Ion-Bombarded and Plasma-Passivated Charge Storage Layer for SONOS-Type Nonvolatile Memory

Abstract

This paper examined the application of ion bombardment (IB) and NH3 plasma treatment (PT) techniques in fabricating a high-performance Si3N4 charge storage layer. The IB technique can be used for creating numerous additional trap sites in the storage layer to enhance charge trapping efficiency and also causes changes in trap centroid location. In addition, the effect of centroid location on operation efficiency and reliability was investigated. Using gate-sensing and channel-sensing analysis, the changes in centroid location were demonstrated. In addition, the energy-level distribution of trap sites was clearly delineated by performing discharge-based multipulse analysis. The NH3 PT technique can substantially passivate IB-induced shallow trap sites to increase data retention time. The influence of the NH3 PT time on the memory characteristics of an IB-induced Si3N4 sample was investigated. The optimal characteristics of an ion-bombarded and plasma-passivated Si3N4 storage layer are presented. Compared with the conventional Si3N4 storage layer, the optimal ion-bombarded and plasma-passivated Si3N4 sample exhibited higher operation efficiency and superior reliability.