Ceramic Substrate Cu-Au Layer Structure for Corrosion Resistance
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Solution Overview
Problem
Copper (Cu) wiring in semiconductor devices is prone to corrosion due to moisture in the air, which affects the reliability of the substrate and can be exacerbated by etching processes during manufacturing, and existing methods to protect copper, such as nickel or gold plating, may not adequately address this issue.
Innovation Solution
A ceramic substrate design featuring a Cu layer covered by a seed layer, an intermediate layer, and an Au layer, where the seed layer and intermediate layer contact each other but the Au layer does not contact the ceramic plate, with the seed layer's edge positioned outside the Cu layer's edge, and a manufacturing process involving resist layers and electrolytic plating to form these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If copper is used for wiring lines due to its high conductivity, then electrical conductivity is improved, but corrosion resistance deteriorates because copper is easily corroded by moisture in the air
Solution Approach 1:
The patent introduces an intermediate layer between the Cu layer and the Au layer to prevent direct contact between copper and gold. This intermediate layer acts as a mediator that blocks the electrochemical reaction that would otherwise occur between Cu and Au, thereby preventing corrosion of the copper wiring while maintaining its high conductivity. The intermediate layer is specifically designed to be in contact with both the Cu layer and the Au layer, creating a protective barrier that eliminates the harmful interaction between these two metals.
2Reliability
If nickel or gold plating is applied to protect copper from corrosion, then corrosion resistance is improved, but the complexity of the manufacturing process increases and may not adequately address the corrosion issue
Solution Approach 1:
The patent divides the protective structure into multiple distinct layers: a seed layer, a Cu layer, an intermediate layer, and an Au layer. Each layer serves a specific function - the seed layer provides initial adhesion, the Cu layer provides conductivity, the intermediate layer prevents corrosion by blocking direct contact between Cu and Au, and the Au layer provides environmental protection. This segmented approach allows for optimized manufacturing of each layer while achieving comprehensive corrosion protection.
Solution Approach 2:
The patent applies different materials with specific properties to different locations and functions within the wiring structure. The intermediate layer is strategically positioned only where needed - between the Cu layer and Au layer - to provide localized corrosion protection. The edge portion of the seed layer extends beyond the Cu layer to provide additional protective coverage at critical areas. This local quality approach ensures that each material is used where it provides the most benefit, optimizing both protection and manufacturing efficiency.
3Stability of the object's composition
If the Au layer is arranged to contact the ceramic plate, then structural stability is improved, but the corrosion protection of the Cu layer is compromised due to potential direct contact between Cu and Au
Solution Approach 1:
The intermediate layer serves as a crucial mediator that allows the Au layer to contact the ceramic plate for structural stability while preventing direct contact between the Au layer and the Cu layer. This intermediate layer is in contact with both the Cu layer and the Au layer, creating a protective barrier that eliminates the harmful electrochemical interaction between copper and gold, thereby maintaining both structural stability and corrosion protection.
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 configuration effectively suppresses copper corrosion, enhancing the reliability and longevity of the ceramic substrate by isolating the Cu layer from environmental exposure and ensuring robust connections with light-emitting elements.
Implementation Method 1
arranging, by electrolytic plating, a Cu layer on the upper surface of the seed layer exposed from the second resist layer having been exposed to light and developed
Data Source
AI summary
A ceramic substrate including a ceramic plate, a seed layer arranged on an upper surface of the ceramic plate, a Cu layer arranged on an upper surface of the seed layer, an intermediate layer of one or more layers arranged on an upper surface of the Cu layer and a lateral surface of the Cu layer, and an Au layer arranged on an upper surface of the intermediate layer and a lateral surface of the intermediate layer. The upper surface of the seed layer and the intermediate layer contact each other. The upper surface of the ceramic plate and the Au layer do not contact each other. An edge portion of the upper surface of the seed layer is located outside an edge portion of a lower surface of the Cu layer in a horizontal direction.