Trap Profiling in Nitride Storage Layer in 3-D NAND Flash Memory Using Retention Characteristics and AC- $\text{g}_{\mathrm {m}}$ Method

The trap density (N
_t
) in nitride storage layer of 3-D NAND flash memory cells with tube-type channel structure is extracted. To extract N
_t
profile in the nitride layer, retention characteristics, and ac-transconductance (g
_m
) method are used, and equations are derived in cylindrical coordinate. The N
_t
profile at E - E
_T
smaller than 1 eV is extracted using retention characteristics of the cells measured at high temperature. The peak value of extracted N
_t
is ~1 × 1019 cm
^-3
eV
^-1
at a E
_C
- E
_T
of 0.93 eV. AC-g
_m
method is used to profile the N
_t
in E - E
_T
higher than 1 eV. Extracted N
_t
profile shows a reasonable continuity between both approaches and looks like a Gaussian function.