Nonvolatile Memory Block Erase Control for Lifespan Extension
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Solution Overview
Problem
Existing nonvolatile semiconductor memory devices face issues with data loss during sudden power-offs, leading to premature memory block erasure and reduced lifespan due to immediate erase operations on memory blocks with clean pages.
Innovation Solution
A method is introduced that involves a memory controller performing a dummy program operation on the boundary page and clean pages of a memory block after a sudden power-off, followed by an erase operation, to prevent deep erase and extend the memory block's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an immediate erase operation is performed on a memory block after sudden power-off, then data loss is prevented, but the memory block lifespan is reduced due to premature erasure of clean pages
Solution Approach 1:
The memory controller performs a preliminary check of the memory block state before executing the erase operation. It identifies whether the block contains clean pages (pages that have never been programmed or have been erased but not yet programmed) and selectively applies dummy program operations to these clean pages before the erase operation, thereby preventing the need for deep erase and extending memory block lifespan
Solution Approach 2:
The patent applies different treatment to different regions of the memory block. Clean pages receive a dummy program operation followed by normal erase, while dirty pages (pages containing valid data) undergo only the normal erase operation. This localized differentiation prevents unnecessary deep erase on clean pages while maintaining data integrity on dirty pages
2Duration of action of stationary object
If a dummy program operation is performed on clean pages before erase, then memory block lifespan is extended, but operation time is increased
Solution Approach 1:
The patent applies dummy program operation only to clean pages rather than all pages in the memory block. The memory controller identifies clean pages through status flags or read operations and selectively applies the dummy program operation only to those specific pages, thereby minimizing the additional time required while still achieving the lifespan extension benefit
Solution Approach 2:
The memory controller performs preliminary identification of clean pages using status flags or quick read operations before executing the dummy program operation. This preliminary sorting allows the system to prepare a list of target pages in advance, reducing the overall operation time by avoiding unnecessary operations on dirty pages
Data Source
AI summary
In a method of operating a storage device including at least one nonvolatile memory device and a memory controller configured to control the at least one nonvolatile memory device, a boundary page of a first memory block among a plurality of memory blocks included in the at least one nonvolatile memory device is searched for, at least one clean page, in which data is not written, of the first memory block is searched for, a dummy program operation is performed on a portion of the boundary page and the at least one clean page, and an erase operation is performed on the first memory block.