Piezoelectric Device Insulation Layer Slant Design
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Solution Overview
Problem
Piezoelectric devices face breakage of wiring electrodes due to stress concentration at bent portions caused by step differences between insulation and piezoelectric thin films, leading to potential cracks.
Innovation Solution
A piezoelectric device design where the insulation layer has a thinner first region and a slanted second region that connects to the multilayer body without extending to the top of the piezoelectric layer, reducing the bending angle and stress concentration of the wiring electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation layer extends to the top of the piezoelectric layer, then the wiring electrode can be properly supported, but a large step difference occurs causing stress concentration and potential breakage
Solution Approach 1:
The insulation layer is designed with a slanted second region that transitions from the first region to the multilayer body, creating a gradual height transition instead of a vertical step. This dimensional change in the insulation layer profile reduces the step difference and minimizes bending stress on the wiring electrode.
Solution Approach 2:
The insulation layer parameters are changed by creating two distinct regions: a first region with thickness less than the multilayer body thickness, and a second region with a slanted profile that gradually increases in height. This parameter variation eliminates the abrupt step difference while maintaining proper wiring electrode support.
2Stress or pressure
If the insulation layer is made thinner to reduce step difference, then stress concentration is reduced, but the wiring electrode may lack sufficient support
Solution Approach 1:
Instead of uniformly thinning the insulation layer, the design introduces a slanted second region that provides gradual height transition. This maintains adequate support for the wiring electrode while reducing the abrupt step difference that causes stress concentration.
Solution Approach 2:
The second region of the insulation layer acts as an intermediary transition zone between the thinner first region and the multilayer body. This intermediate structure provides gradual support for the wiring electrode, reducing stress concentration while maintaining sufficient support strength.
3Reliability
If the insulation layer has a slanted second region not extending to the top, then the bending angle of the wiring electrode is reduced, but the insulation layer structure becomes more complex
Solution Approach 1:
The insulation layer is segmented into two distinct regions: a first region with uniform thickness and a second region with a slanted profile. This segmentation allows the structure to reduce wiring electrode bending while maintaining manufacturing feasibility through clear regional definitions.
Solution Approach 2:
The slanted profile is applied locally only in the second region of the insulation layer, rather than throughout the entire structure. This localized quality change reduces wiring electrode bending stress while keeping the overall device structure relatively simple and manufacturable.
Data Source
AI summary
A piezoelectric device includes a support substrate, an intermediate layer on the support substrate, a piezoelectric layer on the intermediate layer, a functional element on the piezoelectric layer, an insulation layer, and a wiring electrode. The insulation layer is on the support substrate and in contact with the intermediate layer and the piezoelectric layer. The wiring electrode extends from a top of the insulation layer to a top of the piezoelectric layer and is connected to the functional element. The insulation layer includes first and second regions. The first region is thinner than a thickness of the multilayer body. The second region connects the first region and the multilayer body, and includes a portion slanted from the first region toward an upper surface of the piezoelectric layer. The second region of the insulation layer does not extend to the top of the piezoelectric layer.