Implementation of nitride oxidation in the 2D process simulator IMPACT-4

To shrink the dimension of devices, new isolation technologies, with respect to classical LOCOS, have to be evaluated. This paper deals with the study of one of these possible alternatives: the LOCOS/Recessed-LOCOS NCLAD structure. In this process a thin nitride layer encapsulates the oxide-nitride stack to prevent the formation of long bird\´s beak. The efficiency of this technique is dependent on the nitride oxidation. In order to study this process, via simulation, it is therefore necessary to model nitride oxidation: a "modified Deal and Grove" model has been implemented and calibrated in the 2D Process simulator IMPACT-4. The implementation problems and relative solutions are described.