MLC Block Mode Transition for Memory Yield
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Solution Overview
Problem
The challenge in semiconductor memory devices is the limited allocation of SLC blocks due to high product endurance requirements, which restricts the number of MLC blocks that can be allocated, especially in systems with high random write cycling or data snapshot needs, leading to inefficient use of memory capacity.
Innovation Solution
The technique involves transitioning a portion of MLC blocks to SLC mode at various times in the memory device's lifetime, reallocating program-erase cycles to reduce the number of dedicated SLC blocks and maintain uniform endurance, using separate or weighted cycle counts to manage the transition effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of dedicated SLC blocks is increased to meet high product endurance requirements, then reliability is improved, but the number of MLC blocks that can be allocated is reduced, leading to loss of storage capacity
Solution Approach 1:
The patent implements dynamic block mode transition where MLC blocks can be temporarily transitioned to SLC mode during high-write periods and then returned to MLC mode. This dynamic reconfiguration allows the same physical blocks to serve different functions at different times, resolving the contradiction between needing dedicated SLC blocks for endurance and maximizing MLC block allocation for capacity.
Solution Approach 2:
The patent changes the operational parameters of memory blocks by transitioning them between SLC and MLC modes. By adjusting the data storage mode (parameter) of existing MLC blocks, the system can provide SLC-level endurance without requiring separate dedicated SLC block allocations, thus maintaining both reliability and storage capacity.
2Ease of manufacture
If a fixed number of SLC blocks are allocated at manufacturing, then manufacturing simplicity is maintained, but adaptability to different workload patterns is reduced
Solution Approach 1:
The system transitions from static block allocation to dynamic block mode transition. Blocks can be flexibly switched between SLC and MLC modes based on real-time workload characteristics, enabling the system to adapt to different usage patterns while maintaining the same physical block structure.
Solution Approach 2:
The patent makes MLC blocks multi-functional by enabling them to operate in both MLC and SLC modes. This universality allows the same blocks to serve different purposes (high-capacity storage vs. high-endurance storage) depending on system needs, eliminating the need for separate dedicated SLC blocks.
3Quantity of substance
If MLC blocks are used exclusively for capacity, then storage density is maximized, but endurance performance is reduced
Solution Approach 1:
The system dynamically transitions MLC blocks to SLC mode when high endurance performance is needed, allowing the same blocks to provide both high storage density (in MLC mode) and high endurance performance (in SLC mode) at different times, resolving the contradiction between these two properties.
Solution Approach 2:
By changing the operational parameter (mode) of MLC blocks between SLC and MLC configurations, the system can adjust the balance between storage density and endurance performance based on workload requirements, allowing MLC blocks to exhibit both high density and high endurance characteristics as needed.
Data Source
AI summary
Apparatuses and techniques are described for more efficiently allocating blocks of data in a memory device. The number of dedicated single-level cell (SLC) blocks which are allocated at the time of manufacture of a memory device can be reduced by transitioning a portion of the multi-level cell (MLC) blocks to an SLC mode at various times in the lifetime of the memory device. In one approach, separate counts are maintained for an MLC block in the SLC and MLC modes. The separate counts can be used to select an MLC block to transition to the SLC mode, or to select an MLC block to program. In another approach, a single count is maintained, where the SLC cycles are weighted less heavily than the MLC cycles.