Abstract: Fowler-Nordheim（F-N） tunnelling is widely used as the erase mechanism in EEPROM and Flash memories.Poly-to-poly F-N tunnelling has greatly enhanced tunnelling efficiency.In this paper,the F-N tunnelling characteristics of the non-planar poly/tunnel oxide/poly structure are studied in a split-gate flash structure.Compared with the planar structure,the non-planar structure shows evidently improved F-N tunnelling efficiency,which could be further improved by thinner tunnel oxide thickness or a pre-thermal oxidation of tunnel oxide.Higher tunnelling efficiency could reduce the erase voltage of split-gate flash.The degradation under constant F-N tunnelling current is also studied.Normalized to the same tunnel charges,lower F-N current is found to have slower oxide degradation rate.Thinner oxide thickness or a pre-thermal oxidation could also slow down the tunnel oxide degradation.Finally,the research result is useful to improve the erase and endurance performance of split-gate flash memory.