Standard Cell Power Rail Segmentation for Electromigration Mitigation
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Solution Overview
Problem
As integrated circuits become more complex and semiconductor fabrication processes become finer, the reduced cross-sectional area of wiring leads to increased resistance and electromigration issues, causing wiring opens and shorts between different wires.
Innovation Solution
The integration of standard cells with embedded power rails and doping regions on a substrate, where the power rails are formed within isolation trenches to maintain a wider width and reduce resistance, and the use of doping regions to efficiently transfer power source voltage, thereby minimizing electromigration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cross-sectional area of wiring is reduced to increase integration density, then the number of devices per unit area increases, but the resistance of the wiring increases and electromigration occurs
Solution Approach 1:
The power supply network is segmented into multiple independent power rails (first power rail, second power rail, third power rail) that are distributed throughout the standard cell. Each power rail serves a specific region, reducing the current density in each individual rail and thereby reducing resistance and electromigration effects while maintaining overall power delivery capability.
Solution Approach 2:
Different regions of the standard cell are provided with different power rail configurations tailored to their specific needs. The first device region receives power through the first and second power rails, while the second device region receives power through the third power rail. This localized power distribution optimizes the balance between integration density and power delivery quality in each region.
2Productivity
If the width of wiring is reduced to increase device integration, then more devices can be placed in the same area, but the resistance increases and electromigration causes wiring opens and shorts
Solution Approach 1:
The power rails extend in the first direction (horizontal) rather than only in the second direction (vertical), creating a three-dimensional power distribution network within the standard cell. This dimensional expansion allows power to be delivered through multiple paths, reducing the current burden on any single wiring segment and mitigating electromigration effects.
Solution Approach 2:
The third power rail acts as an intermediary power supply for the second device region, providing an additional power path that reduces the current density in the first power rail. This intermediary structure distributes the power load more evenly, reducing electromigration and preventing wiring failures while maintaining high device integration.
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 effectively reduces the likelihood of increased resistance and electromigration in power rails, maintaining the integrity of the wiring and preventing opens and shorts, even as the widths of conductive patterns decrease with increasing integration.
Implementation Method 1
a first doping region between the first power rail and the well, the first doping region configured to transfer the power source voltage from the first power rail to the well
Data Source
AI summary
An integrated circuit according to some example embodiments of inventive concepts includes a substrate including a well including dopants of a first conductivity type, a first device region on the well, the first device region extending in a first direction parallel to the substrate, and a first isolation element inside the well, the first isolation element extending in the first direction. The first isolation element includes a first power rail configured to receive a power source voltage, and a first doping region between the first power rail and the well, the first doping region configured to transfer the power source voltage from the first power rail to the well, and including dopants of the first conductivity type.