Interconnect Adhesion Layer Structure for Electro-Migration Reduction
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Solution Overview
Problem
Existing interconnect structures in semiconductor ICs face challenges with electro-migration, particularly due to poor adhesion between capping barrier layers and conductive features, leading to issues like void formation, hillocks, and increased resistance, which accelerate defects and reduce device performance.
Innovation Solution
A method is introduced to improve adhesion by selectively depositing an adhesion layer on the dielectric layer and undergoing an annealing process to increase its crystallinity, thereby enhancing the adhesion between the capping barrier layer and the dielectric layer, reducing electro-migration-related defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capping barrier layer is deposited over the conductive feature to prevent electro-migration, then the conductive feature is protected from material migration, but poor adhesion between the capping barrier layer and dielectric layer leads to void formation and hillocks
Solution Approach 1:
An adhesion layer is introduced as an intermediary between the dielectric layer and the capping barrier layer. This adhesion layer specifically addresses the poor adhesion problem by providing a bonding interface that prevents void formation and hillock formation, while allowing the capping barrier layer to continue its function of preventing electro-migration.
Solution Approach 2:
The interconnect structure uses a composite multi-layer approach combining dielectric material, adhesion layer material, and capping barrier layer material. Each layer is selected for its specific properties: the dielectric for insulation, the adhesion layer for bonding, and the capping barrier for electro-migration protection, creating a composite structure that solves multiple problems simultaneously.
2Productivity
If the conductive feature is scaled down to increase functional density, then production efficiency increases and costs decrease, but electro-migration effects are exacerbated
Solution Approach 1:
The invention changes the structural parameters of the interconnect by adding the adhesion layer with specific material properties and thickness. This structural parameter change enhances the overall reliability of the scaled-down conductive feature by preventing the formation of voids and hillocks that would otherwise accelerate electro-migration in smaller dimensions.
3Device complexity
If existing interconnect structures are used without an adhesion layer, then the structure is simpler and manufacturing is easier, but voids and hillocks form due to poor adhesion
Solution Approach 1:
The adhesion layer serves as a mediating layer that resolves the conflict between structural simplicity and reliability. While it does add a layer to the structure, it is a thin, specialized layer that provides critical bonding function, enabling the overall system to achieve better reliability without significantly complicating the manufacturing process.
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 improved adhesion structure effectively reduces voids, hillocks, and resistive-conductive delays, enhancing the reliability and longevity of semiconductor devices by mitigating electro-migration effects.
Implementation Method 1
undergoing an annealing process to increase its crystallinity
Implementation Method 2
electro-migration reduction
Data Source
AI summary
The present disclosure provides a structure and a method to reduce electro-migration. An interconnect structure according to the present disclosure includes a conductive feature embedded in a dielectric layer, a capping barrier layer disposed over the conductive feature and the dielectric layer, and an adhesion layer sandwiched between the capping barrier layer and the dielectric layer. The adhesion layer includes a degree of crystallinity between about 40% and about 70%.