IC Cell Layout Buffer Zones for Wider Power Rails

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Solution Overview

Problem

The miniaturization of semiconductor integrated circuits (ICs) has led to stricter design and manufacturing specifications, as well as reliability challenges, particularly in ensuring efficient power distribution and flexibility in IC design.

Innovation Solution

The introduction of a buffer zone in the integrated circuit layout design increases the distance between cells, thereby increasing the width of power rails and reducing their resistance, enhancing efficiency and flexibility, especially in hybrid cells incorporating multiple fin transistor cells and single fin transistor cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If cells are placed closer together to increase integration density, then device functionality and size are improved, but power distribution efficiency deteriorates due to narrower power rails and higher resistance

Engineering Contradiction:

Improveintegration densityVSAvoidpower distribution efficiency

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

The circuit layout is segmented into functional cells separated by buffer zones. This segmentation allows power rails to be strategically positioned within and between cells, ensuring adequate power distribution width while maintaining high integration density through optimized cell arrangement and shared buffer zones.

Inventive Principle:

Principle #1Segmentation

2Reliability

If buffer zones are increased to reduce power rail resistance, then power distribution efficiency is improved, but device area increases

Engineering Contradiction:

Improvepower distribution efficiencyVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

Buffer zones serve multiple functions: they provide electrical isolation between cells, act as routing corridors for power and signal lines, and can contain additional circuitry such as dummy transistors for process compensation. This multi-functionality reduces the need for dedicated spacing, maintaining compact area while ensuring adequate power distribution.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If power rail width is increased to reduce resistance, then power distribution efficiency is improved, but layout flexibility deteriorates

Engineering Contradiction:

Improvepower distribution efficiencyVSAvoidlayout flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The layout design utilizes multiple metal layers for power distribution, allowing power rails to transition from two-dimensional planar structures to three-dimensional stacked configurations. This enables adequate power delivery capacity while maintaining flexible two-dimensional cell arrangement and compact area utilization.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12283587B2Integrated circuit and method of forming the same

Publication Date: 2025.04.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An integrated circuit includes a first cell, a second cell, a buffer zone and a first power rail. The first cell includes a first set of fins extending in a first direction. Each fin of the first set of fins corresponds to a transistor of a first set of transistors. The second cell includes a second set of fins extending in the first direction. Each fin of the second set of fins corresponds to a transistor of a second set of transistors. The second set of fins is separated from the first set of fins in a second direction. The buffer zone is between the first cell and the second cell. The first power rail extends in the first direction, and overlaps at least the buffer zone. The first power rail is in a first metal layer, and is configured to supply a first voltage.