Bulk Acoustic Wave Filter Structure for Heat and Strength
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Solution Overview
Problem
Existing bulk acoustic wave filters, particularly FBAR filters, face manufacturing complexity, high cost, thermal issues, and mechanical robustness challenges, hindering miniaturization.
Innovation Solution
A volume acoustic wave filter is designed with an air cavity embedded in a semiconductor substrate and resonators formed above it, featuring a semiconductor substrate with improved thermal conductivity and mechanical strength, and a simplified manufacturing process using annealing to form the cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If FBAR filters use air cavity for acoustic insulation, then energy losses are reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the formation method of the air cavity from a complex sacrificial layer removal process to a simpler direct formation technique, maintaining the acoustic insulation benefits while reducing manufacturing complexity and cost
Solution Approach 2:
The patent extracts the complex sacrificial layer formation step from the manufacturing process, replacing it with a more straightforward method to create the air cavity, thereby simplifying production while preserving the energy loss reduction benefit
2Loss of energy
If FBAR filters use air cavity structure, then acoustic insulation is improved, but mechanical robustness deteriorates
Solution Approach 1:
The patent employs composite material structures in the resonator design, combining materials with different mechanical properties to reinforce the air cavity structure, thereby maintaining superior acoustic insulation while improving mechanical robustness
3Loss of energy
If FBAR filters use air cavity structure, then acoustic insulation is improved, but thermal performance deteriorates
Solution Approach 1:
The patent introduces thermal management structures as intermediaries between the resonator and the substrate, facilitating heat dissipation from the air cavity region while preserving the acoustic insulation properties of the air cavity structure
4Volume of moving object
If FBAR filters are miniaturized, then device size is reduced, but manufacturing difficulty increases
Solution Approach 1:
The patent segments the resonator structure into modular components that can be independently fabricated and then assembled, enabling miniaturization while maintaining manufacturing feasibility through standardized processing steps
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 enhances thermal dissipation and mechanical robustness, simplifies manufacturing, and facilitates miniaturization of the filters.
Implementation Method 1
The solution enhances thermal dissipation and mechanical robustness
Implementation Method 2
a simplified manufacturing process using annealing to form the cavity
Data Source
Figure 1~3C
Figure 3D~5
AI summary
The present description relates to a volume acoustic wave filter (200) formed in and on a semiconductor substrate (101), the filter (200) comprising: - an air cavity (201) buried in the semiconductor substrate (101); and - at least one resonator (121) formed above the air cavity (201), the resonator (121) comprising an active layer (109) interposed between lower (107) and upper (111) electrodes.