A novel method to separately investigate program and erase degradation mechanisms in flash memory cells

A novel method using a capacitor charging technique and a flash cell with access to the floating gate (FG) is developed to characterize the program and erase degradation independently without the effect of each other. The hole injection during the source-side Fowler-Nordheim (FN) erase is responsible for the erase degradation. The interface-state generation during channel hot electron (CHE) programming appears to be the dominant degradation mechanism. Unlike the conventional methods of applying a constant voltage stress on the FG transistor, the dynamic change of FG potential during program or erase cycles was taken into account in our method. As a result, the trapped oxide charge density and interface-state profile in the tunnel oxide are significantly different from those obtained by the conventional methods.