Geometry Dependent Bird’s Beak Formation for Submicron LOCOS Isolation

Abstract

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.