Temperature-Based Memory Operations for NAND Flash
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Solution Overview
Problem
Memory devices, particularly NAND flash memory, experience increased raw bit error rates (RBER) due to temperature variations, leading to performance reduction and reduced useful lifetime, as existing temperature compensation schemes fail to effectively manage voltage shifts in extreme cross-temperature conditions.
Innovation Solution
A method that determines the operating temperature and strategically selects write strategies by allocating data to single-level cell (SLC) or multi-level cell (MLC) blocks based on temperature ranges, writing data in SLC at low and high temperatures and allowing conversion of SLC data to MLC at moderate temperatures for improved reliability and storage density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is written at a first temperature and read at a second temperature (different from the first), then storage capacity is maintained, but raw bit error rate increases
Solution Approach 1:
The memory device is divided into multiple memory blocks, each designated for specific temperature ranges. The controller segments data storage across different blocks based on operating temperature, writing data to temperature-appropriate blocks to minimize cross-temperature errors while maintaining full storage capacity.
Solution Approach 2:
Different memory blocks are assigned different temperature optimization characteristics. Some blocks are optimized for low-temperature operation, others for high-temperature operation, and others for moderate temperatures. This local quality differentiation allows data to be stored in blocks matching the current temperature conditions, reducing bit error rates.
2Reliability
If temperature compensation schemes are implemented, then data reliability is improved, but device complexity increases
Solution Approach 1:
Memory blocks are pre-designated and pre-configured for specific temperature ranges during manufacturing or initialization. This preliminary action eliminates the need for complex real-time temperature compensation algorithms, as the controller simply needs to select the appropriate pre-designated block based on current temperature readings.
Solution Approach 2:
The system uses the temperature sensor and pre-designated block structure to automatically select appropriate storage locations without requiring complex external compensation mechanisms. The temperature-based block designation system serves itself by inherently accommodating temperature variations through its structure.
3Reliability
If SLC mode is used at low and high temperatures, then reliability is improved, but storage density is reduced
Solution Approach 1:
The system dynamically switches between SLC and MLC modes based on temperature conditions. At low and high temperatures, data is written to blocks in SLC mode for maximum reliability. At moderate temperatures, the system transitions to MLC mode in appropriate blocks to maximize storage density. This dynamic adaptation allows the system to optimize both reliability and capacity based on real-time temperature conditions.
4Quantity of substance
If MLC mode is used at moderate temperatures, then storage density is improved, but reliability is reduced
Solution Approach 1:
The system changes the operational parameters of memory blocks based on temperature. At moderate temperatures (e.g., between threshold temperatures), blocks are configured in MLC mode to achieve higher storage density. When temperature drops below or rises above these thresholds, the same blocks switch to SLC mode for enhanced reliability. This parameter change approach allows the system to capture the advantages of both modes under different conditions.
Data Source
AI summary
Apparatuses, methods, and devices that can be utilized to provide temperature-based memory operations are described. One or more apparatuses can include a memory device and a controller coupled to the memory device and configured to: determine an operating temperature of the apparatus, determine one of a plurality of designated open blocks of the memory device to write data based on the operating temperature of the apparatus and a size of the data, and write the data in the determined one of the plurality of designated blocks of the memory device.