Investigation for Narrow Cell Threshold Voltage Distribution in NOR Flash Device

Abstract

Resonant and nonresonant diffusion of electrons has been studied in a toroidal magnetic field with pulsed injection of electrons.We have experimental evidence of the theoretical predictions of B l 3/2 dependence of the diffusion coefficients in strong perturbation fields. We have observed the transition from Bla to B 1 3 / 2 behavior for Bl/Bo < 1 per cent where BL is the perturbing and Bo the uniform magnetic field. Theoretical models based on unperturbed orbit calculations are shown to be invalid for surprisingly small valuesWe have conducted measurements of nonresonant diffusion applicable to dissociation experiments in nonadiabatic traps. We find that the diffusion coefficient depends strongly on how nearly resonant the electron is with the perturbed field. For a 50 per cent change in effective perturbation frequency, the diffusion coefficient changes by a factor 1000.Our results can be scaled to the problem of nonadiabatic trapping and dissociation of molecular ions. We infer the resulting nonresonant protons would have a lifetime against nonadiabatic scattering 10,OOQ times longer than the parent molecular ioos.

Suppression of Threshold Voltage Fluctuation by Control of Channel Profile for NOR Flash Memory Scaling

“…These technologies were introduced in our previous work. 1,4) Figure 1(a) shows the V th fluctuation of one cell for each NOR generation. Figure 1(b) shows the measurement method used to measure the V th fluctuation of one memory cell.…”

“…It is known that the reason for the wide V th distribution in the array cells to be downscaled is mainly caused by the coupling ratio dispersion related to variation in dimensional such as tunnel oxide thickness, interlayer dielectric thickness, and height of the floating gate. 1) Since NOR flash memory is programmed by the channel hot electron injection (CHIE) method, channel doping is relatively high, and it significantly increases as the cell size is scaled down. Higher channel doping for achieving NOR cell size downscaling leads to mobility degradation owing to dopant scattering during the read operation, which can result in a larger V th fluctuation of one memory cell.…”