Extraction of Effective Charge Diffusivity in the Charge Trapping Layer of SONOS Flash Memory

In this study, the effective electron diffusivity in a silicon nitride is extracted experimentally explaining the lateral charge migration in Silicon-Oxide-Nitride-Oxide-Silicon memory device whose charge trapping layer is formed continuously along the memory string. The diffusivities were compared in two types of silicon nitride by changing the deposition conditions. The enhanced charge loss is found to be related with the Si–O–N bonding which shows 5.28% versus 23.72%, analyzed by X-ray photoelectron spectroscopy and larger shallow trap density by the thermal activated electron retention model. The analysis results show that less oxygen bonds are more favorable in data retention properties suppressing the lateral charge migration and this can be represented by lower diffusivity about 3.8 × 10–11–5.1 × 10–10 cm2/s.