Flash Memory Block Remapping Across Planes for Bad Block Recovery
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Solution Overview
Problem
Flash memory devices suffer from defective or bad blocks that hinder normal operation and reduce available capacity, necessitating effective management and replacement strategies.
Innovation Solution
A nonvolatile memory device employs an address replacing circuit that remaps bad blocks to spare or normal blocks within the same or different planes, utilizing a comparator and address table to manage bad block information and ensure seamless operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bad blocks are replaced within the same plane, then operational integrity is maintained, but available capacity is reduced when all blocks in a plane are bad
Solution Approach 1:
The patent introduces cross-plane block replacement capability, allowing blocks to be replaced across different planes rather than being confined to the same plane. This dimensional expansion enables the system to access spare blocks from other planes when all blocks in the current plane are defective, thereby maintaining both reliability and available capacity simultaneously.
2Quantity of substance
If reserved blocks are used to replace bad blocks, then available capacity is improved, but device complexity increases due to additional management requirements
Solution Approach 1:
The system automatically manages reserved blocks and performs cross-plane replacement operations without requiring manual intervention or complex user-side management. The memory controller autonomously identifies bad blocks, locates suitable replacement blocks in other planes, and executes the replacement process, thereby reducing the operational complexity burden on users while maintaining high available capacity.
3Speed
If multi-plane operations are implemented, then operating speed is improved, but the impact of bad blocks increases when distributed across planes
Solution Approach 1:
The patent dynamically adjusts the block replacement strategy based on the distribution and severity of bad blocks across different planes. When bad blocks are detected, the system changes its operational parameters to utilize cross-plane replacement, selecting replacement blocks from planes with the fewest bad blocks. This adaptive parameter adjustment maintains multi-plane operation speeds while mitigating the impact of distributed bad blocks through intelligent resource allocation.
Data Source
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AI summary
Disclosed is a nonvolatile memory device which includes a first plane that includes a plurality of memory blocks, a second plane that includes a plurality of memory blocks, an address replacing circuit that receives a first input address from an external controller, the first input address corresponding to a first memory block of the plurality of memory blocks of the first plane from an external controller and outputs a replaced address based on the first input address and bad block information, and an address decoder that controls word lines connected with a second memory block based on the replaced address, the word lines corresponding to the replaced address from among the plurality of memory blocks of the second plane. The first memory block of the first plane is a bad block.