Copper Plug Via Structure for Electromigration Resistance

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Solution Overview

Problem

Semiconductor devices using aluminum layers face issues with electromigration and structural reliability, which affect the performance and longevity of flip chip joining in semiconductor packages.

Innovation Solution

Replaces the traditional aluminum layer with a copper plug in the insulation layer, accompanied by a barrier layer and a cap layer to protect the copper from oxidation, enhancing the structural integrity and electromigration resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an aluminum layer is used in the wiring structure, then the device can be manufactured with conventional processes, but electromigration issues and structural reliability problems occur

Engineering Contradiction:

Improveelectromigration resistanceVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from aluminum to copper in the plug structure, which fundamentally improves electromigration resistance while maintaining compatibility with conventional semiconductor manufacturing processes through established copper deposition and barrier layer techniques

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure consisting of multiple layers including copper plug, barrier layer, and cap layer. This composite approach combines the high conductivity and electromigration resistance of copper with the protective functions of barrier and cap layers, achieving superior reliability while using standard manufacturing processes

Inventive Principle:

Principle #40Composite materials

2Reliability

If a copper plug is used to improve electromigration resistance, then reliability improves, but additional barrier and cap layers are required to prevent oxidation

Engineering Contradiction:

Improveelectromigration resistanceVSAvoidnumber of layers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces barrier layers and cap layers as intermediary protective structures between the copper plug and the environment. These intermediary layers prevent oxidation of copper while maintaining the electrical and structural integrity of the plug, resolving the contradiction between using copper for reliability and preventing its oxidation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The multi-layer composite structure (barrier layer + copper plug + cap layer) is designed where each layer serves a specific function: barrier layer prevents diffusion, copper provides conductivity and electromigration resistance, and cap layer prevents oxidation. This composite approach achieves superior reliability with manageable complexity through clear functional division

Inventive Principle:

Principle #40Composite materials

3Reliability

If the aluminum layer is replaced with copper plug, then electromigration resistance improves, but protection from oxidation becomes necessary

Engineering Contradiction:

Improvestructural integrityVSAvoidoxidation susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The barrier layer and cap layer act as intermediary protective structures that isolate copper from oxidizing environments. The barrier layer prevents atomic diffusion while the cap layer provides environmental protection, together eliminating oxidation susceptibility while preserving copper's superior structural integrity and electromigration resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The barrier and cap layers create an inert protective environment around the copper plug, preventing exposure to oxygen and other reactive species. This effectively shields the copper from oxidation while allowing copper to provide its full structural and electrical benefits in the wiring structure

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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 copper plug improves the reliability and performance of semiconductor devices by reducing electromigration issues and providing a conductive path for wafer finishing and subsequent metallurgy deposition processes, while preventing damage to underlying copper wiring layers.

Implementation Method 1

a barrier layer formed on the aluminum layer

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

a copper plug formed on the barrier layer and filling the via opening

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

providing a conductive path for wafer finishing and subsequent metallurgy deposition processes, while preventing damage to underlying copper wiring layers

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Data Source

PatentUS8922019B2Semiconductor device having a copper plug

Publication Date: 2014.12.30 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Disclosed is a semiconductor device wherein an insulation layer has a via opening with an aluminum layer in the via opening and in contact with the last wiring layer of the device. There is a barrier layer on the aluminum layer followed by a copper plug which fills the via opening. Also disclosed is a process for making the semiconductor device.