Modeling and Verification of Interface and Bulk Trap Level Density Extraction in SONOS Memory Charge Trapping Layer

Retention characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory are affected by properties such as energy level and spatial location. In this study, a model was presented that separately evaluated the bulk and interface trap level density distributions in the SONOS nonvolatile memory charge trapping layer (CTL). This model is proposed in the form of a first-order function of nitride thick XN, so the bulk and interface trap densities, gbulk and ginterface, respectively, can be extracted from the slope and y-intercept. Measurements were performed on various thickness samples. For verification, CTL1 and CTL2 were formed by different processes. The extracted CTL1 gbulk and ginterface are on the order of 1017 cm−3 and 1011 cm−2, and the CTL2 gbulk and ginterface are of the order of 1018 cm−3 and 1012 cm−2, respectively. Using this model, a direction to improve the SONOS device retention characteristics can be suggested.