MEMS Resonator Lateral Vibration Single-Crystal Piezoelectric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MEMS resonators face challenges in achieving high-Q, low loss, stability, low temperature coefficient of frequency, high repeatability, and accuracy, with resonant frequency dependent on layer thickness, limiting the ability to produce multiple resonators with different frequencies on a single die.
Innovation Solution
A micro-electromechanical systems (MEMS) vibrating structure with dominant lateral vibrations supported by a MEMS anchor system, utilizing a single-crystal piezoelectric thin-film layer grown with specific crystal orientation, allowing resonant frequency control by size and shape rather than layer thickness, and incorporating a mechanically efficient construction with Lithium Tantalate or Lithium Niobate for enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin-film piezoelectric material is used in an FBAR, then the resonator can be manufactured with thin-film deposition processes, but the resonant frequency becomes dependent on the thickness of the deposited layer which is difficult to control
Solution Approach 1:
The patent changes the controlling parameter for resonant frequency from layer thickness to lateral dimensions (length and width). By making the resonator operate in lateral vibration mode rather than thickness mode, the resonant frequency becomes f ∝ 1/√(L×W) instead of being dependent on the difficult-to-control thin-film thickness, thus improving manufacturing precision while maintaining ease of manufacture through standard deposition processes
Solution Approach 2:
The patent transitions from controlling resonance in the thickness dimension (vertical) to controlling resonance in the lateral dimensions (horizontal). This dimensional shift allows the resonant frequency to be controlled by the length and width of the resonator structure, which are easier to control during fabrication than thin-film thickness, thereby resolving the contradiction between ease of manufacture and manufacturing precision
2Adaptability or versatility
If a deposited thin-film is used in an FPOSR, then the resonator can resonate in lateral mode with frequency independent of thickness, but the deposited thin-film has resonant frequency inaccuracies and high losses
Solution Approach 1:
The patent uses a composite structure consisting of a piezoelectric thin-film layer deposited on a suspended substrate (such as silicon). This composite approach combines the advantages of both materials: the piezoelectric film provides the necessary piezoelectric effect for actuation and sensing, while the suspended substrate provides mechanical support and enables lateral vibration modes with low loss and high Q-factor, thereby improving reliability while maintaining lateral mode resonance capability
Solution Approach 2:
The suspended substrate acts as an intermediary between the piezoelectric thin-film and the surrounding environment. It provides a mechanically efficient structure that supports lateral vibrations with low damping, reducing the high losses inherent in deposited thin-films while maintaining the frequency independence from thickness. The substrate mediates the mechanical stress and vibration, improving overall resonator reliability
3Device complexity
If the resonant frequency is controlled by layer thickness, then a single FBAR structure can be manufactured, but multiple resonators with different frequencies require separate layers which is limiting and expensive
Solution Approach 1:
The patent creates a universal resonator structure where a single piezoelectric thin-film layer on a suspended substrate can serve multiple functions by varying the lateral dimensions. Different resonators with different resonant frequencies can be created from the same layer by simply changing the length and width of different regions, enabling multiple resonators per die without requiring separate deposition layers, thus improving productivity while maintaining manageable device complexity
Solution Approach 2:
The patent segments the resonator structure into regions with different lateral dimensions (length and width) while using a common piezoelectric thin-film layer. This segmentation allows each region to have a different resonant frequency determined by its specific dimensions, enabling multiple resonators with different frequencies to be manufactured from a single deposited layer, thereby increasing productivity without proportionally increasing device complexity
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 high-Q, low loss, stable, and repeatable MEMS resonators with low motional impedance, capable of producing multiple resonators with different frequencies on a single substrate, improving accuracy and reducing manufacturing complexity and costs.
Implementation Method 1
The grown single-crystal piezoelectric thin-film layer has piezoelectric properties, such that an applied alternating current (AC) voltage may cause mechanical vibrations
Data Source
AI summary
The present invention relates to a micro-electro-mechanical systems (MEMS) vibrating structure having dominant lateral vibrations supported by a MEMS anchor system, and includes a single-crystal piezoelectric thin-film layer that has been grown with a specific crystal orientation. Since the MEMS vibrating structure has dominant lateral vibrations, its resonant frequency may be controlled by its size and shape, rather than layer thickness, which provides high accuracy and enables multiple resonators having different resonant frequencies on a single substrate.