Acoustic Resonator Reinforcing Layer for Release-Edge Collapse

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Solution Overview

Problem

Conventional Film Bulk Acoustic Resonators face mechanical strength issues due to stress-induced collapse of the piezoelectric oscillation stack at the edge of the cavity, leading to performance degradation.

Innovation Solution

An acoustic resonator with a reinforcing structure, featuring a reinforcing layer fitted to the edge of an opening between the piezoelectric and lower electrodes, which reduces stress and prevents collapse, and a manufacturing method that integrates the reinforcing layer with the upper electrode to enhance mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If etching is performed to form a release hole for sacrificial material release, then the cavity can be formed, but the piezoelectric layer and lower electrode are damaged and easily collapse due to stress

Engineering Contradiction:

Improvecavity formationVSAvoidmechanical strength of piezoelectric layer and lower electrode

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

A reinforcing layer is formed on the piezoelectric layer before the sacrificial material is released. This preliminary reinforcement prevents the piezoelectric layer and lower electrode from collapsing due to stress after etching, while still allowing the cavity to be formed through the reinforcing layer for sacrificial material release.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The reinforcing layer is made of a material different from the piezoelectric layer (such as a metal or metal alloy), creating a composite structure that combines the piezoelectric properties of the piezoelectric layer with the mechanical strength of the reinforcing layer, preventing collapse while maintaining functionality.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the piezoelectric oscillation stack is made thin to improve resonator performance, then the resonator performance improves, but the mechanical strength decreases and collapse becomes more likely

Engineering Contradiction:

Improveresonator performanceVSAvoidmechanical strength of piezoelectric oscillation stack

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The reinforcing layer made of a different material (metal or metal alloy) is combined with the piezoelectric layer to form a composite structure. This provides the necessary mechanical strength to support thin piezoelectric oscillation stacks, preventing collapse while allowing the resonator to achieve high performance through reduced thickness.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The structure is segmented into distinct functional layers: the piezoelectric layer for electrical-to-mechanical energy conversion and the reinforcing layer for mechanical support. This segmentation allows each layer to be optimized independently - the piezoelectric layer can be made thin for performance while the reinforcing layer provides the necessary structural integrity.

Inventive Principle:

Principle #1Segmentation

3Strength

If a reinforcing layer is added to prevent collapse, then mechanical strength improves, but device complexity increases

Engineering Contradiction:

Improvemechanical strength of resonant functional layerVSAvoidstructural complexity of resonator

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The reinforcing layer is applied locally at specific positions where stress concentration occurs, such as around the release hole or at critical support points, rather than uniformly across the entire piezoelectric layer. This localized reinforcement provides necessary mechanical strength while minimizing the increase in device complexity and material usage.

Inventive Principle:

Principle #3Local quality

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 reinforcing structure improves the uniformity and yield of the resonator by preventing stress-induced collapse, ensuring the designed performance and allowing for a simple and efficient manufacturing process.

Implementation Method 1

the input electrical signal is converted into a mechanical resonant wave through the piezoelectric film by using an inverse piezoelectric effect

Methodology Applied

Scientific EffectInverse piezoelectric effect: Piezoelectric Effect

Implementation Method 2

the mechanical resonant wave is converted into an electrical signal by using a piezoelectric effect to be outputted

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11973484B2Acoustic resonator with reinforcing structure and manufacturing method therefor

Publication Date: 2024.04.30 HANGZHOU XINGHE TECH CO LTD

AI summary

An acoustic resonator with a reinforcing structure is provided according to the present disclosure. The acoustic resonator includes a substrate and a cavity formed on the substrate, a piezoelectric layer is arranged above the substrate and an opening passing through the piezoelectric layer is formed in a peripheral region of the piezoelectric layer. The reinforcing structure includes a reinforcing layer, part of the reinforcing layer is formed at the edge of the opening with being fitted to the edge, to reinforce a resonant functional layer near the edge of the opening, which can reduce a change in stress of the piezoelectric layer and the lower electrode near the edge of the opening after the cavity is released, so that the piezoelectric layer and the lower electrode do not easily collapse due to stress, thereby ensuring the performance of a device. A method for manufacturing the same is further provided.