Healing Pattern Programming for Memory Block Data Retention
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Solution Overview
Problem
Non-volatile semiconductor devices experience reliability degradation due to deteriorating data retention characteristics over time, necessitating regular refresh operations to prevent memory block deterioration.
Innovation Solution
A semiconductor device and method that includes a circuit group for performing program, read, and erase operations on memory blocks, with a control circuit that programs memory cells in a healing pattern with alternately arranged erased and programmed cells, and a method to check and reset refresh operations based on Error Correction Code usage, moving data when necessary to maintain memory block reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is retained in non-volatile memory blocks over time, then data storage capability is maintained, but data retention characteristics deteriorate causing reliability degradation
Solution Approach 1:
The patent applies preliminary action by performing a healing pattern program operation on memory blocks before they fully deteriorate. The control circuit detects when a memory block has been erased and proactively programs it with alternating erased and programmed cells pattern, preventing future data retention issues before they occur. This proactive maintenance approach resolves the contradiction by extending reliable data retention time while maintaining high reliability standards.
Solution Approach 2:
The patent implements discarding and recovering by temporarily discarding the normal data storage function of erased memory blocks and recovering them through healing pattern programming. When the control circuit detects an erased memory block, it temporarily repurposes that block for healing pattern programming instead of normal data storage. This recovery process rejuvenates the memory block's electrical characteristics, allowing it to return to reliable service with extended data retention capability.
2Reliability
If refresh operations are performed frequently on memory blocks, then data retention characteristics are maintained, but device wear and electrical characteristic deterioration increase
Solution Approach 1:
The patent applies local quality by selectively applying healing pattern programming only to erased memory blocks that need rejuvenation, rather than uniformly refreshing all memory blocks. The control circuit individually monitors and identifies erased blocks, applying the healing pattern locally to those specific blocks. This targeted approach maintains data retention characteristics for blocks that need it while minimizing unnecessary operations on already healthy blocks, thereby extending overall device lifespan.
Solution Approach 2:
The patent implements parameter changes by altering the programming state parameters of memory blocks through healing pattern operations. Instead of traditional uniform programming, the healing pattern uses alternating erased and programmed cells configuration, which changes the electrical stress distribution parameters. This parameter change rejuvenates erased blocks without requiring frequent full refresh operations, reducing cumulative wear while maintaining reliability.
3Reliability
If memory blocks are erased and reprogrammed repeatedly, then data retention is refreshed, but electrical characteristics of the memory block deteriorate
Solution Approach 1:
The patent implements periodic action through the healing pattern program operation that periodically rejuvenates erased memory blocks. The control circuit detects erased blocks and applies the healing pattern at appropriate intervals, creating a periodic maintenance cycle. This periodic healing operation restores electrical characteristics without requiring continuous or frequent full reprogramming, thereby preventing electrical characteristic deterioration while maintaining data retention reliability.
Solution Approach 2:
The patent applies preliminary action by performing healing pattern programming on erased memory blocks before their electrical characteristics significantly deteriorate. The control circuit detects the erased state and proactively applies the healing pattern to prevent future electrical characteristic degradation. This preliminary maintenance approach preserves manufacturing precision by addressing issues early, avoiding the cumulative damage that would result from repeated aggressive reprogramming cycles.
Data Source
AI summary
A semiconductor device includes a plurality of memory blocks each including a plurality of memory cells, a circuit group performing a program operation, a read operation and an erase operation on a selected memory block, among the plurality of memory blocks, and a control circuit controlling the circuit group to program the memory cells of the selected memory block in a healing pattern. The healing pattern is programmed before a subsequent program operation is performed on the selected memory block. The memory cells of the healing pattern include erased memory cells and programmed memory cells arranged alternately.