Edgeless Storage Elements for Uniform Programmable Layer Thickness
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Solution Overview
Problem
Conventional storage elements with edge-based topography suffer from undesirable variations in performance due to thinning of the programmable layer, leading to irregular thickness and impaired functionality.
Innovation Solution
The development of storage elements with an 'edgeless' structure, featuring a programmable layer formed on a bottom structure with sloped or offset openings, ensuring uniform thickness and minimizing adverse topographical effects, using materials like tantalum and tungsten for the bottom electrode and metal oxides or chalcogenides for the programmable layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional storage element uses an edge-based bottom electrode structure, then the electrode can be formed with standard planarization steps, but the programmable layer thickness becomes non-uniform due to edge effects
Solution Approach 1:
The patent transitions from a planar 2D bottom electrode to a 3D structure with offset openings. The bottom electrode is positioned at a first level while the programmable layer is formed at a second level, creating vertical separation that eliminates edge effects on layer uniformity.
Solution Approach 2:
The structure is divided into distinct levels: the bottom electrode at a first level and the programmable layer at a second level, separated by insulating layers. This segmentation allows each component to be optimized independently without edge interference.
2Device complexity
If the bottom electrode has a sharp edge after planarization, then fabrication is simplified, but the programmable layer experiences thinning at the edges leading to performance variations
Solution Approach 1:
An insulating layer is introduced as an intermediary between the bottom electrode and the programmable layer. This mediator prevents direct interaction at edges, allowing the electrode to maintain its simple formed structure while the programmable layer achieves uniform thickness without edge thinning.
Solution Approach 2:
By separating the bottom electrode and programmable layer into different vertical levels with an insulating layer in between, the patent eliminates the harmful edge interaction while maintaining structural simplicity.
3Ease of manufacture
If planarization steps are performed to flatten the bottom electrode surface, then subsequent layer deposition is facilitated, but edge effects still cause programmable layer thinning
Solution Approach 1:
The insulating layer serves as a mediator that decouples the topography of the bottom electrode from the programmable layer. Even if the bottom electrode has edge features, the insulating layer provides a uniform deposition surface, ensuring uniform programmable layer thickness.
Solution Approach 2:
Separating the electrode and programmable layer into different levels with an insulating intermediate layer allows independent optimization of each layer's formation process without edge-induced thickness variations.
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 storage elements with improved uniformity and reduced performance variations, enabling stable impedance states and enhanced reliability by avoiding the thinning issues associated with edge-based topographies.
Implementation Method 1
In response to electric fields, conductive regions can be created and dissolved within the layer 1405 with metal ions provided from active layer 1407 (or an ion buffer layer)
Data Source
AI summary
A storage element can include a bottom structure having at least one edge formed by a top surface and a side surface; a programmable layer, programmable between at least two different impedance states, and formed over the at least one edge and in contact with a portion of the bottom structure; an insulating layer that extends above the top surface of the bottom structure having an opening to the bottom structure formed therein, the opening having sloped sides; and at least one top layer formed within the opening and in contact with the programmable layer. Methods of making such a storage element are also disclosed.