Narrowed Interconnect Features via Mandrel Extraction
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Solution Overview
Problem
Current interconnect structures in semiconductor fabrication, particularly in the back-end-of-line (BEOL) process, face challenges in achieving precise and efficient formation of narrow features and electrical fuses with adequate tip-to-tip spacing, which affects the performance and reliability of integrated circuits.
Innovation Solution
The method involves forming mandrel lines and non-mandrel lines with selective etching and patterning techniques to create narrowed sections and electrical fuses, using sidewall spacers and sacrificial layers to define trenches in the interlayer dielectric layer, allowing for precise control of wire widths and spacings, and enabling the formation of electrical fuses with programmable resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography patterning is used to form interconnect features, then the manufacturing process is relatively simple, but the manufacturing precision of narrow features and tip-to-tip spacing is insufficient
Solution Approach 1:
The patterning process is divided into multiple stages: first forming mandrels with initial pitch, then using sidewall spacers to create additional features with half the pitch. This segmentation enables precise control of narrow features and tip-to-tip spacing that cannot be achieved with single-step lithography
Solution Approach 2:
Mandrels are formed first as sacrificial structures to establish the feature pitch before the actual interconnect features are created. The mandrels serve as preliminary guides that define the positions of subsequent features through sidewall spacer formation
2Manufacturing precision
If mandrels are used to establish feature pitch with sidewall spacers, then the manufacturing precision of narrow features is improved, but the device complexity increases
Solution Approach 1:
The mandrels are extracted as sacrificial structures after serving their purpose of defining feature pitch. They are removed after sidewall spacers are formed, leaving only the desired narrow features without the complex mandrel structures
Solution Approach 2:
Sidewall spacers act as intermediary structures that transfer the pitch information from mandrels to the final interconnect features. They mediate between the mandrel geometry and the desired narrow feature dimensions
3Manufacturing precision
If electrical fuses are formed with standard width, then the manufacturing process is simple, but the programmable resistance control is insufficient
Solution Approach 1:
The fuse link is created with locally narrowed width at specific positions along the interconnect line. This local quality change enables controlled resistance characteristics at the fuse location while maintaining standard width elsewhere in the interconnect structure
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 fabrication of interconnect structures with improved precision and functionality, allowing for effective programming of electrical fuses and enhancing the reliability and performance of integrated circuits by achieving narrower wire sections and controlled tip-to-tip spacings.
Implementation Method 1
the sidewall spacers are used as an etch mask to etch an underlying hardmask, for example, with a directional reactive ion etch (ME) process
Data Source
AI summary
Interconnect structures and methods of fabricating an interconnect structure. A first mandrel line, a second mandrel line, and a non-mandrel line between the first mandrel line and the second mandrel line are provided. A first sidewall spacer is formed adjacent to a section of the first mandrel line and is arranged between the section of the first mandrel line and the non-mandrel line. A first cut is formed that extends partially across the non-mandrel line adjacent to the first spacer to narrow a section of the non-mandrel line. The section of the first mandrel line is removed selective to the first sidewall spacer to form a second cut. An interconnect is formed using the non-mandrel line. The interconnect includes a narrowed section coinciding with a location of the narrowed section of the non-mandrel line.