Low-H SiO2 Dielectric Joined Body for Selective Hollow Etching
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Solution Overview
Problem
Existing methods for forming hollow structures in elastic wave devices face challenges due to differences in etching rates between dielectric and sacrificial layers, leading to unintended etching of the dielectric film during sacrificial layer removal.
Innovation Solution
A joined body structure with a dielectric film comprising SiO2 as the main component and a hydrogen content of 0% to 1% atomic ratio, and a method involving sacrificial layer formation, joining, thinning, and selective removal to create a hollow part, using controlled etching conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sacrificial layer is used to form a hollow structure, then the hollow part can be formed, but the dielectric film may be etched along with the sacrificial layer due to similar etching rates
Solution Approach 1:
The invention changes the chemical composition parameters of the dielectric film by controlling the SiO2 content to 50-100 at% and H content to 0-1 at%, which fundamentally alters the etching rate characteristics of the dielectric film to achieve selective etching of the sacrificial layer while preserving the dielectric film
Solution Approach 2:
The invention applies different material compositions to different layers: the dielectric film uses low-H SiO2-based composition for etching resistance, while the sacrificial layer uses materials like SiN4 or SiOxNy that are highly susceptible to the same etching conditions, creating local quality differences that enable selective removal
2Ease of manufacture
If the etching rate difference between dielectric film and sacrificial layer is small, then the hollow structure can be formed, but selective removal of the sacrificial layer becomes difficult
Solution Approach 1:
The invention dramatically changes the etching rate parameter by controlling the dielectric film's H content to be extremely low (0-1 at%), which creates a large etching rate difference between the dielectric film and sacrificial layer, enabling precise selective removal of the sacrificial layer while leaving the dielectric film intact
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
Enables the formation of a desired hollow part with controlled etching rates, ensuring selective removal of the sacrificial layer and maintaining the dielectric film integrity.
Implementation Method 1
a small difference in etching rate between the dielectric film and the sacrificial layer causes a concern that not only the sacrificial layer but also the dielectric film may be etched
Data Source
AI summary
A joined body 1 includes a piezoelectric layer 11a including a piezoelectric material; a dielectric film 13 arranged under the piezoelectric layer 11a; a support substrate 14 joined with the piezoelectric layer 11a via the dielectric film 13; and a sacrificial layer provided between the support substrate 14 and the piezoelectric layer 11a, and capable of including a hollow part 17 formed therein. The dielectric film 13 includes SiO2 as a main component, and has a H content of 0% or more and 1% or less in terms of atomic ratio. As a result of this, a desired joined body including a hollow part is provided. Further, there is provided a method for manufacturing a joined body, in which the etching rate of the dielectric film is small, and by which the sacrificial layer can be selectively removed during etching.