Geometry Dependent Bird´s Beak Formation for Submicron LOCOS Isolation

Bird´s beak formation is one of the major problems for LOCOS field isolation. In this paper we demonstrate that the bird´s beak length is not a constant, but depends strongly on geometry of the oxidatioin mask for submicron mask dimensions. The bird´s beak length can vary up to a factor of 4, dependent on mask geometry. Four independent geometry effects are distinguished and their impact on an IC-process is discussed.