Flash Memory Device Cycle-Adaptive Read Voltage Control
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Solution Overview
Problem
As the number of operation cycles increases in flash memory devices, the threshold voltage of memory cells changes, leading to data reading malfunctions due to electron trapping in the tunnel insulating layer, causing unreliable operations.
Innovation Solution
The flash memory device adjusts the voltage or current conditions during reading operations based on the accumulated number of programming, erasing, or reading cycles, using a bit line current control unit to modify the reference current and word line voltage, ensuring accurate data retrieval by compensating for threshold voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the number of operation cycles increases, then the memory device can store more data over time, but the threshold voltage of memory cells changes causing reading malfunctions
Solution Approach 1:
The patent changes the reading voltage parameter dynamically based on the number of operation cycles. As the threshold voltage drifts due to electron trapping in the tunnel insulating layer, the reading voltage is adjusted to compensate for this drift, thereby maintaining reliable reading operations throughout the device's operational lifetime
Solution Approach 2:
The patent implements a feedback mechanism where the number of programming and erasing cycles is tracked and used to determine the appropriate reading voltage. This feedback loop allows the system to adapt the reading conditions based on the accumulated wear and threshold voltage changes, preventing reading malfunctions
2Productivity
If electrons are trapped in the tunnel insulating layer during programming operations, then more data can be programmed, but the threshold voltage increases causing reading errors
Solution Approach 1:
The patent adjusts the reading voltage parameter to compensate for threshold voltage shifts caused by electron trapping. By dynamically changing the reading voltage based on the number of programming cycles, the system maintains accurate data retrieval even as the threshold voltage drifts due to accumulated trapped electrons
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the reliability of reading operations by adjusting the voltage and current conditions according to the number of cycles, preventing malfunctions and maintaining data integrity as the device ages.
Implementation Method 1
a programming operation and an erasing operation are performed through an F-N (Fowler-Nordheim) tunneling phenomenon
Data Source
AI summary
A flash memory device and a method of operating the same is disclosed, in which the conditions of voltage (or current) applied during the reading operation are differently adjusted according to an accumulated number of times of a programming operation, an erasing operation or a reading operation (an accumulated number of operation cycle). Even if a level of the threshold voltage is changed to a level which differs from that of the target voltage by an increase of the accumulated number of operation cycle regardless of the programming operation (or the erasing operation) being normally performed, the reliability of the reading operation can be enhanced to prevent a malfunction of the memory cell from being generated.