Memory Controller Read-Voltage Tuning for NAND Data Reliability
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Solution Overview
Problem
High integration in semiconductor memory devices leads to reduced reliability due to new issues such as data damage, necessitating a method to improve the reliability of nonvolatile memory and storage devices.
Innovation Solution
An operating method for a storage device that includes a memory controller adjusting read schemes and voltages for nonvolatile memory, utilizing a three-dimensional cell array with charge trap type memory cells and select transistors, and implementing error correction and interleaving techniques to enhance data access and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high integration is implemented in nonvolatile memory to reduce production cost, then manufacturing cost decreases, but reliability deteriorates due to new issues such as data damage
Solution Approach 1:
The memory system is segmented into multiple components: nonvolatile memory device, memory controller, and host device. The memory controller is further divided into voltage adjustment unit, read unit, and determination unit. This segmentation allows each component to specialize in specific functions, improving overall reliability while maintaining manufacturing efficiency.
Solution Approach 2:
The memory controller acts as an intermediary between the host device and nonvolatile memory device. It includes a voltage adjustment unit that adjusts read voltages based on threshold voltage distribution, and a determination unit that determines whether to adjust read schemes. This intermediary layer protects the memory system from reliability issues by managing voltage variations and data access strategies.
2Measurement precision
If read voltage levels are adjusted according to target data to improve read accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The read voltage is made dynamic rather than fixed. The voltage adjustment unit adjusts the read voltage level based on the threshold voltage distribution of the nonvolatile memory device. The determination unit dynamically decides whether to adjust the read scheme based on data location and voltage distribution characteristics. This dynamic adaptation improves read accuracy without requiring permanently complex hardware.
Solution Approach 2:
The system changes the voltage parameter (read voltage level) based on the state of the memory device. When the determination unit identifies that threshold voltage distribution requires adjustment, it changes the read voltage parameter to optimize reading. This parameter adjustment approach improves measurement precision while maintaining relatively simple device architecture through software/firmware control.
Data Source
AI summary
An operating method is for a storage device that includes a nonvolatile memory and a memory controller configured to control the nonvolatile memory. The operating method may include the memory controller receiving a read request from an external device, the memory controller adjusting a read scheme according to target data indicated by the read request among data of one page of the nonvolatile memory, and the memory controller reading the target data from the nonvolatile memory according to the adjusted read scheme.