Self-Aligned Diode Recesses for Memory Device Alignment Precision
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Solution Overview
Problem
Conventional memory device fabrication processes often lead to device defects and poor performance due to misalignment of diodes and other features, resulting in electrical conductivity issues and hot spots.
Innovation Solution
The use of perpendicular masking structures to self-align diodes and memory elements within recesses, reducing misalignment and enhancing electrical conductivity by forming conductive materials with lower resistivity, such as cobalt silicide or nickel silicide, between and over diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used to form memory devices, then manufacturing simplicity is maintained, but device defects and poor performance occur due to misalignment
Solution Approach 1:
The patent applies preliminary action by forming masking structures and recesses before forming the diodes and memory elements. The recesses are etched into the substrate first, then masking structures are formed, and finally the diodes and memory elements are formed within these pre-prepared structures. This sequence ensures proper alignment without requiring complex alignment processes during subsequent fabrication steps.
Solution Approach 2:
The patent implements self-service through self-aligned formation of diodes and memory elements. The masking structures and recesses automatically define the positions and boundaries of these components during formation, eliminating the need for separate alignment operations. The structures serve their own alignment function, reducing manufacturing complexity while improving precision.
2Reliability
If misalignment of diodes and features occurs, then fabrication is simpler, but electrical conductivity issues and hot spots result
Solution Approach 1:
The patent introduces conductive materials into the recesses to improve electrical conductivity. The recesses act as conduits that guide and concentrate the conductive material between diodes and memory elements, ensuring reliable electrical connections without requiring precise alignment of separate conductive features.
Solution Approach 2:
The patent uses composite material structures by forming diodes with p-type and n-type semiconductor regions, and by introducing conductive materials (such as metal silicides) into the recesses. These composite structures improve electrical conductivity and prevent hot spots by providing multiple pathways for current flow and reducing contact resistance.
3Manufacturing precision
If conventional processes form separate parts and connections, then process flexibility is maintained, but device defects occur due to misalignment
Solution Approach 1:
The patent merges the formation of diodes and memory elements into a single integrated process sequence within the recesses. The masking structures serve dual purposes for both diode and memory element formation, and the conductive materials are deposited in a single step to connect both components. This merging reduces the number of separate alignment operations required.
Solution Approach 2:
The masking structures and recesses perform multiple functions: they define the positions of diodes, define the positions of memory elements, and provide pathways for conductive materials. This multi-functionality eliminates the need for separate alignment processes for each component, simplifying manufacturing while improving precision.
Data Source
AI summary
Some embodiments include apparatus and methods having a memory device with diodes coupled to memory elements. Each diode may be formed in a recess of the memory device. The recess may have a polygonal sidewall. The diode may include a first material of a first conductivity type (e.g., n-type) and a second material of a second conductive type (e.g., p-type) formed within the recess.