Ruthenium Alloy Electrode for Non-Volatile Switching Element
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Solution Overview
Problem
Non-volatile switching elements face challenges in maintaining the ON or OFF state for extended periods with low electrical current usage, as the amount of current required for rewriting is high due to the need for a thick metal bridge, which is prone to electro-migration and ionization, leading to increased resistance and potential disconnection.
Innovation Solution
A variable resistance element with a second electrode made from a ruthenium alloy and a polymer ion conduction layer, where the ruthenium alloy has a higher standard Gibbs energy for oxidation, reducing the current required for rewriting and improving the stability of the metal bridge, allowing for low-power programming with high holding ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick metal bridge is formed in the ion conduction layer, then the holding ability to maintain ON state is improved, but the amount of current required for rewriting increases and the metal bridge becomes prone to electro-migration and ionization
Solution Approach 1:
The invention changes the material parameter of the second electrode from conventional materials to ruthenium alloy, which has a higher standard Gibbs energy for oxidation. This parameter change allows the metal bridge to be thinner while maintaining stability, thereby reducing the rewriting current requirement while preserving holding ability.
Solution Approach 2:
The invention uses a composite structure consisting of a polymer ion conduction layer and a ruthenium alloy second electrode. This composite material system provides both the necessary ion conduction pathway and the high stability interface that prevents excessive metal ion generation, resolving the contradiction between holding ability and rewriting current.
2Reliability
If a thick metal bridge is formed in the ion conduction layer, then the holding ability to maintain ON state is improved, but the metal bridge becomes prone to electro-migration and ionization leading to increased resistance and potential disconnection
Solution Approach 1:
By changing the electrode material parameter to ruthenium alloy with higher oxidation resistance, the invention suppresses the harmful electro-migration and ionization effects while maintaining a thin metal bridge structure, thereby improving reliability without requiring a thick bridge.
Solution Approach 2:
The invention effectively makes the metal bridge 'short-living' in terms of ion generation by using the ruthenium alloy electrode that prevents excessive ionization. This approach reduces the cumulative damage from electro-migration and ionization events over time.
3Ease of manufacture
If copper wiring is used as the first electrode to simplify manufacturing, then the manufacturing process is simplified and element size is reduced, but the copper surface oxidizes when the porous polymer ion conduction layer is directly formed on it
Solution Approach 1:
The invention introduces an oxidation prevention film as an intermediary layer between the copper first electrode and the porous polymer ion conduction layer. This mediator prevents direct oxidation of copper while allowing the ion conduction layer to function properly, thus maintaining both ease of manufacture and preventing harmful oxidation.
4Use of energy by moving object
If the second electrode is made from ruthenium alloy with higher standard Gibbs energy for oxidation, then the current required for rewriting is reduced and metal bridge stability is improved, but the device complexity increases
Solution Approach 1:
The invention changes the material parameter of the second electrode to ruthenium alloy, which inherently provides both low rewriting current and high stability. This single parameter change addresses multiple performance requirements simultaneously, offsetting the increased material complexity with improved overall device performance.
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 solution enables reliable long-term operation with reduced power consumption by improving the adhesion and stability of the metal bridge, maintaining low resistance values and preventing disconnection, thus enhancing the reliability of programmable-logic wiring changeover switches.
Implementation Method 1
a metal ion is generated due to metal oxidation
Implementation Method 2
a metal is ionized and a generated metal ion is introduced into the ion conduction layer
Implementation Method 3
metal deposition due to reduction of the metal ion is utilized
Implementation Method 4
the metal ion is reduced and the metal deposits. Since the deposited metal forms a metal bridge
Implementation Method 5
a porous polymer ion conduction layer
Implementation Method 6
an ion conduction layer conducting a metal ion
Implementation Method 7
improving the adhesion and stability of the metal bridge
Data Source
AI summary
The present invention provides a non-volatile switching element that can be applied to a programmable-logic wiring changeover switch and in which an electrochemical reaction is used. Of the two electrodes for applying a bias voltage to the variable resistance layer of the non-volatile switching element, the electrode that does not feed metal ions to the variable resistance layer when the switch is in the ON state is made from a ruthenium alloy. The ruthenium alloy includes ruthenium and a metal in which the standard Gibbs energy of forming ΔG when metal ions are generated from the metal is higher in the negative direction than ΔG of ruthenium. As a result, it becomes possible to maintain the low-resistance state in the ON state for a longer period of time without increasing the amount of electrical current required when a switch is made between the ON state and the OFF state.