IC Routing Layout With Non-Preferred Direction Wiring Layers
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Solution Overview
Problem
Existing integrated circuit (IC) designs face challenges in optimizing wiring layouts due to limitations in preferred and non-preferred direction wiring architectures, leading to inefficiencies in wire connection and congestion.
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, utilizing EDA tools to optimize routing and minimize penalization of non-preferred directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If preferred direction wiring architecture is used, then manufacturing process is simplified, but wire routing flexibility is reduced leading to increased wire length and via counts
Solution Approach 1:
The patent segments the wiring system into multiple layers with different routing characteristics. Lower layers (first and second layers) implement unrestricted curvilinear routing for flexibility, while upper layers (third layer and above) implement preferred direction routing for manufacturing simplicity. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between routing flexibility and manufacturing ease.
Solution Approach 2:
Different wiring layers are assigned different routing qualities and constraints based on their local requirements. The lower layers near the substrate are given curvilinear routing capability where flexibility is needed for complex local connections, while upper layers are given preferred direction constraints where manufacturing simplicity is prioritized. This local differentiation resolves the contradiction by applying the appropriate routing mode to each specific location in the wiring hierarchy.
2Ease of operation
If unrestricted curvilinear routing is allowed on all layers, then wire routing flexibility is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the wiring architecture into two segments: lower layers (first and second layers) that support curvilinear routing for flexibility, and upper layers (third layer and above) that support only preferred direction routing for manufacturing simplicity. This segmentation allows the system to achieve overall routing flexibility while maintaining manufacturing simplicity in the majority of layers.
Solution Approach 2:
The patent changes the routing parameters (constraints and capabilities) based on the layer position in the wiring hierarchy. Lower layers have relaxed parameters allowing curvilinear paths, while upper layers have constrained parameters limiting routes to preferred directions. This parameter differentiation resolves the contradiction by optimizing each layer's routing characteristics for its specific role in the overall wiring system.
3Ease of operation
If more wiring layers are added to provide routing options, then wire routing flexibility is improved, but device complexity increases
Solution Approach 1:
The patent segments the multi-layer wiring architecture into functionally distinct groups: lower layers with curvilinear routing capability and upper layers with preferred direction routing. This segmentation provides routing flexibility through layer differentiation rather than simply adding more layers, thereby achieving flexibility while controlling the overall device complexity through systematic organization.
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.