Flash Memory Thermal Treatment for Cycling Endurance
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Solution Overview
Problem
Flash memories experience data loss due to charge traps formed during repeated programming and erasing cycles, leading to cycling-induced failures as trapped electrons are released, causing threshold voltage shifts and potential information loss.
Innovation Solution
Incorporating a heater within the memory package to apply controlled heat and detrap electrons from the tunnel oxide, using a Joule heater powered by a memory controller to maintain temperatures between 120° C and 150° C for several hours, which reduces the total charge trapped and extends the memory's useful life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flash memory is repeatedly programmed and erased, then data storage capacity is utilized, but charge traps form in the oxide leading to data loss
Solution Approach 1:
The patent applies preliminary thermal treatment to the flash memory device to proactively remove trapped electrons from the oxide layer before they can cause data loss. By heating the device to elevated temperatures (e.g., 85°C to 150°C) for specific durations, electrons are thermally activated and released from trap states, preventing the formation of threshold voltage shifts that would otherwise lead to cycling-induced failures.
Solution Approach 2:
The patent changes the temperature parameter of the flash memory device to alter the energy states of trapped electrons. By controlling temperature during storage or before read operations, the system can thermally activate electrons to escape from trap states in the oxide, thereby restoring proper threshold voltage levels and maintaining data integrity despite repeated programming and erasing cycles.
2Duration of action of moving object
If electrons are trapped during programming and erase operations, then memory cycling is enabled, but trapped electrons are released during storage causing threshold voltage shifts
Solution Approach 1:
The patent implements continuous or periodic thermal treatment during the storage phase to continuously manage trapped electron populations. By maintaining the device at elevated temperatures during storage periods, the system ensures that electrons remain thermally activated and do not accumulate in trap states, thereby maintaining stable threshold voltages throughout the memory's operational lifetime and enabling sustained cycling capability.
3Productivity
If more memory cycling occurs, then data storage utility increases, but more trapped electrons accumulate increasing failure probability
Solution Approach 1:
The patent periodically discards trapped electrons from the oxide layer through thermal treatment, effectively resetting the memory device's electrical state. By heating the device to release accumulated trapped electrons and then allowing it to cool, the system recovers from cycling-induced degradation, restoring threshold voltage levels and preventing failure even after extensive programming and erasing cycles.
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
The thermal treatment effectively reduces charge traps, minimizing data loss and extending the flash memory's cycling lifetime by maintaining data integrity and refreshing threshold voltages, allowing for prolonged device usage without significant performance degradation.
Implementation Method 1
using a Joule heater powered by a memory controller to maintain temperatures between 120° C and 150° C for several hours
Implementation Method 2
providing a heater within the memory package to provide controlled application of heat under particular conditions to detrap trapped electrons from the tunnel oxide
Implementation Method 3
The applied temperature may be sensed by an in-package temperature probe which supplies information over the connection to the temperature controller which, in turn, regulates the flow of current to the heater to achieve a desired temperature
Data Source
AI summary
A memory controller can provide current to a heater in a flash memory to reduce cycling induced errors. If necessary, after heating, the memory may be refreshed. In non-battery powered systems, data may be removed from the memory prior to heating and restored to the memory after heating.