Wiring Substrate Via Seed Layer Adsorption for Copper Filling

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Solution Overview

Problem

The thinning of wiring layers in wiring substrates leads to insufficient copper filling in via holes, resulting in defective connections between vias and wiring layers, which affects the reliability of the electrical connections.

Innovation Solution

A wiring substrate design that includes a via seed layer formed on the wall surface of the insulation layer and a wiring seed layer on the upper surface, where the via seed layer is made from copper to adsorb a plating enhancement agent, enhancing the electrolytic plating process to fill the via holes with copper, while the wiring seed layer, made from nickel, does not adsorb the agent, allowing for efficient deposition of copper without interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If wiring layers are made thinner to achieve finer wiring patterns, then wiring density is improved, but copper filling in via holes becomes insufficient leading to defective connections

Engineering Contradiction:

Improvewiring pattern finenessVSAvoidvia connection reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies local quality by using different seed layer materials in different locations: copper-based seed layers in via holes that adsorb plating enhancement agents to ensure complete copper filling, and nickel-based seed layers on wiring patterns that do not adsorb the agents for efficient copper deposition. This localized material differentiation resolves the contradiction by ensuring via holes receive enhanced copper filling while maintaining fine wiring pattern quality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces plating enhancement agents as intermediaries that mediate between the electrolytic plating solution and the seed layers. These agents selectively adsorb on copper-based seed layers to enhance copper deposition in via holes, while being repelled by nickel-based seed layers. This intermediary substance enables differentiated plating behavior that simultaneously achieves reliable via connections and fine wiring patterns.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If via holes are filled with copper to ensure electrical connection, then connection reliability is improved, but insufficient copper filling occurs when wiring layers are thin

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidcopper filling amount

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by forming copper-based via seed layers before the electrolytic plating process. These seed layers serve as pre-prepared surfaces that actively adsorb plating enhancement agents, ensuring that when copper plating occurs, the via holes receive sufficient copper filling. This preliminary preparation resolves the contradiction by guaranteeing adequate copper quantity in via holes even when wiring layers are thin.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes parameter changes by selecting specific metal materials (copper-based vs. nickel-based) for different seed layers, which fundamentally changes the surface properties and adsorption characteristics. This material parameter change enables the via seed layers to adsorb plating enhancement agents while wiring pattern seed layers do not, thereby controlling copper filling distribution to ensure reliability without excessive copper usage.

Inventive Principle:

Principle #35Parameter changes

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 ensures complete filling of via holes with copper, forming reliable connections and enabling the creation of finer wiring patterns by preventing copper deficiency and ensuring consistent electrical connectivity.

Implementation Method 1

The via seed layer is formed from a metal material that acts to adsorb a plating enhancement agent, which enhances formation of the filled portion and the pattern layer in an electrolytic plating solution

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

The filled portion is formed in the via hole in which the via seed layer is formed. The via hole is filled with the filled portion... forming the filled portion and the pattern layer in an electrolytic plating solution

Methodology Applied

Scientific EffectElectrolytic plating: Electroplating

Data Source

PatentUS9814138B2Wiring substrate

Publication Date: 2017.11.07 SHINKO ELECTRIC IND CO LTD

AI summary

A wiring substrate includes a first insulation layer covering a first wiring layer, a wiring pattern formed on an upper surface of the first insulation layer, and a via formed in a via hole of the first insulation layer to electrically connect the wiring pattern and the first wiring layer. The via includes a via seed layer and a filled portion filling the via hole. The wiring pattern includes a wiring seed layer formed on the upper surface of the first insulation layer and a pattern layer formed on the wiring seed layer. The via seed layer is formed from a metal acting to adsorb a plating enhancement agent, which enhances formation of the filled portion and the pattern layer in an electrolytic plating solution. The wiring seed layer is formed from a metal not acting to adsorb the plating enhancement agent as compared to the via seed layer.