Image Number 7 for United States Patent #5421934.
A new surface reaction model has been presented to simulate topological evolutions by taking into account the existence of absorbed radicals on the substrate surface. The model treats the etching rate as a function of the coverage ratio by absorbed radicals on the surface. Based on the model, a two-dimensional topography simulator has been provided. The simulator is applied to silicon-dioxide trench teachings made by hydrofluorcarbon gases. The topography simulator is used in a dry-etching process for realizing sub-half micron patternings.