Bonded Body Oxygen Gradient for Piezoelectric Substrate
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Solution Overview
Problem
Existing bonded bodies with piezoelectric single crystal substrates and supporting substrates face challenges in achieving high bonding strength and insulation properties, leading to peeling issues during processing due to insufficient oxygen diffusion in the bonding layer.
Innovation Solution
A bonded body structure with a piezoelectric single crystal substrate and a single crystal silicon supporting substrate, featuring a bonding layer with a specific composition of Si(1-x)Ox (0.008≤x≤0.408) and an amorphous layer containing silicon, oxygen, and argon atoms, where the oxygen concentration gradient is optimized to enhance bonding strength and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high-resistance bonding layer is used to improve insulation properties, then noise and loss are reduced, but bonding strength decreases causing peeling during processing
Solution Approach 1:
The bonding layer has non-uniform oxygen concentration distribution, with higher oxygen content near the piezoelectric substrate interface and lower oxygen content near the supporting substrate interface. This local variation in composition allows different regions to serve different functions: the high-oxygen region provides strong bonding and insulation, while the low-oxygen region maintains adequate bonding strength, resolving the contradiction between insulation and bonding strength.
Solution Approach 2:
The invention changes the oxygen concentration parameter within the bonding layer from uniform to gradient distribution. By controlling the oxygen concentration to range from 0.5-5 at% near the piezoelectric substrate to 0.1-2 at% near the supporting substrate, the bonding layer achieves both high insulation properties and sufficient bonding strength, preventing peeling during processing.
2Object-affected harmful factors
If oxygen concentration is increased in the bonding layer to improve insulation, then electrical resistance increases, but bonding strength decreases due to stress concentration
Solution Approach 1:
The bonding layer exhibits spatially varying oxygen concentration, with the region adjacent to the piezoelectric substrate containing more oxygen (0.5-5 at%) to provide insulation, while the region adjacent to the supporting substrate contains less oxygen (0.1-2 at%) to maintain bonding strength. This local differentiation resolves the contradiction between electrical resistance and bonding strength.
Solution Approach 2:
The oxygen concentration parameter is optimized to vary continuously through the bonding layer thickness. The gradient profile ensures that electrical resistance is sufficiently high where needed while bonding strength is maintained where mechanical stress occurs, achieving both insulation and structural integrity.
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 optimized bonding layer and amorphous layer structure improves the insulation properties and bonding strength, reducing peeling and enhancing the durability of the bonded body, particularly by generating a peak oxygen concentration within the amorphous layer to facilitate oxygen diffusion.
Implementation Method 1
the concentration of oxygen atoms at an end part of the amorphous layer on a side of the supporting layer is higher than an average concentration of the oxygen atoms in the bonding layer
Data Source
AI summary
A bonded body includes: a piezoelectric single crystal substrate; a supporting substrate composed of a single crystal silicon; a bonding layer—provided between the supporting substrate and piezoelectric single crystal substrate and having a composition of Si(1-x)Ox (0.008≤x≤0.408); and an amorphous layer provided between the supporting substrate and bonding layer and containing silicon atoms, oxygen atoms, and argon atoms. The concentration of the oxygen atoms in an end part of the amorphous layer on a side of the bonding layer is higher than the average concentration of the oxygen atoms in the bonding layer.