BAW Filter Cavity Layout With Release Holes for Smaller Footprint

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing bulk acoustic wave filters are limited by their size, as they require a larger footprint due to the independent boundary structures for each resonator, which hinders miniaturization and increases parasitic capacitance.

Innovation Solution

The design incorporates a bulk acoustic wave resonator with a polygon-shaped cavity and strategically placed release holes, allowing for shared boundary structures between adjacent resonators, thereby reducing the overall size and minimizing parasitic capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If independent boundary structures are used for each resonator, then structural stability is maintained, but device size increases

Engineering Contradiction:

Improvestructural stabilityVSAvoiddevice size

Core Design Contradiction:

Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

Adjacent resonators share common boundary structures, merging previously independent boundaries into shared structures. This reduces the total boundary material required and decreases the overall device footprint while maintaining the necessary structural stability for each resonator's operation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shared boundary structure serves multiple functions simultaneously: it acts as a boundary for both adjacent resonators and provides structural support for both. This multi-functional design eliminates redundant structures and achieves miniaturization without compromising stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If larger footprint is used, then manufacturing simplicity is maintained, but parasitic capacitance increases

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidparasitic capacitance

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

By merging boundary structures between adjacent resonators, the patent reduces the total electrode area and inter-resonator spacing, thereby decreasing parasitic capacitance while maintaining manufacturability through standardized fabrication processes.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent optimizes the spatial arrangement of resonators and their shared boundaries in the planar dimension, carefully positioning release holes and structuring the shared boundaries to minimize capacitive coupling between adjacent resonators while maintaining ease of manufacture.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If release holes are positioned to overlap electrodes, then cavity release is achieved, but electrode integrity may be compromised

Engineering Contradiction:

Improvecavity releaseVSAvoidelectrode integrity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent applies different designs for release holes depending on their location: release holes adjacent to electrodes include openings in the electrodes to ensure proper cavity release, while release holes not adjacent to electrodes maintain electrode integrity. This localized differentiation optimizes both cavity release and electrode strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the structural parameters of release holes based on their position relative to electrodes. Release holes overlapping electrodes have different characteristics (openings in electrodes) compared to those that don't overlap, allowing optimization of both release functionality and electrode integrity through parameter variation.

Inventive Principle:

Principle #35Parameter changes

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 approach enables the creation of smaller-sized bulk acoustic wave filters with reduced parasitic capacitance, improving performance and allowing for more compact integration in devices such as mobile communication devices.

Implementation Method 1

a piezoelectric layer disposed on the support layer

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12334904B2Bulk acoustic wave filter having release hole and fabricating method of the same

Publication Date: 2025.06.17 SHENZHEN NEWSONIC TECH CO LTD

AI summary

A bulk acoustic wave resonator includes a substrate, a support layer disposed on the substrate, the support layer including a cavity having a polygon shape with more than three sides in a plane crossing a first direction from the substrate to the support layer, a piezoelectric layer disposed on the support layer, a bottom electrode disposed below the piezoelectric layer, partially overlapping the cavity, and extending across a first side of the cavity, and a top electrode disposed above the piezoelectric layer, partially overlapping the cavity, and extending across a second side of the cavity. The bulk acoustic wave resonator further includes at least one release hole formed in the piezoelectric layer and overlapping a portion of the cavity.