Silicon-Enriched Copper Diffusion Barriers for Semiconductor Interconnects

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional barrier layers in semiconductor devices, such as pure ruthenium, fail to prevent copper diffusion due to poor nucleation and adhesion issues, leading to increased resistance and electrical leakage in advanced interconnect structures.

Innovation Solution

A method involving the formation of silicon enriched layers over dielectric layers, followed by the deposition of barrier layers, which enhances nucleation and adhesion, reducing copper diffusion and electrical leakage by sealing surface pores and improving bi-layer barrier properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If pure ruthenium is used as the barrier layer, then the barrier layer can be deposited thinly, but copper diffusion increases due to poor nucleation and columnar growth

Engineering Contradiction:

Improvebarrier layer thicknessVSAvoidcopper diffusion prevention

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

A silicon enriched layer is formed on the dielectric layer surface before depositing the ruthenium barrier layer. This preliminary silicon enrichment modifies the surface properties to enhance nucleation of the ruthenium layer, enabling it to grow as a continuous amorphous film rather than columnar structure, thereby preventing copper diffusion even at thin thicknesses

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The surface composition of the dielectric layer is changed by enriching it with silicon through exposure to silicon-containing ambient. This parameter change in surface composition improves the nucleation properties for subsequent ruthenium deposition, transforming the growth mode from columnar to amorphous continuous film

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If pure ruthenium is used as the barrier layer, then the deposition process is simple, but adhesion to the dielectric layer is poor

Engineering Contradiction:

Improvedeposition process simplicityVSAvoidadhesion to dielectric layer

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The silicon enriched layer acts as an intermediary between the dielectric layer and the ruthenium barrier layer. It provides a surface with improved nucleation properties that enhances adhesion of ruthenium to the dielectric, while the ruthenium layer itself remains in direct contact with the silicon enriched surface, maintaining the simple deposition process

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a bi-layer barrier is used, then copper diffusion is improved, but adhesion between the two barrier layers becomes a new problem

Engineering Contradiction:

Improvecopper diffusion preventionVSAvoidadhesion between barrier layers

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The complex bi-layer barrier structure is replaced by extracting the essential function (improved nucleation and adhesion) and implementing it through a single ruthenium layer deposited on a silicon enriched dielectric surface. This eliminates the adhesion problem between two barrier layers while maintaining copper diffusion prevention

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If a bi-layer barrier is used, then copper diffusion is improved, but the barrier layer thickness increases leading to higher resistance

Engineering Contradiction:

Improvecopper diffusion preventionVSAvoidbarrier layer thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

By performing silicon enrichment of the dielectric layer before ruthenium deposition, the nucleation properties are improved in advance. This allows a single thin ruthenium layer to form a continuous amorphous film that effectively prevents copper diffusion, eliminating the need for thicker bi-layer structures

Inventive Principle:

Principle #10Preliminary action

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 silicon enriched layers promote amorphous growth of barrier materials, improve adhesion, and reduce copper diffusion rates, potentially eliminating the need for composite barriers and minimizing via resistance.

Implementation Method 1

forming a first silicon enriched layer over the dielectric layer by exposing the dielectric layer to a silicon-containing ambient

Methodology Applied

Scientific EffectSilicon enrichment through exposure to silicon-containing ambient: Adsorption

Implementation Method 2

The silicon enriched layers promote amorphous growth of barrier materials

Methodology Applied

Scientific EffectAmorphous growth promotion: Nucleation

Implementation Method 3

a barrier layer over the first silicon enriched layer

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Data Source

PatentUS8211794B2Properties of metallic copper diffusion barriers through silicon surface treatments

Publication Date: 2012.07.03 TEXAS INSTRUMENTS INC

AI summary

In accordance with the invention, there are diffusion barriers, integrated circuits, and semiconductor devices and methods of fabricating them. The method of fabricating a diffusion barrier can include providing a dielectric layer, forming a first silicon enriched layer over the dielectric layer by exposing the dielectric layer to a silicon-containing ambient, and forming a barrier layer over the first silicon enriched layer.