MEMS Resonator Layer Stack for Lower Thermoelastic Loss

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing MEMS resonators face challenges in maximizing the quality factor Q and minimizing equivalent series resistance (ESR) due to high thermoelastic dissipations, particularly in piezoelectric materials like AlN.

Innovation Solution

Incorporating layers of material with low thermal diffusivity between the single-crystalline silicon layer and the piezoelectric layer, and between the piezoelectric layer and the electrically conducting layer, to reduce thermoelastic dissipations and enhance thermal isolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If piezoelectric material layers are used in MEMS resonators, then the resonator can be manufactured with standard semiconductor processes and integrated circuits, but thermoelastic dissipations increase leading to lower quality factor Q

Engineering Contradiction:

ImprovemanufacturabilityVSAvoidthermoelastic dissipation

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

A layer of material with low thermal diffusivity is introduced as an intermediary between the single-crystalline silicon layer and the piezoelectric layer, and between the piezoelectric layer and the electrically conducting layer. This intermediary layer reduces thermal coupling between the piezoelectric material and adjacent layers, thereby minimizing thermoelastic dissipations while maintaining the benefits of piezoelectric actuation and standard manufacturing processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If material layers are added to reduce thermal diffusivity, then quality factor Q increases, but device complexity increases

Engineering Contradiction:

Improvequality factorVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the thermal diffusivity parameter of specific layers by selecting materials with appropriately low thermal diffusivity values. This parameter change allows the piezoelectric layer to be thermally isolated from adjacent layers, reducing thermoelastic losses and improving quality factor Q without requiring fundamental changes to the device architecture or manufacturing process.

Inventive Principle:

Principle #35Parameter changes

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 configuration significantly reduces thermoelastic energy losses, leading to a higher quality factor Q and lower equivalent series resistance (ESR), thereby improving the overall performance of MEMS resonators.

Implementation Method 1

at least one layer made of material with low thermal diffusivity... to reduce thermoelastic dissipations and enhance thermal isolation

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

a layer of piezoelectric material

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12212300B2MEMS resonator with high quality factor and its use

Publication Date: 2025.01.28 KYOCERA TECH OY

AI summary

A MEMS (microelectromechanical system) resonator with a material layer of single-crystalline silicon, at least one layer made of material with low thermal diffusivity to reduce thermoelastic dissipations in the MEMS resonator, a layer of piezoelectric material, and a layer made of electrically conducting material. The layer with low thermal diffusivity is between the single-crystalline silicon layer and the piezoelectric layer, or between the piezoelectric layer and the electrically conducting layer. The use of a material layer of low thermal diffusivity.