Interconnect Capping Layout for Low-Resistance Via Contacts

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Solution Overview

Problem

The miniaturization of interconnect structures in semiconductor devices leads to increased current density, causing electromigration issues that can result in IC failure, while metallic capping layers used to mitigate this introduce extra resistance, degrading performance.

Innovation Solution

The proposed solution involves an interconnect structure with a metal wire, a metallic capping layer, and a via conductor layer, where portions of the capping layer are removed to reduce contact resistance between the via conductor and the metal wire, and an insulating layer is included to further enhance the structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metallic capping layers are used to mitigate electromigration, then reliability is improved, but resistance increases and performance degrades

Engineering Contradiction:

Improveelectromigration resistanceVSAvoidcontact resistance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The capping layer is segmented into portions that are removed to form openings, creating discrete contact regions rather than a continuous layer. This segmentation allows the structure to maintain electromigration protection in remaining areas while eliminating resistance in contact regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Portions of the metallic capping layer are selectively removed (taken out) to form openings that expose the metal wire. This extraction eliminates the high-resistance interface at contact points while retaining the protective capping layer in other regions to continue mitigating electromigration.

Inventive Principle:

Principle #2Taking out (Extraction)

2Productivity

If interconnect structures are miniaturized to increase storage capacity and processing speed, then productivity is improved, but current density increases causing electromigration issues

Engineering Contradiction:

Improvestorage capacity and processing speedVSAvoidelectromigration resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The capping layer structure implements local quality by having different configurations in different regions: continuous capping in non-contact areas for electromigration protection, and removed portions in contact areas for low resistance. This localized differentiation resolves the contradiction between miniaturization benefits and electromigration risks.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If portions of the capping layer are removed to reduce contact resistance, then performance is improved, but the structure becomes more complex

Engineering Contradiction:

Improvecontact resistanceVSAvoidinterconnect structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The metallic capping layer serves multiple functions: it provides electromigration protection in covered regions and creates low-resistance contact paths where removed portions expose the metal wire. This multi-functionality reduces the need for separate structures, thereby limiting complexity increase despite the performance improvement.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12199036B2Low resistance interconnect structure for semiconductor device

Publication Date: 2025.01.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure describes an interconnect structure and a method forming the same. The interconnect structure can include a substrate, a layer of conductive material over the substrate, a metallic capping layer over the layer of conductive material, a layer of insulating material over top and side surfaces of the metallic capping layer, and a layer of trench conductor formed in the layer of insulating material and the metallic capping layer.