Nonvolatile Memory Bad Block Replacement Across Planes
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Solution Overview
Problem
Flash memory devices often encounter defective or bad blocks due to manufacturing or operational issues, leading to reduced performance and available capacity, as these blocks cannot store data normally.
Innovation Solution
A nonvolatile memory device with a dual-plane structure, including an address replacing circuit that receives input addresses and outputs replaced addresses based on bad block information, allowing for the normal operation of memory blocks by replacing defective blocks with functional ones within the same or different planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bad blocks are replaced with functional blocks from the same plane, then reliability is improved, but available capacity of the plane is reduced
Solution Approach 1:
The patent extends bad block replacement from a single-plane system to a multi-plane system. When a bad block is detected in a first plane, the address replacing circuit can map it to a functional block in a second plane, thereby utilizing the third dimension (plane dimension) to resolve the capacity loss problem within a plane.
Solution Approach 2:
The address replacing circuit acts as an intermediary between the controller and the memory planes. It intercepts address requests, identifies bad blocks, and transparently redirects them to functional blocks in other planes, allowing the controller to operate normally without knowing about the underlying plane structure or bad blocks.
2Quantity of substance
If bad blocks are replaced with functional blocks from different planes, then available capacity is maintained, but device complexity increases
Solution Approach 1:
The address replacing circuit is designed with universal functionality to handle bad block replacement across multiple planes. It maintains a bad block information structure that can store mappings for any plane, and the replacement logic works uniformly regardless of which plane the bad block is in, making the system scalable to N planes without proportionally increasing complexity.
Solution Approach 2:
The patent creates a virtual copy of the address space through the address replacing circuit. The circuit maintains a mapping table that copies bad block addresses from one plane to corresponding addresses in another plane, allowing the system to present a unified address space to the controller while handling the complexity internally.
3Productivity
If multiple planes are used for bad block replacement, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The memory device is segmented into multiple independent planes, each with its own set of memory blocks. This segmentation allows bad blocks in one plane to be replaced by functional blocks in another plane, thereby maintaining overall productivity. The segmentation isolates manufacturing defects to specific planes rather than affecting the entire device.
Data Source
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.