Layer Acoustic Wave Device Without Bonding
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Solution Overview
Problem
Surface acoustic wave (SAW) devices are bulky and expensive due to the need for cavities and complex bonding processes, which also lead to elastic wave leakage, increasing manufacturing complexity and cost.
Innovation Solution
A layer acoustic wave device is developed without requiring a bonding process, using a substrate with interdigital transducers, a dielectric layer, and isolation layers with varying acoustic impedances to minimize wave leakage and eliminate the need for separate substrates and mechanical bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cavity is created in SAW devices to maintain free space on the piezoelectric substrate surface, then elastic wave propagation is enabled, but the device becomes bulky and expensive to manufacture
Solution Approach 1:
The patent combines the substrate and the acoustic waveguide layer into a single integrated structure. The piezoelectric substrate serves dual functions as both the mechanical support and the acoustic waveguide medium, eliminating the need for separate cavity structures and reducing overall device volume while maintaining elastic wave propagation capability.
Solution Approach 2:
The patent transitions from a three-dimensional cavity structure to a two-dimensional planar waveguide structure. By confining elastic waves to propagate along the surface of the piezoelectric substrate rather than requiring a volumetric cavity, the device achieves compact form factor while maintaining functional performance.
2Object-generated harmful factors
If separate substrates are assembled and bonded together to form boundary wave device, then elastic wave leakage is minimized, but manufacturing complexity and expense increase
Solution Approach 1:
The patent extracts the acoustic waveguide function from a separate bonded substrate structure and integrates it directly into the piezoelectric substrate through a deposited dielectric layer. This eliminates the need for complex multi-substrate assembly and bonding processes while maintaining effective confinement of elastic waves and minimizing leakage.
Solution Approach 2:
The patent introduces a dielectric layer as an intermediary structure deposited on the piezoelectric substrate. This dielectric layer serves as the acoustic waveguide medium that confines elastic waves, replacing the need for bonded substrate interfaces and simplifying the manufacturing process while effectively minimizing wave leakage.
3Reliability
If bonding process is used to attach secondary substrate, then proper wave boundary is formed, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces the mechanical bonding process with a deposition process. Instead of mechanically assembling and bonding separate substrates, the acoustic waveguide structure is formed by depositing a dielectric layer onto the piezoelectric substrate, which is a simpler, more integrated manufacturing approach that achieves the same wave boundary formation function.
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 effectively minimizes particle displacement and wave leakage, reducing manufacturing complexity and cost while maintaining efficient acoustic wave propagation, thus addressing the bulkiness and expense issues of traditional SAW devices.
Implementation Method 1
The at least one isolation layer has sufficient properties to minimize particle displacement on the top surface of the at least one isolation layer. The at least one isolation layer has a greater acoustic impedance than that of the dielectric layer.
Implementation Method 2
The elastic waves are created upon exciting an interdigital transducer (IDT) by electrical signals
Data Source
AI summary
The present invention provides a layer acoustic wave device that is formed without requiring a bonding process to attach a secondary substrate. In particular, the layer acoustic wave device is formed from a substrate, an interdigital transducer created on the substrate, a dielectric layer formed over the interdigital transducer and substrate, and at least one isolation layer formed over the dielectric layer. The at least one isolation layer has sufficient properties to minimize particle displacement on a top surface of the at least one isolation layer. The at least one isolation layer has a greater acoustic impedance than that of the dielectric layer.