Instabilities induced by electron trapping/detrapping in high-k gate dielectrics of Flash memories: Evaluation and suppression

High density of electron trapping in high-κ gate dielectrics remains a major concern for flash memory cells. In this work, by using the ultrafast I-V measurements, it is demonstrated that a significant portion of the Program/Erase windows are actually contributed by electrons trapped initially in the high-κ dielectric during program/erase and then discharged/recharged during the following operations, which can cause severe abnormal program/erase window instabilities and read/pass disturbances. Importantly, it is demonstrated that these fast charge transition induced window instabilities can be suppressed by using novel multilayer high-κ structures.