Nonvolatile Memory Open Word Line Closure
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Solution Overview
Problem
Non-volatile memory devices, such as EEPROM, face challenges in efficiently managing open word lines during programming operations, which can lead to data reliability issues due to insufficient coupling and increased error probabilities.
Innovation Solution
A memory system comprising a non-volatile memory device with a memory controller that identifies open word lines in second memory blocks and closes them by performing a 3-step program operation on adjacent upper word lines, using data from first memory blocks or random data to ensure valid data storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If programming operations are performed on second memory blocks, then data storage capacity is improved, but open word lines are generated causing data reliability to deteriorate
Solution Approach 1:
The patent applies preliminary action by performing a reprogram operation on an upper word line immediately adjacent to the open word line before finalizing the programming of the second memory block. This preliminary reprogram operation closes the open word line by programming memory cells on the adjacent upper word line, preventing potential data reliability issues before they can manifest during subsequent read or write operations.
2Reliability
If reprogram operation is performed on upper word lines to close open word lines, then data reliability is improved, but programming time increases
Solution Approach 1:
The patent applies partial action by performing the reprogram operation only on the specific upper word line immediately adjacent to the open word line, rather than reprogramming all word lines in the memory block. This targeted approach closes the problematic open word line while minimizing the additional programming time required, avoiding unnecessary reprogram operations on other word lines that do not have open line issues.
3Reliability
If random data or data from first memory blocks is used for reprogram operation, then open word lines are closed, but data management complexity increases
Solution Approach 1:
The patent applies self-service by utilizing data from the first memory blocks (which store m-bit data) to perform the reprogram operation on the second memory block. The memory system uses its own existing data resources internally, eliminating the need for external data sources or complex data management protocols. The first memory blocks serve themselves by providing the data needed to close open word lines in the second memory blocks.
Data Source
AI summary
A memory system includes a nonvolatile memory device and a memory controller. The nonvolatile memory device includes first memory blocks configured to store m-bit data per cell and second memory blocks configured to store n-bit data per cell. The memory controller is configured to control the nonvolatile memory device to close an open word line generated in a second memory block of the second memory blocks when a program operation is performed on the second memory block.