Memory Cell State Shaping for Data Reliability in Dense Storage
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Solution Overview
Problem
The increasing integration and decreasing size of storage devices lead to temporary or permanent defects, deteriorating data reliability due to poor distribution and degradation of memory cells, which affects the integrity of stored data.
Innovation Solution
A storage device and method that perform a state-shaping operation based on the speed characteristic of memory cells, selecting target cells for programming and converting their data states to reduce degradation and error bits by using a state-shaping module to alter data values in memory cells prone to degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of storage devices is decreased and integration level is increased, then storage capacity is improved, but data reliability deteriorates due to defects and degradation
Solution Approach 1:
The patent performs a state shaping operation before the actual programming operation. The memory controller identifies target memory cells based on speed characteristics and converts their data values in advance to prevent them from being programmed into degradation-prone states, thereby proactively improving data reliability while maintaining high storage capacity
Solution Approach 2:
The patent applies different operations to different memory cells based on their individual speed characteristics. Fast memory cells are identified and subjected to state shaping operations, while other cells follow normal programming procedures. This localized approach targets specific cells that are more susceptible to degradation, improving overall data reliability without affecting the entire storage device's capacity
2Reliability
If state shaping operation is performed on all memory cells, then data reliability is improved, but operation time and complexity increase
Solution Approach 1:
The patent performs state shaping operations only on a subset of memory cells identified as having fast speed characteristics and being prone to degradation. By applying the operation selectively rather than universally, the patent achieves improved data reliability while minimizing the additional operation time and complexity
Solution Approach 2:
The patent segments the memory cell population into different groups based on their speed characteristics. The memory controller identifies and separates fast memory cells from others, applying state shaping operations only to the fast cell group. This segmentation allows the system to improve reliability where needed while avoiding unnecessary operations on cells that don't require intervention
Data Source
AI summary
A storage device according to an embodiment includes a memory device configured to apply a first program voltage and a first verification voltage to a first word line and output, based on a program state of each of a plurality of memory cells connected to the first word line, a speed information representing a speed characteristic of each of the plurality of memory cells; and a memory controller configured to determine at least one memory cell to be programmed into a predetermined program state; determine, among the at least one memory cell, at least one target memory cell having a first speed characteristic based on the speed information; and perform a state-shaping operation to convert a data corresponding to the predetermined program state for the at least one target memory cell into a value corresponding to a program state different from the predetermined program state.