Piezoelectric Layer Surface Unevenness via Metal Oxidation
Solution Overview
Problem
Existing methods for forming unevenness on the surface of piezoelectric layers, such as wet etching, often damage the piezoelectric layer and are difficult to precision-control, particularly in manufacturing piezoelectric elements for liquid ejecting heads and ultrasonic transducers.
Innovation Solution
A method involving the formation of an oxidizable metal layer on the piezoelectric layer, followed by thermal oxidation to create convex portions, and then isotropic dry etching to form pinpoint unevenness without using etchants, which reduces damage and enhances precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If wet etching is performed to form unevenness on the piezoelectric layer, then unevenness can be formed on the surface, but the etchant damages the piezoelectric layer causing changes in piezoelectric characteristics and foreign matter injection
Solution Approach 1:
The process is segmented into multiple steps: first forming an oxidizable metal layer on the piezoelectric layer, then performing thermal oxidation to create convex portions, and finally performing isotropic dry etching on the metal layer. This segmentation allows the piezoelectric layer to be protected from direct etchant contact while still achieving the desired unevenness formation.
Solution Approach 2:
An oxidizable metal layer is introduced as an intermediary between the piezoelectric layer and the etching process. This metal layer serves as a sacrificial protective barrier that can be selectively removed to form the desired unevenness pattern without exposing the piezoelectric layer to damaging etchants.
2Shape
If wet etching is performed to form unevenness on the piezoelectric layer, then unevenness can be formed, but it is difficult to achieve pinpoint precision and control in specific regions
Solution Approach 1:
The metal layer is formed with spatially varying thickness or selective coverage in different regions, allowing local control over where unevenness will form after etching. This enables pinpoint precision in specific regions by controlling the metal layer deposition pattern rather than relying on etchant diffusion control.
3Manufacturing precision
If isotropic dry etching is performed on the metal layer, then pinpoint unevenness can be precisely formed without damaging the piezoelectric layer, but an additional metal layer formation step is required
Solution Approach 1:
The oxidizable metal layer serves multiple functions: it acts as a protective barrier during etching, provides a sacrificial material for unevenness formation, and can be integrated with existing electrode structures in the piezoelectric device. This multi-functionality justifies the additional step by providing multiple benefits from a single 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 approach minimizes damage to the piezoelectric layer, allows for precise formation of unevenness, and simplifies the manufacturing process by integrating the metal layer as part of the electrode, thereby improving the adhesion and reducing the risk of altering the piezoelectric characteristics.
Implementation Method 1
aggregating the metal layer by thermal oxidation
Data Source
AI summary
A method of manufacturing a piezoelectric element includes a first electrode, a piezoelectric layer, and a second electrode, in which unevenness on one surface of the piezoelectric layer is formed by forming an oxidizable metal layer on the one surface of the piezoelectric layer; aggregating the metal layer by thermal oxidation; and performing isotropic etching on the metal layer aggregated on the one surface of the piezoelectric layer.