Semiconductor Memory Word Line Voltage Control for Inter-Cell Interference
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Solution Overview
Problem
Current semiconductor memory devices face challenges in accurately reading data due to inter-cell interference, which affects the reliability of data retrieval, especially when threshold levels of adjacent cells are similar or different.
Innovation Solution
The semiconductor memory device employs a method where varying voltages are applied to word lines during read operations to compensate for inter-cell interference, using specific voltage patterns and levels to differentiate and correctly read data from memory cells with different threshold levels, ensuring precise estimation and correction of threshold variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional read operations are used in NAND flash memory, then the device structure is simple and manufacturing is easy, but inter-cell interference causes inaccurate data reading and reduces reliability
Solution Approach 1:
The patent applies preliminary action by performing a read operation on an adjacent word line before reading the target word line. This preliminary read compensates for inter-cell interference effects in advance, allowing the main read operation to achieve higher accuracy. The method proactively addresses interference issues before they affect the primary data retrieval operation.
Solution Approach 2:
The patent implements feedback by using the result from the preliminary read operation on the adjacent word line to adjust and improve the accuracy of the subsequent read operation on the target word line. The information gained from the first read operation feeds into the second read operation, enabling dynamic compensation for inter-cell interference and enhancing overall reading precision.
2Measurement precision
If varying voltages are applied to compensate for inter-cell interference, then data reading accuracy is improved, but the number of voltage levels and control parameters increases
Solution Approach 1:
The patent applies local quality by using different voltage levels specifically for adjacent word lines compared to the target word line during read operations. Instead of uniformly applying the same voltage to all word lines, the method tailors the voltage application to the specific spatial relationship and interference characteristics of adjacent cells, thereby improving threshold level differentiation while maintaining manageable control complexity.
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes: first and second memory cells; first and second word lines coupled to the first and second memory cells, respectively. When data is read from the first memory cell, first and second voltages are applied to the first word line. A voltage of the second word line varies continuously by a first potential difference with time while the first voltage is applied to the first word line, and the voltage of the first word line varies continuously by a second potential difference with time while the second voltage is applied to the first word line.