Memory Device Pass Voltage Timing for Interference Control
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Solution Overview
Problem
The existing memory devices face a challenge in managing threshold voltage distribution deterioration due to interference between adjacent memory cells, which worsens as the density of memory cells increases, leading to reduced performance and reliability.
Innovation Solution
A memory device design that includes a control logic system to apply a program voltage to a selected word line and a pass voltage to adjacent word lines, with the pass voltage increasing at multiple time points during the program operation, thereby managing the interference and maintaining optimal threshold voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cell density is increased, then storage capacity is improved, but interference between adjacent memory cells worsens
Solution Approach 1:
The patent applies different voltage levels to different word lines during programming operations. Specifically, a first pass voltage is applied to unselected word lines and a second pass voltage is applied to selected word lines, creating local quality differences that prevent interference between adjacent cells while maintaining high density
Solution Approach 2:
The patent dynamically adjusts voltage parameters during the programming process. The control logic modifies the voltage applied to word lines based on whether they are selected or unselected, and adjusts voltage levels across multiple pass loops to ensure proper programming without causing interference between adjacent memory cells
2Device complexity
If a single pass voltage is applied to all word lines, then the programming process is simplified, but threshold voltage distribution deteriorates
Solution Approach 1:
The patent segments the word lines into selected and unselected groups, and applies different voltage levels to each group. The programming process is divided into multiple pass loops where different voltage combinations are applied to different word line segments, ensuring uniform threshold voltage distribution across all memory cells
Solution Approach 2:
The patent employs dynamic voltage adjustment during the programming process. The control logic adapts the voltage applied to word lines based on the programming loop number and the selection status of each word line, optimizing the threshold voltage distribution through dynamic parameter changes rather than static fixed voltages
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively improves the threshold voltage distribution and reduces interference between adjacent memory cells, enhancing the memory device's performance and reliability by concentrating the electric field on the selected word line and optimizing the programming process.
Implementation Method 1
enhancing the memory device's performance and reliability by concentrating the electric field on the selected word line
Implementation Method 2
managing the interference and maintaining optimal threshold voltage distribution
Data Source
AI summary
According to an embodiment of the present disclosure, a memory device, a peripheral circuit configured to perform a program operation, including a plurality of program loops, and a control logic configured to, in some of the plurality of loops of the program operation, control the peripheral circuit to apply a program voltage to a selected word line, apply a first pass voltage to adjacent word lines that are adjacent to the selected word line, and then apply a second pass voltage to adjacent word lines at a predetermined time point, wherein the second pass voltage has a different magnitude compared to the first pass voltage, and in the rest of the plurality of loops of the program operation, control the peripheral circuit to apply the second pass voltage to the adjacent word lines at a time point that is different from the predetermined time point from a selected loop.