BEOL Conductive Structure With Bottom-Less Barrier for Low Contact Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Copper diffusion into surrounding dielectric material increases resistivity and causes semiconductor device failures, while existing barrier layers and ruthenium deposition increase contact resistance and surface roughness, affecting electrical performance and manufacturing yield.

Innovation Solution

Selective deposition of a blocking material on the bottom surface of BEOL conductive structures, with a barrier layer on sidewalls and thinner ruthenium layer at the interface to prevent copper diffusion and reduce contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a barrier layer is deposited on the bottom surface of BEOL conductive structures, then copper diffusion is prevented, but contact resistance increases

Engineering Contradiction:

Improvecopper diffusion preventionVSAvoidcontact resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies different materials to different locations: ruthenium is deposited only on sidewalls where copper diffusion prevention is needed, while the bottom surface remains free of barrier material to maintain low contact resistance. This spatial differentiation of material properties resolves the contradiction between diffusion prevention and contact resistance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces a blocking material (e.g., benzotriazole) as an intermediary that selectively prevents ruthenium deposition on the bottom surface while allowing it on sidewalls. This intermediary controls the spatial distribution of the barrier layer, enabling copper diffusion prevention on sidewalls without increasing contact resistance at the bottom interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If ruthenium is deposited to reduce surface roughness, then surface smoothness is improved, but contact resistance increases

Engineering Contradiction:

Improvesurface roughnessVSAvoidcontact resistance

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies ruthenium deposition selectively to sidewalls where surface roughness control is needed, while avoiding the bottom surface where contact resistance would increase. This localized application of the smoothing material resolves the contradiction between surface quality and electrical contact performance.

Inventive Principle:

Principle #3Local quality

3Reliability

If barrier layers are deposited on all surfaces, then copper diffusion is completely prevented, but manufacturing complexity increases

Engineering Contradiction:

Improvecopper diffusion preventionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the barrier layer function from the bottom surface while retaining it on sidewalls. By removing the barrier material from locations where it is not needed (bottom surface), the patent simplifies the manufacturing process and reduces contact resistance while maintaining copper diffusion prevention where required (sidewalls).

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a blocking material applied in advance to the bottom surface to prevent ruthenium deposition in that area. This preliminary action controls the subsequent ruthenium deposition process, ensuring barrier material is only formed on sidewalls where copper diffusion prevention is needed, thereby simplifying the overall manufacturing process.

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

Enhances electrical performance and manufacturing yield by preventing copper diffusion and reducing contact resistance, maintaining low resistivity and surface smoothness.

Implementation Method 1

a blocking material is selectively deposited on a bottom surface of a back end of line (BEOL) conductive structure

Methodology Applied

Scientific EffectSelective deposition: Deposition (physical)

Implementation Method 2

at least one barrier layer over sidewalls of the recessed portion... preventing copper diffusion

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 3

a ruthenium layer is deposited on the at least one barrier layer and a lesser amount on the exposed copper

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS20250364324A1Conductive structures with bottom-less barriers and liners

Publication Date: 2025.11.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A blocking material is selectively deposited on a bottom surface of a back end of line (BEOL) conductive structure such that a barrier layer is selectively deposited on sidewalls of the BEOL conductive structure but not the bottom surface. The blocking material is etched such that copper from a conductive structure underneath is exposed, and a ruthenium layer is deposited on the barrier layer but less ruthenium is deposited on the exposed copper. Accordingly, the barrier layer prevents diffusion of metal ions from the BEOL conductive structure and is substantially absent from the bottom surface as compared to the sidewalls in order to reduce contact resistance. Additionally, the ruthenium layer reduces surface roughness within the BEOL conductive structure and is thinner at the bottom surface as compared to the sidewalls in order to reduce contact resistance.