Copper Connector Bonding via Tin Solder Alloying

Solution Overview

Problem

Copper connectors, despite their superior electrical properties and cost-effectiveness, are susceptible to oxidation and require high temperatures and pressures during bonding, which can damage semiconductor chips and necessitate additional costly inert gas purging steps in ball bonding processes.

Innovation Solution

The use of tin solder to alloy with copper connectors, forming a bronze surface that resists oxidation and allows for electrical connection at lower temperatures and pressures without ultrasonic energy, minimizing chip damage and eliminating the need for inert gas purging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If copper connectors are used for bonding to semiconductor chips, then electrical properties and cost-effectiveness are improved, but high temperatures and pressures during bonding can damage the chip

Engineering Contradiction:

Improveelectrical propertiesVSAvoidchip damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary material (such as a nickel or palladium layer) between the copper connector and the semiconductor chip. This intermediate layer acts as a buffer that reduces the direct thermal and mechanical stress from copper bonding, protecting the chip from damage while maintaining the electrical benefits of copper connectors.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs composite material structures where copper connectors are combined with protective coating layers (such as nickel, palladium, or other barrier materials). This composite approach allows the copper to provide superior electrical conductivity while the outer layers protect the chip from the harsh bonding conditions and prevent oxidation.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If copper connectors are used for bonding, then cost-effectiveness is improved, but copper is highly susceptible to oxidation requiring additional inert gas purging steps

Engineering Contradiction:

Improvecost-effectivenessVSAvoidprocess complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent uses composite material structures where copper connectors are combined with protective coating layers (such as nickel, palladium, or other barrier materials). This composite approach allows the copper to provide superior electrical conductivity while the outer layers protect the chip from the harsh bonding conditions and prevent oxidation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs thin protective coating layers on copper connectors that serve as sacrificial barriers against oxidation. These thin protective layers are cost-effective to apply and prevent the expensive inert gas purging steps while maintaining the cost advantages of copper connectors.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Strength

If high force is applied during copper connector bonding, then connection strength is improved, but chip damage increases

Engineering Contradiction:

Improveconnection strengthVSAvoidchip damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary material (such as a nickel or palladium layer) between the copper connector and the semiconductor chip. This intermediate layer acts as a buffer that reduces the direct thermal and mechanical stress from copper bonding, protecting the chip from damage while maintaining the electrical benefits of copper connectors.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs composite material structures where copper connectors are combined with protective coating layers (such as nickel, palladium, or other barrier materials). This composite approach allows the copper to provide superior electrical conductivity while the outer layers protect the chip from the harsh bonding conditions and prevent oxidation.

Inventive Principle:

Principle #40Composite materials

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

Enables reliable copper connector attachment to semiconductor chips at lower temperatures and pressures, reducing chip damage and increasing wafer yield while preventing oxidation, thus improving the efficiency and cost-effectiveness of the bonding process.

Implementation Method 1

a solder material configured to couple the copper connector to the contact area

Methodology Applied

Scientific EffectAlloying:

Implementation Method 2

forming a bronze surface that resists oxidation

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Implementation Method 3

allows for electrical connection at lower temperatures and pressures without ultrasonic energy

Methodology Applied

Scientific EffectThermal bonding: Heating

Implementation Method 4

connection at lower temperatures and pressures

Methodology Applied

Scientific EffectPressure bonding: Compression

Data Source

PatentUS7911061B2Semiconductor device

Publication Date: 2011.03.22 INFINEON TECHNOLOGIES AG

AI summary

A semiconductor device includes a carrier, a chip including a first face having a contact area, where the chip is attached to the carrier such that the contact area faces away from the carrier, a copper connector configured for attachment to the contact area, and a solder material configured to couple the copper connector to the contact area.