Analysis of TANOS Memory Cells With Sealing Oxide Containing Blocking Dielectric

The effect of oxygen source on atomic layer deposited Al2O3 as blocking oxide in metal/aluminum oxide/nitride/oxide/silicon memory capacitors

“…Neither Fowler-Nordheim nor Poole-Frenkel mechanisms can interpret the J-E characteristics. These findings are in line with a recent model, which suggests that electron transport through the Al 2 O 3 layers can be explained via a phonon trap assisted tunneling mechanism [9,14,19]. Consequently, since the examined MANOS structures are almost identical in terms of layer thickness and dielectric permittivity, the enhanced conduction in the high negative gate voltage regime is attributed to the different trap distributions within the Al 2 O 3 .…”

“…Al 2 O 3 has excellent chemical and thermal stability [7,8], and a wide band-gap, combined with a moderate permittivity. In addition, Al 2 O 3 is characterized by a high defect density [9][10][11][12] leading to enhanced trap assisted conduction [13,14] with obvious concerns about the reliability of the memory stack. In our previous work, the influence of atomic layer deposition (ALD) conditions of high-k dielectrics on the electrical properties of memory stacks has been studied [15].…”

Electron trapping in amorphous Al2O3

“…It was reported that charge trapping nonvolatile memories with Al 2 O 3 as blocking layer, like TaN/Al 2 O 3 /Si 3 N 4 / SiO 2 /Si (TANOS) cells, exhibit a non-negligible fraction of stored electrons within the Al 2 O 3 layer after programming. 6,[16][17][18][19] This modifies program/erase transients, cyclic endurance, and data retention. 6,16,19 The hysteresis traps we reported are in agreement with the traps reported in these works, which can be cyclically charged and discharged.…”

“…This contributes to a non-negligible charge captured inside the Al 2 O 3 layer during program operation and a low-field leakage current due to trap-assisted tunneling affecting memories reliability and data retention. [16][17][18][19] The change in the structure of the Al 2 O 3 layer from amorphous to crystalline could be accompanied by a modification of the defects' main traits. An increase in the density of shallow electron traps during high temperature PDA was reported, 20 maintaining a similar value for deep traps.…”

Work Function Adjustment by Using Dipole Engineering for TaN-Al2O3-Si3N4-HfSiOx-Silicon Nonvolatile Memory

“…According to studies on SONOS flash, TaN-Al 2 O 3 -Si 3 N 4 -SiO 2 -silicon (TANOS) structure flash memory [8,9,10] exhibits excellent performance because of its immunity to gate injection when metal gate TaN with a high work function is used. Moreover, several studies have presented various types of high- k dielectric trapping layers as potential candidates for replacing Si 3 N 4 to provide discrete NVM charge storage [11,12,13,14,15,16].…”