Wiring Electrode Layer Layout to Block Au Diffusion
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Solution Overview
Problem
Wiring electrodes in electronic components face issues with alloy formation due to metal diffusion, leading to increased electric resistance and reliability concerns, particularly when the Au layer from the outermost layer diffuses to the side surfaces of the AlCu layer during the lift-off process.
Innovation Solution
A wiring electrode configuration with a stacked structure including an adhesive layer, a low-resistance layer, and a barrier layer, where the outer peripheral edge of the low-resistance layer is positioned inside the barrier layer, and the adhesive layer's edge is outside the low-resistance layer, preventing metal diffusion and alloy formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer peripheral edge of the low-resistance layer is positioned inside the barrier layer, then alloy formation is prevented, but the adhesive layer edge must be outside the low-resistance layer, increasing structural complexity
Solution Approach 1:
The patent divides the protective function into distinct segments: the barrier layer handles Au migration prevention at the interface between outermost and low-resistance layers, while the adhesive layer handles substrate bonding. The staggered positioning of outer peripheral edges creates spatially separated functional zones, where each layer performs its specific function without interfering with others, managing complexity through functional segmentation.
Solution Approach 2:
The structure creates a nested arrangement where the low-resistance layer is positioned within the horizontal footprint of the barrier layer, which itself is positioned within the footprint of the adhesive layer. This nested configuration ensures that each layer is properly contained and supported while maintaining the necessary edge offsets for their respective functions.
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 reduces or prevents alloy formation between metal layers, thereby improving the reliability and reducing electric resistance of the wiring electrodes.
Implementation Method 1
a barrier layer between the low-resistance layer and the outermost layer
Data Source
AI summary
A wiring electrode on a piezoelectric substrate includes layers including an adhesive layer in contact with the piezoelectric substrate, an outermost layer indirectly above the adhesive layer, a low-resistance layer between the adhesive layer and the outermost layer, including first and second principal surfaces, and having a lowest electric resistance among the layers, and a barrier layer between the low-resistance layer and the outermost layer. An outer peripheral edge of the second principal surface of the low-resistance layer is inside an outer peripheral edge of the barrier layer, and an outer peripheral edge of the adhesive layer is outside an outer peripheral edge of the low-resistance layer, in plan view.