Study the effect of bird’s beak on Fully Recessed LOCOS and Poly Buffered LOCOS using 2 different pad Oxide

Abstract

Device isolation is one of the most important technology features towards the realization of very large scale CMOS device integration. Since the early days of semiconductor industry, LOCOS isolation has been the major isolation scheme. However, one of it is major drawback is the oxide encroachment, or so called, bird’s beak beneath under active areas which limits its application in deep sub-micron CMOS technology. This project investigates the use of modified LOCOS structures for example Poly Buffered LOCOS (PBL) and Fully Recessed LOCOS as a bird’s beak suppressing technique. It was found that, Poly Buffered LOCOS and Fully Recessed LOCOS structures, have been dramatically reduce the oxide encroachment beneath the active areas.