Stresses in local oxidation

This paper presents simulations of LOCOS oxide shapes as well as calculations of stresses during oxidations by using a two-dimensional oxidation model based on a slow incompressible viscous flow. Stress distributions and variations along the silicon surface during oxidation are revealed for the first time. The calculated values of stress-time integral show the same trend with the measured defect densities with respect to nitride thicknesses. From an analysis of calculated stresses, this work proposes a first-order model which can easily estimate the stress during oxidation by observing SEM pictures.