Bimorph Piezoelectric Element with Sputtered Oxide Films
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Solution Overview
Problem
Bimorph piezoelectric elements with thin film configurations have low rigidity and difficulty in manufacturing, leading to challenges in handling and productivity, and the use of perovskite type oxides in vapor deposition methods results in spontaneous polarization issues and heterogeneous phase growth, causing cracking and low durability.
Innovation Solution
A laminate structure with a vibration plate of 10 μm to 500 μm thickness, where perovskite type oxide films are formed using a sputtering method, and pyrochlore type oxide layers are introduced in interfaces between the piezoelectric films and electrode layers, with symmetrical structures and inorganic adhesive layers for enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If two thin film piezoelectric elements are bonded to create a bimorph structure, then the generative force is improved, but the rigidity becomes insufficient for high resonance frequency applications
Solution Approach 1:
The patent employs a composite structure combining thin film piezoelectric elements with a thicker substrate material. The piezoelectric films (first and second) are bonded to opposite surfaces of a substrate, creating a bimorph configuration that maintains high generative force while the substrate provides the necessary rigidity for high resonance frequency applications.
2Force
If film piezoelectric elements are used in bonding configurations, then the generative force is improved, but handling difficulty and manufacturing complexity increase
Solution Approach 1:
The patent divides the piezoelectric structure into separate thin film layers (first piezoelectric film and second piezoelectric film) that are independently formed on opposite surfaces of the substrate. This segmentation allows each film to be manufactured and processed separately before final assembly, simplifying handling and manufacturing compared to bonding complete assembled elements.
3Reliability
If perovskite type oxide films are formed using vapor deposition method, then high piezoelectricity is achieved, but spontaneous polarization occurs causing increased potential difference and drive circuit load
Solution Approach 1:
The patent introduces asymmetric electrode configurations on opposite surfaces of the piezoelectric films. By designing the electrode patterns and connections asymmetrically, the spontaneous polarization effects in the perovskite type oxide films are compensated, reducing the net potential difference and thereby decreasing the load on the drive circuit while maintaining high piezoelectricity.
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 approach results in a bimorph piezoelectric element with high rigidity and durability, improved withstand voltage, and reduced stress concentration, enabling the use in high resonance frequency devices with enhanced manufacturing efficiency.
Implementation Method 1
perovskite type oxide films are formed using a sputtering method
Implementation Method 2
a piezoelectric body, there is a physical limit in the generative force of the unimorph actuator
Data Source
AI summary
A piezoelectric element is obtained using a method including: preparing a first structure; preparing a second structure; disposing a first facing electrode layer of the first structure to face a first surface of a vibration plate substrate and bonding the first structure to the first surface of the vibration plate substrate; processing the vibration plate substrate into a vibration plate by polishing or etching a second surface of the vibration plate substrate to which the first structure is bonded; preparing a laminate structure by disposing a second facing electrode layer of the second structure to face an exposed surface of the vibration plate and bonding the second structure to the vibration plate; and removing at least a part of a first silicon substrate of the first structure and a second silicon substrate of the second structure from the laminate structure.