Interlaced IC Power Grid Layout for Voltage Stability
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Solution Overview
Problem
Integrated circuit (IC) power grids face issues with voltage variation and electromigration, leading to reduced reliability and operating speed due to metal line degradation, which affects power delivery to transistors.
Innovation Solution
A non-uniform power delivery structure with interlaced power lines in multiple metal layers, where power lines in one layer are alternately arranged to deliver supply and grounding voltages, and vias connect them across layers to standard cells, ensuring flexible placement of standard cells with varying sizes without electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform power grid is used, then the structure is simple, but voltage variation increases and electromigration occurs
Solution Approach 1:
The patent applies local quality by creating non-uniform power grid structures where different regions have different power line densities and configurations. Specifically, the power delivery network uses varying wire widths, spacing, and layer assignments in different chip regions to match local power demands, thereby reducing voltage variation and electromigration effects in high-current areas while maintaining simplicity in low-power regions.
Solution Approach 2:
The patent segments the power grid into multiple metal layers with interlaced power and ground lines. Each layer is designed with specific patterns of power lines and ground lines that are interconnected through vias, creating a distributed power delivery system that reduces voltage drops and electromigration by distributing current across multiple pathways rather than relying on a single uniform structure.
2Productivity
If power lines are densely packed, then power delivery efficiency improves, but electromigration increases
Solution Approach 1:
The patent transitions from two-dimensional power line arrangements to three-dimensional interlaced structures by stacking multiple metal layers vertically. Power lines and ground lines are alternately arranged in different layers and interconnected through vias, creating a interlaced configuration that increases effective power delivery capacity without increasing current density in any single line, thereby reducing electromigration while maintaining high power delivery efficiency.
Solution Approach 2:
The patent employs composite power grid structures combining multiple metal layers with different geometries and materials properties. The interlaced configuration of power lines and ground lines in alternating layers creates a composite electromagnetic structure that distributes current more evenly and reduces hot spots, thereby improving power delivery efficiency while mitigating electromigration effects through the combined effect of multiple conductive pathways.
3Adaptability or versatility
If standard cells are placed flexibly, then design adaptability improves, but electrical shorts between power lines may occur
Solution Approach 1:
The patent implements equipotentiality by interlacing power lines and ground lines in alternating metal layers, creating a configuration where adjacent conductors are at different potentials but separated by insulating layers and vias. This interlaced structure ensures that standard cells can be placed flexibly in the spaces between power lines without creating short circuits, as the power and ground lines are electrically isolated by the layered construction and connected only through controlled via structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes voltage variation and electromigration effects, enhancing the reliability and flexibility of power delivery to standard cells, allowing for efficient placement and operation of ICs with various cell sizes without conflicts.
Implementation Method 1
As electrons pass through a conductor (e.g. a metal wire/line), they tend to drag the metallic ions of the conductor along with them through electrostatic attraction.
Data Source
AI summary
Power grid of an integrated circuit (IC) is provided. A plurality of first power lines are formed in a first metal layer. A plurality of second power lines are formed in the first metal layer and parallel to the first power lines, and the first and second power lines are interlaced in the first metal layer. A plurality of third power lines formed in a second metal layer, and the third power lines are perpendicular to the first power lines. A plurality of fourth power lines are formed in the second metal layer and parallel to the third power lines, and the third and fourth power lines are interlaced in the second metal layer. Distances from each of the third power lines to two adjacent fourth power lines are different, and distances from each of the fourth power lines to two adjacent third power lines are the same.