MIIM Diode Fabrication via Sacrificial Void Formation
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Solution Overview
Problem
Metal-insulator-insulator-metal (MIIM) diodes suffer from undesirable chemical intermixing and edge leakage due to conventional deposition processes, leading to poor rectifying behavior and asymmetry in their current-voltage curves, which hinders their scaling to smaller sizes and efficient performance.
Innovation Solution
The method involves forming MIIM diodes with a gas-filled open volume as a high bandgap insulator and using sacrificial materials and self-assembly techniques to create diodes with a void between the conductive materials, supported by insulative spacers, to minimize intermixing and enhance rectifying behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition processes are used to form MIIM diodes, then the insulator layers can be deposited, but chemical intermixing occurs at the metal-insulator interfaces leading to poor rectifying behavior
Solution Approach 1:
A sacrificial layer is introduced as an intermediary between the metal electrode and the insulator stack. This sacrificial layer prevents direct contact between the metal and insulator during deposition, eliminating chemical intermixing at the interface. The sacrificial layer is later removed to create a void, leaving a clean interface without intermixing.
Solution Approach 2:
The sacrificial layer is deposited beforehand before forming the insulator stack. This preliminary action protects the future interface from chemical intermixing during the subsequent insulator deposition process, ensuring interface quality is maintained from the outset.
2Speed
If MIIM diodes are formed with thin insulator layers for quantum tunneling, then high-speed performance is achieved, but edge leakage increases due to high electric fields at the contact periphery
Solution Approach 1:
The sacrificial layer is completely removed after serving its protective function during deposition. This extraction leaves a void that eliminates the metal-insulator contact periphery where edge leakage occurs, while maintaining the thin insulator structure needed for high-speed quantum tunneling.
Solution Approach 2:
The sacrificial layer, which occupies space that could be used for active functionality, is converted into a beneficial void structure after removal. This void eliminates edge leakage by removing the harmful metal-insulator interface periphery, while the thin insulator layers maintain quantum tunneling capability.
3Speed
If the insulator layers are made thinner to enable quantum tunneling, then tunneling speed increases, but chemical intermixing becomes more significant relative to the de Broglie electron wavelength
Solution Approach 1:
The sacrificial layer acts as a mediator that prevents direct interaction between metal and insulator atoms during deposition. This is especially critical for thin insulator layers where any intermixing would represent a significant portion of the total layer thickness, thereby maintaining sharp interface definition.
Solution Approach 2:
The sacrificial layer is deposited in advance to establish a protective barrier before the thin insulator layers are formed. This preliminary protection is crucial when insulator layers are thin, as it prevents even small amounts of intermixing from degrading the interface quality.
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 reduces edge leakage and improves the asymmetrical current-voltage performance of MIIM diodes, enabling their scaling to smaller sizes while maintaining efficient rectifying behavior, thus enhancing their performance in memory devices.
Implementation Method 1
removing an entirety of the sacrificial material to leave a gap between the first conductive material and the at least one dielectric material
Implementation Method 2
a quantum well forms between the two insulators in response to application of a forward bias, enabling high-energy quantum tunneling
Data Source
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AI summary
Some embodiments include methods of forming diodes. A stack may be formed over a first conductive material. The stack may include, in ascending order, a sacrificial material, at least one dielectric material, and a second conductive material. Spacers may be formed along opposing sidewalls of the stack, and then an entirety of the sacrificial material may be removed to leave a gap between the first conductive material and the at least one dielectric material. In some embodiments of forming diodes, a layer may be formed over a first conductive material, with the layer containing supports interspersed in sacrificial material. At least one dielectric material may be formed over the layer, and a second conductive material may be formed over the at least one dielectric material. An entirety of the sacrificial material may then be removed.