Piezoelectric Device Diaphragm Stress Reduction via Impurity Diffusion
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Solution Overview
Problem
The existing piezoelectric devices used in ink jet recording heads face issues with the destruction of insulator films due to tensile stress caused by deformation of the piezoelectric actuator, leading to instability and inefficiency in ink ejection.
Innovation Solution
A piezoelectric device structure is developed with a substrate, diaphragm, and piezoelectric actuator laminated in a specific order, where the diaphragm includes a silicon layer, a zirconium oxide layer, and an impurity element layer that diffuses into the zirconium oxide layer, reducing tensile stress and enhancing mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulator film made of zirconium oxide is formed on the elastic film by thermal oxidation, then the electrical insulation performance is improved, but the insulator film is destroyed due to tensile stress when external force is applied
Solution Approach 1:
The patent applies composite materials by creating a multi-layer diaphragm structure consisting of a silicon oxide layer, a zirconium oxide layer, and an impurity element layer. The impurity element layer (containing elements like Ti, Cr, Al, or B) diffuses into the zirconium oxide layer to reduce tensile stress while maintaining electrical insulation. This composite approach allows the system to simultaneously achieve good electrical insulation and reduced mechanical stress that would otherwise destroy the insulator film.
Solution Approach 2:
The patent changes the chemical composition parameters of the diaphragm by introducing impurity elements (Ti, Cr, Al, B, etc.) into the zirconium oxide layer. By controlling the type and concentration of impurity elements, the internal stress state of the insulator film is modified from tensile to reduced stress, preventing film destruction while preserving electrical insulation properties. The impurity content is specifically controlled at 0.1-10 at% to achieve optimal stress reduction.
2Ease of manufacture
If the diaphragm is made with a simple structure, then the manufacturing process is simplified, but the tensile stress causes destruction of the insulator film
Solution Approach 1:
The patent introduces a composite multi-layer structure with silicon oxide layer, zirconium oxide layer, and impurity element layer. This composite approach maintains manufacturing feasibility through sequential deposition processes while solving the insulator film destruction problem. The additional layering does not significantly complicate the manufacturing process but effectively prevents film destruction by stress reduction.
Solution Approach 2:
The impurity element layer acts as an intermediary between the silicon oxide elastic film and the zirconium oxide insulator film. This intermediate layer modifies the stress distribution and reduces tensile stress in the zirconium oxide layer, preventing its destruction while maintaining the functional properties of both adjacent layers. The impurity elements serve as mediators that transfer and redistribute mechanical stress.
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
The proposed structure significantly reduces tensile stress in the diaphragm, preventing damage from external forces and improving the reliability and efficiency of ink ejection by enhancing the mechanical and electrical properties of the piezoelectric device.
Implementation Method 1
the impurity element diffuses into the third layer
Implementation Method 2
forming the second layer containing an oxide of the impurity element and the third layer containing zirconium oxide in which the impurity element is diffused by heating the impurity element layer and the zirconium layer
Implementation Method 3
a piezoelectric actuator provided on the diaphragm, and causes a pressure change in the ink in the pressure chamber by driving the piezoelectric actuator
Implementation Method 4
a diaphragm that vibrates by driving the piezoelectric actuator
Data Source
AI summary
A piezoelectric device includes a substrate, a diaphragm; and a piezoelectric actuator, in which the substrate, the diaphragm, and the piezoelectric actuator are laminated in this order in a first direction, the diaphragm includes a first layer containing silicon as a constituent element, a third layer disposed between the first layer and the piezoelectric actuator and containing zirconium as a constituent element, and a second layer disposed between the first layer and the third layer and containing at least one impurity element selected from the group consisting of a metal, a metalloid, and a semiconductor other than silicon and zirconium, as a constituent element, and the impurity element diffuses into the third layer.