3D Nonvolatile Memory Pass Voltage Slope Control
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Solution Overview
Problem
In nonvolatile semiconductor memory devices with three-dimensional array structures, the varying rising slopes of driving signals applied to word lines can cause overshooting, electric field coupling between adjacent memory cells, and reduced read margins, leading to reliability issues.
Innovation Solution
The implementation of a voltage control circuit that adjusts the number of current paths in pass voltage generators to control the rising slopes of driving signals, ensuring they have the same slope for unselected word lines, thereby preventing overshooting and improving read margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pass voltage generators use fixed current paths to generate driving signals, then device structure is simple, but rising slopes of driving signals vary causing overshooting and electric field coupling
Solution Approach 1:
The patent implements dynamic control of current path configuration in pass voltage generators. The voltage control circuit dynamically selects and connects different numbers of current paths based on which word line is being selected, ensuring that unselected word lines receive pass driving signals with consistent rising slopes. This dynamic adaptation prevents overshooting and electric field coupling while maintaining reliable read margins.
Solution Approach 2:
The patent changes the parameter of current path quantity in pass voltage generators to control the rising slope of pass driving signals. By adjusting the number of active current paths based on word line selection status, the system maintains uniform rising slopes across all unselected word lines, preventing signal overshooting and improving read margin stability without requiring complete structural redesign.
2Reliability
If the number of current paths is adjusted to control rising slopes, then driving signal consistency is improved, but control circuit complexity increases
Solution Approach 1:
The patent applies local quality control by configuring different numbers of current paths in different pass voltage generators based on their specific word line positions. Each pass voltage generator is locally optimized with an appropriate number of current paths to ensure its output signal has the correct rising slope characteristic, achieving overall signal consistency through localized adjustments rather than uniform design.
Solution Approach 2:
The voltage control circuit implements feedback control by monitoring word line selection status and dynamically adjusting the number of active current paths in pass voltage generators accordingly. This feedback mechanism ensures that pass driving signals are consistently generated with appropriate rising slopes only when needed, maintaining signal reliability while minimizing unnecessary control complexity.
Data Source
AI summary
According to example embodiments, a nonvolatile memory device includes a memory cell array including a plurality of memory cells stacked on a substrate, a plurality of word lines connected with the memory cell array, a plurality of pass voltage generators, and a voltage control circuit. The pass voltage generators each include a plurality of current paths and are configured to generate pass driving signals applied to unselected word lines of the plurality of word lines. The voltage control circuit is configured to control rising slopes of the pass driving signals generated from the plurality of pass voltage generators, based on adjusting the number of current paths in each pass voltage generator used to generate each driving signal.