Viabar Interconnect Structure for IC Power Rail Redundancy
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Solution Overview
Problem
Current integrated circuit (IC) design rules for back-end-of-line (BEOL) interconnect structures restrict via placements, leading to reduced redundancy and lower yield due to mandated design rule spacing constraints, which negatively impact reliability and prevent 2-dimensional designs in metal layers.
Innovation Solution
The introduction of a viabar, a metal structure that vertically extends from a first metal layer to a third metal layer through a dielectric layer, eliminating the need for intermediate metal layers and vias on the power rail side, allowing direct electrical connection between the first and third metal layers while maintaining connections on the circuit side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If design rule spacing constraints are imposed on troughs in dielectric material, then spacing requirements are met, but via placements in power rails are reduced
Solution Approach 1:
The patent transitions from conventional via connections (vertical dimension only) to viabar connections that extend in both vertical and horizontal dimensions. The viabar horizontally connects power rails within the same metal layer and vertically connects different metal layers, utilizing multiple dimensions to provide redundant connection paths that improve yield while complying with spacing constraints.
Solution Approach 2:
The patent changes the geometric parameters of the connection structure by extending the conductor horizontally as well as vertically. This dimensional expansion creates additional connection paths and redundancy, allowing the design to meet spacing constraints while maintaining or improving reliability through multiple potential connection routes.
2Adaptability or versatility
If bi-directional wiring is allowed at any metal layer, then wiring flexibility is improved, but 2-dimensional designs are precluded
Solution Approach 1:
The viabar structure enables 2-dimensional wiring design by extending conductors in both horizontal and vertical dimensions simultaneously. This allows power rails to be connected in multiple directions within the same metal layer and across different layers, providing wiring flexibility without increasing overall design complexity.
3Manufacturing precision
If via placements are reduced due to spacing constraints, then spacing requirements are satisfied, but redundancy is lowered
Solution Approach 1:
By extending the conductor horizontally in addition to vertically, the viabar creates multiple connection paths through the same physical structure. This dimensional expansion provides inherent redundancy without requiring additional via placements, thus maintaining spacing compliance while improving reliability.
4Ease of manufacture
If conventional via structures are used, then manufacturing simplicity is maintained, but connection complexity increases
Solution Approach 1:
The patent merges the functions of multiple vias and intermediate metal layer connections into a single viabar structure. This consolidation simplifies the manufacturing process by reducing the number of discrete components and steps required, while simultaneously reducing connection complexity by providing direct connections between power rails.
Data Source
AI summary
Disclosed herein is an integrated circuit (IC) including a first metal layer running in a first direction, a second metal layer running in a second direction perpendicular to the first direction, the second metal layer above the first metal layer and a third metal layer running in the first direction above the second metal layer. A viabar electrically connects the first metal layer to the third metal layer, the viabar running in the first direction wherein the viabar vertically extends from the first metal layer to the third metal layer. A method of manufacturing the IC is provided.