Memory Cell Latch Restoration for Sudden Power-Off Recovery
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Solution Overview
Problem
Memory systems face challenges in accurately resuming program operations after sudden power-offs due to incomplete or altered data states, leading to potential errors and reduced reliability.
Innovation Solution
A memory system and method that includes a memory device with latches for storing code values and a controller to manage operations, which detects sudden power-offs, suspends programming, restores altered code values to original states using threshold voltage comparisons, and divides multi-bit data into single-bit units for reliable resumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the memory device suspends programming in response to sudden power-off, then data accuracy is improved, but program operation completion is delayed
Solution Approach 1:
The memory device performs preliminary actions by storing the initial code value in latches before programming completes, and by preparing verification results. When sudden power-off occurs, these preliminary stored values enable rapid recovery without re-programming, thus resolving the contradiction between data accuracy and time loss.
2Reliability
If the memory device restores changed code values to original values, then reliability is improved, but device complexity increases
Solution Approach 1:
The memory device uses latches to create a copy of the initial code value before programming. This copied value is stored separately and used for restoration when needed, allowing reliable recovery without increasing the fundamental device structure, thus resolving the contradiction between reliability and device complexity.
3Manufacturing precision
If the memory device divides multi-bit data into 1-bit units for programming, then programming accuracy is improved, but programming time increases
Solution Approach 1:
The memory device segments multi-bit data into individual 1-bit units for separate programming operations. Each bit is programmed and verified independently, ensuring high accuracy. The latches store the segmented data values for potential restoration, resolving the contradiction between programming accuracy and productivity by enabling selective restoration of segmented data.
Data Source
AI summary
Provided herein are a memory system and a method of programming the same. The memory system may include a memory device including memory cells for storing data and a plurality of latches for storing code values indicating the data. The memory device may be configured to program data into each of the memory cells, store an original code value indicating the data in the plurality of latches, and change the original code value stored in the plurality of latches to an erase code value in response to a verification pass, and a memory controller configured to output, to the memory device, a suspend command for suspending at least the programming in response to detecting a sudden power-off and a recovery command for restoring a code value changed to the erase code value.