Minimization of germanium penetration, nanocrystal formation, charge storage, and retention in a trilayer memory structure with silicon nitride/hafnium dioxide stack as the tunnel dielectric

Abstract

The penetration of Ge atoms into the silicon substrate with the help of trilayer structures, for devices with the smaller rapid thermal oxide (RTO) thickness was discussed. The trilayer structures consisted of a rapid thermal oxide (RTO) layer, a sputtered Ge middle layer and a 50-nm-thick sputtered silicon oxide capping layer. By replacing the RTO layer with a high dielectric constant silicon nitride/hafnium dioxide stack having a larger physical thickness, the Ge penetration was minimized. The results show that the high dielectric constant trilayer structure exhibited better charge retention and better charge storage capability performance than RTO trilayer structure.