Models for the oxidation of silicon

The dependence of the Si/SiO2 interface characteristics on the thickness and oxidation temperature for SiO2 films grown on different Si orientations was studied by spectroscopic immersion ellipsometry (SIE) and atomic force microscopy (AFM). Essentially, SIE uses liquids that match the refractive index of the films, thereby optically removing the films and consequently increasing the sensitivity to the interface. We show that as the thickness of the thermally grown SiO2 overlayer increases, the thickness of the suboxide layer at the interface also increases, and the average radius of the crystalline silicon protrusions (roughness) at the interface decreases for the three different Si orientations (100), (110), and (111), and two different oxidation temperatures (800 and 1000 °C) studied. The dependence of the interface roughness on the thickness of the SiO2 overlayer was confirmed by AFM. The results include unintentionally and intentionally roughened Si samples and are shown to be consistent with the commonly accepted Si oxidation model.

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“…19 According to the LP model, the relationship between film thickness, L, and oxidation time, t, is:…”

Section: H Experimental Procedures and Data Analysismentioning

confidence: 99%

Si/SiO2 interface studies by spectroscopic immersion ellipsometry and atomic force microscopy

Liu

Wall

Irene

1994

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…It should be noted that all those constants vary with temperature and that the so called 'help time', T , can be of appreciable length: For silicon at 1700°C we have a time of at least several tens of hours, during which the kinetics are basically linear! A nice review of the complexity of the 'simple' parabolic oxidation of Si, particularly in its initial stages, has been given by Irene [20].…”

Section: Basic Passive Corrosion Kineticsmentioning

confidence: 99%

“…(20) because only the Na20 is attacking the protective scale of Si02 by This is the reason why other compounds releasing alkali oxide on decomposition, such as Na2C03, have similar hot corrosion effects. It should be noted that complex salts, in particular those containing vanadium, can have an even stronger hot corrosion effect, as is well known from metals and oxides [69,70].…”

Section: Corrosion By Salt Melts (Hot Corrosion)mentioning

confidence: 99%

“…(19) it can be calculated that only for conditions with a low P(SO3) will we have a dissociation sufficient to drive reaction (20) to the right side. Consequently the window of hot corrosion has a third axis, the P ( S 0 3 ) of the combustion, and it has been computed [71] that the window should only open for low-S fuels (<0.5%, a condition met by many modern fuels) and at comparatively high temperatures (FZ>IOOO"C).…”

Section: Corrosion By Salt Melts (Hot Corrosion)mentioning

confidence: 99%

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Corrosion of Hard Materials

Nickel¹,

Gogotsi²

2000

Handbook of Ceramic Hard Materials

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Corrosion may be defined as the physical and chemical alteration of a material due to its interaction with the environment of interest. It must be emphasized that corrosion resistance is not a material property but a system property and real environments have a high variability in both chemical and physical boundary conditions.Corrosive alteration leads to a change in the desired original properties and so corrosion usually, but not exclusively, has adverse effects and causes a decrease in strength, toughness, hardness, and increases wear. There are many reasons for the degradation of properties by corrosion. Decrease of the cross-section carrying the load, pitting, stress induced by phase changes, and grain separation are some of the common features.Some hard materials, namely Sic and Si3N4, are designed to serve at high temperatures, where corrosion resistance is an essential feature. This is the reason why a large proportion of the ceramic literature on corrosion, including recent textbooks [ 1-51, deals with these materials.In order to react with the environment, the material must not be in equilibrium with it. The hard materials covered in this chapter are non-oxides and hence this condition is fulfilled for all of them in almost every application environment, including ambient air. The applicability of hard materials thus rests on the kinetics of the processes.Before discussing individual materials we will introduce important terms and concepts in corrosion like attack modes, media classes, location of attack, kinetics, and their parameters. We feel that this is necessary for understanding of the discussion of the materials, because there is no generally accepted standard procedure that allows us to compare the corrosion behavior of materials as easily as other properties like mechanical strength or hardness. Corrosive MediaThe compositional variability of environments is so vast that only very few attempts have been made to classify corrosion behavior from the point-of-view of the discrete environment at hand. A noteworthy exception is the Dechema handbook [6],in which valuable information may be found if the corrosive agent is simple and known (e.g. acetates, chlorine, steam). However, its main thrust is on the corrosion of metals.

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“…This is called electronic passivation, and it has not been realized to the same extent with any other semiconductor/dielectric combination. Although oxidation of Si occurs naturally in air, high-quality oxides with controllable properties and thickness are usually prepared by the thermal oxidation of extremely clean single crystal Si wafers at 900-1000 o C 20 . The Si/SiO 2 interface has been extensively studied using ellipsometry.…”

Section: Applications Si/sio 2 Systemmentioning

confidence: 99%

Fundamentals and applications of spectroscopic ellipsometry

Gonçalves¹,

Irene²

2002

Quím. Nova

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Recebido em 1/8/01; aceito em 8/11/01 This paper describes the use of ellipsometry as a precise and accurate technique for characterizing substrates and overlayers. A brief historical development of ellipsometry and the basic principles necessary to understand how an ellipsometer works are presented. There are many examples of studies performed in addressing materials science issues, and several are presented here: measurements of thickness, optical properties, and modeling of surface roughness. These selected results obtained in our laboratory for substrates, Si/SiO 2 interfaces, and polymers provide evidence that ellipsometry can play a critical role in characterizing different types of materials.Keywords: ellipsometry; polarization; films. BRIEF HISTORICAL OVERVIEWEllipsometry (reflection ellipsometry) measures the changes in the state of polarization of light upon reflection from a surface. The fact that changes are measured rather than the absolute intensity of light renders ellipsometry sensitive to submonolayer surface coverage. As a non-invasive and non-destructive tool, ellipsometry requires only a low-power light source and, consequently, it does not affect most processes, which renders ellipsometry a convenient tool for in situ studies 1,2 . P. Drude 3 was the first to build an ellipsometer even before Rothen has coined the word 'ellipsometry ' in 1945 4 . The equipment built by Drude is surprisingly very similar to many types of instruments in use today. Except for sparse papers, this technique received little attention for several decades after Drude, but in the 1970's and 1980's, ellipsometry became widely utilized, and relevant technical papers [5][6][7] and a classical book 8 were produced during this period. In 1991, Azzam compiled a considerable number of papers on ellipsometry 9 . As a search of the literature indicates, the number of papers on experimental improvement of ellipsometers has been decreasing in the last years, because many of the problems that existed before the advance of computers have been solved, including measurement speeds and spectral range. Most of the equipment used today is automated with wide band light sources, scanning monochromators, optical multichannel analyzers, and interfaces with acquisition and analysis software. Early studies on ellipsometry were performed using single wavelength equipment, usually a wide band visible light source with a filter, and later lasers. However, spectroscopic ellipsometers are commonly used nowadays in different research fields. BASIC CONCEPTSA description of ellipsometry as an optical technique would not be complete without mentioning J.C. Maxwell (1831-1879). Maxwell's theory predicts that light is a wave represented by two mutually perpendicular vectors: E, the amplitude of the electric field strength, and B, the amplitude of the magnetic field strength, and both E and B are also perpendicular to the direction of propagation, z. The electromagnetic wave is described by its amplitude and frequency in complex form:where E ...

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Models for the oxidation of silicon

Cited by 93 publications

References 139 publications

Si/SiO2 interface studies by spectroscopic immersion ellipsometry and atomic force microscopy

Si/SiO2 interface studies by spectroscopic immersion ellipsometry and atomic force microscopy

Corrosion of Hard Materials

Fundamentals and applications of spectroscopic ellipsometry

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