Semiconductor Bump I/O Contact With Diffusion Barrier

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Solution Overview

Problem

Bump contacts in semiconductor devices experience structural and electrical reliability issues due to current-induced intermetallic compound phase alterations, leading to mechanical brittleness and increased electrical resistance, which can result in premature failure.

Innovation Solution

A control layer, made from materials like nickel (Ni), palladium (Pd), tantalum nitride (TaN), or titanium-tungsten (Ti—W) alloys, is interposed between the conductive pillar and the solder crown to retard the diffusion of copper and tin, preventing the formation of undesirable intermetallic compound phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bump contact is used to electrically connect a contact pad to a conductor, then the electrical distance is reduced and mechanical robustness is improved, but current-induced intermetallic compound phase alterations cause mechanical brittleness and increased electrical resistance

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidintermetallic compound phase stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

A control layer is introduced as an intermediary between the conductive pillar and solder crown to prevent harmful intermetallic compound formation. This control layer acts as a diffusion barrier that mediates the interaction between copper and tin, preventing the formation of brittle intermetallic phases while maintaining electrical connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bump contact structure is designed as a composite material system consisting of multiple layers with different properties: a copper conductive pillar, a control layer made from nickel or palladium, and a solder crown. This composite structure combines the electrical conductivity of copper with the protective properties of the control layer to achieve both electrical performance and structural stability.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If copper and tin are allowed to diffuse freely in the bump contact, then manufacturing is simplified, but undesirable intermetallic compound phases form causing mechanical brittleness

Engineering Contradiction:

Improvebump contact manufacturing simplicityVSAvoidmechanical strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The control layer serves as a diffusion barrier that mediates between copper and tin atoms, preventing their direct interaction and the formation of brittle intermetallic compounds. This intermediary layer allows the manufacturing process to remain simple while preventing harmful material interactions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control layer changes the diffusion parameters at the copper-tin interface by introducing a material with different atomic structure and bonding characteristics. This parameter change prevents the formation of intermetallic phases by blocking the diffusion pathway while maintaining the overall manufacturing process.

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If the bump contact operates for extended periods, then electrical connections are maintained, but intermetallic compound phase alterations lead to premature failure

Engineering Contradiction:

Improveoperational durationVSAvoidlong-term reliability

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The control layer acts as a protective intermediary that prevents harmful chemical reactions between copper and tin during extended operation. By blocking diffusion pathways, it maintains the structural integrity of the bump contact over long operational periods, preventing premature failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control layer is pre-installed during manufacturing to prevent intermetallic compound formation before it can occur during operation. This preliminary protective action ensures long-term reliability by preventing degradation mechanisms from initiating in the first place.

Inventive Principle:

Principle #10Preliminary action

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 control layer significantly reduces the formation of brittle intermetallic phases and maintains the structural and electrical integrity of bump contacts during operation, enhancing the reliability and longevity of semiconductor packages.

Implementation Method 1

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS9368466B2Bump I/O contact for semiconductor device

Publication Date: 2016.06.14 MAXIM INTEGRATED PROD INC

AI summary

A bump contact electrically connects a conductor on a substrate and a contact pad on a semiconductor device mounted to the substrate. The first end of an electrically conductive pillar effects electrical contact and mechanical attachment of the pillar to the contact pad with the pillar projecting outwardly from the semiconductor device. A solder crown reflowable at a predetermined temperature into effecting electrical contact and mechanical attachment with the conductor is positioned in axial alignment with the second end of the pillar. A diffusion barrier electrically and mechanically joins the solder bump to the second end of the pillar and resists electro-migration into the first end of the solder crown of copper from the pillar. One diffusion barrier takes the form of a 2-20 micron thick control layer of nickel, palladium, titanium-tungsten, nickel-vanadium, or tantalum nitride positioned between the pillar and the solder crown.