Copper Fuse Target Formation with Adhesion Layer

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Solution Overview

Problem

Current-generation processes for forming copper-topped interconnect structures are not compatible with aluminum fuse targets, as the chemistry used to remove unused seed layer regions damages the aluminum fuse targets, rendering them undetectable by optical recognition systems and preventing fuse programming.

Innovation Solution

A method of forming a copper-based fuse target that involves depositing a seed layer with titanium and copper, followed by electroplating copper traces and targets, and using an adhesion enhancing layer with a metallic layer that includes aluminum, allowing the fuse target to be electrically isolated and compatible with copper fabrication processes, eliminating the need for a stacked metal ring structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If aluminum fuse targets are used in copper fabrication processes, then the fuse target material is compatible with traditional aluminum interconnect structures, but the chemistry used to remove unused seed layer regions damages the aluminum fuse targets, rendering them undetectable by optical recognition systems

Engineering Contradiction:

Improvecompatibility with traditional aluminum interconnect structuresVSAvoiddetectability by optical recognition systems

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A tungsten-based stacked metal ring structure is introduced as an intermediary protective element surrounding the aluminum fuse target. This structure acts as a barrier that prevents the seed layer removal chemistry from damaging the aluminum fuse target, while allowing the optical recognition system to still detect the fuse target through or around the protective rings.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies a protective coating or protective structure formation before the seed layer removal process. This protective layer is applied in advance to cushion or protect the aluminum fuse target from the harmful chemistry used to remove unused seed layer regions, preventing damage before it occurs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If a stacked metal ring structure is used to protect the aluminum fuse target, then the fuse target is protected from damage during seed layer removal, but the device complexity increases and space for other metal interconnects is reduced

Engineering Contradiction:

Improveprotection from damage during seed layer removalVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The stacked metal ring structure is designed to serve multiple functions: it protects the aluminum fuse target from damage during seed layer removal, provides a defined geometric pattern for optical recognition, and maintains electrical isolation. By combining multiple functions into a single structure, the overall device complexity is reduced despite the added protective functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a stacked metal ring structure is used to protect the aluminum fuse target, then the fuse target is protected from damage during seed layer removal, but the area available for other metal interconnects is reduced

Engineering Contradiction:

Improveprotection from damage during seed layer removalVSAvoidspace for other metal interconnects

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The protective structure is segmented into multiple thin metal rings stacked at different heights rather than a single solid structure. This segmentation allows the protective function to be distributed across multiple layers, reducing the lateral footprint and freeing up space for other metal interconnects while maintaining protection during the seed layer removal process.

Inventive Principle:

Principle #1Segmentation

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 method enables the formation of a fuse target that remains detectable by optical recognition systems, allowing for accurate programming of fuses, even in copper-topped interconnect structures, and increases space for other metal interconnects by eliminating the need for a stacked metal ring structure.

Implementation Method 1

depositing a seed layer with titanium and copper

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

electroplating copper traces and targets

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS7964934B1Fuse target and method of forming the fuse target in a copper process flow

Publication Date: 2011.06.21 NAT SEMICON CORP

AI summary

A fuse target is fabricated in a copper process by forming a number of copper targets at the same time that the copper traces are formed. After the copper targets and the copper traces have been formed, metal targets, such as aluminum targets, are formed on the copper targets at the same time that metal bonding pads, such as aluminum bonding pads, are formed on the copper traces.