Alumina Adhesion Layer Prevents Titanium Diffusion in Platinum Bottom Electrodes
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Solution Overview
Problem
Conventional electromechanical conversion elements in inkjet recording apparatuses face issues with hole formation in platinum films due to titanium diffusion, leading to reduced conductive oxide crystal continuity, surface roughness, and decreased withstand voltage, which complicates the formation of high-quality crystalline orientation and increases costs.
Innovation Solution
The use of an alumina film as an adhesion layer between the vibrating plate and the metal film prevents hole formation in the metal film, ensuring a dense structure and reducing lead diffusion, thereby enhancing the crystallinity and withstand voltage of the electromechanical conversion element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a titanium film is used as the bottom electrode to form the electromechanical conversion film, then good crystalline orientation properties are achieved, but titanium diffuses in the platinum film forming holes, reducing conductive oxide film continuity and surface quality
Solution Approach 1:
An alumina film is introduced as an intermediary layer between the titanium film and the platinum film. This mediator prevents direct contact between titanium and platinum, thereby stopping titanium diffusion into the platinum film and preventing hole formation, while still allowing the titanium film to provide its crystalline orientation function to the electromechanical conversion film
2Reliability
If the thickness of the platinum film is increased to eliminate holes, then conductive oxide film continuity is improved, but manufacturing cost increases due to more expensive metal usage
Solution Approach 1:
The alumina film acts as a protective intermediary that prevents titanium diffusion into the platinum film. This eliminates the need to increase platinum film thickness to prevent hole formation, thereby maintaining conductive oxide film continuity while using only the necessary minimum amount of expensive platinum material
3Reliability
If the thickness of the titanium film is reduced to decrease titanium diffusion, then less titanium diffuses in the platinum film, but adhesion between the platinum film and the vibrating plate deteriorates causing peeling
Solution Approach 1:
The alumina film serves as an adhesion-promoting intermediary layer between the titanium film and the platinum film. This allows the titanium film to be kept thin (reducing diffusion) while the alumina layer ensures strong bonding between the titanium and platinum layers, preventing peeling of the bottom electrode
4Manufacturing precision
If a platinum film and conductive oxide film are formed by sputtering method, then the electromechanical conversion film can be formed, but high temperature is required causing titanium diffusion and hole formation
Solution Approach 1:
The alumina film acts as a thermal barrier and diffusion prevention intermediary. It allows the sputtering process to be performed at high temperatures necessary for forming quality electromechanical conversion films, while the alumina layer blocks titanium diffusion into the platinum film even at these elevated temperatures
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 improves the continuity and crystallinity of the conductive oxide film, increases the withstand voltage, and stabilizes the ink jetting properties, reducing the likelihood of ink droplet jetting failures and maintaining stable performance.
Implementation Method 1
an alumina film, a metal film, and a conductive oxide film are sequentially laminated
Implementation Method 2
an electromechanical conversion film is disposed between a bottom electrode and a top electrode
Data Source
AI summary
An electromechanical conversion element for converting an electric signal into mechanical displacement or converting mechanical displacement into an electric signal, includes a bottom electrode in which an alumina film, a metal film, and a conductive oxide film are sequentially laminated; an electromechanical conversion film disposed on the conductive oxide film of the bottom electrode; and a top electrode disposed on the electromechanical conversion film, wherein the metal film is solid.