Integrated BAW Resonator-Capacitor for Spurious Wave Suppression
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Solution Overview
Problem
Existing bulk acoustic wave (BAW) resonators suffer from spurious acoustic waves due to transverse acoustic waves generated perpendicular to the main acoustic wave, degrading frequency response, and integrating capacitors as separate components increases device size and complexity.
Innovation Solution
An integrated bulk acoustic wave resonator-capacitor structure is designed with recessed and raised frames on the piezoelectric film to dissipate or scatter transverse acoustic waves, and a peripheral capacitor region is integrated to reduce acoustic coupling, using existing die materials for the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate capacitors are integrated into the BAW resonator device, then device functionality is improved, but device size and complexity increase
Solution Approach 1:
The patent combines the capacitor and resonator into a single integrated structure where the capacitor is formed within the same device footprint as the resonator. The capacitor electrodes are created using the same piezoelectric film and electrode layers as the resonator, eliminating the need for separate capacitor components and reducing overall device complexity while maintaining enhanced functionality.
Solution Approach 2:
The piezoelectric film and electrode structures serve dual functions: they form both the resonator active region that generates acoustic waves and the capacitor electrodes that store electrical charge. This multi-functional design allows a single structure to provide both resonant filtering and capacitive coupling capabilities, reducing the need for additional components.
2Speed
If transverse acoustic waves are generated in the BAW resonator, then acoustic wave propagation occurs, but spurious signals are generated that degrade frequency response
Solution Approach 1:
The patent converts the harmful transverse acoustic waves into beneficial effects by using them to generate piezoelectric charge in the capacitor region. The transverse waves that would normally cause spurious signals are instead harnessed to charge the integrated capacitor, transforming a harmful effect into a useful function that improves overall device performance.
Solution Approach 2:
The integrated capacitor acts as an intermediary that absorbs and manages the transverse acoustic wave energy. Instead of allowing these waves to propagate and create spurious signals, the capacitor structure provides a controlled path for the acoustic energy, converting it into electrical charge and preventing the generation of harmful spurious signals.
3Adaptability or versatility
If additional capacitor components are added to the BAW resonator, then capacitive functionality is improved, but additional processing steps are required
Solution Approach 1:
The capacitor manufacturing process is merged with the resonator fabrication process. The same piezoelectric film deposition, electrode patterning, and layer formation steps that create the resonator structures are used to form the capacitor electrodes. This integrated manufacturing approach eliminates the need for separate capacitor fabrication steps and reduces overall processing complexity.
Solution Approach 2:
The fabrication process is designed to create multi-functional structures where each processing step serves multiple purposes. The electrode layers are patterned to form both resonator electrodes and capacitor electrodes simultaneously, and the piezoelectric film serves both as the active resonator material and as the capacitor dielectric, reducing the total number of manufacturing steps required.
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 integrated structure effectively suppresses spurious signals, reduces device size, and minimizes additional processing steps, resulting in improved frequency response and cost-effectiveness.
Implementation Method 1
a membrane including a piezoelectric film, an upper electrode disposed on a top surface of the piezoelectric film, and a lower electrode disposed on a lower surface of the piezoelectric film
Implementation Method 2
a resonator region of the membrane defining a main active domain in which a main acoustic wave is generated during operation, and a capacitor region of the membrane surrounding the resonator region
Data Source
AI summary
An integrated bulk acoustic wave resonator-capacitor comprises a membrane including a piezoelectric film, an upper electrode disposed on a top surface of the piezoelectric film, and a lower electrode disposed on a lower surface of the piezoelectric film, a resonator region of the membrane defining a main active domain in which a main acoustic wave is generated during operation, and a capacitor region of the membrane surrounding the resonator region, the capacitor region including a layer of conductive material disposed on the upper electrode, an inner capacitor raised frame defined on an inner peripheral region of the layer of conductive material, and an outer capacitor raised frame defined on an outer peripheral region of the layer of conductive material.