The Journal of Physical Chemistry C, 2013

Continued miniaturization of metal-oxide-semiconductor field-effect transistors (MOSFETs) requires an ever-decreasing thickness of the gate oxide. The structure of ultrathin silicon oxide films, however, critically depends on the oxidation mechanism. Using reactive atomistic simulations, we here demonstrate how the oxidation mechanism in hyperthermal oxidation of such structures may be controlled by the oxidation temperature and the oxidant energy. Specifically, we study the interaction of hyperthermal oxygen with energies of 1−5 eV with thin SiO x (x ≤ 2) films with a native oxide thickness of about 10 Å. We analyze the oxygen penetration depth probability and compare with results of the hyperthermal oxidation of a bare Si(100){2 × 1} (c-Si) surface. The temperature-dependent oxidation mechanisms are discussed in detail. Our results demonstrate that, at low (i.e., room) temperature, the penetrated oxygen mostly resides in the oxide region rather than at the SiO x |c-Si interface. However, at higher temperatures, starting at around 700 K, oxygen atoms are found to penetrate and to diffuse through the oxide layer followed by reaction at the c-Si boundary. We demonstrate that hyperthermal oxidation resembles thermal oxidation, which can be described by the Deal−Grove model at high temperatures. Furthermore, defect creation mechanisms that occur during the oxidation process are also analyzed. This study is useful for the fabrication of ultrathin silicon oxide gate oxides for metal-oxide-semiconductor devices as it links parameters that can be straightforwardly controlled in experiment (oxygen temperature, velocity) with the silicon oxide structure.

Physica Status Solidi (a), 1992

Thermal oxidation of silicon in the thin regime is of vital importance to VLSI device engineers because thin layers of SiO, are exclusively used as the gate dielectric for high performance of MOS devices. There exists a number of models to explain this kinetics of oxidation. However there is a considerable variance among the reported rate constants, which are supposed to describe the oxidation process. Rather than arriving at an alternative model, the present study aims at simulation of existing models of oxidation in dry oxygen, with a set of experimental data and arrive at the best possible model and provide accurate rate constants for oxidation in dry oxygen. These experimental data have been obtained, earlier, using high-resolution transmission electron microscopy (HRTEM) and ellipsometry techniques to measure thickness of silicon oxide, grown at 800 "C in dry oxygen, in the thickness range of 2 to 20 nm. Die thermische Oxydation von Si im diinnen Bereich ist besonders wichtig fur VLSI-Device-Ingenieure, weil diinne Si0,-Schichten ausschlieljlich als Gate-Dielektrikum fur Hochleistungs-MOS-Devices verwendet werden. Es gibt eine Reihe von Modellen zur Erklarung der Oxydationskinetik. Die angegebenen Werte der den Prozelj beschreibenden Konstanten variieren jedoch erheblich. Es wird hier kein neues Modell entwickelt, sondern die existierenden Modelle werden mit experimentellen Daten simuliert, urn zum besten Modell und genauen Konstanten fur die Oxydation in trockenem Sauerstoff zu gelangen Die experimentellen Daten stammen von friiheren HRTEM und ellipsometrischen Messungen der Dicke des bei 800 "C in trockenem Sauerstoff gewachsenen SiO, im Bereich von 2 bis 20 nm.

Materials Research Bulletin, 1999

In the present investigation, ultrathin oxides of silicon (Ͻ250 Å) were grown on p-type (100) oriented monocrystalline silicon, employing a low-temperature wet oxidation technique. The effect of furnace temperature (600 and 700°C), water vapor pressure (0.3-1.0 atm), and oxidation time (15-180 min) on the rate of oxide growth was studied. The oxidation rates observed in the present investigation were fitted to the theoretical model proposed by da Silva and Stosic (Semicond.

Applied Physics Letters, 1993

Advanced Materials for Optics and Electronics, 1993

The oxidation of single-crystal silicon wafers has been investigated using an industrial thermal oxidation system. The growth characteristics and electrical properties of the oxides resulting from pure hydrogen/ oxygen (H2/ 02), t richloroet hane/ oxygen (TCA/ 0 2) and hydrogen chloride/oxygen (HC1/02) mixtures have been investigated and compared. The addition of both HCI and TCA to oxygen produces higher growth rates and improved electrical characteristics. It is shown that the oxidation rate for TCA/02 is approximately 30%-40% higher than for HC1/02 and that comparable electrical properties can be readily obtained. A TCA/02 ratio of 1 mot% gives the optimum process for VLSl applications, though 3 mot% HCI/02 gives comparable results. It is suggested that the overall mechanisms governing the processes are similar. However, the TCA process is a safer and cleaner alternative because it generates HCI in situ in the oxidation chamber. KEYWORDS Thermal oxidation Kinetics Electrical properties Trichloroethane (TCA) Hydrogen chloride (HCI) Hydrogenloxygen (H2/02

Materials Science and Engineering: B, 1998

A pyrogenic steam generator is implemented in a conventional AST SHS2800m RTP system to produce H 2 O gas ambient for oxide growth enhancement in a Wet Rapid Thermal Oxidation process (WRTO). For similar thermal budgets of wet and dry oxidation, the growth rate is several times higher for the wet process. The temperature sensitivity (unit: Å /K) of the process changes strongly with the grown oxide thickness. The influence of H 2 O:O 2 proportion in the process gas on final oxide thickness is also determined and leads to a definition of a 'wet' process. Isothermal and isochronal thickness data are summarized for the wet oxidation process. All results are analysed with the theoretical growth model of Deal and Grove [1] and compared to previous results with conventional furnace technology. Electrical breakdown properties of the various oxides grown on epitaxial wafers with an average thickness of 140 Å are presented.

Computational Materials Science, 2001

Oxidation of silicon surfaces at relatively low temperatures is shown to go through several activated steps, in the form of con®gurations inert to further uptake of oxygen. Starting from room temperature adsorption, dierent con®gurations of oxygen atoms adsorbed on and in the Si(1 1 1) and Si(0 0 1) surfaces are found, with history and/or coverage dependent energy barriers connecting them. From well below to slightly above an eective oxide coverage of a monolayer, clustering of up to three oxygen atoms around one single silicon atom has been predicted for the Si(0 0 1) surface to represent one such energy minimum; this model is con®rmed here experimentally. These and other clusters are shown to agglomerate into silicon dioxide islands before coalescing into a contiguous, inert layer upon higher oxygen supplies. Another problem addressed here is the presence of molecular adsorbates in the oxidation reaction path, an issue which is still debated in the literature. For the Si(1 1 1) surface a molecular, charged oxygen species has earlier been found at temperatures up to room temperature, but not for the Si(0 0 1) surface. This is con®rmed in the present experiments, and new data for this state shows that it is highly mobile until quenched at a critical oxygen coverage. It is not the initial state of oxygen on silicon, and therefore not the precursor for atomic insertion of oxygen; rather, it is found to co-exists with atomic oxygen inserted in back-bonds, at a certain, low coverage regime in which parts of the Si(1 1 1) surface are still ordered.

MRS Proceedings, 1991

ABSTRACTThermal oxidation of Silicon in the thin regime is of vital importance to VLSI device engineers because thin layers of SiO2 are exclusively used as the gate dielectric for high performance of MOS devices. There exists a number of models to explain this kinetics of oxidation. However there is a considerable variance among the reported rate constants, which are supposed to describe the oxidation process. Rather than arriving at an alternative model, the present study aims at simulation of existing models of oxidation in dry oxygen, with a recent set of experimental data and arrive at the best possible model and provide accurate rate constants for oxidation in dry oxygen. These experimental data have been obtained, earlier, using high-resolution transmission electron microscopy (HRTEM) and ellip-sometry techniques to measure thicknesses of silicon oxide, grown at 800° in dry oxygen, in the thickness range of 2–20 nm.

Applied Physics Letters, 1994

Rapid thermal oxidation of Si in a mixed oxygen and ozone ambient in the temperature range of 600-1200 "C is reported. Between 600 and 800 "C a large enhancement in oxidation is observed compared with conventional oxide growth in a pure oxygen ambient. For temperatures above 950 "C conventional thermal oxidation dominates and no significant enhancement is found.

Electrochimica Acta, 2004

Anodic oxidation under ultraviolet (UV) illumination and rapid photothermal processing technique used for high quality oxide preparation in terms of device surface passivation and gate or tunnel dielectrics are reported. A number of samples of SiO 2 thin films were prepared using this technique. It is shown that anodic oxidation under UV illumination followed by rapid photothermal processing (450 • C, 15 s) in the inert ambient yields the best optimization of the SiO 2 thin films properties. Avoiding high temperature process should result in a better performance of the semiconductor devices. Anodic oxidation under UV illumination at low temperature and post-oxidation photothermal processing can be a possible alternative to the furnace growth silicon oxide; not only because of the low temperature process, but also because this technology essential improves the oxides properties.