Acoustic Wave Electrode Layout for Substrate Defect Inspection
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Solution Overview
Problem
Existing acoustic wave devices face defects in substrates, leading to decreased production efficiency and reliability due to the difficulty in identifying defective substrates during manufacturing.
Innovation Solution
Incorporating a piezoelectric substrate with a first electrode layer that overlaps the crossing region of the IDT electrode and non-formation regions between electrode fingers, allowing for easy visual inspection of defects through transparent layers, and enhancing electrostatic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is formed on a rigid substrate with Zno layer and IDT, then the acoustic wave device can be constructed, but substrate defects cannot be easily identified leading to decreased production efficiency
Solution Approach 1:
The patent applies transparency changes to the substrate structure. The rigid substrate is designed to be transparent or translucent in specific wavelength ranges, allowing visual inspection of defects. This enables operators to see through the substrate to detect flaws, cracks, or contamination that would otherwise be hidden, thereby improving reliability without sacrificing production efficiency
Solution Approach 2:
The patent introduces an intermediate transparent layer between the rigid substrate and the piezoelectric layer. This intermediate layer serves as a mediator that maintains structural integrity while allowing optical transmission for defect detection. The transparent layer acts as a window through which substrate defects can be visually inspected without compromising the functional layers
2Volume of moving object
If the device size is reduced, then smaller devices can be manufactured, but maintaining desirable electrostatic capacitance becomes difficult
Solution Approach 1:
The patent employs composite material structures with multiple layers having different dielectric properties. By combining materials with high dielectric constants in strategic locations, the design achieves enhanced electrostatic capacitance density. This allows the device to maintain desirable capacitance values even when the overall device volume is reduced
Solution Approach 2:
The patent uses transparent electrode layers that serve dual functions: they maintain electrical functionality while allowing optical transmission. The electrode structure is designed with transparency in mind, enabling defect detection through the electrode layer itself, thus eliminating the need for separate inspection windows and reducing overall device size
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
Facilitates identification of defective substrates, reduces faults in products, increases production efficiency, and allows for smaller device size with desirable electrostatic capacitance.
Implementation Method 1
a piezoelectric substrate including a piezoelectric layer
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer and a support substrate stacked on a second main surface side of the piezoelectric layer, a first electrode layer between the support substrate and the piezoelectric layer and not connected to a signal potential, and an IDT electrode on a first main surface of the piezoelectric layer and including electrode fingers. A region where adjacent electrode fingers overlap each other is a crossing region. The first electrode layer is provided at a position overlapping the crossing region in plan view. The piezoelectric substrate includes a first formation region overlapping the crossing region and the first electrode layer and a first non-formation region overlapping the crossing region and not overlapping the first electrode layer, and the first non-formation region overlaps a portion between the adjacent electrode fingers.