Nonvolatile Memory Reprogramming Using ECC for Charge-Loss Errors
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Solution Overview
Problem
Nonvolatile memory devices experience data degradation due to charge loss over time, leading to errors and reduced reliability, and existing methods do not effectively address this issue.
Innovation Solution
A method of reprogramming data in nonvolatile memory devices involves reading data page-by-page, performing error correction code (ECC) decoding, and selectively applying a reprogram voltage to specific bits based on threshold voltage distribution and program loop completion information to enhance data reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If data is stored in nonvolatile memory devices, then data retention is achieved, but data degradation occurs due to charge loss over time
Solution Approach 1:
The patent applies preliminary action by performing ECC decoding and identifying degraded pages before complete data loss occurs. The memory controller proactively detects charge loss and triggers reprogramming operations on affected pages, preventing further degradation and maintaining data integrity over extended retention periods.
Solution Approach 2:
The patent implements feedback through the ECC decoding process that continuously monitors data integrity. When degraded pages are detected, the system responds by reprogramming those specific pages, creating a closed-loop feedback mechanism that maintains reliability despite long-term storage challenges.
2Reliability
If reprogramming operations are performed frequently to maintain data integrity, then reliability improves, but productivity decreases due to additional write operations
Solution Approach 1:
The patent applies local quality by reprogramming only the specific degraded pages identified through ECC decoding, rather than reprogramming entire memory blocks or all pages. This targeted approach maintains data integrity where needed while minimizing unnecessary write operations and preserving overall system productivity.
Solution Approach 2:
The patent segments the memory space into individual pages and processes them independently. By identifying and reprogramming only the degraded pages rather than treating the entire memory uniformly, the system optimizes the balance between reliability and productivity through selective maintenance operations.
Data Source
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AI summary
In a method of reprogramming data in a nonvolatile memory device including a plurality of pages each of which includes a plurality of memory cells, first page data programmed in a first page is read from among a plurality of page data programmed in the plurality of pages. The plurality of page data have a threshold voltage distribution including a plurality of states. An error correction code (ECC) decoding is performed on the first page data. A reprogram operation is selectively performed on target bits in which an error occurs among a plurality of bits included in the first page data based on a result of performing the ECC decoding on the first page data and a reprogram voltage. The target bits correspond to a first state among the plurality of states. A voltage level of the reprogram voltage is adaptively changed.