Integrated Circuit Contact Using Carbon Nanotubes

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Solution Overview

Problem

Integrated circuit technology faces challenges in manufacturing high-quality contacts with high aspect ratios, leading to high contact resistance, particularly at small geometry technology nodes, which affects device performance and reliability.

Innovation Solution

The integration of carbon nanotubes within selective metal vias over silicide layers in integrated circuits, with a cap formed over the nanotubes to reduce contact resistance and enhance operating speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If contact diameter is reduced to increase packing density, then circuit density is improved, but contact resistance increases due to high aspect ratio

Engineering Contradiction:

Improvecircuit densityVSAvoidcontact resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The contact structure uses a composite material system consisting of a metal fill (e.g., cobalt, nickel, or copper) combined with carbon nanotubes. The metal provides low-resistance bulk conduction while the carbon nanotubes provide high-quality interfaces with the semiconductor, reducing contact resistance despite the small contact diameter required for high packing density.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the material parameters at the contact interface by using carbon nanotubes instead of conventional metal-semiconductor interfaces. This parameter change enables low contact resistance even at high aspect ratios by providing superior interface quality and reducing Schottky barrier effects.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional metallization materials are used at small dimensions, then manufacturing is simplified, but contact resistance increases due to mean free path limitations

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcontact resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention replaces conventional single-material metallization with a composite structure of carbon nanotubes and metal fill. This composite approach overcomes the mean free path limitations of conventional metals at small dimensions by using carbon nanotubes, which have superior electron transport properties at nanoscale dimensions.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention substitutes conventional metal-based conduction with carbon nanotube-based conduction. Carbon nanotubes provide ballistic or near-ballistic electron transport at small dimensions, replacing the diffusive transport in conventional metals and eliminating mean free path limitations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 results in lower contact resistance and higher operating speeds, addressing the manufacturing and performance issues associated with small geometry technology nodes.

Implementation Method 1

forming at least one nanotube over the selective metal

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

forming a cap over the nanotubes

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS8709941B2Method for forming contact in an integrated circuit

Publication Date: 2014.04.29 ADVANCED MICRO DEVICES INC

AI summary

A method for forming an integrated circuit system includes providing an integrated circuit device; and forming an integrated contact over the integrated circuit device including: providing a via over the integrated circuit device; forming a selective metal in the via; forming at least one nanotube over the selective metal; and forming a cap over the nanotubes.