Wiring Substrate Direct Copper Bonding for Delamination Prevention
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Solution Overview
Problem
In multi-layer wiring substrates, such as interposers, the adhesion between copper wiring layers and electrode layers is compromised due to differences in thermal expansion coefficients, leading to delamination and unreliable electrical connections when subjected to thermal loads.
Innovation Solution
The use of a titanium adhesive layer between the oxide insulating layer and the copper wiring layer is eliminated, and instead, the copper wiring layer is directly stacked on the through electrode, ensuring high adhesion between the copper layers and maintaining adhesion between the oxide layer and the titanium layer, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a titanium adhesive layer is formed between the wiring layer and electrode layer to improve adhesion, then the adhesion property between layers is improved, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent removes the titanium adhesive layer from the structure, extracting the problematic intermediate layer that caused delamination. The wiring layer is made to contact directly with the electrode layer, eliminating the source of thermal expansion mismatch while maintaining electrical connectivity and adhesion through direct copper-to-copper bonding.
Solution Approach 2:
The patent merges the functions of the wiring layer and electrode layer by allowing direct contact between them. Instead of having separate adhesive and conductive layers, the copper wiring layer serves both structural and electrical functions by directly bonding to the copper electrode layer, simplifying the overall structure.
2Strength
If a titanium adhesive layer is formed between the wiring layer and electrode layer to improve adhesion, then the adhesion property between layers is improved, but the manufacturing steps and time increase
Solution Approach 1:
The titanium adhesive layer formation steps are completely removed from the manufacturing process. This eliminates the sputtering or deposition processes required for titanium layers, as well as the associated cleaning and preparation steps, significantly reducing manufacturing time and process complexity.
Solution Approach 2:
The patent discards the titanium adhesive layer approach entirely in favor of direct copper bonding. This eliminates the need to manufacture, handle, and process the titanium layer, recovering manufacturing time and simplifying the production workflow.
3Strength
If an adhesive layer is formed between the wiring layer and insulating layer to improve adhesion, then the adhesion property is improved, but the device complexity increases
Solution Approach 1:
The patent applies different adhesion strategies to different interfaces: direct copper bonding at the wiring-electrode interface where electrical connectivity is needed, and titanium adhesive layers only where mechanical support is needed (between wiring and insulating layers). This localized approach optimizes both electrical and mechanical properties while managing complexity.
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 ensures reliable electrical connections between the electrode and wiring layers while maintaining adhesion properties, preventing delamination and ensuring consistent performance under thermal loads.
Implementation Method 1
thermal oxidation is performed to form an oxide layer 15 on the outer surface of a silicon substrate 10 and the inner wall surface of a through hole 13
Implementation Method 2
a titanium layer 17 is formed on a surface of the silicon substrate 10 through sputtering
Implementation Method 3
a copper layer 18 is formed on the titanium layer 17 through sputtering
Implementation Method 4
the wiring pattern 11 is formed on the copper layer 18 through electrolytic copper plating
Data Source
AI summary
A wiring substrate includes a wiring layer made of copper, an electrode layer made of copper, and an insulating layer arranged adjacent to the electrode layer. The wiring layer is stacked on the electrode layer and the insulating layer. The insulating layer and the wiring layer are stacked with an adhesive layer interposed between the wiring insulating layer and the wiring layer. The electrode layer and the wiring layer are stacked without the adhesive layer interposed between the electrode layer and the wiring layer.