Nanoscale Interconnect Segmentation for Electromigration Resistance
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Solution Overview
Problem
As semiconductor circuits are scaled to smaller dimensions, metal interconnects become increasingly susceptible to electromigration, leading to mechanical stress and failure due to high current densities, which reduces the reliability of the circuits.
Innovation Solution
The introduction of electromigration blocking islands in the interconnect structure, which divide the interconnects into segments of length equal or less than the Blech length, using a combination of diffusion barriers, liners, and conductive materials to impede metal atom migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal interconnects are scaled to smaller dimensions to increase density, then circuit density and performance are improved, but susceptibility to electromigration increases
Solution Approach 1:
The interconnect structure is segmented into multiple sections by introducing electromigration blocking islands. These islands divide the continuous metal interconnect into discrete segments, each with length less than the Blech length. This segmentation prevents continuous electromigration across the entire interconnect, thereby maintaining reliability while allowing overall interconnect density to increase through smaller dimensions.
Solution Approach 2:
Electromigration blocking islands serve as intermediary structures inserted within the metal interconnect. These blocking islands act as mediators that interrupt the path of electromigration without completely blocking current flow. The blocking islands are positioned at strategic locations to create segments that are short enough to prevent electromigration while maintaining electrical connectivity through the interconnect structure.
2Reliability
If electromigration blocking islands are introduced to prevent metal atom migration, then electromigration resistance is improved, but interconnect structure complexity increases
Solution Approach 1:
The electromigration blocking islands are formed using a nested structure of multiple material layers. The blocking islands consist of a first material layer containing the blocking structure, a second material layer surrounding the first layer, and a third material layer surrounding the second layer. This nested configuration integrates multiple functions within a compact structure, reducing overall complexity while maintaining electromigration resistance.
Solution Approach 2:
The electromigration blocking islands are constructed using composite material structures with at least three different materials. This composite approach allows each material layer to perform specific functions (electromigration blocking, electrical conduction, mechanical support), thereby achieving reliable electromigration protection without requiring a single complex material system.
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 solution effectively impedes electromigration, enhancing the reliability of metal interconnects by preventing long-range metal atom migration and reducing the risk of interconnect failure, thereby improving the reliability of semiconductor circuits.
Implementation Method 1
Electromigration occurs when a high density of current flows through a metal interconnect, which in turn causes metal atoms to migrate toward the anode end of the metal interconnect
Data Source
AI summary
After forming a trench opening including narrow trench portions spaced apart by wide trench portions and forming a stack of a first diffusion barrier layer and a first liner layer on sidewalls and a bottom surface of the trench opening, a reflow process is performed to fill the narrow trench portions but not the wide trench portions with a first conductive material layer. A stack of a second diffusion barrier layer and a second liner layer is formed on portions of the first liner layer and ends of the first conductive material layer exposed by the wide trench portions. A second conductive material layer is deposited to fill the wide trench portions. Portions of the second diffusion barrier layer and the second liner layer located between the first conductive material layer and the second conductive material layer act as vertical blocking boundaries to prevent the electromigration of metal atoms.