NAND Memory Read Voltage Control for Temperature-Shifted Cells
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Solution Overview
Problem
The increasing number of layers in NAND memory devices leads to reduced channel current, narrowed spacing between memory cells, and temperature-induced shifts in threshold voltage, causing decreased read window and reliability due to coupling effects and read disturbances.
Innovation Solution
A memory device with a peripheral circuit that applies a read voltage to a selected word line and a pass voltage to adjacent non-selected word lines, with the pass voltage adjusted based on working temperature and read storage state to improve read performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of layers in NAND memory is increased to improve storage density, then storage capacity is improved, but channel current decreases and read reliability deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the pass voltage level based on working temperature conditions. At higher temperatures, the pass voltage is increased to compensate for threshold voltage shifts and maintain adequate read window, thereby preserving read reliability while supporting high storage density through multi-layer structure
2Quantity of substance
If the spacing between memory cells is reduced to increase storage density, then storage capacity is improved, but coupling effects increase and read performance deteriorates
Solution Approach 1:
The patent changes the pass voltage parameter to counteract coupling effects. By increasing pass voltage at elevated temperatures, the system maintains sufficient voltage margins that compensate for interference from adjacent cells, enabling tight cell spacing while preserving read performance
3Speed
If working temperature increases to improve device performance, then speed is improved, but threshold voltage shifts occur and read window narrows
Solution Approach 1:
The patent implements temperature-dependent pass voltage adjustment. As working temperature increases, the pass voltage is raised to compensate for threshold voltage shifts caused by temperature effects, thereby maintaining stable read window and reliable operation across a wide temperature range
4Reliability
If pass voltage is increased to compensate for temperature effects, then read reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies dynamics by making the pass voltage adaptive rather than fixed. The pass voltage dynamically adjusts based on working temperature conditions, using higher voltages only when temperature requires compensation, thereby maintaining read reliability while minimizing unnecessary energy consumption at lower temperatures
Data Source
AI summary
Examples of the present disclosure provide a memory device, an operation method thereof, a memory system and a storage medium. The memory device includes a memory cell array including: a plurality of memory cells, and a peripheral circuit coupled with the memory cell array and configured to apply a read voltage to a selected word line coupled to a target memory cell of the plurality of memory cells and apply a pass voltage to a non-selected word line adjacent to the selected word line when performing a read operation on the target memory cell, wherein the pass voltage is related to the read voltage and a working temperature of the memory device when the read operation is performed.