Improvement in Electrical Characteristics of BE-SONOS Using High-k Dielectrics in Tunneling Barrier

Abstract

In this paper, we have analyzed the effect of high-k dielectrics in the tunneling barrier of bandgap engineered Silicon Oxide Nitride Oxide Silicon (BE-SONOS). The high-k materials used, hereby, are scandates and aluminates of the rare earth materials such as GdScO, LuAlO, and LaAlO. These materials have high permittivity and low valence band offset that helps in improving the erase speed and retention trade-off. Also, lower conduction band offset of these high-k dielectrics leads to the improvement of program speed. Here, scandate of the rare earth material, GdScO, substitutes the nitride (SiN) layer and the aluminates of the rare earth material, LuAlO and LaAlO, are used in place of top oxide (SiO2) layer in tunneling barrier (SiO2/SiN/SiO2) of BE-SONOS. Further, with the scaling of the gate length; for the same effective oxide thickness, it has been observed that the investigated stacks encompass the same memory dynamics as before the gate length scaling. Consequently, the investigated tunneling barrier stacks represent robustness in terms of retention (at room temperature and 150 oC) and enhanced program speed as well as erase speed and retention trade-off.