A Comprehensive Characterization Method for Lateral Profiling of Interface Traps and Trapped Charges in P-SONOS Cell Devices

A comprehensive characterization method has been developed in this paper for reliable lateral profiling of the interface traps (AN
_it
), localized charges (AN
_ot
), and trapped holes (AN
_hole
) in P-SONOS cell devices. Charge pumping current (I
_CP
) measurement can be used to probe AN
_it
and AN
_ot
from the increase of maximum I
_CP
(I
_CP,max
) and the shift of I
_CP
curve along the base level voltage (V
_b
). When increasing the program and erase (P/E) cycles, the negative threshold voltage (V
_T
) shift at both program and erase states suggests the generation of AN
_hole
. The evolution of AN
_it
, AN
_ot
, and AN
_hole
during P/E cycling can consistently explain the nonmonotonic variations of gate induced drain leakage current (I
_GIDL
) and substrate current (I
_SUB
) as well as dramatic differences between the source and drain. The lateral migration of AN
_ot
caused by extending P/E cycles may lead to the failure of two-bit operation in SONOS cell devices. The larger V
_T
shift and subthreshold swing, smaller read current, and lower transconductance may degrade the endurance and retention of P-SONOS when applied in Flash memory.