Variable Resistance Device Set Current Control
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Solution Overview
Problem
Next-generation memory devices require improved reliability and durability due to issues with current variable resistance devices, such as high dispersion of reset current and potential overshoot or undershoot when switching states, which affect storage capacity and power consumption.
Innovation Solution
A method to determine a set current for a variable resistance device based on the dispersion of its reset current, specifically the off resistance, to improve current dispersion and reduce overshoot/undershoot, thereby enhancing the semiconductor device's reliability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed set current is applied to the variable resistance device, then the device can be operated, but high dispersion of reset current occurs leading to poor reliability
Solution Approach 1:
The patent applies dynamics by making the set current variable rather than fixed. The set current is dynamically adjusted based on the measured reset current characteristics of each device. This allows the system to adapt to device-to-device variations and achieve reliable operation despite manufacturing dispersion, resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
The patent changes the parameter of set current from a fixed value to a variable value that depends on the reset current measurement. By measuring the actual reset current of each device and setting the set current accordingly (e.g., as a percentage of the measured reset current), the system compensates for manufacturing variations and achieves consistent reliable operation across all devices.
2Speed
If high voltage is applied to switch the variable resistance device from off state to on state, then the device switches faster, but overshoot or undershoot occurs reducing durability
Solution Approach 1:
The patent applies dynamics by adjusting the set current magnitude based on the measured reset current characteristics. By optimizing the set current to be appropriate for each device's specific characteristics rather than using a fixed high voltage, the system achieves fast switching while avoiding overshoot and undershoot that would damage the device, thus resolving the contradiction between speed and durability.
Solution Approach 2:
The patent applies preliminary action by measuring the reset current characteristics before setting the operating parameters. This preliminary measurement allows the system to pre-determine the appropriate set current that will achieve fast switching without causing damaging overshoot or undershoot, resolving the contradiction between switching speed and device durability.
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 improves the reliability and durability of semiconductor devices with variable resistance devices by maintaining a uniform energy level during state switching, reducing current dispersion and enhancing storage capabilities.
Implementation Method 1
RRAM is based on the phenomenon that a path along which current flows is generated thus lowering electrical resistance when a sufficiently high voltage is applied to a nonconductive material
Implementation Method 2
a set current of a variable resistance device may be determined based on a dispersion of the reset current, e.g., a dispersion of an off resistance of the variable resistance device
Data Source
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AI summary
According to an example embodiment, a method of operating a semiconductor device having a variable resistance device includes: applying a first voltage to the variable resistance device to change a resistance value of the variable resistance device from a first resistance value to a second resistance value that is different from the first resistance value; sensing a first current flowing through the variable resistance device to which the first voltage is applied; determining a second voltage used for changing the variable resistance device from the second resistance value to the first resistance value, based on a dispersion of the sensed first current; and applying the determined second voltage to the variable resistance device.