Nonvolatile Memory Buffer Region Closing Program Operation
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Solution Overview
Problem
Nonvolatile memory devices face challenges in managing the erase program interval (EPI) problem, where pages of a memory block may remain in an open state after programming, leading to deteriorated characteristics and reduced data reliability due to prolonged unprogrammed states.
Innovation Solution
A program method is introduced that involves a buffer program operation using single level cells, followed by a main program operation using multi level cells, and a closing program operation where data from the buffer region is written to open pages of the main region, ensuring all pages are programmed within a short time after the main program is finished.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a main program operation is performed to store data in the main region using multi-level cell method, then storage capacity is improved, but pages may remain in an open state leading to deteriorated characteristics and reduced data reliability
Solution Approach 1:
The buffer region is used to preliminarily store data before the main program operation. After the main program operation completes, the buffer region is used to fill open pages in the main region, ensuring all pages are programmed within a short time frame. This preliminary preparation and subsequent completion action prevents pages from remaining in an open state, thereby maintaining data reliability while achieving high storage capacity through multi-level cell method.
2Quantity of substance
If multi-level cell method is used in the main region, then storage capacity is improved, but the erase program interval problem is exacerbated due to prolonged unprogrammed states
Solution Approach 1:
The buffer region acts as an intermediary between data input and the main region. It temporarily holds data during the programming process and is subsequently used to fill open pages in the main region. This intermediary mechanism ensures that all pages are programmed within a short time after the main program operation, preventing prolonged unprogrammed states and thereby solving the erase program interval problem while maintaining high storage capacity through multi-level cell method.
3Speed
If buffer program operation is performed using single level cell method, then programming speed is improved, but storage capacity is reduced compared to multi-level cell method
Solution Approach 1:
The memory device is segmented into two distinct regions: a buffer region using single-level cell method for high-speed programming operations, and a main region using multi-level cell method for high-capacity storage. The buffer region handles temporary data storage and programming operations at high speed, while the main region provides the required storage capacity. This segmentation allows each region to optimize for its specific function, resolving the contradiction between programming speed and storage capacity.
4Reliability
If all pages are programmed within a short time after main program operation, then EPI problem is solved and data reliability is improved, but additional program operations are required increasing process complexity
Solution Approach 1:
The buffer region and main region are merged into a unified memory structure where the buffer region is logically integrated with the main region. The buffer region is used both during the main program operation and subsequently to fill open pages in the main region. This merging approach allows the same physical structure to serve multiple functions, reducing the overall complexity compared to having separate independent regions, while still achieving the goal of programming all pages within a short time frame to solve the EPI problem.
Data Source
AI summary
According to example embodiments, a storage device in accordance includes a nonvolatile memory device and a memory controller. The nonvolatile memory device includes memory blocks divided into a buffer region and a main region. The memory controller is configured to control the nonvolatile memory device to perform a buffer program operation that includes storing data provided from the outside in the buffer region, to perform a main program operation that includes storing data provided from the outside in the main region, and to perform a closing program operation that includes writing data stored in the buffer region in the main region such the that at least part of the data stored in the buffer region is written to open pages of a memory block including a page programmed last in the main program operation.