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5.4.1 First approach of Local Oxidation

The first problem that has been successfully solved had a comparable simple geometry. Nevertheless it was a big progress in the development, since it was not sure if the developed model will lead to acceptable results because of the numerical conditions:

As first example two typical three-dimensional effects occurring in the corners of the nitride mask have been calculated (Fig. 5.7 and Fig. 5.8). Starting from a pure silicon block the results show, that the introduced model can even handle structures without pad oxide below the nitride mask. This leads to the effect that the interface meets the nitride layer vertically that can hardly be solved by algorithms based on a sharp interface formulation. Nevertheless, the interface conditions are too smooth for a physical interpretation of the material interface and an improvement must be made using grid adaptation to accurately resolve the interface layer.

Figure 5.7: Oxide growth around a nitride mask covering one quarter of the geometry
\resizebox{8.0cm}{!}{\includegraphics{/iue/a39/users/radi/diss/fig/modeling/small_mask.eps}}

Figure 5.8: Oxide growth around a nitride mask covering three quarters of the geometry
\resizebox{8.0cm}{!}{\includegraphics{/iue/a39/users/radi/diss/fig/modeling/big_mask.eps}}


next up previous
Next: 5.4.2 Local oxidation with Up: 5.4 Three-Dimensional Simulation Results Previous: 5.4 Three-Dimensional Simulation Results
Mustafa Radi
1998-12-11