Effect of Lateral Charge Diffusion on Retention Characteristics of 3D NAND Flash Cells

Yoo, Ho-Nam; Choi, Byoung Ho; Back, Jong-Won; Kang, Hyo; Kwon, Eunmee; Chung, Sungkwon; Bae, Jong-Ho; Park, Byung‐Gook; Lee, Jong‐Ho

doi:10.1109/led.2021.3088851

Cited by 12 publications

(3 citation statements)

References 12 publications

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“…where VT,N (T) is the VT of the E-N-E pattern at TREAD = T. The neutral cell has no trapped charges in CTL, which causes negligible ΔVT,CL during retention [6,27]. Figure 4a shows the IBL-VREAD curves at TREAD = 30 °C and 120 °C for the E-N-E pattern.…”

Section: Cross-temperature Effects On Retention Characteristicsmentioning

confidence: 99%

“…where V T,N (T) is the V T of the E-N-E pattern at T READ = T. The neutral cell has no trapped charges in CTL, which causes negligible ∆V T,CL during retention [6,27]. Figure 4a where VT,N (T) is the VT of the E-N-E pattern at TREAD = T. The neutral cell has no trapped charges in CTL, which causes negligible ΔVT,CL during retention [6,27]. Figure 4a shows the IBL-VREAD curves at TREAD = 30 °C and 120 °C for the E-N-E pattern.…”

Section: Cross-temperature Effects On Retention Characteristicsmentioning

confidence: 99%

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Effects of Poly-Si Grain Boundary on Retention Characteristics under Cross-Temperature Conditions in 3-D NAND Flash Memory

An,

Yoon,

et al. 2023

Micromachines

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Electrical characteristics with various program temperatures (TPGM) in three-dimensional (3-D) NAND flash memory are investigated. The cross-temperature conditions of the TPGM up to 120 °C and the read temperature (TREAD) at 30 °C are used to analyze the influence of grain boundaries (GB) on the bit line current (IBL) and threshold voltage (VT). The VT shift in the E-P-E pattern is successfully decomposed into the charge loss (ΔVT,CL) component and the poly-Si GB (ΔVT,GB) component. The extracted ΔVT,GB increases at higher TPGM due to the reduced GB potential barrier. Additionally, the ΔVT,GB is evaluated using the Technology Computer Aided Design (TCAD) simulation, depending on the GB position (XGB) and the bit line voltage (VBL).

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Section: Cross-temperature Effects On Retention Characteristicsmentioning

confidence: 99%

Section: Cross-temperature Effects On Retention Characteristicsmentioning

confidence: 99%

Effects of Poly-Si Grain Boundary on Retention Characteristics under Cross-Temperature Conditions in 3-D NAND Flash Memory

An,

Yoon,

et al. 2023

Micromachines

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“…Lateral charge spreading is caused by the electric field [15][16] from charges in WL spaces and adjacent cells. Charge loss has a greater impact on 3D NAND flash memory as it is scaled down, and there is a steady stream of research about this [17][18][19][20][21][22]. In this work, we propose a new structure of 3D NAND CTF with thin doping in the SiN layer (CTL) between WL spaces using high SiN/SiO2 etching selectivity [23].…”

Section: Introductionmentioning

confidence: 99%

Improvement of Retention Characteristics Using Doped SiN Layer Between WL Spaces in 3D NAND Flash

Kyung,

Suh,

Jung

et al. 2024

IEEE Access

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We propose a novel structure of a charge trapping layer, that is doped between Word Line(WL) spaces in 3D NAND flash memory. To estimate the retention characteristics, the ∆Vth of each structure by doping type is compared to a reference structure during retention operation. In this study, lateral charge spreading, rather than vertical loss, is mainly studied as an indicator to determine how long stored data can survive on the selected cell. When the SiN layer is doped with p-type, the electrostatic potential decreases and SRH recombination increases in the doping region. As a result, the p-type doping structure has better retention characteristics than others. In addition, for an optimized structure between retention characteristics and cell current, the doping region of the SiN layer is split and analyzed by the thickness of the doping region. Since the p-type doping region is thicker, lateral spreading is effectively blocked although the cell current decreased slightly.

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3D NAND flash memory based on junction-less a-Si:H channel with high on/off current ratio

Leng

et al. 2022

AIP Advances

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As the key hardware unit of computing in memory, 3D NAND flash memory has been the focus of the artificial intelligence (AI) era due to its high efficiency in processing massive and diverse data, which is superior to the conventional von-Neumann architecture. To push the realization of computing in a memory chip, 3D flash memory with a large on/off current ratio and simple fabrication technology is highly demanded. Here, we first report that 3D NAND flash memory with a high on/off current ratio can be obtained by tuning the width of the a-Si:H channel without a junction. Compared with the traditional 3D NAND flash memory consisting of a polysilicon channel, the junctionless a-Si:H channel can be obtained at low temperature without doping, which can reduce the difficulty induced by the diffusion and the distribution of the doping atoms. Only by tuning the width of the junctionless a-Si:H channel from 0.3 to 0.2 μm, the on/off current ratio increases from 102 to 106. The analysis of ESR and Fourier transform infrared spectroscopy reveals that the positive charge induced by the Si dangling bonds in the narrower a-Si:H channel results in the formation of a thicker depletion layer, which is beneficial to efficiently control the negative charge in the a-Si:H channel. The strong coupling of the thinner charge layer and the electric field of gate bias is the origin of the high on/off current ratio from the narrower a-Si:H channel. Our successful fabrication of 3D NAND flash memory based on the junctionless a-Si:H channel with a high on/off current ratio provides a new way to construct a hardware unit for computing in-memory.

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Effect of Lateral Charge Diffusion on Retention Characteristics of 3D NAND Flash Cells

Cited by 12 publications

References 12 publications

Effects of Poly-Si Grain Boundary on Retention Characteristics under Cross-Temperature Conditions in 3-D NAND Flash Memory

Effects of Poly-Si Grain Boundary on Retention Characteristics under Cross-Temperature Conditions in 3-D NAND Flash Memory

Improvement of Retention Characteristics Using Doped SiN Layer Between WL Spaces in 3D NAND Flash

3D NAND flash memory based on junction-less a-Si:H channel with high on/off current ratio

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