Nonvolatile Memory Using Carbon Nano Material Resistance Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current resistance change-type nonvolatile memory devices face challenges in achieving high recording density, small size, and low power consumption due to instability in electric characteristics and high dependence on process conditions, particularly with carbon-based materials where low resistivity leads to high power consumption and unclear resistance change mechanisms.
Innovation Solution
A nonvolatile storage device configuration utilizing a carbon nano material as the resistance change layer, with a titanium oxide interface layer between the carbon nano material and electrodes, and a current rectifying device in series, allowing for efficient switching operations and reduced current requirements by optimizing electrode materials and interface formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a carbon film is produced at high temperature with high pressure to form a graphite structure, then the electric resistivity is low, but a large current has to flow in the memory cell to change the electric resistance state, increasing power consumption
Solution Approach 1:
The patent changes the production parameters of the carbon film by controlling the carbonization temperature (500-1000°C) to form amorphous carbon with sp3 hybridized bonds instead of graphite structure. This parameter change achieves both high resistivity (reducing leakage current) and stable electric characteristics without requiring excessive current for resistance switching
Solution Approach 2:
The patent creates a composite structure by forming a carbon film with specific sp3-bonded amorphous carbon structure that combines the advantages of high resistivity and stable resistance switching characteristics, achieving a balance between energy efficiency and reliability
2Reliability
If metal oxides are used as resistance change layer materials, then resistance change can be achieved, but composition and crystal structure control is difficult, leading to high degree of electric characteristic instability and variation
Solution Approach 1:
The patent replaces complex metal oxide materials with carbon-based materials that are simpler, more controllable, and more stable. The carbon film can be produced through straightforward carbonization processes without requiring precise control of complex compositions and crystal structures, thereby achieving better manufacturing precision and electrical characteristic stability
Solution Approach 2:
The patent achieves precise control over the carbon film properties by controlling the carbonization temperature and atmosphere parameters, forming a reproducible amorphous carbon structure with sp3 hybridized bonds that provides stable resistance switching characteristics across different devices
3Loss of energy
If a carbon film is produced at high temperature with high pressure forming graphite structure, then the electric resistivity is low, but a large current has to flow in the memory cell, increasing power consumption
Solution Approach 1:
The patent changes the production parameters of the carbon film by controlling the carbonization temperature (500-1000°C) to form amorphous carbon with sp3 hybridized bonds instead of graphite structure. This parameter change achieves both high resistivity (reducing leakage current) and stable electric characteristics without requiring excessive current for resistance switching
Solution Approach 2:
The patent creates a composite structure by forming a carbon film with specific sp3-bonded amorphous carbon structure that combines the advantages of high resistivity and stable resistance switching characteristics, achieving a balance between energy efficiency and reliability
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 proposed configuration enhances the reproducibility and efficiency of resistance state changes, reducing power consumption and improving the reliability of data storage operations in nonvolatile memory devices.
Implementation Method 1
The carbon nano material is a generic term meaning carbon materials having a three-dimensional structure such as carbon nanotube and fullerene. The layer in which the carbon nano material is laminated is different from a bulk film formed as a uniform film in that the layer with the carbon nano material has a three-dimensional structure in which minute tubes are stacked and there is much space, and therefore, a current path is spacially-limited.
Implementation Method 2
The resistance change layer stores two or more different electric resistance states, such as a low resistance state and a high resistance state, in a nonvolatile manner. That is, the resistance state of the resistance change layer is changed by applying voltage, current, charge, heat or the like, which is equal to or more than a threshold value, to the electrodes, whereby difference in the resistance value is recorded in association with data.
Data Source
AI summary
A nonvolatile storage device is formed by laminating a plurality of memory cell arrays, the memory cell array including a plurality of word lines, a plurality of bit lines, and memory cells. The memory cell includes a current rectifying device and a variable resistance device, the variable resistance device includes a lower electrode, an upper electrode, and a resistance change layer including a conductive nano material formed between the lower electrode and the upper electrode, one of the variable resistance devices provided adjacent to each other in the laminating direction has titanium oxide (TiOx) between the resistance change layer and the lower electrode serving as a cathode, the other of the variable resistance devices provided adjacent to each other in the laminating direction has titanium oxide (TiOx) between the resistance change layer and the upper electrode serving as a cathode.