Feedthrough Via Cell Using Dummy Gate Metal for Low Resistance

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Solution Overview

Problem

The scaling down of integrated circuits increases complexity and requires efficient electrical connections between backside and front side metal lines while minimizing area penalty and resistance.

Innovation Solution

A feedthrough via structure is introduced, combining dummy source/drain contacts and a dummy metal with a gate metal, positioned between transistors, to create a low resistance connection using a dummy gate metal with lower resistance than the gate metal of functioning transistors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional gate metal is used in feedthrough structure, then manufacturing process is simplified, but resistance is too high causing power consumption increase

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidpower consumption

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent changes the material parameter of the gate metal from conventional high-resistance material to low-resistance material (such as tungsten, cobalt, or copper) in the feedthrough cell. This parameter change reduces the electrical resistance of the feedthrough structure, thereby reducing power consumption while maintaining the same manufacturing process flow.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If low resistance dummy gate metal is used, then power consumption and processing speed improve, but device complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoiddevice complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The dummy gate structure in the feedthrough cell serves multiple functions: it provides a low-resistance electrical connection path, acts as a placeholder maintaining structural continuity, and enables backside-to-frontside signal routing. By making the dummy gate metal conductive with low resistance, it simultaneously performs electrical conduction and structural support functions, reducing power consumption without significantly increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If feedthrough via structure is implemented, then resistance and area penalty are minimized, but manufacturing precision requirements increase

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidalignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The feedthrough via is formed to extend through the substrate and contact the dummy gate structure at predetermined locations before final metal layer deposition. This preliminary action ensures proper alignment and electrical contact between the via and the low-resistance gate metal, improving connection reliability while managing manufacturing precision requirements through pre-planned positioning.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250261434A1Low resistance feedthrough cell with contacted poly pitch by metal gate connected to feedthrough via

Publication Date: 2025.08.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An integrated circuit includes a feedthrough via structure includes a dummy transistor with a dummy gate metal. The dummy transistor is positioned between a first transistor and a second transistor. The dummy gate metal is a different material than the gate metal of the first and second transistors. The feedthrough via structure and electrically connects a backside metal line with a front side metal line. The first and second transistors are positioned between the front side of backside metal lines.