Triangular Interconnect Layout for Uniform Current Distribution
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Solution Overview
Problem
Conventional back-end-of-line interconnect structures in semiconductor devices experience non-uniform current distribution and increased resistance as the device area increases, particularly in large-area devices with multiple active regions, leading to inefficiencies in field-effect transistors.
Innovation Solution
The implementation of a triangular-shaped layout for interconnects of varying lengths over active device regions, which improves current distribution and reduces resistance without increasing chip area, achieved through a combination of metallization levels and damascene processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equal-length interconnects are used in conventional BEOL structures, then the layout is simple and easy to manufacture, but the current distribution becomes non-uniform and resistance increases as device area increases
Solution Approach 1:
The interconnect structure is segmented into multiple fingers of different lengths (first through fourth fingers) instead of using a single equal-length interconnect. This segmentation allows each finger to carry a portion of the current, distributing the current more uniformly across the large-area device while maintaining manufacturability through standard photolithography patterning processes.
Solution Approach 2:
The interconnect fingers are designed with asymmetric lengths where the first and second fingers have a first length and the third and fourth fingers have a second length that is longer than the first length. This asymmetric design compensates for the non-uniform current distribution that would occur with equal-length fingers, ensuring more uniform current density across the entire device area.
2Area of stationary object
If device area is increased to accommodate more active device regions, then the device functionality is improved, but the resistance of interconnects increases and current distribution becomes non-uniform
Solution Approach 1:
Different portions of the interconnect structure have different lengths tailored to their specific locations. The longer fingers (third and fourth) are positioned to reach farther active device regions, while the shorter fingers (first and second) serve closer regions. This local optimization ensures that current is distributed uniformly across the entire large-area device, maintaining reliability despite the increased device area.
3Ease of manufacture
If equal-length interconnects are used, then the manufacturing process is simpler, but the electrical resistance increases with increasing device area
Solution Approach 1:
The interconnect is divided into multiple parallel fingers of varying lengths that can all be formed in a single photolithography and metallization step. This segmentation approach maintains ease of manufacture by using standard fabrication processes while reducing the effective resistance through multiple parallel current paths, as the total resistance is reduced when current can flow through multiple fingers simultaneously.
Data Source
AI summary
Back-end-of-line layout structures and methods of forming a back-end-of-line layout structure. A metallization level includes a plurality of interconnects positioned over a plurality of active device regions. The plurality of interconnects have a triangular-shaped layout and a plurality of lengths within the triangular-shaped layout.