Carbon Nanostructure Memory with Metal Atoms for Low Power
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Solution Overview
Problem
Current nonvolatile semiconductor memory devices face challenges in achieving high recording density, miniaturization, and low power consumption due to unstable characteristics of metal oxides and high current requirements for carbon-based materials, which hinder their integration and efficiency.
Innovation Solution
A nonvolatile semiconductor memory device is developed using a carbon nanostructure with metal atoms diffused into gaps, allowing for controlled resistance changes and reduced current flow, enabling miniaturization and efficient operation with lower power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon-based materials are used for the variable resistance layer, then composition control is easier and manufacturing is simpler, but large current is required to change the bonding state
Solution Approach 1:
The patent uses a composite structure combining carbon atoms with metal atoms (such as titanium, nickel, or copper) within the variable resistance layer. This composite material approach allows the carbon-based material to maintain its ease of composition control while the metal atoms facilitate resistance changes at lower current levels by providing alternative conduction paths and reducing the energy barrier for bonding state transitions.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the carbon-based material by incorporating metal atoms and controlling the film formation conditions (temperature, pressure, composition ratios). These parameter changes enable the material to achieve desired resistance characteristics with lower operating currents while maintaining manufacturing simplicity.
2Productivity
If memory cells are arranged in a matrix with long wirings, then integration is achieved, but voltage drop in wirings becomes significant and signal detection accuracy decreases
Solution Approach 1:
The patent changes the electrical resistance parameter of the variable resistance layer to achieve a balance between integration density and signal detection accuracy. By optimizing the resistance value through material composition control (carbon-to-metal atom ratio) and film formation conditions, the device can operate effectively in high-density matrix configurations while maintaining sufficient signal strength for accurate detection despite wiring resistance.
3Reliability
If metal oxides are used for the variable resistance layer, then nonvolatile memory characteristics are achieved, but composition and crystalline structure control is difficult and characteristics are unstable
Solution Approach 1:
The patent changes from metal oxide materials to carbon-based materials with metal atom incorporation. This fundamental material parameter change eliminates the difficulties associated with metal oxide processing while maintaining nonvolatile memory characteristics. The carbon-based system allows precise control of composition and structure through film formation parameters (temperature, pressure, gas flow ratios) without the crystallization issues that plague metal oxide processing.
Solution Approach 2:
The patent employs a composite material system combining carbon and metal atoms to achieve the desired electrical characteristics. This composite approach provides stability and reproducibility in resistance characteristics while allowing precise control over composition through sputtering parameters, avoiding the manufacturing precision issues inherent in metal oxide processing.
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 device achieves miniaturization and efficient data storage with reduced power consumption by utilizing a carbon nanostructure and metal atoms, allowing for precise resistance control and accurate signal detection, addressing the limitations of existing technologies.
Implementation Method 1
metal atoms which are diffused into the gaps
Implementation Method 2
The variable resistance layer can take two or more different electrical resistance states, for example, a low-resistance state and a high-resistance state. In the nonvolatile semiconductor memory, the resistance state of the variable resistance layer is caused to change by applying a voltage, current, or charge not less than threshold value between the electrodes
Implementation Method 3
a carbon film tends to be formed as black lead or a so-called graphite structure, leading to low resistivity. Varying of the resistance state is considered to be caused by change in bonding state, that is, change between sp3 bond and sp2 bond, of carbon in the film. Accordingly, a large current is required to change the bonding state
Data Source
AI summary
A nonvolatile semiconductor memory device in accordance with an embodiment comprises a lower electrode layer, a variable resistance layer, and an upper electrode layer. The lower electrode layer is provided over a substrate. The variable resistance layer is provided on the lower electrode layer and is configured such that an electrical resistance of the variable resistance layer can be changed. The upper electrode layer is provided on the variable resistance layer. The variable resistance layer comprises a carbon nanostructure and metal atoms. The carbon nanostructure is stacked to have a plurality of gaps. The metal atoms are diffused into the gaps.