Interconnect Capping Barrier Adhesion for Electro-Migration Control
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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 defects like voids and hillocks, which accelerate electro-migration and degrade device performance.
Innovation Solution
A method is introduced to improve adhesion by selectively depositing an adhesion layer on the dielectric layer and increasing its crystallinity through annealing, which enhances the adhesion between the capping barrier layer and the dielectric layer, thereby reducing electro-migration-related defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capping barrier layer is deposited over the conductive feature and dielectric layer, then protection against electro-migration is improved, but adhesion between layers deteriorates leading to voids and hillocks
Solution Approach 1:
An adhesion layer is introduced as an intermediary between the dielectric layer and the capping barrier layer. This intermediate layer specifically addresses the adhesion problem by providing a surface that bonds well to both the dielectric layer below and the capping barrier layer above, thereby preventing voids and hillocks while maintaining the protective function against electro-migration.
Solution Approach 2:
The structure employs a composite multi-layer system consisting of the dielectric layer, the adhesion layer, and the capping barrier layer. Each layer is selected for its specific properties: the dielectric layer provides insulation, the adhesion layer provides bonding, and the capping barrier layer provides electro-migration protection. This composite structure resolves the contradiction by combining materials with complementary functions.
2Stability of the object's composition
If the adhesion layer is deposited to improve layer bonding, then adhesion between capping barrier layer and dielectric layer is improved, but process complexity increases
Solution Approach 1:
The original single-layer barrier structure is segmented into multiple functional layers: the dielectric layer, the adhesion layer, and the capping barrier layer. This segmentation allows each layer to perform its specific function optimally, with the adhesion layer dedicated solely to bonding, thereby improving adhesion without significantly complicating the overall 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 and hillocks, minimizing electro-migration and associated defects such as via bond defects, time-dependent dielectric breakdown, and resistive-conductive delays, thereby enhancing the reliability and longevity of semiconductor devices.
Implementation Method 1
increasing its crystallinity through annealing
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%.