Molecular simulator: A basic tool for submicron MOS processes development
Abstract
Scaling down under micron of MOS (Metal Oxide Semiconductor) silicon devices is accomplished by fabricating oxide layers whose thickness is not in excess of a few tens of Angstrom. At this thickness, an atomic scale model capable of accounting for the microstrip and localized information is needed. A simulator based on energy models involving two body and three body interactions was completed and the Metropolis test was carried out. Many validity tests performed bore out the simulator's ability to simulate silicon and silicon oxide crystals. To analyze the growth of the first oxide monolayers, the oxygen atoms were deposited on the surface of the silicon substrate and the structure was relaxed. By converting the oxygen rate into the growth time, this method could then be applied to the practical example of oxide growth at room temperature and under atmospheric pressure on a Si(001) surface. It was found that the formation of the first oxide layers resulted from a distortion-relaxation process occurring between the oxygen and the silicon ones. From the simulated results, a logarithmic-linear law was formulated, approximating to within the experimental results of oxide growth in the thickness range less than ten Angstrom. In addition, the introduction of point defects in the substrate allowed the model to be refined. In particular two cases of defect mixture, namely 1.5% of interstitials (that is, 3 interstitials for 200 silicon atoms of the substrate) and 6% of vacancies; and 6% of interstitials and 6% of vacancies enable the deviation between the simulated and experimental results to be reduced by half.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1992
- Bibcode:
- 1992PhDT........18R
- Keywords:
-
- Crystal Growth;
- Metal Oxide Semiconductors;
- Microstructure;
- Oxidation;
- Silicon Dioxide;
- Thin Films;
- Atomic Structure;
- Interstitials;
- Mathematical Models;
- Point Defects;
- Silicon;
- Vacancies (Crystal Defects);
- Very Large Scale Integration;
- Solid-State Physics