MeV implantation introduced damage at the LOCOS bird's beak in 0.35 /spl mu/m flash memory devices

This paper reports on the impact of high energy (MeV) retrograde well implants on the reliability of Flash Memory devices. These implants are shown to severely damage the oxide at the LOCOS bird's beak edge. The degree of SiO/sub 2/ amorphization caused by the high-energy ion implantation is shown to be enhanced by the LOCOS structure. The amorphization causes accelerated oxide loss during subsequent oxide etch-backs. Both performance and reliability of Flash Memory cells is degraded due to this damage. We demonstrate a technique for reducing the implant induced damage and thereby improve device performance and reliability.