Multi-Gradient Raised Frame for Stable BAW Quality Factor
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Solution Overview
Problem
Existing bulk acoustic wave (BAW) devices face challenges in achieving high quality factor (Q) stability due to manufacturing variations and other factors, leading to inconsistent performance.
Innovation Solution
The implementation of a multi-gradient raised frame structure in BAW devices, which includes a first raised frame layer with lower acoustic impedance and a second raised frame layer with higher acoustic impedance, tapered on opposing sides to reduce lateral energy leakage and enhance Q stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional BAW device structure is used, then the device can be manufactured with standard processes, but the quality factor (Q) stability varies due to manufacturing variations
Solution Approach 1:
The patent applies local quality by creating a raised frame structure with specific acoustic impedance properties at the boundaries of the piezoelectric layer. This localized structural modification with distinct material properties (different acoustic impedance than the piezoelectric layer) addresses the specific problem of lateral energy leakage at the edges, thereby improving Q stability without requiring uniform changes throughout the entire device structure.
Solution Approach 2:
The patent employs composite materials by combining the piezoelectric layer with a raised frame structure made of different materials having distinct acoustic impedance characteristics. This composite structure, where the frame material differs from the piezoelectric material, creates acoustic boundaries that reduce lateral energy leakage and improve quality factor stability while maintaining compatibility with standard manufacturing processes.
2Loss of energy
If the raised frame structure is made with uniform acoustic impedance, then the structure is simpler to manufacture, but lateral energy leakage is not effectively reduced
Solution Approach 1:
The patent implements local quality by varying the acoustic impedance of the raised frame structure across different regions. The frame structure contains multiple portions with different acoustic impedances, creating a gradient that optimally reflects lateral acoustic energy back into the piezoelectric layer. This spatial variation in material properties effectively reduces lateral energy leakage while maintaining a manufacturable structure.
Solution Approach 2:
The patent applies parameter changes by modifying the acoustic impedance parameter of the raised frame structure across different spatial locations. The acoustic impedance varies from one portion of the frame to another, creating an impedance gradient that optimizes acoustic energy confinement. This parameter variation is achieved through different materials or structural configurations within the frame portions.
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 multi-gradient raised frame structure effectively improves the quality factor stability and reduces sensitivity to manufacturing variations, resulting in better performance and reliability of BAW devices.
Implementation Method 1
a multi-gradient raised frame structure configured to cause lateral energy leakage from a main acoustically active region of the bulk acoustic wave device to be reduced
Data Source
AI summary
Aspects of this disclosure relate to a bulk acoustic wave device with a multi-gradient raised frame. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a multi-gradient raised frame structure. The multi-gradient raised frame structure includes a first raised frame layer and a second raised frame layer. The second raised frame layer extends beyond the first raised frame layer. The second raised frame layer is tapered on opposing sides.