Three-dimensional numerical simulation of local oxidation of silicon

The nitride mask bending stress is modeled in three dimensions by using the beam bending theory. The stress effect on the oxide growth is taken into account for the accurate evaluation of the oxide shape. The three-dimensional behavior of oxide growth is investigated by using three typical mask structures, which are called the hole (contact), island, and line structures. The mask structure effect and narrow mask effect on the bird´s beak length are simulated and discussed in comparison with the experimental data obtained by the top-view scanning electron microscopy (SEM) observation. Three-dimensional effects of the oxide thickness of local oxidation of silicon (LOCOS) structures are predicted by comparing simulations with two-dimensional effects obtained by the cross-sectional SEM observation. It is found that the bird´s beak length at the corner of the mask edge is much enhanced in the hole structure and retarded in the island structure. This result is explained by the three-dimensional effect on the oxidant diffusion and the nitride bending stress