Redistribution Layer Protection for IC Testing

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Solution Overview

Problem

The existing manufacturing processes for integrated circuits face challenges in preventing corrosion and oxidation of copper surfaces during electrical testing and packaging, leading to degradation and potential detachment of protection layers, which affects the reliability and stability of the redistribution layer.

Innovation Solution

A method involving a thin protection layer made of insulating materials like Aluminum or Hafnium, deposited using atomic layer deposition, is applied to cover the conductive region, preventing oxidation and corrosion, and allowing for reliable electrical testing at various temperatures without exposing the copper surface, thus ensuring the integrity of the redistribution layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the copper surface is exposed during electrical testing, then electrical testing can be performed, but corrosion and oxidation occur leading to degradation and potential detachment of protection layers

Engineering Contradiction:

Improvereliability of electrical testingVSAvoidcorrosion and oxidation of copper surface

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A thin protection layer is deposited on the copper surface before electrical testing to prevent corrosion and oxidation. This preliminary protective action ensures the copper surface remains protected throughout the testing process, eliminating the need to expose the copper surface while maintaining testing capability through the protection layer

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A thin protection layer made of insulating materials (Aluminum, Hafnium, or their oxides/nitrides) is introduced as an intermediary between the copper surface and the external environment. This intermediate layer allows electrical testing to proceed while preventing direct contact between copper and corrosive/oxidizing agents, thus resolving the contradiction between testing access and corrosion prevention

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a thick protection layer is used to prevent corrosion, then corrosion protection is improved, but delamination and detachment of the protection layer occur

Engineering Contradiction:

Improveprotection against corrosionVSAvoidadhesion of protection layer

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The thickness of the protection layer is optimized to a specific range (1 nm to 100 nm, preferably 5 nm to 50 nm) to balance corrosion protection and adhesion. This parameter optimization ensures the layer is thick enough to provide effective corrosion protection while remaining thin enough to maintain strong adhesion to the copper surface and avoid delamination

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protection layer is applied with locally optimized thickness and material composition tailored to specific regions of the copper surface. This localized approach ensures adequate protection in high-risk areas while maintaining optimal adhesion properties, preventing both corrosion and delamination through region-specific quality control

Inventive Principle:

Principle #3Local quality

3Ease of operation

If the copper surface is exposed for electrical testing, then testing access is enabled, but the redistribution layer stability is compromised

Engineering Contradiction:

Improveaccess for electrical testingVSAvoidstability of redistribution layer

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The protection layer is deposited on the copper surface before electrical testing to maintain redistribution layer stability. This preliminary action ensures the copper surface remains protected throughout testing, enabling stable operation and preventing composition degradation while still allowing testing to proceed through the protection layer

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 solution effectively prevents corrosion and oxidation, enabling reliable electrical testing at high temperatures, reducing delamination risks, and maintaining the stability of the redistribution layer throughout the manufacturing and operational life of the integrated circuit.

Implementation Method 1

Methodology Applied

Scientific EffectAtomic layer deposition: Chemical Vapour Deposition

Data Source

PatentUS20230187389A1Method of manufacturing a redistribution layer, redistribution layer, integrated circuit and methods for electrically testing and protecting the integrated circuit

Publication Date: 2023.06.15 STMICROELECTRONICS SRL

AI summary

To manufacture a redistribution layer for an integrated circuit, a first insulating layer is formed on a conductive interconnection layer of a wafer. A conductive body is then formed in electrical contact with the interconnection layer. The conductive body is then covered with an insulating region having an aperture that exposes a surface of the conductive body. The surface of the conductive body and the insulating region are then covered with an insulating protection layer having a thickness less than 100 nm. This insulating protection layer is configured to provide a protection against oxidation and/or corrosion of the conductive body.