Effects of blocking oxide layer types on the performance of nonvolatile floating gate memory containing AgInSbTe-SiO2 nanocomposite thin films

Abstract

Influence of blocking oxide layer types on the performance of nonvolatile floating gate memory (NFGM) containing AgInSbTe (AIST)-SiO2 nanocomposite as the charge-trapping layer was investigated. In the NFGM containing a 7-nm thick SiO2 blocking oxide layer deposited by plasma-enhanced chemical vapor deposition (PECVD), a fairly large memory window (ΔVFB) shift of 20.9V with the charge density of 1.3×1013cm−2 at ±15V gate voltage sweep was achieved. As to the NFGM containing HfO2 blocking oxide layer, the device performance was inferior to that of PECVD-SiO2 device due to the diffusion of HfO2 into the nanocomposite layer. Interdiffusion resulted in the formation of HfSiOx phase and oxygen defects which might act as the leakage paths, consequently deteriorating the charge trapping efficiency of AIST nanocrystals (NCs) embedded in nanocomposite layer. Analytical results illustrated that the film quality and barrier height feature of blocking oxide layer are essential to form the deep trap sites in the programming layer to achieve a satisfactory NFGM performance with long-term reliability.