Nitrogen-Doped Metal Oxide RRAM for Low Voltage Operation
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Solution Overview
Problem
Existing RRAM technologies using metal oxide memory materials face issues such as large memory cell size, complex fabrication processes, and performance degradation due to leaky conductive paths and limited resistance window, particularly with tungsten oxide, which requires high forming voltages and results in a low set-to-reset resistance ratio.
Innovation Solution
The method involves forming a nitrogen-containing metal oxide layer, such as tungsten oxynitride, over a transition metal electrode using a rapid thermal oxidation process, which reduces the forming voltage and improves the flatness of the metal oxide surface, facilitating subsequent processing and enhancing device performance by lowering the set and reset voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal oxide memory material is used in RRAM, then non-volatile memory function is achieved, but high forming voltage and low set-to-reset resistance ratio result
Solution Approach 1:
The patent introduces nitrogen as a dopant element into the metal oxide memory layer, changing the chemical composition parameter. This nitrogen doping modifies the electrical properties of the metal oxide, reducing the forming voltage from high levels to lower levels while maintaining the non-volatile memory function. The nitrogen atoms create additional conduction paths and reduce the energy barrier for resistance switching.
2Reliability
If metal oxide memory material is used in RRAM, then non-volatile memory function is achieved, but low set-to-reset resistance ratio results
Solution Approach 1:
Nitrogen doping changes the electrical parameters of the metal oxide by introducing nitrogen atoms into the crystal lattice. This modifies the resistance characteristics, creating a larger difference between the set and reset states. The nitrogen dopants create localized states that enhance the resistance contrast, improving the set-to-reset resistance ratio from low to high levels.
3Ease of manufacture
If conventional metal oxide fabrication process is used, then memory cell is formed, but large memory cell size results
Solution Approach 1:
The patent creates a composite material structure by combining metal oxide with nitrogen dopants. This composite approach allows the memory cell to achieve the desired electrical characteristics with a smaller physical footprint. The nitrogen-doped metal oxide provides enhanced functionality per unit area, enabling smaller memory cell dimensions while maintaining ease of fabrication through conventional processes.
4Ease of manufacture
If conventional metal oxide fabrication process is used, then memory cell is formed, but leaky conductive paths occur
Solution Approach 1:
Nitrogen doping modifies the chemical and electrical parameters of the metal oxide, creating a more stable material structure. The nitrogen atoms passivate defect sites and reduce unwanted conductive paths, thereby eliminating the leaky conductive path issue while maintaining compatibility with conventional fabrication processes. This results in improved reliability without sacrificing ease of manufacture.
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 results in a more efficient resistive memory device with improved yield and performance, as evidenced by lower forming, set, and reset voltages, and a more stable resistance state, thereby addressing the limitations of existing metal oxide-based RRAM technologies.
Implementation Method 1
forming a nitrogen-containing metal oxide layer, such as tungsten oxynitride, over a transition metal electrode using a rapid thermal oxidation process
Data Source
AI summary
A structure for a resistive memory device and a method to fabricate the same is disclosed. The method includes providing a bottom electrode comprising a metal and forming a memory layer on the bottom electrode. The memory layer includes a first layer of metal oxide, and a second layer including the nitrogen-containing metal oxide. A top electrode is formed over the memory layer.