Non-volatile Memory Index Cells for Wear Reduction
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Solution Overview
Problem
Conventional flash memory devices require erasing an entire sector to program a single physical word, leading to prolonged program operations and reduced device lifetime due to excessive wear from unnecessary erase cycles.
Innovation Solution
Incorporating index memory cells associated with each physical word in the sector, allowing the controller to determine if a physical word is available for programming without a pre-erase operation, thereby reducing unnecessary erase operations and wear on memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the entire sector is erased before programming a single physical word, then programming accuracy is ensured, but program operation time is lengthened and device lifetime is reduced
Solution Approach 1:
The sector is divided into multiple physical words, and index memory cells are assigned to track the state of each physical word individually. This segmentation allows the controller to identify and program only the specific physical word that needs updating, rather than erasing the entire sector. The index memory cells serve as independent status indicators for each physical word, enabling granular control over programming operations.
Solution Approach 2:
The index memory cells are pre-configured to indicate whether each physical word is in an erased or programmed state. This preliminary status information allows the controller to make informed decisions about which physical words require programming, avoiding unnecessary erase operations on physical words that are already in the correct state.
2Manufacturing precision
If the entire sector is erased before programming a single physical word, then programming accuracy is ensured, but device lifetime is reduced due to excessive wear
Solution Approach 1:
The sector is divided into multiple physical words, and index memory cells are assigned to track the state of each physical word individually. This segmentation allows the controller to identify and program only the specific physical word that needs updating, rather than erasing the entire sector. The index memory cells serve as independent status indicators for each physical word, enabling granular control over programming operations.
Solution Approach 2:
The index memory cells, which consume additional space in the sector, are converted into a beneficial resource by using them to track the programming state of each physical word. This transforms the potential harm of reduced storage capacity into a benefit that enables wear reduction and extends device lifetime through targeted programming operations.
3Productivity
If index memory cells are added to track physical word states, then unnecessary erase operations are reduced, but device complexity increases
Solution Approach 1:
The index memory cells serve multiple functions: they track the programming state of physical words, guide the controller's programming decisions, and reduce the need for unnecessary erase operations. This multi-functionality justifies the additional complexity by providing significant productivity benefits through intelligent resource management.
Solution Approach 2:
The index memory cells act as intermediaries between the physical words and the controller. They provide the controller with status information about each physical word without requiring the controller to directly monitor or manage the state of every physical word, thereby simplifying the control logic while still enabling targeted programming operations.
Data Source
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AI summary
A memory device that includes a memory array having pluralities of non-volatile memory cells, a plurality of index memory cells each associated with a different one of the pluralities of the non-volatile memory cells, and a controller. The controller is configured to erase the pluralities of non-volatile memory cells, set each of the index memory cells to a first state, and program first data into the memory array by reading the plurality of index memory cells and determining that a first one of the index memory cells is in the first state, programming the first data into the plurality of the non-volatile memory cells associated with the first one of the index memory cells, and setting the first one of the index memory cells to a second state different from the first state.