Memory Erase Resume Control for Special Word Line Stability
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Solution Overview
Problem
The frequent suspension and resumption of erase operations in memory systems due to erase suspend and resume commands lead to decreased stability and performance.
Innovation Solution
Implementing a method where the voltage of a special word line is released at specific thresholds of erase suspends during the erase pulse phase to prevent excessive shifting of the threshold voltage in special cells, thereby maintaining memory stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the voltage of the special word line is maintained during erase suspend and resume operations, then the erase operation can be resumed quickly, but the threshold voltage of special cells shifts excessively leading to memory instability
Solution Approach 1:
The patent dynamically adjusts the voltage state of the special word line based on the erase operation status. During erase suspend, the voltage is released; during erase resume, the voltage is reapplied. This dynamic voltage management allows the system to balance between quick resume capability and threshold voltage stability, resolving the contradiction between speed and reliability
Solution Approach 2:
The patent changes the voltage parameter of the special word line from a static maintained state to a conditional state that varies based on operation phase. By controlling whether voltage is applied or released based on suspend/resume status, the system optimizes both resume speed and threshold voltage stability
2Reliability
If the voltage of the special word line is released early to prevent threshold voltage shifting, then memory stability is improved, but the erase operation cannot be resumed as quickly
Solution Approach 1:
The system transitions from a static voltage release approach to a dynamic approach where voltage is released only when needed (during suspend) and reapplied when resuming. This allows early voltage release for stability while enabling quick resume through voltage reapplication, resolving the speed-reliability tradeoff
Solution Approach 2:
The patent prepares the special word line for quick resume by maintaining the capability to rapidly reapply voltage when resume is commanded. This preliminary preparation ensures that while voltage may be released early for stability, the resume operation can still proceed quickly when needed
3Adaptability or versatility
If erase operations are frequently suspended and resumed, then memory access flexibility is improved, but the threshold voltage of special cells degrades due to excessive voltage differences
Solution Approach 1:
The patent applies different voltage management strategies to different parts of the memory system. The special word line connected to select gates receives conditional voltage release during suspend, while other word lines maintain normal operation. This localized quality control protects threshold voltage precision in critical areas while maintaining overall access flexibility
Solution Approach 2:
The patent changes the voltage parameter of the special word line based on suspend/resume operations to prevent excessive threshold voltage shifting. By dynamically adjusting this parameter during frequent access operations, the system maintains both flexibility and precision
Data Source
AI summary
According to one aspect of the present disclosure, a method for operating a memory is provided. The method may include receiving an erase resume command. The erase resume command may indicate a resume of an erase operation on a memory block in a memory. The method may include, if the erase operation is in an erase pulse phase, releasing, at a first time, a voltage of a special word line to which the memory block is connected in response to a quantity of erase suspends of the memory block being less than a threshold. The quantity of erase suspends may refer to a quantity that the erase operation is suspended in the erase pulse phase. The method may include releasing, at a second time, the voltage of the special word line in response to the quantity of erase suspends being greater than or equal to the threshold, wherein the second time is earlier than the first time.