Orthogonal Power Rail Layout for Low-IR-Drop IC Routing
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Solution Overview
Problem
The miniaturization of integrated circuits has led to stricter design and manufacturing specifications, as well as reliability challenges due to electromigration effects and IR drops, which are not adequately addressed by existing technologies.
Innovation Solution
Implementing underlayer power rails extending in a direction orthogonal to signal conducting lines in the first connection layer, allowing for reduced cell widths and increased power rail density, thereby reducing electromigration effects and IR drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If integrated circuits are miniaturized to reduce device size, then device size and power consumption are reduced, but electromigration effects and IR drops increase, compromising reliability
Solution Approach 1:
The patent introduces power rails in a second connection layer beneath the first connection layer, transitioning from a single-layer power distribution to a multi-layer configuration. This dimensional change allows power rails to extend in directions orthogonal to signal conducting lines, providing additional pathways for current flow and reducing electromigration effects and IR drops in miniaturized circuits
Solution Approach 2:
The patent segments the power distribution network into multiple independent power rails extending in different directions within and between connection layers. This segmentation creates redundant current paths, so that if one path experiences electromigration or voltage drop, other paths can compensate, thereby improving overall reliability
2Area of stationary object
If cell width is reduced to increase circuit density, then more circuits fit in the same area, but power rail design becomes more difficult and electromigration effects worsen
Solution Approach 1:
By adding power rails in a second connection layer beneath the first layer, the patent provides additional dimensional space for power distribution. This allows power rails to extend orthogonal to signal lines without increasing the planar cell footprint, maintaining high density while improving power delivery and reducing electromigration through multi-path current flow
3Reliability
If power rail density is increased to reduce electromigration effects, then reliability improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent configures power rails in the second connection layer to extend in directions orthogonal to signal conducting lines, allowing the same power rail structure to serve multiple cells and functions simultaneously. This universal configuration reduces the need for custom-designed power rails for each specific circuit, simplifying manufacturing while maintaining high power rail density and reliability
Data Source
AI summary
An integrated circuit includes a first-voltage underlayer power rail and a second-voltage underlayer power rail extending in a first direction below a first connection layer. A first-type transistor and a second-type transistor are underneath the first connection layer. The source region of the first-type transistor is connected to the first-voltage underlayer power rail, and the source region of the second-type transistor is connected to the second-voltage underlayer power rail. The integrated circuit also includes a first-voltage power rail, a second-voltage power rail, and a signal conducting line, each of which extends in a second direction in the first connection layer. The first-voltage power rail is connected to the first-voltage underlayer power rail, and the second-voltage power rail is connected to the second-voltage underlayer power rail. The signal conducting line is conductively connected to either a terminal-conductor or a gate-conductor.