Alternating Sidewall Assisted Patterning for Flash Memory Bit Lines
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Solution Overview
Problem
The challenge in forming conductive lines, such as bit lines, in close proximity within integrated circuits is exacerbated by capacitive coupling issues due to the close spacing of metal lines, which affects the resistance and quality of connections in flash memory systems.
Innovation Solution
A sidewall-assisted process is employed to form trenches with alternating profiles, where one trench profile is wider at the top and narrower at the bottom, and another is uniformly wide, allowing for void-free metal deposition in some trenches and air gaps in others, facilitating efficient connection of contact plugs and reducing capacitive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal lines are placed in close proximity to increase density, then productivity is improved, but capacitive coupling increases causing harmful effects
Solution Approach 1:
The patent divides the continuous dielectric layer into regions with air gaps inserted between metal lines. This segmentation creates isolated capacitive regions, reducing the harmful capacitive coupling between adjacent metal lines while maintaining high line density for improved productivity.
Solution Approach 2:
The patent extracts the dielectric material and replaces it with air gaps in specific regions between metal lines. This removal of dielectric material eliminates the source of capacitive coupling, allowing metal lines to be placed in close proximity without suffering from harmful capacitive effects.
2Ease of manufacture
If trenches are formed with uniform width to simplify manufacturing, then ease of manufacture is improved, but misalignment tolerance deteriorates
Solution Approach 1:
The patent applies different trench width characteristics at different locations within the same trench structure. The trench width varies from the top surface to the bottom, creating a tapered profile that provides both manufacturing simplicity and improved alignment tolerance for contact plug formation.
Solution Approach 2:
The patent employs asymmetric trench profiles where the trench width at the top differs from the trench width at the bottom. This asymmetric design allows the wider top portion to accommodate manufacturing variations and provide better alignment tolerance, while the narrower bottom portion maintains manufacturing efficiency.
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 the formation of conductive lines with improved tolerance for misalignment and reduced capacitive coupling, enhancing the efficiency and reliability of memory operations in flash memory systems.
Implementation Method 1
depositing copper in the plurality of first trenches to form a plurality of bit lines
Data Source
AI summary
A dielectric layer extending over a substrate has alternating first and second trenches extending in a first direction. The first trenches have a first shape in cross section along a plane that is perpendicular to the first direction and the second trenches have a second shape in cross section along the plane. Bit lines are located in at least the first trenches.