NAND Top Select Line Timing for Program Crosstalk Suppression
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Solution Overview
Problem
Existing NAND flash memory devices face challenges in effectively managing program crosstalk due to varying distances of memory cells from top select lines, leading to inefficiencies in programming operations.
Innovation Solution
The memory device dynamically adjusts the application approach of select voltages on the second top select line based on the distance between the selected word line and the third top select line, ensuring the instants of time and voltage magnitudes are optimized to minimize program crosstalk by using a peripheral circuit that controls the application of select voltages on multiple top select lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed select voltage application approach is used for all word lines, then the control circuit is simple, but program crosstalk cannot be effectively suppressed for word lines at different distances from top select lines
Solution Approach 1:
The patent implements dynamic adjustment of select voltage application timing based on the distance between the selected word line and the third top select line. The peripheral circuit determines whether to apply select voltage to the second top select line at the same time as the first or third top select lines, or with a time offset, depending on the detected distance. This dynamic control enables effective program crosstalk suppression for word lines at different distances while maintaining manageable circuit complexity through automated distance-based decision making.
2Productivity
If select voltage is applied to all top select lines simultaneously, then the control approach is simple, but program crosstalk varies significantly for memory cells at different distances from top select lines
Solution Approach 1:
The patent applies different select voltage application strategies to different word lines based on their local distance from the third top select line. Word lines closer to the third top select line receive delayed select voltage application to suppress program crosstalk, while word lines farther away receive simultaneous application. This localized differentiation optimizes programming efficiency for each region while managing program crosstalk effects specific to each word line's position.
3Reliability
If the instant of time for second top select line voltage is fixed, then the control circuit is simple, but it cannot optimize programming for different distances between word lines and third top select line
Solution Approach 1:
The peripheral circuit detects the distance between the selected word line and the third top select line and uses this feedback information to determine the appropriate select voltage application timing for the second top select line. This feedback mechanism enables the circuit to automatically adjust control parameters based on actual physical conditions, improving programming reliability without requiring complex manual configuration or overly complicated circuit architecture.
Data Source
AI summary
The present application provides memory devices, operating methods, and memory systems. An example memory device includes: a first, second, and third top select line, multiple word lines, multiple memory cells, and a peripheral circuit configured to: in a process of programming the multiple memory cells coupled to a selected word line of the multiple word lines, dynamically adjust an application approach of a select voltage on the second top select line depending on a distance between the selected word line and the third top select line; wherein when the first top select line reaches its select voltage is different from when the third top select line reaches its select voltage, and when the second top select line reaches its select voltage is not earlier than when the first top select line reaches its select voltage and not later than when the third top select line reaches its select voltage.