Characteristics of Elliptical Gate-All-Around SONOS Nanowire With Effective Circular Radius

Characteristics of cylindrical gate-all-around (GAA) SONOS nanowires with elliptical cross sections have been investigated. The mechanism of the program efficiency degradation for the elliptical GAA SONOS is analyzed by 3-D TCAD simulation depending on the geometry aspect ratios (ARs). Moreover, we proposed an effective circular radius (
R
_eff1
) for the elliptical silicon body through a conformal mapping. The
ID
-
V
_GS
curves of the elliptical and circular GAA SONOS devices with
R
_eff1
in initial state are almost consistent with each other for
AR
≤ 2. However, their program properties differ in less than ~4.2% due to the localized charge-trapping effect in nitride layer of the elliptical geometry.