Vertical BAW Bulk Filter Structure for Easier Integration
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Solution Overview
Problem
Existing BAW and FBAR filters face high process requirements and integration difficulties, leading to increased device costs and reduced integration degree due to their horizontal structure and complex manufacturing processes.
Innovation Solution
A vertical structure BAW filter design with a piezoelectric layer having electrodes on vertical faces, utilizing materials like AlN, lithium tantalate, and ZnO, and a substrate interface for epitaxial growth, along with a thermal conductive layer and acoustic reflectors, allowing for simpler manufacturing and higher integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BAW-SMR or FBAR structures are used to achieve vibration isolation and heat dissipation, then the resonant region performance is improved, but the process requirements become high and implementation difficulty increases
Solution Approach 1:
The patent transitions from horizontal electrode arrangements to vertical electrodes disposed on vertical faces of the piezoelectric layer. This dimensional change simplifies the manufacturing process while maintaining vibration isolation and heat dissipation performance through the vertical CFBAR structure.
Solution Approach 2:
The patent employs composite material structures including piezoelectric layers with specific crystal orientations (c-axis or m-axis), acoustic reflectors with alternating acoustic impedances, and thermal conductive layers. These composite structures achieve both performance requirements and manufacturing feasibility.
2Reliability
If complex BAW/FBAR structures are implemented to achieve high Q value and low insertion loss, then signal filtering performance is improved, but device costs increase and integration degree decreases
Solution Approach 1:
The vertical configuration of electrodes on vertical faces enables simpler fabrication processes compared to horizontal structures, reducing manufacturing complexity and costs while maintaining high Q value and low insertion loss through optimized acoustic wave propagation paths.
Solution Approach 2:
The vertical CFBAR structure integrates multiple functions including acoustic wave filtering, thermal management, and mechanical support within a single configuration, enabling higher integration degrees and reduced device costs through multi-functionality.
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 vertical structure reduces manufacturing complexity, facilitates higher integration, lowers costs, and enhances heat dissipation, resulting in improved signal filtering with better selectivity and reduced signal loss.
Implementation Method 1
a piezoelectric layer; a first electrode, disposed at a first vertical face of the piezoelectric layer and configured to receive an electric signal; and a second electrode, disposed at a second vertical face of the piezoelectric layer and configured to output an electric signal
Implementation Method 2
a substrate, which includes a vertical interface, where the piezoelectric layer is formed by epitaxial growth of the vertical interface
Implementation Method 3
a thermal conductive layer, where the substrate is between the piezoelectric layer and the thermal conductive layer
Data Source
AI summary
A filter (100) includes a piezoelectric layer (105); a first electrode (108), disposed at a first vertical face of the piezoelectric layer (105) and configured to receive an electric signal; and a second electrode (109), disposed at a second vertical face of the piezoelectric layer (105) and configured to output an electric signal, where the first vertical face and the second vertical face are two opposite sides of the piezoelectric layer (105).