Impact of gate-to-source/drain misalignments on source-side injection Schottky barrier charge-trapping memory cells evaluated using numerical programming-trapping iterations

Abstract

This work numerically elucidates the effects of gate-to-source/drain misalignments on source-side injection Schottky barrier charge-trapping memory cells. The coupling of Schottky barriers and trap charges generate particular Schottky barrier lowering and source-side injection, while the charge-coupled Schottky barriers must be considered concurrently with the precise positions of metallic source/drain junctions. Numerical programming-trapping iterations were employed to examine the distribution of electron injections and trapped charges in the charge-coupled cells, and to discuss the differences of physical mechanisms among the aligned, overlapped, and underlapped cells. The overlapped cells produce a mildly high programming and reading currents because of the shorter effective lengths. However, the underlapped cells suffer severely from the degradation of electron drain current, hot-carriers injection, and threshold-voltage shift because of widened tunneling barrier, reduced electric field, and invalid injection location. Mildly gate-to-source/drain overlap should be designed in Schottky barrier charge-trapping memories to avoid the underlapped offsets, ensuring favorable programming and reading performance.