Stepwise Pass Voltage Control for Semiconductor Memory Disturbance
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Solution Overview
Problem
In semiconductor memory devices, the self-boosting method for programming memory cells can lead to a pass disturbance phenomenon where unselected memory cells are inadvertently programmed due to excessive channel voltage, necessitating a controlled pass voltage to maximize programming efficiency while minimizing disturbance.
Innovation Solution
A semiconductor memory device and method where the pass voltage supplied to unselected word lines is raised in a stepwise manner during program and read operations, with multiple voltage levels applied in a pulse form to optimize channel voltage boosting and reduce program and pass disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high pass voltage is supplied to unselected word lines to maximize program inhibition effect, then the program inhibition effect is improved, but pass disturbance phenomenon occurs where unselected memory cells are inadvertently programmed
Solution Approach 1:
The patent applies dynamics by transitioning from a static pass voltage to a dynamic multi-level pass voltage that changes over time. The pass voltage is applied in multiple levels (first level, second level higher than first, third level higher than second) during different time periods of the program operation, allowing the voltage to adapt dynamically to different stages of the programming process and balance program inhibition with pass disturbance prevention
Solution Approach 2:
The patent implements periodic action by applying the pass voltage in a stepped, periodic manner rather than as a single continuous voltage. The voltage is increased in discrete steps at specific time intervals during the program operation, creating a periodic voltage profile that systematically builds up the pass voltage to achieve optimal program inhibition while controlling pass disturbance
2Object-affected harmful factors
If a high pass voltage is supplied to unselected word lines during read operation to prevent pass disturbance, then pass disturbance is reduced, but programming efficiency may be compromised
Solution Approach 1:
The patent uses dynamics by implementing a time-varying pass voltage profile with multiple increasing levels during program operation. This dynamic voltage adjustment allows the system to optimize both pass disturbance prevention and programming efficiency by applying appropriate voltage levels at different stages, rather than using a fixed high voltage that would compromise efficiency
Solution Approach 2:
The patent applies parameter changes by systematically varying the pass voltage parameter through multiple discrete levels (first, second, and third levels with increasing magnitudes). This parameter variation allows optimization of both pass disturbance reduction and programming efficiency by matching voltage levels to different operational requirements at different time periods
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 enhances programming efficiency by minimizing pass disturbance and maintaining effective program inhibition, reducing the risk of unselected cells being programmed while maintaining the desired programming effect.
Implementation Method 1
there may be a memory cell that should not be programmed, from among memory cells coupled to the same word line. For this reason, a self-boosting method is employed in order to boost the channel voltage of a cell string coupled to a memory cell which should not be programmed.
Data Source
AI summary
A semiconductor memory device includes a memory cell array having memory cells coupled to a plurality of word lines and a peripheral circuit group configured to supply a pass voltage to unselected word lines among the plurality of word lines, wherein the peripheral circuit group stepwise raises the pass voltage supplied to the unselected word lines to a target level.