Single-Crystal Piezoelectric MEMS Films for High-Q Sensing
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Solution Overview
Problem
Existing piezoelectric single-crystal materials face challenges in maintaining high dielectric and piezoelectric constants while improving coercive field and mechanical quality factor, and there is a lack of effective processes for manufacturing MEMS devices using these materials, particularly for medical and sensor applications requiring precise unit elements.
Innovation Solution
A piezoelectric single-crystal element with improved dielectric and piezoelectric constants is achieved by applying alternating and direct currents to electrodes, and enhanced by adding a specific additive, combined with a manufacturing process involving electrode patterning, etching, and bonding to create a MEMS device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If piezoelectric fine particles are sintered to form a piezoelectric sintered body, then the manufacturing process is simple and low-cost, but the piezoelectric characteristics and Q-factor are insufficient for high-frequency applications
Solution Approach 1:
The invention changes the physical state parameter of the piezoelectric material from polycrystalline sintered form to single-crystal form. This parameter change fundamentally improves the piezoelectric characteristics and Q-factor while maintaining manufacturability through solution-based crystal growth methods rather than traditional bulk single-crystal growth
Solution Approach 2:
The invention transitions from bulk single-crystal growth to thin-film single-crystal formation on substrates. This dimensional change enables the application of piezoelectric materials in MEMS devices where thin-film structures are required, combining the advantages of single-crystal properties with micro-scale device integration
2Ease of manufacture
If piezoelectric sintered bodies are used in MEMS devices, then manufacturing is easier, but high-frequency characteristics above 100 MHz cannot be achieved
Solution Approach 1:
The invention changes the material structure parameter from polycrystalline to single-crystal, which fundamentally improves the Q-factor and enables high-frequency operation above 100 MHz while maintaining compatibility with MEMS fabrication processes
Solution Approach 2:
The invention performs preliminary crystal orientation control during the film formation process by selecting specific substrate orientations and controlling crystal growth conditions. This preliminary action ensures that the piezoelectric crystals are properly oriented before device fabrication, enabling high-frequency characteristics without requiring complex post-processing
3Adaptability or versatility
If conventional piezoelectric materials are used, then compatibility with existing processes is maintained, but acoustic wave attenuation is high and energy loss occurs
Solution Approach 1:
The invention changes the material microstructure parameter from polycrystalline with grain boundaries to single-crystal without grain boundaries. This eliminates the primary source of acoustic wave attenuation and energy loss while maintaining compatibility with existing MEMS fabrication processes through solution-based deposition methods
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 resulting MEMS device exhibits superior response characteristics, capable of converting minute mechanical motions or sound waves into electrical signals, enabling the commercialization of devices that can detect subtle body movements or sounds, and operates without a separate battery.
Implementation Method 1
a piezoelectric single-crystal element comprising a piezoelectric single crystal
Data Source
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AI summary
The present disclosure relates to a piezoelectric single-crystal element, a MEMS device using same, and a method for manufacturing same. Specifically, according to one embodiment of the present disclosure, there may be provided a piezoelectric single-crystal element that includes a wafer, a lower electrode stacked on the wafer, a piezoelectric single-crystal thin film stacked on the lower electrode, and an upper electrode stacked on the piezoelectric single-crystal thin film, wherein the piezoelectric single-crystal thin film is composed of PMN-PT, PIN-PMN-PT or Mn:PIN-PMN-PT, and the piezoelectric single-crystal thin film has a polarization direction set to a <001> axis, a <011> axis or a <111> axis, and a MEMS device using same.