Solidly Mounted Acoustic Resonators With Bragg Leakage Control
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Solution Overview
Problem
Piezoelectric MEMS resonators face challenges in manufacturing complexity and susceptibility to mechanical shock, and existing designs struggle to support high-frequency applications with reduced energy consumption.
Innovation Solution
The development of solidly-mounted, two-dimensional mode acoustic resonators that constrain acoustic energy in the piezoelectric layer and electrodes, using Bragg reflectors and air or other barriers to minimize energy leakage into the substrate, allowing for tuning of resonance frequencies in high-frequency ranges and simplifying fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cavity-based resonator designs are used, then certain vibrational modes are enabled, but manufacturing complexity increases and susceptibility to mechanical shock damage worsens
Solution Approach 1:
The invention extracts and eliminates the cavity structure from the resonator design, transitioning from a cavity-based configuration to a solidly-mounted configuration. This removal of the cavity simplifies manufacturing by eliminating the need for complex release processes and cavity formation steps, while maintaining the essential vibrational mode capabilities through the solid mounting structure.
2Adaptability or versatility
If cavity-based resonator designs are used, then certain vibrational modes are enabled, but resistance to mechanical shock worsens
Solution Approach 1:
By removing the cavity structure that creates susceptibility to mechanical shock, the solidly-mounted design provides direct structural support to the piezoelectric layer, significantly improving resistance to mechanical shock and enhancing overall device reliability.
Solution Approach 2:
The invention merges the piezoelectric layer directly with the substrate through solid mounting, creating an integrated structure that eliminates the vulnerability of suspended cavity designs to mechanical shock while preserving vibrational mode functionality.
3Ease of manufacture
If acoustic energy is allowed to leak into the substrate, then manufacturing is simpler, but quality factor decreases at high frequencies
Solution Approach 1:
The invention introduces Bragg reflectors as intermediary structures between the piezoelectric layer and the substrate. These reflectors act as acoustic barriers that prevent energy leakage into the substrate while maintaining the solidly-mounted simplified structure, thereby preserving high quality factor at high frequencies without complicating the fabrication process.
4Use of energy by moving object
If resonators are designed for high frequency applications, then energy consumption is reduced, but maintaining quality factor becomes difficult
Solution Approach 1:
The Bragg reflectors serve as intermediary acoustic confinement structures that prevent energy loss into the substrate at high frequencies, enabling the resonator to maintain high quality factor while operating in energy-efficient high frequency modes.
Solution Approach 2:
The invention adjusts the thickness and material parameters of the piezoelectric layer and Bragg reflectors to optimize acoustic confinement at high frequencies, enabling maintained quality factor across the high frequency operating range with reduced energy consumption.
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 solution maintains a high quality factor at high frequencies, reduces manufacturing complexity and cost, and enhances resistance to mechanical shock, while enabling lithographic tunability and improved power handling.
Implementation Method 1
a layer of piezoelectric material solidly mounted on a surface of the substrate
Implementation Method 2
with the optional use of Bragg reflectors and/or placement of air or other barriers
Data Source
AI summary
The present technology provides solidly-mounted, bi-dimensional mode acoustic resonators for use in high frequency electronic applications. The resonator devices are designed to constrain acoustic energy in the piezoelectric layer and electrodes. By concentration of the acoustic waves on the surface and reducing substrate leakage, the quality factor of the system is maintained, even at high frequencies where other resonators fail. The resonance frequency of the devices can be tuned in the 1-27 GHz range. Fabrication of the devices is simplified and cost reduced compared to similar technologies, because the piezoelectric layer is solidly supported and does not have to be released from the substrate.