Piezoelectric Single-Crystal Thin Film for High-Q MEMS Sensing
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Solution Overview
Problem
Existing piezoelectric single-crystal materials face challenges in maintaining high mechanical quality factors while ensuring superior piezoelectric and dielectric constants, particularly in third-generation materials used for high-power military sonar systems and industrial ultrasonic motors, and there is a lack of processes for manufacturing MEMS devices using these materials.
Innovation Solution
A piezoelectric single-crystal element with improved piezoelectric and dielectric constants is achieved by applying alternating and direct currents to electrodes and adding specific additives, and a MEMS device is manufactured using a method involving wafer bonding, etching, and electrode patterning, with a structure that includes a piezoelectric thin film and electrodes stacked on a wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If third generation piezoelectric single crystal (Mn:PIN-PMN-PT) is used to increase mechanical quality factor, then mechanical quality factor is improved, but dielectric constant and piezoelectric constant decrease
Solution Approach 1:
The patent applies domain engineering methods to change the domain structure parameters of the piezoelectric single crystal. By controlling domain orientation and distribution through specific poling processes and crystal orientation selection, the patent achieves simultaneous improvement in mechanical quality factor and piezoelectric constant, resolving the contradiction between these two parameters in third generation materials.
2Reliability
If PZN-PT single crystal is developed using Flux method, then new piezoelectric material is created, but mass production of small single crystals becomes difficult
Solution Approach 1:
The patent transitions from the Flux method to the Bridgman method for crystal growth. This parameter change in the manufacturing process enables mass production of small single crystals while maintaining the superior piezoelectric properties of PZN-PT and PMN-PT materials, resolving the contradiction between material performance and manufacturability.
3Reliability
If AC polling method is applied to improve piezoelectric constant and dielectric constant, then these constants are improved, but repolarization difficulties arise making wide application difficult
Solution Approach 1:
The patent performs domain engineering and poling processes during the crystal growth stage itself, rather than requiring subsequent repolarization steps. This preliminary action integrates the polarization process into the manufacturing workflow, eliminating the need for complex post-processing repolarization and enabling direct application in devices.
4Stability of the object's composition
If existing piezoelectric single crystal materials are used, then material properties are established, but further improvement in piezoelectric and dielectric constants is limited
Solution Approach 1:
The patent employs composite domain structures and multi-phase single crystal compositions (such as PIN-PMN-PT and Mn:PIN-PMN-PT) to achieve superior piezoelectric and dielectric constants. By combining different phases and domains within a single crystal structure, the patent overcomes the limitations of existing single-phase materials while maintaining compositional stability.
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 enhances the piezoelectric and dielectric constants, improves coercive field and mechanical quality factor, and enables the production of MEMS devices capable of sensing minute motions and sound waves without requiring a separate battery, suitable for medical and industrial applications.
Implementation Method 1
piezoelectric single-crystal element, MEMS device using same
Implementation Method 2
applying an alternating current and a direct current to both ends of a piezoelectric single crystal having electrodes
Data Source
AI summary
The present disclosure relates to a piezoelectric single-crystal element, a MEMS device using same, and a method for manufacturing same, wherein the piezoelectric single-crystal element 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.