Piezoelectric Element with Interlayer for High Force
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Solution Overview
Problem
Existing piezoelectric actuators face limitations in generative force, complex manufacturing processes, high costs due to the use of SOI substrates, rigidity issues without a vibration plate, and challenges in forming high-rigidity thin films without cracking or peeling.
Innovation Solution
A piezoelectric element is designed with a silicon substrate, laminated electrodes, and interlayers of varying thicknesses to enhance rigidity and adhesion, using a vapor phase epitaxial method for uniform film formation, and optimizing thermal expansion coefficients and crystal orientations to prevent warping and improve durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a unimorph actuator structure is used, then the structure is simple, but the generative force is limited
Solution Approach 1:
The patent combines multiple piezoelectric layers (first and second piezoelectric films) with different crystal orientations into a single integrated actuator structure. This merging of multiple functional layers enables the actuator to generate higher force compared to a simple unimorph structure, while maintaining manufacturing simplicity through a unified design approach.
2Force
If two piezoelectric bodies are bonded to each other, then the generative force increases, but the manufacturing process becomes complicated and costs increase
Solution Approach 1:
Instead of bonding separate piezoelectric bodies, the patent merges multiple piezoelectric films into a single integrated structure formed on one substrate. This approach achieves high generative force through the combined effect of multiple layers with different crystal orientations, while avoiding the complicated bonding processes and associated cost increases.
Solution Approach 2:
The patent uses a single substrate that supports multiple piezoelectric films with different crystal orientations, making the substrate serve multiple functions. This multi-functionality approach allows the manufacturing process to produce a complex multi-layer structure without requiring separate processing steps for each layer, thereby simplifying the overall manufacturing process.
3Manufacturing precision
If an SOI substrate is used, then the manufacturing precision is improved, but the cost increases
Solution Approach 1:
The patent applies different crystal orientations to different regions of the piezoelectric films locally. The first piezoelectric film has a first crystal orientation and the second piezoelectric film has a second crystal orientation different from the first. This local differentiation of crystal orientations enables precise control of piezoelectric properties in specific regions without requiring an expensive SOI substrate.
4Quantity of substance
If a laminated piezoelectric body without a vibration plate is used, then the manufacturing cost decreases, but the rigidity deteriorates
Solution Approach 1:
The patent creates a composite structure by laminating piezoelectric films with different crystal orientations onto a substrate. This composite arrangement provides the necessary rigidity through the combined mechanical properties of multiple layers with different orientations, while avoiding the need for additional vibration plate components and associated manufacturing costs.
5Ease of manufacture
If there is a difference in thermal expansion coefficient between silicon layer and piezoelectric film, then the manufacturing is simplified, but warping occurs due to temperature variation
Solution Approach 1:
The patent intentionally creates an asymmetric structure with piezoelectric films having different crystal orientations (first and second different orientations) deposited on the substrate. This asymmetric configuration balances the thermal expansion differences between the silicon substrate and piezoelectric films, preventing warping while maintaining ease of manufacture through standard deposition processes.
6Length of moving object
If the thickness of piezoelectric films is reduced, then the device size is minimized, but cracking and peeling occur
Solution Approach 1:
The patent deposits piezoelectric films with different crystal orientations at different locations on the substrate. The first piezoelectric film with its specific crystal orientation provides strong adhesion to the substrate, while the second piezoelectric film with a different crystal orientation provides structural stability. This local quality differentiation prevents cracking and peeling even when the overall film thickness is minimized.
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 results in a piezoelectric element with higher stability and efficiency, capable of operating at high resonance frequencies with reduced manufacturing complexity and costs, while maintaining high durability and reliability.
Implementation Method 1
each of the first electrode, the first piezoelectric film, the second electrode, the interlayer, the adhesion layer, the third electrode, the second piezoelectric film, and the fourth electrode is formed using a vapor phase epitaxial method
Implementation Method 2
a piezoelectric element using a piezoelectric thin film material, which is used for various uses such as an actuator, a sensor, or a power generation device
Data Source
AI summary
Provided are a piezoelectric element having high stability, which operates with high efficiency, and a method for manufacturing the piezoelectric element. The piezoelectric element (10) has a laminate structure in which a first electrode (14), a first piezoelectric film (16), a second electrode (18), an adhesion layer (20), an interlayer (22), a third electrode (24), a second piezoelectric film (26), and a fourth electrode (28) are laminated in this order on a silicon substrate (12). The interlayer (22) is formed of a material different from that of the second electrode (18) and has a thickness of 0.4 μm to 10 μm. A device having a diaphragm structure or a cantilever structure is formed by removing a part of the silicon substrate (12). The respective layers (14 to 28) laminated on the silicon substrate (12) can be formed using a thin film formation method represented by a vapor phase epitaxial method.