Memory Controller Die Status Adaptation
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Solution Overview
Problem
Three-dimensional memory devices face reliability issues during program operations due to variations in electrical characteristics among dies, leading to potential errors and disturbances in threshold voltage distributions.
Innovation Solution
A memory system and operating method that differentiate between normal and low-status dies by using a memory controller to output specific commands, such as partial program and partial erase commands, based on electrical characteristics, to manage and stabilize the program operations in low-status dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normal program command is used for all dies, then the operation is simple and fast, but reliability deteriorates due to electrical characteristic variations among dies
Solution Approach 1:
The patent segments the program operation into two distinct modes: normal program command for dies with electrical characteristics above the reference value, and partial program command for dies below the reference value. This segmentation allows tailored operations for different die conditions, improving reliability without excessive complexity.
Solution Approach 2:
The system dynamically selects the appropriate program command type based on real-time die status evaluation. The memory controller adjusts the command issued to each die according to its electrical characteristics, enabling adaptive operation that balances reliability and complexity.
2Stability of the object's composition
If uniform program operations are applied to all dies, then the control logic is simple, but threshold voltage distribution stability deteriorates
Solution Approach 1:
The patent applies local quality by evaluating each die's electrical characteristics individually and applying different program operations based on its specific status. Dies above the reference value receive normal program commands, while those below receive partial program commands, ensuring each die is treated according to its local condition.
Solution Approach 2:
The system incorporates feedback through die status evaluation, where the memory controller continuously monitors electrical characteristics and adjusts program commands accordingly. This feedback mechanism maintains threshold voltage distribution stability by responding to actual die conditions.
3Reliability
If partial program and erase commands are used for low status dies, then program operation reliability improves, but operation time increases
Solution Approach 1:
The patent applies partial action by issuing partial program commands that target only the necessary portions of low status dies, rather than performing complete program operations. This approach achieves the minimum required reliability improvement while minimizing the time penalty.
Solution Approach 2:
The system changes operational parameters by switching between normal and partial program commands based on die status. This parameter adjustment allows the system to optimize the balance between reliability improvement and time consumption for each individual die.
Data Source
AI summary
A memory system includes: a plurality of dies including a plurality of memory blocks; and a memory controller for outputting a normal program command when a die including a selected memory block is a normal die having an electrical characteristic higher than or equal to a reference value in a program operation, and outputting a partial program command and a partial erase command when the die including the selected memory block is a low status die having an electrical characteristic lower than the reference value.