Patterned Metal Interconnect Cuts at Sub-20 Nm Pitch
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Solution Overview
Problem
Existing semiconductor technologies face challenges in forming narrow metal lines and tight metal line pitches, particularly in sub-20 nm scales, which can lead to difficulties in etch control and increased risk of defects during metal wire fabrication.
Innovation Solution
A method involving the formation of metal wires with sacrificial layers and selective metal growth to increase wire width, combined with dielectric fills to maintain electrical isolation, allowing for precise cuts and reduced damage to adjoining wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If narrow metal lines and tight metal line pitches are formed in sub-20 nm scales, then chip area shrinkage is enabled, but etch control difficulty increases and defect risk increases
Solution Approach 1:
The patent segments the metal wire formation process into multiple stages: first forming initial metal wires at relaxed dimensions, then selectively growing additional metal layers on specific regions. This segmentation allows the etching process to work at larger, more controllable dimensions while achieving final narrow pitch dimensions through controlled metal removal and selective growth, thereby resolving the etch control difficulty associated with direct sub-20 nm patterning
Solution Approach 2:
The patent performs preliminary actions by first forming metal wires with larger initial dimensions that are easier to control during etching, then subsequently modifying these wires through selective metal growth and removal. This preliminary formation at larger dimensions establishes a foundation that reduces defect risk, while later steps achieve the final narrow pitch requirements without subjecting the entire process to the constraints of direct sub-20 nm fabrication
2Length of moving object
If metal wire width is increased through selective metal growth, then wire width dimension increases, but process complexity increases
Solution Approach 1:
The patent applies local quality by using selectively grown metal layers that deposit only on specific regions of the metal wire structure. The selective growth occurs on exposed metal surfaces in certain areas while leaving other areas unchanged, allowing different parts of the same wire to have different final dimensions. This localized modification achieves variable wire widths without requiring complete restructuring of the entire fabrication process
Solution Approach 2:
The patent introduces an intermediary approach where selectively grown metal layers act as a mediator between the initial metal wire formation and the final desired wire dimensions. These intermediate metal layers are deposited, patterned, and selectively removed to achieve the target wire width, providing a controllable intermediate step that simplifies the overall process compared to direct single-step patterning
Data Source
AI summary
Interconnect structures including parallel metal lines and cut regions in selected ones of the parallel metal lines are fabricated without damage, even at a very small metal pitch. A dielectric fill in the cut regions has a smaller width than the width of the metal lines. Metal line width can be increased by selective metal deposition on sidewalls of the metal lines subsequent to forming the cut regions.