Quasi-three-dimensional modeling of sub-micron LOCOS structures

A quasi-three-dimensional simulation of local oxidation is presented. The approach employs the solution of three-dimensional oxidant diffusion, a set of analytical solutions which can predict two-dimensional local oxidation of silicon (LOCOS) shape and parameterization to consider the three-dimensional oxidation enhancement effects. A synthesis step is used to combine the three-dimensional oxidant profile and two-dimensional analytical solutions for the creation of full three-dimensional LOCOS shapes. Oxidation characteristics are investigated based on atomic force microscopy (AFM) measurements that produce three-dimensional structural effects such as the bird's eye phenomena. The narrow window and narrow mask effects on the bird's beak length are simulated and compared with SEM photographs obtained using AFM measurements. Differences between two- and three-dimensional oxidation effects are shown by the comparison of simulation and experiments.<
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