Simulated Programming Characteristics of Stacked-Gate Flash Memories with High-k Tunnel Dielectrics

Abstract

Due to the reduced gate coupling ratio, the channel Fowler-Nordheim (CFN) programming speed of stacked-gate flash memories with high-permittivity (k) tunnel dielectrics (TDs) is helpless in operation voltage reduction. Although the electric field on high-k tunnel dielectrics is lower than SiO2 tunnel oxide, enhanced impact ionization rate and lower barrier height contribute to higher channel hot-electron (CHE) injection current and efficiency. Consequently, high-k TDs are only effective for the memories programmed with hot electron injection rather than FN tunneling, which is suitable for the NOR-type stacked-gate flash memories.