Backside Power Rail IC Layout for Transistor Consistency

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Solution Overview

Problem

The miniaturization of integrated circuits has led to stricter design and manufacturing specifications, along with challenges in reliability and consistency of transistor characteristics due to complex layout patterns and increased density.

Innovation Solution

The integration of backside power and interconnect metal rails, which provide reliable supply voltage and flexible routing, allows for a more compact design by reducing the number of front side metal rails and via contacts, resulting in consistent transistor shapes and improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If miniaturization is pursued to reduce device size and increase functionality, then device area and power consumption are reduced, but manufacturing precision and reliability become more difficult to maintain

Engineering Contradiction:

Improvedevice areaVSAvoidmanufacturing precision

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

The patent introduces backside metal rails and via contacts that extend the interconnect architecture into the vertical dimension and utilize the backside of the substrate. This dimensional expansion allows power and signal distribution without increasing the planar footprint, enabling continued miniaturization while maintaining manufacturing feasibility through standardized rail geometries on the backside surface

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Area of moving object

If miniaturization is pursued to reduce device size, then device area is reduced, but transistor characteristic consistency deteriorates due to complex layout patterns

Engineering Contradiction:

Improvedevice areaVSAvoidtransistor characteristic consistency

Core Design Contradiction:

Area of moving objectVSStability of the object's composition

Solution Approach 1:

The patent segments the power distribution function from the signal routing function by introducing dedicated backside power rails separate from frontside signal interconnects. This segmentation simplifies the layout patterns by assigning specific functions to specific layers and locations, reducing the complexity that adversely affects transistor characteristic consistency while enabling further miniaturization

Inventive Principle:

Principle #1Segmentation

3Reliability

If front side metal rails and via contacts are increased to provide reliable power supply and routing, then power distribution reliability is improved, but device area increases

Engineering Contradiction:

Improvepower distribution reliabilityVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

The patent inverts the conventional approach by placing metal rails on the backside of the substrate rather than only on the front side. This inversion relocates power distribution infrastructure to the opposite surface, eliminating the need for extensive frontside metal rails and via contacts, thereby reducing device area while maintaining or improving power distribution reliability through the dedicated backside rail architecture

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS20250331307A1Integrated circuit with backside power rail and backside interconnect

Publication Date: 2025.10.23 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An integrated circuit includes metal rails. The integrated circuit includes a first layer including a first metal rail and a second layer including a second metal rail, where the second layer is above the first layer along a first direction. The integrated circuit includes a third layer including an active region of a transistor, where the third layer is above the second layer along the first direction. The integrated circuit includes a fourth layer including a third metal rail, where the fourth layer is above the third layer along the first direction. The integrated circuit includes a fifth layer including a fourth metal rail, where the fifth layer is above the fourth layer along the first direction.