Acoustic Wave Reflector Layout to Prevent Resist Residue
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Solution Overview
Problem
Acoustic wave devices face issues with resist residue remaining on reflectors during manufacturing, leading to potential impedance characteristic deterioration.
Innovation Solution
The acoustic wave device design includes a piezoelectric layer with interdigital transducer electrodes and reflectors, featuring specific busbar and electrode finger configurations that prevent resist residues from forming, ensuring the impedance characteristics are maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the reflector is formed by the lift-off method, then the manufacturing process is simplified, but resist residues remain on the reflector surface
Solution Approach 1:
The reflector is divided into multiple segments: a first reflector portion and a second reflector portion formed at different stages. This segmentation allows the resist removal process to be separated from the reflector formation process, enabling complete resist removal while maintaining the reflector's functionality.
Solution Approach 2:
The first reflector portion is formed preliminarily before the interdigital transducer electrode, allowing resist to be completely removed. Subsequently, the second reflector portion is formed to complete the reflector structure. This preliminary action ensures no resist residues remain on the final reflector surface.
2Speed
If the busbar includes cavities surrounded by inner busbar, outer busbar, and connection electrodes, then the acoustic velocity distribution is improved, but the manufacturing complexity increases
Solution Approach 1:
The busbar structure incorporates cavities with specific acoustic velocity characteristics in localized regions. The inner busbar, outer busbar, and connection electrodes create distinct zones with different acoustic velocities, optimizing the overall acoustic performance while maintaining a manageable manufacturing process.
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 configuration effectively prevents resist residues from forming, thereby maintaining the impedance characteristics and reducing the risk of failures such as ripples in the acoustic wave device.
Implementation Method 1
an acoustic wave device includes a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate, an interdigital transducer electrode on the piezoelectric substrate, and reflectors. The interdigital transducer electrode includes first and second busbars including first and second cavities in a first direction, and first and second edge regions and first and second gap regions. The first and second edge regions include low acoustic velocity regions. Regions in which the first and second cavities are provided include high acoustic velocity regions. The reflector includes first and second reflector busbars and first reflection electrode fingers each including a second end portion that faces the second reflector busbar. The first reflection electrode fingers overlap the entire or substantially the entire second gap region when viewed in the first direction.