Temperature Impacts on Endurance and Read Disturbs in Charge-Trap 3D NAND Flash Memories.

Yachen Kong,Xuepeng Zhan,Xin Liu,Bo Chen,Jiezhi Chen,Hongzhe Lin,Fei Chen

doi:10.3390/mi12101152

Yachen Kong, Xuepeng Zhan + Show 5 more

Open Access

https://doi.org/10.3390/mi12101152

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Journal: Micromachines	Publication Date: Sep 25, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Shandong University, Analysis and Testing Centre

Abstract

Temperature effects should be well considered when designing flash-based memory systems, because they are a fundamental factor that affect both the performance and the reliability of NAND flash memories. In this work, aiming to comprehensively understanding the temperature effects on 3D NAND flash memory, triple-level-cell (TLC) mode charge-trap (CT) 3D NAND flash memory chips were characterized systematically in a wide temperature range (−30~70 °C), by focusing on the raw bit error rate (RBER) degradation during program/erase (P/E) cycling (endurance) and frequent reading (read disturb). It was observed that (1) the program time showed strong dependences on the temperature and P/E cycles, which could be well fitted by the proposed temperature-dependent cycling program time (TCPT) model; (2) RBER could be suppressed at higher temperatures, while its degradation weakly depended on the temperature, indicating that high-temperature operations would not accelerate the memory cells’ degradation; (3) read disturbs were much more serious at low temperatures, while it helped to recover a part of RBER at high temperatures.

Highlights

After a decade of rapid technological developments, 3D NAND flash memory has been widely utilized in various kinds of storage applications, especially in file memoryrelated products such as laptops and data centers
For charge-trap (CT) 3D NAND flash memory, the endurance can largely be improved because the effects of the tunneling layer degradations are weak, and the program time can be faster because the effects of intercell interference (ICI) are well suppressed with larger cell-to-cell space
An effective temperature-dependent cycling program time (TCPT) model was proposed to simulate the program time changes by the P/E cycles and the temperature; We characterized the cross-temperature measurements to study the temperaturedependent degradations, indicating that high-temperature operations will not accelerate the degradation of the memory cells; We characterized the measurements of temperature-dependent read disturbs

Summary

Introduction

After a decade of rapid technological developments, 3D NAND flash memory has been widely utilized in various kinds of storage applications, especially in file memoryrelated products such as laptops and data centers. An effective TCPT model was proposed to simulate the program time changes by the P/E cycles and the temperature; We characterized the cross-temperature measurements to study the temperaturedependent degradations, indicating that high-temperature operations will not accelerate the degradation of the memory cells; We characterized the measurements of temperature-dependent read disturbs. It showed that read disturb degrades at cold temperature, but it helps to recover a part of RBER at high temperatures. The rest of the paper is organized as follows: Section 2 introduces the background and related work; Section 3 presents the evaluation setup; Section 4 describes the measured results of P/E cycling; Section 5 shows the temperature-dependent read disturbs; Section 6 concludes this work

Background and Related Work

Evaluation Setup

Conclusions