Flash Memory Erase Flow With Adaptive Soft-Program Verification
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Solution Overview
Problem
Flash memory apparatuses face inefficiencies in erase operations due to prolonged times, particularly after multiple cycling operations, where the soft-program procedure significantly contributes to the overall erase time, especially when over-erasure occurs.
Innovation Solution
A flash memory apparatus and erase method that dynamically adjust the erase operation flow by incorporating an ERASE verification circuit, degradation determination circuit, and soft-program verification circuit to determine and respond to degradation conditions, allowing for alternate execution of soft-program procedures and adjusted voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the soft-program procedure is executed after every ERASE verification to prevent over-erasure, then the reliability of the flash memory apparatus is improved, but the ERASE operation time increases significantly
Solution Approach 1:
The patent applies dynamics by making the ERASE operation flow adaptive and variable rather than fixed. The control circuit dynamically adjusts the sequence of operations based on real-time verification results and degradation conditions, allowing the system to switch between different operational modes (standard ERASE vs. degraded mode with soft-program procedures) to optimize both time and reliability
Solution Approach 2:
The patent changes the parameter of operation sequence based on degradation conditions. When degradation is detected, the system modifies the ERASE flow to include soft-program procedures at specific points; when no degradation is present, the system uses the faster standard ERASE flow without unnecessary soft-program steps, thus balancing reliability and speed
2Reliability
If the soft-program procedure is executed frequently to handle over-erasure after multiple cycling operations, then the reliability is improved, but the productivity of the ERASE operation deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where verification results and degradation conditions are continuously monitored and fed back to the control circuit. This feedback loop allows the system to intelligently determine when soft-program procedures are actually needed, avoiding unnecessary executions that would reduce productivity while still maintaining reliability when required
Solution Approach 2:
The patent segments the ERASE operation into distinct phases and conditions. Instead of uniformly applying soft-program procedures throughout, the system divides the ERASE flow into standard paths and degraded paths, applying soft-program procedures only in specific segments where degradation is detected, thereby maintaining overall productivity
Data Source
AI summary
A flash memory apparatus and an ERASE method thereof are provided. The ERASE method includes: applying an ERASE voltage to a target memory block and determining whether an ERASE verification passes during an ERASE operation period; determining whether the target memory block meets a degradation condition when the ERASE verification fails; determining whether the target memory block passes a soft-program verification when the degradation condition is met, and returning to the step of applying the ERASE voltage after the target memory block passes the soft-program verification; returning to the step of applying the ERASE voltage when the target memory block does not meet the degradation condition; and determining whether the target memory block passes the soft-program verification when the ERASE verification passes, and applying a soft-program voltage to the target memory block after the soft-program verification fails.