Alkaline Niobate Piezoelectric Device with Barrier Layer
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Solution Overview
Problem
Current piezoelectric materials like PZT and AlN face challenges due to lead content regulations and deposition difficulties, with materials like KNN and LNO being hard to deposit and requiring scarce and expensive elements, leading to inefficiencies in RF filters and actuators.
Innovation Solution
Incorporating a barrier layer of inert, conductive oxide or nitride materials like RuO2 or TiN between the metal electrode and piezoelectric material to prevent alkali diffusion and reaction, ensuring stoichiometric deposition and improved crystal orientation, using sputtering processes at controlled temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-free piezoelectric materials like KNN or LNO are used to replace PZT and AlN, then environmental compliance and coupling coefficient improve, but deposition difficulty and manufacturing complexity increase
Solution Approach 1:
A barrier layer is introduced as an intermediary between the metal electrode and the lead-free piezoelectric material layer. This barrier layer prevents harmful interactions and enables successful deposition of KNN or LNO materials that would otherwise be difficult to manufacture directly on metal substrates.
2Reliability
If scarce and expensive elements like Sc are used in AlNSc to improve piezoelectric performance, then coupling coefficient improves, but material cost increases
Solution Approach 1:
The invention uses abundant and inexpensive elements (K, Na, Nb, O) to create piezoelectric materials with high coupling coefficients, replacing scarce and expensive elements like Scandium while maintaining or improving performance.
3Ease of manufacture
If sputtering processes are used to deposit piezoelectric materials on metal electrodes, then deposition maturity and industrial applicability improve, but alkali diffusion and reaction with metal occur causing poor layer quality
Solution Approach 1:
The barrier layer serves as a protective intermediary that prevents alkali metals from diffusing into the metal electrode during sputtering deposition, thereby maintaining layer stoichiometry and crystal quality while enabling the use of mature sputtering processes.
4Device complexity
If no barrier layer is used between metal electrode and piezoelectric material, then device structure simplicity improves, but alkali diffusion causes stoichiometric imbalance and poor crystal orientation
Solution Approach 1:
The barrier layer is deposited in advance before the piezoelectric material layer, creating a protective interface that prevents subsequent alkali diffusion during the deposition process, thereby ensuring proper stoichiometry and crystal orientation without complicating the overall device structure.
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
Enhances the quality and orientation of piezoelectric layers, reducing deposition issues and material costs, and achieving better coupling coefficients, thus improving the performance of piezoelectric devices.
Implementation Method 1
a barrier layer of diffusion barrier material of alkalis in said metal and inert to alkalis of said niobate, said layer of barrier material being located between the lower layer of metal and the upper layer of piezoelectric material
Implementation Method 2
Sputtering processes, for which the equipment is already mature and widely used in industry
Data Source
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AI summary
The invention relates to a piezoelectric device comprising at least one upper layer (400) of alkali niobate-based piezoelectric material and a lower layer (200) of metal situated above a substrate (100), characterized in that it comprises a barrier layer (300) of a material that is diffusion-resistant to alkali metals and inert to alkali niobate, and said barrier layer being situated between the lower metal layer and the upper piezoelectric material layer. The invention also relates to a method for implementing the device.