Charge Trap Flash Memory Read Condition Adjustment
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Solution Overview
Problem
Charge trap flash (CTF) memory devices experience read failures due to the fast charge loss phenomenon, which causes threshold voltage variations, leading to incorrect read operations before the stabilization time is reached.
Innovation Solution
A memory controller manages a time mark table to track the program lapse time of CTF cells, dividing the time interval between program completion and stabilization into zones with distinct read conditions, allowing for real-time adjustment of read conditions based on the program lapse time to prevent read failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If read operations are performed immediately after program completion, then access speed is improved, but read reliability deteriorates due to fast charge loss phenomenon
Solution Approach 1:
The patent introduces a waiting period between program completion and read operations. The memory controller determines whether to apply a waiting period based on the program lapse time, ensuring that read operations are delayed until the charge trap cells have stabilized their threshold voltages, thus preventing read failures while maintaining efficient access patterns
Solution Approach 2:
The patent dynamically adjusts read conditions based on program lapse time. The memory controller modifies read voltages and sensing conditions according to the elapsed time since program completion, allowing the system to adapt to the changing electrical characteristics of the charge trap cells and maintain reliable reads across different time intervals
2Device complexity
If read conditions are fixed, then device complexity is reduced, but read reliability deteriorates due to threshold voltage variations
Solution Approach 1:
The patent implements dynamic read condition adjustment where the memory controller modifies read voltages and sensing parameters based on the program lapse time. This dynamic approach allows the system to adapt to threshold voltage variations without requiring complex hardware modifications, maintaining reliability through software-controlled parameter adjustment
Solution Approach 2:
The patent changes read operation parameters (voltages, timing, sensing conditions) based on the program lapse time. By adjusting these parameters dynamically, the system compensates for threshold voltage variations in charge trap cells, ensuring reliable read operations across different time intervals without increasing hardware complexity
Data Source
AI summary
In one embodiment, the method includes receiving a read request for reading data from a memory area of the memory, and determining whether an identifier of the memory area is stored in one of the plurality of entries of a characteristic table. Each of the plurality of entries is associated with a different range of at least one memory area characteristic and each of the plurality of entries is associated with different read condition information. The method further includes obtaining the read condition information associated with the entry storing the identifier of the memory area if the determining determines the identifier is stored in one of the plurality of entries of the characteristic table, and controlling the memory to read data from the memory area using the obtained read condition information.