Nonvolatile Memory Element Low-Voltage Redox Switching
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Solution Overview
Problem
Existing nonvolatile memory elements using transition metal oxides face challenges in high micro-fabrication due to Joule heat generation during resistance variation and require high voltages, making them unsuitable for high-density integration and low power consumption.
Innovation Solution
A nonvolatile memory element with a multiple-layered variable resistance layer comprising a first and second metal oxide layer, where the second metal oxide layer contacts the electrodes, allowing reversible oxidation-reduction reactions at low voltages (≤2 V) without generating Joule heat, using a chemical reaction with reaction energy ≤2 eV, and selecting metal oxides like Cr, Co, Mn, V, Cu, Sn, and Ti for reduced power consumption and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transition metal oxide is used as variable resistance material, then resistance value can be changed, but Joule heat is generated during resistance variation
Solution Approach 1:
The patent changes the fundamental mechanism parameter from Joule heating to chemical reaction energy. By selecting metal oxides with reaction energy ≤2 eV, the invention enables resistance variation through low-voltage electrochemical reactions instead of high-power Joule heating, eliminating the harmful heat generation while maintaining reliable resistance switching.
Solution Approach 2:
The patent substitutes the thermal-mechanical process (Joule heating) with a chemical-electrical process (electrochemical reactions). The resistance variation is achieved through oxidation-reduction reactions driven by low-voltage electric fields, replacing the high-temperature thermal field with a controlled chemical field.
2Reliability
If conventional variable resistance material is used, then resistance change is achieved, but high voltage is required for operation
Solution Approach 1:
The patent fundamentally changes the energy parameter by selecting metal oxide combinations with reaction energy ≤2 eV. This enables operation at low voltages (≤2 V) compared to conventional high-voltage operations, while maintaining stable resistance switching through carefully selected electrochemical reaction pairs.
Solution Approach 2:
The patent applies local quality by selecting specific metal oxide materials with appropriate reaction energies for different layers. The first metal oxide and second metal oxide are chosen to have complementary properties that enable low-voltage operation, with each layer optimized for its specific function in the electrochemical reaction cycle.
3Speed
If high power is used for resistance variation, then fast switching is achieved, but power consumption increases
Solution Approach 1:
The patent replaces the high-power electrical-thermal switching mechanism with a low-power chemical-electrical switching mechanism. The electrochemical reactions proceed efficiently at low voltages, achieving fast resistance switching without the energy dissipation associated with Joule heating, thus reducing power consumption while maintaining speed.
Solution Approach 2:
The patent changes the energy efficiency parameter by utilizing chemical reaction energy instead of thermal energy. The selected metal oxide combinations enable fast switching through low-barrier electrochemical reactions, achieving high-speed operation with minimal power consumption by avoiding resistive heating losses.
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
Enables stable, low-voltage variable resistance operations suitable for micro-fabrication, reducing power consumption, and compatibility with existing MOS transistors, while maintaining high-speed and stable data storage capabilities.
Implementation Method 1
the variable resistance layer having a multiple-layered structure including a first metal oxide layer including a first metal oxide having a first resistivity, and a second metal oxide layer including a second metal oxide having a second resistivity, the second metal oxide layer contacts at least one of the upper electrode layer and the lower electrode layer, and an absolute value of reaction energy of chemical reaction related to the first metal oxide, the second metal oxide, oxygen ions, and electrons is equal to or less than 2 eV
Data Source
AI summary
A nonvolatile memory element (100) includes a variable resistance layer (107) including a first metal oxide MOx and a second metal oxide MOy, and reaction energy of chemical reaction related to the first metal oxide, the second metal oxide, oxygen ions, and electrons is 2 eV or less. The chemical reaction is expressed by a formula 13, where a combination (MOx, MOy) of MOx and MOy is selected from a group including (Cr2O3, CrO3), (Co3O4, Co2O3), (Mn3O4, Mn2O3), (VO2, V2O5), (Ce2O3, CeO2), (W3O8, WO3), (Cu2O, CuO), (SnO, SnO2), (NbO2, Nb2O5), and (Ti2O3, TiO2).[Mathematical Expression 13]MOx+(y−x)O2−MOy+2(y−x)e− (Formula 13)