Bidirectional Self-Aligned Interconnects for BEOL Fabrication
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Solution Overview
Problem
Conventional interconnect structures and fabrication methods for back-end-of-line (BEOL) interconnects face limitations in achieving bidirectional metal lines and efficient pattern transfer due to unidirectional design rules, requiring additional lithography layers and complicating the detection of open circuits in metallization levels.
Innovation Solution
A self-aligned multi-patterning structure is developed, including non-mandrel and mandrel interconnects embedded in an interlayer dielectric layer, with connector interconnects extending transversely between them, allowing for bidirectional connections and reducing the need for lateral connections through overlying via and wiring levels, using mandrel cuts and sidewall spacers to pattern the hardmask and interlayer dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If unidirectional design rules are used for interconnect structures, then conventional fabrication methods can be applied, but additional lithography layers are required and detection of open circuits becomes complicated
Solution Approach 1:
The patent introduces bidirectional metal lines that extend in both lateral directions from a central axis, transforming the conventional unidirectional interconnect design into a two-dimensional pattern. This dimensional change allows the interconnect structure to achieve bidirectional connectivity within the same metallization level, eliminating the need for additional lithography layers and complex via structures.
2Adaptability or versatility
If lateral connections through overlying via and wiring levels are used, then bidirectional connections can be achieved, but the structure becomes more complex and detection of open circuits is difficult
Solution Approach 1:
The patent extracts the bidirectional connectivity function from the upper metallization levels and implements it directly in the current metallization level through laterally extending metal lines. By taking out the need for vertical via connections and implementing bidirectional routing in-plane, the design simplifies the overall structure and makes open circuit detection more straightforward.
Solution Approach 2:
Instead of achieving bidirectional connections through vertical stacking of via and wiring levels, the patent implements bidirectional routing within the same lateral plane by extending metal lines in opposite directions from a central axis. This dimensional approach consolidates multiple routing functions into a single metallization level.
3Ease of manufacture
If conventional unidirectional metal lines are used, then fabrication is simpler, but design limitations prevent efficient pattern transfer and open circuit detection
Solution Approach 1:
The patent transforms the conventional unidirectional metal line design into a bidirectional structure where metal lines extend in both lateral directions from a central axis. This dimensional enhancement enables more efficient pattern transfer by allowing continuous serpentine lines within a single metallization level, improving productivity without significantly complicating the fabrication process.
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 continuous serpentine lines within a metallization level, simplifying the detection of open circuits and reducing design limitations by allowing bidirectional self-aligned multiple patterning, thereby improving the efficiency and complexity of BEOL interconnect fabrication.
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 (RIE) process
Data Source
AI summary
Interconnect structures and methods of fabricating an interconnect structure. First and second non-mandrel interconnects are formed in an interlayer dielectric layer. The first non-mandrel interconnect and the second non-mandrel interconnect have respective side surfaces that extend in a first direction. The connector interconnect extends in a second direction transverse to the first direction from the side surface of the first non-mandrel interconnect to the side surface of the second non-mandrel interconnect.