Selective Etching of Silver Seed Layer for Copper Circuit Integrity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional methods for forming circuits using seed layers face challenges such as poor adhesion, migration issues, and damage to the circuit during the removal of the seed layer, particularly in coreless substrate manufacturing, where the seed layer and circuit are made of the same material, making it difficult to selectively remove the seed layer without damaging the circuit.

Innovation Solution

A method involving the use of a seed layer made of silver and a conductive material like copper, where a selective etching solution is employed to dissolve only the silver seed layer, allowing for its removal without damaging the copper circuit pattern, and the application of a semi-additive process (SAP) to achieve high-density, thin-film circuits on coreless substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the seed layer is physically removed, then the seed layer can be eliminated, but the circuit is damaged causing defects

Engineering Contradiction:

Improveseed layer removalVSAvoidcircuit integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the mechanical removal method (physical scraping or peeling) with a chemical etching method using a selectively formulated etching solution. This chemical approach dissolves the seed layer through chemical reaction rather than mechanical force, thereby preventing physical damage to the adjacent circuit patterns while achieving complete seed layer removal.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a specially formulated etching solution as an intermediary substance that selectively reacts with the seed layer material. This intermediary enables the separation and removal of the seed layer from the circuit structure without requiring direct mechanical contact that would damage the circuit, thus mediating between the need for seed layer elimination and circuit protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If etching or chemical method is used to remove the seed layer and conductive pattern, then the removal process can be achieved, but both are damaged because they are made of one material

Engineering Contradiction:

Improveseed layer removal processVSAvoidselective removal accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies the local quality principle by formulating an etching solution with selective chemical properties that react only with specific components (the seed layer) while leaving other materials (the conductive pattern) unaffected. This localized chemical reactivity enables precise differentiation and selective removal of the seed layer despite both being metallic materials, achieving high manufacturing precision in the removal process.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes parameter changes by adjusting the chemical composition, concentration, and formulation parameters of the etching solution to achieve selective reactivity. By optimizing these chemical parameters, the etching solution is tuned to react with the seed layer material at a different rate or extent compared to the conductive pattern material, enabling selective removal while preserving the circuit integrity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional etching solution is used, then etching can be performed, but not only silver but also other metals, metal alloy or metal compound is etched, damaging metal circuit layer

Engineering Contradiction:

Improveetching speedVSAvoidcircuit layer damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful non-selective etching action of conventional solutions into a beneficial selective process. By reformulating the etching solution with specific chemical additives and adjusting its composition, the solution's reactivity is directed specifically toward the seed layer material while its harmful effect on the conductive pattern is eliminated. This transforms a harmful non-selective etching process into a beneficial selective removal process that protects the circuit layer.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach enables the formation of circuits with improved adhesion, reduced migration, and minimized damage during the seed layer removal process, resulting in higher yield and finer pitch capabilities while maintaining the integrity of the metal circuit layer.

Implementation Method 1

a selective etching solution is employed to dissolve only the silver seed layer, allowing for its removal without damaging the copper circuit pattern

Methodology Applied

Scientific EffectSelective etching: Chemical Bonding

Data Source

PatentUS11317514B2Method for forming circuits using seed layer and etchant composition for selective etching of seed layer

Publication Date: 2022.04.26 INKTEC CO LTD

AI summary

The present invention relates to a method for forming a circuit using a seed layer. The method for forming a circuit using a seed layer according to the present invention, may realize a fine pitch, increase the adhesion of the circuit, and prevent the migration phenomenon.