Flash Memory Endurance via Pre-Erase High Electric Field
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Solution Overview
Problem
Flash memories, such as NAND and NOR, face degradation due to Program/Erase cycling, leading to threshold voltage shifts, poor voltage distribution, read margin loss, and intrinsic charge loss, which limits their useful life.
Innovation Solution
Applying a high electric field to the control gate of a flash memory module using voltage pulses prior to an erase operation to remove trapped charges, thereby reducing degradation and extending the memory's endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If programming and erasing operations are performed repeatedly, then data storage capacity is improved, but threshold voltage shifts and charge loss occur degrading cell performance
Solution Approach 1:
The patent applies a preliminary high voltage pulse to the control gate before the erase operation to remove trapped charges that accumulate during programming and erasing cycles. This pre-action prevents charge-induced degradation and maintains cell reliability while enabling continued data storage operations.
Solution Approach 2:
The patent converts the harmful effect of trapped charges (which cause threshold voltage shifts and read margin loss) into a beneficial process by applying a high voltage pulse that actively removes these trapped charges. The high voltage pulse transforms the harmful charge accumulation into a cleaning process that extends memory endurance.
2Reliability
If high voltage pulses are applied to remove trapped charges, then endurance is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic application of high voltage pulses rather than continuous high voltage. The controller applies voltage pulses at specific intervals or under specific conditions (such as after a certain number of P/E cycles or when degradation thresholds are detected), thereby reducing overall energy consumption while maintaining effectiveness in removing trapped charges and extending endurance.
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 method minimizes threshold voltage shifts, read margin loss, and intrinsic charge loss, effectively extending the useful life of flash memory cells by addressing the P/E cycling degradation.
Implementation Method 1
a high electric field is provided to the control gate of a flash memory module
Implementation Method 2
the high electric field applied to the flash memory module removes trapped charges between a control gate and an active area
Data Source
AI summary
A method and apparatus for improving the endurance of flash memories. In one embodiment of the invention, a high electric field is provided to the control gate of a flash memory module. The high electric field applied to the flash memory module removes trapped charges between a control gate and an active area of the flash memory module. In one embodiment of the invention, the high electric field is applied to the control gate of the flash memory module prior to an erase operation of the flash memory module. By applying a high electric field to the control gate of the flash memory module, embodiments of the invention improve the Program/Erase cycling degradation of the single-level or multi-level cells of the flash memory module.