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

Ukju An; Gilsang Yoon; Donghyun Go; Jounghun Park; Donghwi Kim; Jongwoo Kim; Jeong-Soo Lee

doi:10.3390/mi14122199

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

Micromachines (Basel). 2023 Nov 30;14(12):2199. doi: 10.3390/mi14122199.

Authors

Ukju An¹, Gilsang Yoon¹, Donghyun Go¹, Jounghun Park¹, Donghwi Kim¹, Jongwoo Kim¹, Jeong-Soo Lee¹

Affiliation

¹ Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.

Abstract

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

Keywords: 3-D NAND flash memory; charge loss; cross-temperature; decomposition; grain boundary; poly-Si channel; threshold voltage variation.

Abstract

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