Self-Aligned Metal Cut Structure for Semiconductor Interconnects
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Solution Overview
Problem
Current semiconductor fabrication techniques face challenges in achieving precise alignment and small tip-to-tip spacing between metal lines, leading to issues with yield, performance, and reliability due to limitations in photolithography, which can only achieve distances of not less than 100 nm.
Innovation Solution
The method involves forming trench openings in a dielectric layer, depositing a sacrificial material, removing it from specific segments, and filling with a second dielectric material to create a metallic interconnect structure with self-aligned metal cuts, achieving tip-to-tip spacings as small as 5 nm to 30 nm and correcting misalignment issues through the use of a dielectric liner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to form metal lines, then manufacturing process is simple, but tip-to-tip spacing cannot be less than 100 nm
Solution Approach 1:
The fabrication process is divided into multiple sequential steps: forming sacrificial material in trench openings, selectively removing sacrificial material from specific segments, depositing second dielectric material in the removed segments, and finally depositing metallic material. This segmentation enables precise control of metal line gaps and tip-to-tip spacing beyond photolithography limitations
Solution Approach 2:
Sacrificial material is deposited in advance within the trench openings before metal deposition. This preliminary placement of sacrificial material defines the future metal line gaps, allowing precise spacing control to be established before the actual metal interconnect structure is formed
2Reliability
If metal gaps are formed to avoid shorts, then circuit reliability improves, but alignment precision must be maintained
Solution Approach 1:
Sacrificial material serves as an intermediary element that temporarily occupies the space where metal gaps will eventually form. This intermediary structure enables precise gap formation and alignment during fabrication, ensuring circuit reliability by preventing shorts while maintaining accurate alignment
Solution Approach 2:
The sacrificial material self-aligns with the trench openings through the deposition process, and its selective removal automatically defines the metal line gaps. This self-service mechanism ensures proper alignment without requiring additional alignment steps, maintaining both reliability and precision
Data Source
AI summary
A method includes applying a first dielectric material onto a semiconductor substrate to form a first dielectric layer on the semiconductor substrate, creating a plurality of openings in the dielectric layer, depositing a sacrificial material within the openings of the dielectric layer, removing the sacrificial material from at least a first segment of a first trench of the openings, depositing a second dielectric fill material into the first segment of the first trench opening where the sacrificial material was removed, removing the sacrificial material from at least some of the remaining openings and depositing a metallic material within the first trench opening to define at least first and second lines in the first trench and form a metallic interconnect structure.