A new two-dimensional oxidation simulator based on cellular automata is presented. The advancement of the Si-SiO2 and SiO2-air fronts during oxidation has been successfully simulated. The simulator reproduced satisfactorily the oxidation profiles in the case of a Gaussian temperature distribution over the Si surface, as well as in the case of the presence of contamination on the Si surface. Oxidation of non-planar Si surfaces, as well as oxidation through a mask, and oxidation through a mask of non-planar Si surfaces have also been successfully simulated. The simulation results are in good qualitative agreement with experimental data.

A new simulator for the oxidation process in integrated circuit fabrication based on cellular automata

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.

Growth of Oxide Layer on Germanium (011) Substrate Under Dry and Wet Atmospheres

The growth of ultrathin oxides of silicon by low temperature wet oxidation technique

The growth and optical properties of Ag/dielectric and Au/dielectric bilayer thin films are reported. The metal layer is deposited on top of the dielectric layer, which is either TiO 2 or ZrO 2 . The dielectric films were prepared by the sol–gel method whereas the metal films (5–50 nm thick) were deposited on the dielectrics by ion beam sputter deposition. The surface morphology of the metal layer is strongly dependent on the dielectric layer over which it is deposited. The bilayer thin films show enhanced light absorption in the ultraviolet region and refractive index controlled optical absorption at near infrared wavelengths. In addition, they display the tunability in surface plasmon resonances exhibited normally by core–shell and bimetal nanostructures. In the presence of the metal layer, the absorption coefficient of the bilayer is enhanced, by almost 7 times, in the region of the band gap. The surface plasmon resonance of the metal exhibits a red-shift with increase in refractive index of the dielectric underlayer. The plasmon resonance for Ag is observed at a wavelength of 424 nm on ZrO 2 , which shifts to 434 nm on TiO 2 . Similarly in the case of Au films, the shift is from 630 nm on ZrO 2 to 640 nm on TiO 2 . Interestingly, the optical absorption in the near IR region increases with increase in refractive index of the dielectric underlayer.

Optical behavior of silver/dielectric and gold/dielectric bilayer thin films

In this paper, we perform Monte Carlo simulations of SiO 2 thin film growth on silicon. The results indicate the formation of non-stochiometric SiO x (0 < x < 2) transition layers 1.2-2.5 nm wide depending on the growth simulation parameters, and that the interfacial silicon molar content follows closely an error function profile. We study the role of the SiO x layers on the confinement properties of SiO 2 /Si/SiO 2 single quantum wells by means of the effective mass theory. The electron and heavy-hole energy levels are shown to be strongly blue-shifted in comparison with those calculated when the existence of interfacial SiO, transition layers is disregarded. The recombination energy of the ground-state electron-hole pair is blue-shifted several hundred millielectronvolts when the graded interfaces in 3 nm wide SiO 2 /Si/SiO 2 wells are as thin as a monolayer.

Dynamics of SiO2/SiOx/Si multilayer growth and interfacial effects on silicon quantum well confinement properties

To gain a better understanding of the silicon oxidation process, we perform numerical simulation of thermal thin-film growth. It is shown that the oxidation rate in the early stages of growth is governed by two processes: the rapid initial formation of the oxidation front and its subsequent diffusion. The resulting oxidation rate provides a rather good description of the experimental data with the minimum number of variable parameters, suggesting that the effect of external parameters (such as temperature and pressure) can be explained in terms of scaling concepts. The results of the simulation are also in agreement with the fitting of experimental data to a power law (where is the measured film thickness and t the oxidation time) predicted by a simple model for thin film growth.

Eronides F da Silva

Papers

Simulation of the early stages of thin ? film growth