Piezoelectric Substrate Roughness Layout for Spurious Mode Suppression
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Solution Overview
Problem
Piezoelectric devices generate undesired higher-mode spurious responses that degrade device characteristics and can leak into adjacent regions, affecting overall performance.
Innovation Solution
Increase the surface roughness of the support substrate in regions without the multilayer film to attenuate higher-mode spurious responses, using techniques like laser milling or etching to create varying surface roughness patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the support substrate surface is made smooth in the second region, then the adhesion of the insulating layer is improved, but higher-mode spurious responses leak into the insulating layer region and affect adjacent piezoelectric devices
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions of the support substrate. Specifically, the first region (where the multilayer film is formed) has a first surface roughness, while the second region (where the insulating layer is formed) has a second surface roughness that is greater than the first. This local differentiation allows the insulating layer region to attenuate spurious responses while maintaining adequate adhesion for the insulating layer.
2Object-affected harmful factors
If the surface roughness in the second region is increased, then spurious responses are attenuated, but the adhesion of the insulating layer may be compromised
Solution Approach 1:
The patent controls the surface roughness parameter of the support substrate in the second region to be within a specific range (greater than the first region but within predetermined limits). By optimizing this parameter, the patent achieves a balance between attenuating spurious responses and maintaining adequate adhesion for the insulating 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
Effectively reduces the intensity of spurious responses and minimizes their impact on the main mode signal, while enhancing the adhesion of layers and preventing separation or damage to the device components.
Implementation Method 1
the surface roughness of the support substrate in the second region is greater than a surface roughness of the support substrate in the first region. Thus, when the surface roughness is increased, variations in the thickness of the support substrate in the region is increased, and a resonant mode coinciding with the generated spurious responses is thus hardly generated
Data Source
AI summary
A piezoelectric device includes a support substrate, an intermediate layer on the support substrate in a first region, a piezoelectric layer on the intermediate layer, a functional element on the piezoelectric layer, and an insulating layer. The insulating layer is located on the support substrate in a second region adjacent to the first region. A surface roughness of the support substrate in the second region is greater than a surface roughness of the support substrate in the first region.