Backup Memory for Multi-Level Flash Data Recovery
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Solution Overview
Problem
In nonvolatile memory systems, data loss can occur in multi-level cells due to programming errors or malfunctions, particularly affecting the least significant bit (LSB) when most significant bit (MSB) programming is incomplete, leading to difficulties in determining the LSB's logic state and potentially crippling the system's performance as integration density increases.
Innovation Solution
Incorporating a backup memory within the memory controller to store previously programmed data in multi-level memory cells, ensuring that if errors occur during further programming, the stored data can be recovered and relocated to prevent loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-level nonvolatile memory cells are used to increase data storage capacity, then the amount of stored data per unit memory chip area increases, but data loss occurs during programming due to programming errors or malfunctions
Solution Approach 1:
The patent applies preliminary action by storing a backup copy of data in the buffer memory before programming operations are completed. This allows the system to recover from programming errors by retrieving the original data from the buffer, preventing data loss while maintaining increased storage capacity through multi-level cells
Solution Approach 2:
The patent implements copying by creating a backup copy of the data in the buffer memory that mirrors the data stored in the multi-level nonvolatile memory cells. This copy serves as a safety mechanism that can be used to restore data if programming errors occur, thus resolving the contradiction between increased capacity and data reliability
2Quantity of substance
If integration density increases to store more data, then data storage capacity per unit area increases, but the likelihood of programming errors and data loss increases
Solution Approach 1:
The patent applies beforehand cushioning by maintaining a buffer memory that stores backup copies of data before programming operations. This cushioning mechanism absorbs the impact of programming errors that become more likely with increased integration density, allowing the system to recover without data loss while maintaining high storage capacity
3Reliability
If buffer memory stores backup data to prevent data loss, then data reliability improves, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the buffer memory to serve multiple functions: it acts as both a data transfer buffer during normal operations and as a backup storage mechanism for error recovery. This multi-functionality improves data reliability without proportionally increasing device complexity, as the same hardware structure fulfills multiple roles
Data Source
AI summary
A nonvolatile memory system includes a host system, a memory controller, and a flash memory chip including multi-level flash memory cells. The memory controller includes a backup memory adapted to store a backup copy of previously programmed data from the multi-level flash memory cells when the multi-level flash memory cells are further programmed. Where an error or malfunction occurs during the further programming of the multi-level flash memory cells, the backup copy of the previously programmed data is used to program different multi-level flash memory cells.