Acoustic Wave IDT Electrode Structure for Delamination Resistance
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Solution Overview
Problem
Acoustic wave devices are prone to separation between interdigital transducer (IDT) electrodes and the slow-wave propagation layers due to external forces or thermal stress, leading to failure in achieving intended electric characteristics.
Innovation Solution
The acoustic wave device incorporates a support board with an intermediate layer and a piezoelectric layer, where the first IDT electrode is embedded in the intermediate layer with electrode fingers having side surfaces with different angles of inclination, enhancing the contact area and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IDT electrode is placed on the slow-wave propagation layer, then the acoustic wave device can achieve intended electric characteristics, but the IDT electrode and the slow-wave propagation layer are more likely to separate when external force or thermal stress is applied
Solution Approach 1:
The side surface of the IDT electrode is formed with an inclined surface that curves or slopes gradually rather than being perpendicular. This inclined configuration increases the contact area between the IDT electrode and the intermediate layer, distributing mechanical stress more evenly and preventing sudden separation under external force or thermal stress, thereby improving adhesion reliability
Solution Approach 2:
The IDT electrode transitions from a simple planar structure to a three-dimensional structure with an inclined side surface. This dimensional change adds a slope component that enhances mechanical interlocking with the intermediate layer, preventing separation without requiring additional adhesive materials or complex multi-layer structures
2Reliability
If the IDT electrode is embedded in the intermediate layer, then the contact area is increased, but the manufacturing complexity increases due to the need for precise embedding structure
Solution Approach 1:
Only the side surface of the IDT electrode is formed with an inclined surface, while the top and bottom surfaces maintain their original planar configuration. This localized modification increases contact area where needed (at the sides interfacing with the intermediate layer) without complicating the overall electrode structure or affecting the interdigital transistor's electrical functionality
Solution Approach 2:
The inclination angle of the side surface is optimized to balance adhesion improvement and manufacturing feasibility. By adjusting this geometric parameter, the design achieves enhanced contact area and stress distribution without requiring excessively complex embedding structures or multi-step fabrication processes
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 separation between the IDT electrode and the intermediate layer, thereby maintaining the desired electric characteristics of the acoustic wave device.
Implementation Method 1
a piezoelectric layer on the intermediate layer
Implementation Method 2
a first IDT electrode at the first main surface of the piezoelectric layer, and embedded in the intermediate layer, and a second IDT electrode at the second main surface of the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes a support board, an intermediate layer on the support board, a piezoelectric layer on the intermediate layer, and including first and second main surfaces, a first IDT electrode at the first main surface, and embedded in the intermediate layer, and a second IDT electrode at the second main surface. The first IDT electrode includes electrode fingers each including first and second surfaces opposed to each other in a thickness direction of the electrode fingers, and a side surface connected to the first and second surfaces. The side surface of each of the electrode fingers includes first and second portions, and in at least one of the electrode fingers, the first and second portions have different angles of inclination with respect to the thickness direction.