Bi-Layer Alloy Liner for Interconnect Fill and Electromigration Control

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Solution Overview

Problem

The semiconductor industry faces challenges in scaling down integrated circuit devices due to issues such as pinch-offs in conductive features and electromigration, which affect the reliability and yield of interconnect structures.

Innovation Solution

The formation of conductive features with a combined liner layer composed of multiple liner layers, including a barrier layer and a capping layer material, which improves adherence and flowability of conductive materials, reducing electromigration and pinch-offs through intermixing and dewettability properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single liner layer is used in interconnect metallization, then the structure is simpler and manufacturing is easier, but pinch-offs occur in conductive features and electromigration reduces reliability

Engineering Contradiction:

Improvereliability of conductive featuresVSAvoidstructure of liner layer

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The liner layer is segmented into multiple distinct layers (first liner layer and second liner layer) with different material compositions and functions. The first liner layer provides barrier properties while the second liner layer provides adhesion and flow control, allowing each layer to optimize for its specific function rather than requiring a single complex material to perform all functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite material structure where the liner system consists of multiple materials (e.g., ruthenium and cobalt, or tungsten and molybdenum) stacked together. This composite approach combines the beneficial properties of each material - barrier performance from one material and adhesion/flow properties from another - to achieve overall improved reliability without excessive complexity.

Inventive Principle:

Principle #40Composite materials

2Productivity

If device geometry is scaled down to increase functional density, then production efficiency increases and costs decrease, but pinch-offs and electromigration become more severe

Engineering Contradiction:

Improveproduction efficiencyVSAvoidreliability of interconnect structures

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Different regions of the liner structure are assigned different material properties tailored to local requirements. The first liner layer in contact with the conductive fill material provides barrier properties locally at the interface, while the second liner layer provides adhesion and flow control locally at the opening walls. This localized optimization allows scaling without compromising reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the material parameters (composition, thickness) of the liner layers to optimize performance at scaled dimensions. By adjusting the thickness and material composition of each liner layer, the system maintains appropriate barrier and flow properties even as the overall feature size decreases, enabling continued scaling while preserving reliability.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If conventional liner layers are used, then manufacturing process is straightforward, but conductive material does not flow properly causing pinch-offs in openings

Engineering Contradiction:

Improvefilling quality of openingsVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The liner structure is prepared in advance with specific material properties before conductive material deposition. The second liner layer is pre-configured with adhesion-promoting and flow-enhancing characteristics, creating optimal surface conditions beforehand that guide the conductive material to flow properly into openings without pinch-offs during the filling 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

This approach enhances the yield and reliability of conductive features by ensuring better filling of openings and reducing material diffusion, leading to more efficient and reliable semiconductor device performance.

Implementation Method 1

improves the ability of the conductive material to flow over the combined liner layer

Methodology Applied

Scientific EffectIntermixing: Diffusion

Implementation Method 2

reducing electromigration and pinch-offs through intermixing and dewettability properties

Methodology Applied

Scientific EffectElectromigration resistance: Diffusion Barrier

Implementation Method 3

improves the ability of the conductive material to flow over the combined liner layer

Methodology Applied

Scientific EffectDewettability: Surface Tension

Data Source

PatentUS11854878B2Bi-layer alloy liner for interconnect metallization and methods of forming the same

Publication Date: 2023.12.26 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of forming a semiconductor device includes forming an opening in a dielectric layer, and forming a barrier layer in the opening. A combined liner layer is formed over the barrier layer by first forming a first liner layer over the barrier layer, and forming a second liner layer over the first liner layer, such that the first liner layer and the second liner layer intermix. A conductive material layer is formed over the combined liner layer, and a thermal process is performed to reflow the conductive material layer.