Semiconductor Power Rails and Bridges for Metal Stack Reduction
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Solution Overview
Problem
As semiconductor chip complexity increases, the number of metal stacks required for power supply becomes greater, leading to inefficiencies and increased manufacturing costs.
Innovation Solution
A semiconductor device design that includes multiple power rails and power bridges formed in different metal layers, with branch portions connecting these rails to reduce resistance and enhance signal routing capability while minimizing the number of metal stacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of metal stacks is increased to provide power to complex semiconductor chips, then power supply capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent utilizes the vertical dimension by forming power bridges in lower metal layers (e.g., BL1) that extend vertically to connect power rails in upper metal layers (e.g., M1). This three-dimensional power distribution approach allows power to be delivered through multiple layers without increasing the horizontal footprint or requiring additional metal stacks, thereby resolving the contradiction between power supply capability and device complexity
Solution Approach 2:
The power distribution network is segmented into multiple independent power bridges distributed across different metal layers. Each power bridge independently connects power rails, creating a modular structure that provides redundant power paths. This segmentation allows the system to achieve robust power supply capability without requiring a single complex high-layer metal stack, thus reducing overall device complexity while maintaining reliability
2Power
If more metal stacks are used for power supply, then power delivery is improved, but manufacturing cost increases
Solution Approach 1:
The invention leverages vertical interconnects through multiple metal layers to deliver power efficiently. By using power bridges that span from lower to upper metal layers, the design achieves strong power delivery without requiring additional high-cost metal stacks, thus improving power delivery while controlling manufacturing costs
Solution Approach 2:
The power bridges formed in lower metal layers serve multiple functions: they provide power delivery, act as current paths, and enable voltage distribution across different power rails. This multi-functionality allows the same structural element to achieve multiple objectives, improving power delivery capability without proportionally increasing manufacturing complexity and cost
Data Source
AI summary
A semiconductor device includes a first power rail, a second power rail, at least one standard cell and at least one power bridge. The first power rail extends in a first direction over a substrate. The second power rail extends in the first direction over the substrate, and the second power rail is spaced apart from the first power rail in a second direction that intersects the first direction. The at least one standard cell receives a first voltage from the first and the second power rails. The at least one power bridge connects the first power rail and the second power rail in the second direction. The first power rail and the second power rail are formed in a first metal layer and the least one power bridge is formed in a bottom metal layer that is under the first metal layer.