Memory System Dummy Data Programming for Reliability
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Solution Overview
Problem
Flash memory devices experience degraded threshold voltage distribution characteristics and reliability due to long erase program intervals, leading to inefficiencies in data programming and read operations.
Innovation Solution
A memory system that programs dummy data in specific modes to prevent normal data from being written to memory blocks with long erase program intervals, thereby maintaining data reliability and increasing read reclaim performance by copying normal data based on dummy data stored in the same program mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If normal data is programmed to memory blocks after long erase program intervals, then storage capacity is utilized, but threshold voltage distribution characteristics are degraded and reliability decreases
Solution Approach 1:
The patent applies preliminary action by programming dummy data to memory blocks before they are ready to receive normal data. The memory controller monitors erase program intervals and proactively programs dummy data to blocks that have exceeded the threshold time, preventing them from receiving normal data and thus maintaining data reliability while still utilizing storage capacity.
2Reliability
If dummy data is programmed to prevent normal data programming in blocks with long erase program intervals, then data reliability is maintained, but storage capacity is wasted
Solution Approach 1:
The patent changes the parameter of data type from normal data to dummy data for specific memory blocks based on the erase program interval parameter. By dynamically adjusting what type of data is programmed to which blocks based on time parameters, the system maintains reliability for time-sensitive data while preserving storage capacity utilization through appropriate block selection.
3Reliability
If dummy data is programmed in a program mode with more bits per memory cell, then read reclaim performance is improved, but programming time increases
Solution Approach 1:
The patent applies local quality by using different program modes for different types of dummy data. SLC-mode dummy data is used for blocks requiring fast programming (where speed is the local priority), while MLC-mode dummy data is used for blocks where read reclaim performance is the local priority. This localized approach optimizes overall system performance by matching the programming mode to the specific needs of each block.
Data Source
AI summary
An operating method of a memory system includes storing normal data to a first storage area of a non-volatile memory in a first program mode among multiple program modes defined according to a number of bits stored in each memory cell; storing dummy data in the first storage area in at least one of the multiple program modes including the first program mode; and copying the normal data from the first storage area to a second storage area of the non-volatile memory based on dummy data stored in the first program mode.