Dual-Mode MEMS Resonator With V-Groove for Compact LTE Filtering

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Solution Overview

Problem

Conventional MEMS resonators face challenges in achieving a reduced footprint, high-frequency operation suitable for all LTE bands, and accurate thermal sensing due to thermal drifting, increased footprint, and low electromechanical efficiency.

Innovation Solution

A dual-mode MEMS resonator structure with a V-shaped groove is formed on a semiconductor substrate, incorporating a seed layer, electrodes, and a mass loading layer, allowing for the creation of a dual-band acoustic filter and high-frequency clock source with reduced footprint and improved thermal sensing capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of filters in the RF module is increased to support all LTE bands, then the frequency coverage is improved, but the module footprint area increases

Engineering Contradiction:

Improvefrequency coverageVSAvoidmodule footprint area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent combines two separate resonators into a single dual-mode resonator structure that supports both fundamental and overtone modes. This merging allows one resonator to perform the function of two separate resonators, enabling support for multiple LTE bands while reducing the overall module footprint area.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dual-mode resonator is designed to serve multiple functions simultaneously - it operates in both fundamental mode and overtone mode to support different frequency bands. This multi-functionality allows a single resonator structure to replace multiple separate resonators, reducing the number of components needed in the RF module.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Speed

If AlN resonator oscillators are used for high frequency operation, then the operating frequency is improved, but thermal drifting becomes too small for thermal sensing applications

Engineering Contradiction:

Improveoperating frequencyVSAvoidthermal sensing sensitivity

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent intentionally utilizes the overtone mode of the resonator, which operates at higher frequencies than the fundamental mode. By operating in the overtone mode, the system achieves higher frequency performance while the controlled thermal drifting characteristics remain suitable for both timing and thermal sensing applications.

Inventive Principle:

Principle #16Partial or excessive action

3Adaptability or versatility

If conventional MEMS resonators are used for thermal sensing, then thermal sensing capability is provided, but the thermal gradient between resonators is uncertain which decreases sensitivity and accuracy

Engineering Contradiction:

Improvethermal sensing capabilityVSAvoidthermal sensing sensitivity and accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent employs a single dual-mode resonator where both fundamental and overtone modes are excited within the same physical structure. This ensures identical thermal conditions for both modes, eliminating thermal gradient uncertainties between separate resonators and improving thermal sensing sensitivity and accuracy.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If separate resonators are used for different frequency bands, then frequency separation is achieved, but the device complexity and footprint area increase

Engineering Contradiction:

Improvefrequency band supportVSAvoidnumber of resonators

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The dual-mode resonator is designed to operate in multiple modes (fundamental and overtone) to support different frequency bands. This universal design allows a single resonator structure to replace multiple separate resonators, reducing device complexity while maintaining the ability to support multiple LTE bands.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables a 50% reduction in footprint, high sensitivity for thermal sensing, and stable timing sources, addressing the limitations of conventional MEMS resonators in terms of size and thermal stability.

Implementation Method 1

forming a V-shaped groove in the material, forming a grooved area

Methodology Applied

Scientific EffectAcoustic wave confinement: Acoustics

Implementation Method 2

forming an acoustic layer on the bottom electrode

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS10476480B1Dual-mode MEMS resonator, oscillator, sensor, timing device, acoustic filter and front-end module and the methods of making

Publication Date: 2019.11.12 VANGUARD INT SEMICON SINGAPORE PTE LTD

AI summary

A dual-mode resonator, devices employing the dual-mode resonator, and the methods of making the resonator and the devices are disclosed. Embodiments include a dual-mode resonator including a semiconductor substrate; a material on the semiconductor substrate, having a cavity formed therein; a seed layer over the cavity in a V-shape, wherein sides of the V-shape form an angle of 15 to 25 degrees with a horizontal line; a bottom electrode on the seed layer; an acoustic layer on the bottom electrode; a top electrode on the acoustic layer; and a mass loading layer on the top electrode; and a cap over the dual-mode resonator.