Bi-Layer Alloy Liner for Interconnect Filling and Electromigration
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Solution Overview
Problem
The scaling down of semiconductor devices poses challenges in forming conductive features with reliable adhesion and efficient filling of openings, leading to issues such as pinch-offs and electromigration.
Innovation Solution
A bi-layer alloy liner is formed by intermixing a first liner layer, such as ruthenium, with a second liner layer, such as cobalt, over a barrier layer, followed by a conductive material deposition and reflow, enhancing adherence and reducing electromigration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single liner layer is used in scaling down semiconductor devices, then the manufacturing process is simple, but the adhesion reliability and filling efficiency deteriorate
Solution Approach 1:
The liner layer is segmented into multiple distinct layers (e.g., first liner layer with ruthenium and second liner layer with cobalt) instead of using a single uniform layer. Each layer provides specific functionality: the first liner layer ensures strong adhesion to the barrier layer, while the second liner layer facilitates complete filling of the opening and prevents pinch-offs, thereby resolving the adhesion reliability issue while maintaining manufacturing simplicity through a systematic multi-layer approach.
Solution Approach 2:
The invention uses composite liner structure combining different materials (ruthenium and cobalt) in a layered configuration. This composite approach leverages the complementary properties of each material: ruthenium provides excellent adhesion to the barrier layer, while cobalt offers superior filling characteristics and prevents electromigration, thus achieving enhanced adhesion reliability without significantly complicating the manufacturing process.
2Ease of manufacture
If a single liner layer is used, then the manufacturing process is simple, but the opening filling completeness deteriorates due to pinch-offs
Solution Approach 1:
The liner structure is divided into multiple layers with distinct functions: the first liner layer adheres to the barrier layer, while the second liner layer is specifically designed to facilitate complete opening filling and prevent pinch-offs during conductive material deposition. This segmentation allows each layer to optimize its specific function, ensuring manufacturing precision in opening filling without overly complicating the overall process.
Solution Approach 2:
Different regions of the liner structure are assigned different material compositions and properties: the first liner layer near the barrier layer has optimized adhesion properties, while the second liner layer at the opening region has optimized filling properties. This local quality differentiation ensures that each part of the liner structure performs its specific function effectively, achieving complete opening filling while maintaining process simplicity.
3Device complexity
If conventional liner structures are used, then the device structure is simple, but electromigration and material diffusion increase
Solution Approach 1:
The liner structure employs a composite of different materials (ruthenium and cobalt) in a layered configuration. The first liner layer with ruthenium provides a diffusion barrier at the interface with the barrier layer, while the second liner layer with cobalt prevents electromigration in the upper region. This composite structure effectively suppresses harmful material diffusion and electromigration effects without significantly increasing device structure complexity.
Solution Approach 2:
The multi-layer liner structure acts as an intermediary between the barrier layer and the conductive fill material. The first liner layer serves as an intermediate adhesion layer, while the second liner layer serves as an intermediate protection layer against electromigration. These intermediary layers prevent direct harmful interactions between the barrier layer and conductive material, reducing material diffusion and electromigration while maintaining relatively simple device structure.
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 bi-layer alloy liner improves the yield and reliability of conductive features by ensuring complete filling of openings and minimizing material diffusion during device use.
Implementation Method 1
the multiple liner layers are also selected for their ability to intermix with one another to form one continuous layer
Data Source
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.