Routing Crossbar Layout Using Programmable Vias for Tight Wire Pitch
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Solution Overview
Problem
The reduction of spacing between metal wires in modern semiconductor fabrication processes challenges the layout design rules for structured ASIC devices, making it difficult to place wires in perpendicular directions within a single metal layer, and editing masks for additional metal layers increases manufacturing costs.
Innovation Solution
Implementing layout topologies that allow for routing options by editing a single via mask independently of conductor direction restrictions, enabling any programming for a routing crossbar, and reducing the need for additional via masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wires are placed in perpendicular directions within a single metal layer, then routing flexibility is improved, but wire pitch and spacing restrictions increase
Solution Approach 1:
The patent introduces a via layer between metal layers to enable routing in a third dimension. Instead of placing perpendicular wires in the same metal layer (which causes spacing issues), the invention routes wires through vias to different metal layers, allowing perpendicular routing without compromising wire pitch or spacing in any single layer.
2Adaptability or versatility
If additional metal layers are edited for structured ASIC devices, then routing capability is improved, but manufacturing cost increases due to more masks
Solution Approach 1:
The patent pre-configures the via layer during the standard fabrication process to establish all necessary inter-layer connections. This preliminary action eliminates the need for post-fabrication mask editing of additional metal layers, thereby reducing manufacturing costs while maintaining enhanced routing capability.
Solution Approach 2:
The via layer serves as an intermediary between metal layers, providing the routing flexibility normally achieved by editing multiple metal layers. By using vias as the mediating element, the invention achieves enhanced routing capability without requiring additional mask edits to metal layers, thus avoiding increased manufacturing costs.
3Adaptability or versatility
If vias are programmed during fabrication, then routing configuration flexibility is improved, but fabrication process complexity increases
Solution Approach 1:
The patent segments the routing configuration into two independent parts: the via layer configuration (done during standard fabrication) and the metal layer routing patterns. This segmentation allows via programming to be integrated into the existing fabrication process without requiring complex coordination between via formation and metal routing, thereby maintaining manageable process complexity while achieving routing flexibility.
Data Source
AI summary
An integrated circuit includes first and second routing crossbars. The second routing crossbar includes first conductors routed in a first direction in a first conductive layer and second conductors routed in a second direction that is perpendicular to the first direction in a second conductive layer. A first subset of the first conductors is coupled to the first routing crossbar. The first subset of the first conductors is coupled to a second subset of the first conductors through a first subset of the second conductors that is coupled to the first and second subsets of the first conductors through first vias. The second subset of the first conductors is coupled to a second subset of the second conductors to through second vias. At least one of the first conductors is decoupled from another one of the first conductors by third vias.