Piezoelectric Element Seed Layer Thickness Optimization
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Solution Overview
Problem
Piezoelectric elements used in liquid ejecting heads face a challenge in maintaining effective voltage distribution, leading to reduced displacement due to voltage drop across seed layers, which affects the orientation and performance of the piezoelectric layers.
Innovation Solution
A piezoelectric element with a seed layer composed of a composite oxide having a perovskite structure, including bismuth in the A site and iron and titanium in the B site, is used, with a thickness of less than 20 nm and an island shape configuration to reduce voltage distribution and enhance displacement, while the piezoelectric layer is preferentially oriented to the (100) plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a seed layer is used to preferentially orient the piezoelectric layer to the (100) plane, then the orientation of the piezoelectric layer is improved, but the voltage applied to the piezoelectric layer drops due to voltage distribution to the seed layer
Solution Approach 1:
The patent changes the thickness parameter of the seed layer from conventional dimensions to less than 20 nm. This parameter change reduces the voltage distribution to the seed layer while maintaining its orientation function, thereby resolving the contradiction between achieving (100) plane orientation and preserving sufficient voltage for the piezoelectric layer
Solution Approach 2:
The patent applies different properties to different parts of the system: the seed layer is made extremely thin (less than 20 nm) to minimize voltage distribution, while the piezoelectric layer maintains its full thickness and piezoelectric properties. This local differentiation allows the seed layer to fulfill its orientation function without compromising the voltage available to the piezoelectric layer
2Manufacturing precision
If the seed layer thickness is increased to improve orientation control, then the orientation function is enhanced, but the voltage drop across the seed layer increases
Solution Approach 1:
The patent identifies thickness as a critical parameter and changes it to less than 20 nm. This parameter change creates an optimal balance where the seed layer is thin enough to minimize voltage distribution but still thick enough to provide sufficient orientation control for the piezoelectric layer
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 configuration enhances the displacement amount of the piezoelectric element, leading to improved discharge characteristics in liquid ejecting heads and increased detection sensitivity in sensors.
Implementation Method 1
a piezoelectric layer provided on the seed layer, the piezoelectric layer consisting of a piezoelectric material having a perovskite structure and preferentially oriented to a (100) plane
Data Source
AI summary
A piezoelectric element includes a first electrode; a seed layer comprised of a composite oxide having a perovskite structure and preferentially oriented to a (100) plane, the seed layer including bismuth in an A site and including iron and titanium in a B site, the seed layer having a thickness of less than 20 nm; a piezoelectric layer provided on the seed layer, the piezoelectric layer consisting of a piezoelectric material having a perovskite structure and preferentially oriented to a (100) plane; and a second electrode provided on the piezoelectric layer.