AlN-Cu Wiring Substrate Interlayer for High-Adhesion Reliability
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Solution Overview
Problem
Existing wiring substrates face challenges in achieving high adhesive strength between insulating substrates and conductor layers due to differences in thermal expansion coefficients and contamination from carbon, leading to reduced reliability in electronic devices and modules.
Innovation Solution
A wiring substrate with an insulating substrate containing AlN and a conductor layer of Cu, featuring an interlayer with graded concentrations of Al, N, and Cu, and scattered TiO2 regions, which promotes counter diffusion and gentle thermal expansion gradients, enhancing adhesive strength through sintering under specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a barrier metal layer is used between the insulating substrate and conductor layer, then adhesion is improved, but thermal expansion stress and carbon contamination reduce reliability
Solution Approach 1:
The patent changes the compositional parameters of the interlayer by creating a gradient structure where Al and N concentrations decrease from the insulating substrate side toward the conductor layer side. This parameter gradient allows the interlayer to simultaneously provide strong adhesion to both substrates while accommodating thermal expansion differences and preventing carbon contamination, thereby resolving the contradiction between adhesion strength and device reliability
Solution Approach 2:
The patent applies local quality by creating regions with different compositions within the interlayer. The first region near the insulating substrate has high Al and N concentrations for strong bonding, while the second region near the conductor layer has lower Al and N concentrations to reduce thermal expansion stress and prevent carbon contamination. This spatial variation in material properties resolves the contradiction between adhesion and reliability
2Reliability
If AlN insulating substrate is used with Cu conductor layer, then electrical performance is improved, but thermal expansion coefficient mismatch reduces adhesion
Solution Approach 1:
The patent uses parameter changes by creating a compositional gradient in the interlayer where the concentration of Al and N decreases from the insulating substrate side toward the conductor layer side. This gradient structure allows the interlayer to provide strong adhesion to the AlN substrate while having reduced Al content near the Cu layer to minimize thermal expansion mismatch, thereby maintaining both electrical performance and adhesive strength
Solution Approach 2:
The patent employs composite materials by creating an interlayer that is a gradient composite of Al, N, and Cu. This composite structure combines the benefits of AlN (strong adhesion to insulating substrate) with Cu (compatibility with conductor layer), while the gradient transition between compositions reduces thermal expansion stress and maintains overall adhesion strength
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 significantly improves adhesive strength between the insulating substrate and conductor layer, reducing stress concentrations and increasing the reliability of electronic devices and modules by maintaining low carbon concentrations and promoting gentle thermal expansion gradients.
Implementation Method 1
Cu concentration is higher in the second region than in the first region, and Al concentration is higher in the first region than in the second region
Implementation Method 2
promotes gentle thermal expansion gradients, enhancing adhesive strength through sintering
Implementation Method 3
enhancing adhesive strength through sintering under specific conditions
Data Source
AI summary
A wiring substrate includes an insulating substrate, a conductor layer and an interlayer. The insulating substrate contains AlN. The conductor layer contains Cu. The interlayer is located between the insulating substrate and the conductor layer. In the interlayer, between a first region near the insulating substrate and a second region near the conductor layer, Cu concentration is higher in the second region than in the first region, and Al concentration is higher in the first region than in the second region.