Acoustic Wave Filter Layout With Etched Isolation Between IDTs
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Solution Overview
Problem
Existing acoustic wave devices face challenges in minimizing acoustic coupling between interdigital transducers (IDTs) due to physical layout constraints, which can degrade filter performance and rejection capabilities.
Innovation Solution
Incorporating acoustic obstruction structures, such as physical separations and acoustic obstacles, within the piezoelectric layer to prevent unwanted acoustic coupling between IDTs, including etched regions and polymer walls to reduce acoustic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If physical layout constraints are applied to arrange IDTs, then device area is reduced, but acoustic coupling between IDTs increases degrading filter performance
Solution Approach 1:
An acoustic obstacle structure is introduced as an intermediary element between the first and second IDTs. This obstacle acts as a mediator that blocks acoustic wave propagation from one IDT to the other, preventing harmful acoustic coupling while allowing the IDTs to be positioned closer together, thus reducing device area without compromising filter performance.
2Area of stationary object
If physical layout constraints are applied to arrange IDTs, then device area is reduced, but rejection capabilities are degraded
Solution Approach 1:
The acoustic obstacle serves as a barrier that prevents acoustic waves from coupling between IDTs, thereby maintaining the device's rejection capabilities against unwanted signals and interference even when IDTs are positioned in a compact layout.
3Reliability
If acoustic obstruction structures are added, then acoustic coupling is reduced, but device complexity increases
Solution Approach 1:
The acoustic obstacle's position, size, and shape are optimized as adjustable parameters to achieve effective acoustic coupling reduction with minimal added complexity. By tuning these geometric parameters, the obstacle provides the necessary acoustic isolation while maintaining a simple overall device structure.
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
Enhances filter performance by reducing unwanted acoustic coupling, improving rejection capabilities, and allowing for more flexible physical layouts without increasing filter size.
Implementation Method 1
a piezoelectric layer that includes a first portion over the first substrate portion and a second portion over the second substrate portion
Implementation Method 2
The acoustic obstacle can include a polymer
Data Source
AI summary
A method of forming an acoustic wave device is disclosed. The method can include providing a structure having a support substrate that includes a first substrate portion, a second substrate portion, and a third substrate portion between the first portion and the second portion, a piezoelectric layer that includes a first portion over the first substrate portion and a second portion over the second substrate portion, a first interdigital transducer electrode on the first portion of the piezoelectric layer, and a second interdigital transducer electrode on the second portion of the piezoelectric layer. the method can also include etching at least a portion of the piezoelectric layer such that a region over the third substrate portion is free from the piezoelectric layer.