the defect model), the luminescence originates from carriers localized at extrinsic centers that are defects in the silicon or silicon oxide that covers the surface (Prokes, 1993). In the second model (Koch et al., 1996), absorption occurs in quantum-confined structures, but radiative recombination involves localized surface states. Either the electron, the hole, both or neither can be localized. Hence, a hierarchy of transitions is possible that explains the various emission bands of PSi. The energy difference between absorption and emission peaks is explained well in this model, because photoexcited carriers relax into surface states. The dependence of the luminescence on external factors or on the variation of the PSi chemistry is naturally accounted for by surface state changes. 

An experimental study on the oxidation of alloys containing 0-9 mass% Cr and 0-1 mass% Si in carbon dioxide at 500°C has been reported by [1982Mos], Several experimental techniques were used for this investigation (X-Ray, TEM, SEM, Photoelectron microscopy), fliey studied flic silicon distribution in the alloys and compared the results with theoretical predictions by an oxidation model. An attempt to grow materials with a eutectic composition in this ternary system by directional soUdrfication was made by [1978Hao]. However, the alloys were found to have no eutectic. 

Figure 6.1 Retention of pyridine and phenol on a model silica surface, (a) The model silanol phase, (b) the siloxane phase, (c) the ionized silicon oxide phase, (d) adsorption of pyridine on a silanol phase, and (e) adsorption of phenol on a silanol phase. White, light-gray, gray, and black balls represent hydrogen, nitrogen, silicon, and ojiygen, respectively. Reproduced by permission of Springer, ref. 22.

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