IC Wiring Layer Architecture to Minimize Vias in NPD Routing
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Solution Overview
Problem
Existing integrated circuit (IC) designs face challenges in efficiently routing wires between layers due to limitations in preferred and non-preferred wiring directions, leading to suboptimal wire connections and increased vias.
Innovation Solution
Implementing a novel non-preferred direction (NPD) wiring architecture in ICs, where certain layers have no preferred wiring directions, allowing for curvilinear and rectilinear routes, while other layers have preferred directions, using EDA tools to optimize routing and minimize vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional preferred direction wiring architecture is used, then manufacturing process is simpler, but wire connectivity is reduced and number of vias increases
Solution Approach 1:
The patent segments the wiring system into two distinct sets: a first set of wiring layers with no preferred directions (allowing curvilinear and rectilinear routes) and a second set of wiring layers with preferred directions (Manhattan routing). This segmentation allows each set to optimize for different routing needs, improving overall wire connectivity while managing complexity through structured division of labor between the two wiring systems
Solution Approach 2:
The patent introduces curvilinear routing paths as an additional dimensional freedom beyond traditional rectilinear Manhattan routing. By allowing wires to follow curved paths in the first set of wiring layers, the system gains access to routing dimensions and pathways that were previously unavailable, thereby improving wire connectivity and reducing the need for vias to reach distant destinations
2Adaptability or versatility
If more vias are used to connect layers, then wire routing flexibility is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the wiring architecture into two functional segments: the first set of layers handles long-distance and complex routing needs with curvilinear paths and no preferred directions, while the second set of layers handles local connections with preferred directions. This segmentation allows the system to achieve routing flexibility where needed without requiring excessive vias throughout the entire structure, thereby reducing manufacturing complexity
Solution Approach 2:
The patent applies different routing characteristics to different locations and layers: the first set of wiring layers (where flexibility is needed) has no preferred directions and allows curvilinear routes, while the second set of wiring layers (where simplicity is needed) has preferred directions and uses Manhattan routing. This local differentiation optimizes routing flexibility in critical areas while maintaining manufacturing ease in other areas, reducing overall via count
3Productivity
If curvilinear and rectilinear routes are allowed in first set of wiring layers, then wire connection efficiency is improved, but EDA tool complexity increases
Solution Approach 1:
The patent segments the routing problem into two distinct phases handled by different EDA tool configurations: the first set of wiring layers is routed using tools that support curvilinear and rectilinear paths without preferred direction constraints, while the second set of layers is routed using traditional Manhattan routing tools with preferred direction constraints. This segmentation allows the EDA system to tackle complex routing needs in the first set while maintaining tool simplicity for the second set, improving overall wire connection efficiency without uniformly increasing EDA tool complexity across all layers
Data Source
AI summary
Some embodiments of the invention provide an integrated circuit (IC) that has a novel non-preferred direction (NPD) wiring architecture. In some embodiments, the IC includes a substrate and multiple wiring layers, which include a first set of one or more wiring layers with no preferred wiring directions, and a second set of one or more wiring layers with preferred wiring directions. In some embodiments, the first set of wiring layers includes the third and fourth wiring layers, while the second set of wiring layers includes the fifth and higher metal layers with successive neighboring layers having different (e.g., alternating) preferred wiring directions. The first set of wiring layers in other embodiments includes the third wiring layer but not the fourth wiring layer, which in these embodiments has a preferred wiring direction.