Tapered Electrode Memory Elements for BEOL Density
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Solution Overview
Problem
Conventional back-end-of-line (BEOL) memory elements, such as conductive bridging random access memory (CBRAM), are limited by minimum feature sizes achievable through BEOL processes, leading to constraints in memory density and reliability due to large electrode-solid electrolyte interfaces and non-uniform doping, which result in variations in resistance states and data retention.
Innovation Solution
The implementation of memory elements with tapered structures that narrow in specific directions, allowing for improved localization of electrodes and memory materials within openings, enabling reduced feature sizes below lithographic limits and enhanced data retention through localized filament formation and reduced leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional BEOL processes are used to form memory elements, then manufacturing simplicity is maintained, but minimum feature sizes are limited leading to reduced memory density
Solution Approach 1:
The patent transitions from planar electrode structures to three-dimensional tapered structures. The electrodes extend vertically into the solid electrolyte with varying cross-sectional areas, utilizing the vertical dimension to achieve better localization and smaller effective feature sizes while remaining compatible with BEOL processing capabilities.
Solution Approach 2:
The tapered electrode structures create local variations in geometry where the cross-sectional area changes along the vertical axis. This local geometric quality variation enables precise control of the electrochemical reaction zone, achieving smaller effective feature sizes at the tip of the tapered structure while maintaining manufacturability through standard BEOL processes.
2Reliability
If larger electrode-solid electrolyte interfaces are used, then manufacturing is easier, but resistance state variations and poor data retention occur
Solution Approach 1:
The tapered electrode structure creates a localized region of small cross-sectional area at the tip, concentrating the electrochemical reactions to a specific zone. This local geometric quality ensures consistent filament formation and dissolution, improving data retention and resistance state uniformity while the overall structure remains manufacturable through standard BEOL processes.
Solution Approach 2:
The tapered geometry is pre-formed during the electrode fabrication process before the electrochemical programming occurs. This preliminary structural preparation ensures that subsequent electrochemical reactions are confined to a well-defined, small-volume region, preventing the formation of multiple filaments and ensuring consistent device operation and improved data retention.
3Manufacturing precision
If non-uniform doping is present in the solid electrolyte, then manufacturing is simpler, but resistance state variations increase
Solution Approach 1:
The tapered electrode structure compensates for potential doping non-uniformities by concentrating the electrochemical reactions to a localized region at the electrode tip. This local geometric control ensures that even if the bulk solid electrolyte has varying dopant concentrations, the active switching region experiences consistent local conditions, resulting in uniform resistance states.
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 enables increased memory density, consistent device operation, improved Ron/Roff ratio, reduced operating power, and enhanced data retention by minimizing the anode-solid electrolyte interface and localizing filament formation, thus overcoming the limitations of conventional BEOL processes.
Implementation Method 1
a conductive path can be formed between the electrodes, reducing a resistance of the element 1600
Data Source
AI summary
A programmable memory element can include an insulating layer formed over a bottom structure; an opening formed in the insulating layer; a sidewall structure formed next to side surfaces of the opening; a tapered structure formed within the opening adjacent to the sidewall structure; and a solid electrolyte forming at least a portion of a structure selected from: the bottom structure, the sidewall structure, and the tapered structure.