Ruthenium Interconnect Cap Deposition for Cu Reflow and EM Reliability

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Solution Overview

Problem

Cobalt liners and caps in interconnects face poor reflow characteristics at spacings below 20 nm, while ruthenium liners lead to early electromigration failure due to Co cap diffusion into the Ru liner sidewall, resulting in a weak cap interface.

Innovation Solution

A method involving the selective deposition of a ruthenium metal cap layer using alkyl halides and ruthenium metal precursors in atomic layer deposition cycles, without plasma, to form a robust cap layer atop interconnects, utilizing alkyl moieties and dienes to enhance Cu reflow and prevent early EM failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If interconnect spacing is reduced to scale down devices, then device density is improved, but Co cap diffusion into Ru liner sidewall causes weak cap interface

Engineering Contradiction:

Improveinterconnect spacingVSAvoidcap interface strength

Core Design Contradiction:

Area of moving objectVSStrength

Solution Approach 1:

The cobalt cap serves as an intermediary protective layer that prevents direct contact and diffusion between the ruthenium liner and any cobalt-containing materials during scaling. This mediator approach allows the system to achieve reduced interconnect spacing for higher density while maintaining strong cap interface integrity by blocking the diffusion pathway.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The method provides improved Cu reflow properties and prevents early electromigration failure, ensuring reliable interconnect performance at reduced spacings, with a ruthenium metal cap layer having high purity and minimal carbon content.

Implementation Method 1

contacting the substrate with a ruthenium metal precursor having a general formula (II): R1—Ru—R2

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

performing a plurality of deposition cycles within a deposition chamber, each deposition cycle comprising: a) contacting the substrate with an alkyl halide... b) purging the deposition chamber; c) contacting the substrate with a ruthenium metal precursor... d) purging the deposition chamber

Methodology Applied

Scientific EffectAtomic Layer Deposition:

Data Source

PatentUS12575392B2Method to deposit metal cap for interconnect

Publication Date: 2026.03.10 APPLIED MATERIALS INC

AI summary

Methods to deposit a metal cap for an interconnect are disclosed. In embodiments, a method comprises contacting the substrate with an alkyl halide and a ruthenium metal precursor to form a metal cap for an interconnect.