Programming Efficiency of Stacked-Gate Flash Memories with High-κ Dielectrics

Abstract

The programming efficiency of high-permittivity (κ) inter-poly dielectrics (IPDs) and tunnel dielectrics (TDs) on the stacked-gate flash memory performance is evaluated. By 2D MEDICI simulation, stacked-gate flash memories with high-κ IPDs clearly exhibited significant improvement in operation speed over those with conventional oxide/nitride/oxide IPD programmed with either channel Fowler-Nordheim (CFN) or channel hot electron (CHE) injection. Choosing HfO 2 as the IPD and using CFN programming scheme, the operating voltage can be reduced by more than 48% under a typical 10μs programming time. However, the effect of high-κ TDs was quite different when compared with high-κ IPDs. High-κ TDs were only beneficial for memories programmed with CHE injection instead of CFN tunneling. The operating voltage can be reduced by more than 27% under 10μs programming time by choosing HfO 2 as both the IPD and TD with CHE programming scheme. Due to the contrary improvement in programming schemes, high-κ IPDs and TDs were suitable for next-generation NAND- and NOR-type stacked-gate flash memories, respectively.