PLZT Ferroelectric Thin Film Composition Gradient
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Solution Overview
Problem
Conventional methods for forming thin films of PLZT on silicon substrates result in poor crystallization, leading to suboptimal piezoelectric properties, as the undercoated PLT layer has low piezoelectric properties and does not effectively enhance the overall piezoelectric film properties.
Innovation Solution
A ferroelectric thin film is formed using a composite oxide with a metallic additive other than Pb, Zr, and Ti, where the additive concentration is varied in the thickness direction to achieve satisfactory crystallization and high piezoelectric properties, maintaining the perovskite structure without degrading crystallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin film of PLZT is obtained by film formation, then it is possible to reduce the thickness of the film for size reduction and dense packing, but crystallization is poor as compared with PZT, resulting in suboptimal piezoelectric properties
Solution Approach 1:
The patent changes the chemical composition parameters of the film by incorporating PLZT (lead lanthanum zirconate titanate) with controlled La substitution ratios instead of conventional PZT. This parameter change in material composition enables satisfactory crystallization in thin films while maintaining high piezoelectric properties, resolving the contradiction between thin film formation and crystallization quality.
2Reliability
If La is added to PZT to enhance relative permittivity and piezoelectric property, then high piezoelectric constant is achieved in bulk ceramic, but crystallization deteriorates in thin film formation
Solution Approach 1:
The patent optimizes the La substitution parameter in PLZT, specifically using La content ratios of 2-10% (particularly 5% La substitution) to achieve the balance between enhanced piezoelectric properties and maintained crystallization quality in thin films.
Solution Approach 2:
The patent applies different La substitution ratios at different locations within the film structure, creating a composition gradient that optimizes both crystallization and piezoelectric properties locally throughout the film thickness.
3Manufacturing precision
If an undercoated PLT layer is formed to enhance crystallization of PLZT, then crystallization is improved, but the undercoated layer has low piezoelectric property and is not appropriate for enhancing overall piezoelectric film properties
Solution Approach 1:
The patent removes the separate PLT undercoated layer structure and instead directly forms PLZT with optimized composition on the substrate. This extraction of the intermediate layer eliminates the need for a low piezoelectric property undercoat while achieving satisfactory crystallization through direct PLZT film formation with controlled La substitution.
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
This approach allows for the creation of a ferroelectric thin film with enhanced piezoelectric properties and predetermined thickness, enabling the manufacture of piezoelectric elements with improved performance without compromising crystallization.
Implementation Method 1
piezoelectric property of the film is enhanced
Implementation Method 2
ferroelectric thin film formed with a composite oxide
Data Source
AI summary
In order to obtain a ferroelectric thin film that is formed to have a predetermined thickness on a substrate, that have satisfactory crystallization and that achieves a high piezoelectric property, a method of manufacturing such a ferroelectric thin film and a method of manufacturing a piezoelectric element having such a ferroelectric thin film, when a dielectric material of a perovskite structure is formed into a film on the substrate, a predetermined amount of additive is mixed with PZT, and the concentration of the additive mixed is varied in the thickness direction of the thin film.