Asymmetric Electrode Nonvolatile Memory Element for Crosstalk Reduction
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Solution Overview
Problem
Existing nonvolatile memory elements face challenges with miniaturization, crosstalk between adjacent electrodes, and insufficient current supply to resistance variable elements, particularly in miniaturized configurations, which hinders stable resistance switching and mass production compatibility.
Innovation Solution
A nonvolatile memory element configuration featuring a resistance variable element with a lower and upper electrode, a diode connected in series, and an interlayer insulating layer with a contact hole for the resistance variable layer, ensuring optimal current supply and minimizing crosstalk, allowing for miniaturization and mass production compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the resistance variable element is miniaturized to increase integration density, then the area occupied by each memory element is reduced, but the crosstalk between adjacent electrodes increases and current supply becomes insufficient
Solution Approach 1:
The patent applies asymmetry by making the lower electrode larger than the upper electrode in the resistance variable element. This non-symmetric configuration concentrates current density at the smaller upper electrode, enabling stable resistance switching even in miniaturized structures. The asymmetric design ensures sufficient current flow through the resistance variable layer while maintaining small overall device area for high integration density.
Solution Approach 2:
The patent introduces a vertical stacking dimension by connecting the resistance variable element and diode in series along the thickness direction. This three-dimensional configuration allows current to flow vertically through both elements, providing sufficient current drive capability without increasing the planar area. The vertical arrangement enables miniaturization in the XY plane while maintaining reliable operation through the Z dimension.
2Power
If a diode is connected in series with the resistance variable element to improve current drivability, then current supply is enhanced, but the device complexity increases
Solution Approach 1:
The patent merges the diode and resistance variable element into a single integrated structure where they share common electrodes and are formed in the same fabrication process. The diode's lower electrode connects to the resistance variable element's lower electrode, and the diode's upper electrode connects to the resistance variable element's upper electrode, creating a series connection without requiring separate discrete components. This merging reduces device complexity while maintaining enhanced current drivability.
Solution Approach 2:
The patent utilizes the vertical dimension to stack the diode and resistance variable element, with the diode positioned above the resistance variable element in the thickness direction. This vertical stacking provides sufficient current drive capability through the series connection while minimizing the planar footprint. The three-dimensional arrangement enhances power capability without significantly increasing device complexity.
3Reliability
If the electrodes are made non-symmetric with different areas to enable resistance switching, then stable resistance variation is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent forms the resistance variable layer within a contact hole structure before forming the electrodes. The contact hole provides a pre-defined geometric constraint that guides the formation of the asymmetric electrode areas. By establishing the contact hole dimensions first, the manufacturing process achieves the required asymmetric electrode areas with standard precision, as the contact hole acts as a template for the subsequent electrode formation steps.
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 stable resistance switching and high-density integration of nonvolatile memory elements, facilitating further miniaturization and reducing the size and thickness of electronic devices while maintaining high current drivability and preventing crosstalk.
Implementation Method 1
a diode having a first electrode which is provided to be located farther from the substrate than the upper electrode and is connected in series with the upper electrode
Implementation Method 2
only an EPVR material located adjacent the upper electrode having the smaller area than the lower electrode increases in a current density and enables resistance switching to occur
Data Source
AI summary
A nonvolatile memory element (20) of the present invention comprises a resistance variable element (14) and a diode (18) which are formed on a substrate (10) such that the resistance variable element (14) has a resistance variable layer (11) sandwiched between a lower electrode (12) and an upper electrode (13), and the diode (18) which is connected in series with the resistance variable element (14) in the laminating direction and has an insulating layer or semiconductor layer (15) sandwiched between a first electrode (16) at the lower side and a second electrode (17) at the upper side. The resistance variable layer (11) is embedded in a first contact hole (21) formed on the lower electrode (12). A first area (22) where insulating layer or semiconductor layer (15) of the diode (18) is in contact with a first electrode (16) of the diode (18) is larger than at least one of a second area (23) where the resistance variable layer (11) is in contact with the upper electrode (13) and a third area (24) where the resistance variable layer (11) is in contact with the lower electrode (12).