Film Bulk Acoustic Resonator Perimeter Shaping for Lateral Mode Suppression
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Solution Overview
Problem
Existing film bulk acoustic resonators face challenges in suppressing transverse mode effects while maintaining low manufacturing costs, often requiring additional process layers to achieve higher Q values for high-frequency filtering.
Innovation Solution
A film bulk acoustic resonator design featuring a layered structure with a reflective interface between the bottom electrode and substrate, incorporating a closed perimeter formed by connecting curves and straight line segments, and optionally including protruding blocks or grooved regions, which allows for shape asymmetry without increasing the number of process layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional process layers are added to suppress lateral mode, then the Q value is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies asymmetry by designing the layered structure with an asymmetric outer perimeter consisting of a curve and at least one straight line segment. This asymmetric geometry suppresses lateral modes through the reflective interface without requiring additional process layers, thereby improving Q value while maintaining manufacturing cost effectiveness
Solution Approach 2:
The patent transitions from considering only the vertical layering dimension to incorporating the horizontal perimeter dimension. By defining the outer perimeter with specific geometric features (curve + straight line segments), the solution addresses lateral mode suppression in the horizontal plane, achieving Q value improvement without adding vertical process layers
2Reliability
If the number of process layers is increased to suppress transverse mode, then the filtering response quality is improved, but the device complexity increases
Solution Approach 1:
The asymmetric outer perimeter design with curve and straight line segments creates mode suppression through geometric asymmetry rather than through additional process layers, reducing device complexity while maintaining filtering response quality
Solution Approach 2:
The solution moves the complexity management from the vertical dimension (number of layers) to the horizontal dimension (perimeter geometry). By controlling the outer perimeter shape, the patent achieves transverse mode suppression without increasing the number of process layers
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 design effectively suppresses lateral modes, enhances the Q value, and controls manufacturing costs by defining the shape of the layered structure without adding new process layers, thereby maximizing product development benefits.
Implementation Method 1
a reflective interface is arranged between the bottom electrode and the substrate
Implementation Method 2
a piezoelectric layer
Data Source
AI summary
The invention provides a film bulk acoustic resonator including a layered structure composed of a top electrode, a piezoelectric layer and a bottom electrode, and a substrate; a reflective interface is arranged between the bottom electrode and the substrate; and by defining the shape of all or part of the layered structure, the purpose of suppressing the lateral mode can be achieved, and without adding new process, the manufacturing cost of the device can be controlled, and the benefit of product development can be maximized.