Silicon Oxide Bonding Layer for Piezoelectric Substrates
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Solution Overview
Problem
Existing bonded bodies of piezoelectric single crystal substrates and supporting bodies face challenges in achieving high electrical resistance in the bonding layer for improved insulation while maintaining strong bonding strength, which often results in separation during processing.
Innovation Solution
A bonded body comprising a supporting body made of polycrystalline ceramic or single crystal material, a piezoelectric single crystal substrate, and a bonding layer with a composition of Si(1-x)Ox (0.008≤x≤0.408) is used, where the bonding layer is activated by a neutralized beam for direct bonding, enhancing both insulation and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an organic adhesive layer is used to bond the piezoelectric substrate and supporting body, then bonding strength is improved, but electrical resistance decreases (insulation deteriorates)
Solution Approach 1:
The patent changes the material composition parameters of the bonding layer from organic adhesive to inorganic materials (silicon oxide, silicon nitride, aluminum nitride) with controlled stoichiometry ratios. This parameter change enables the bonding layer to simultaneously achieve high bonding strength and high electrical resistance, resolving the contradiction between bonding strength and insulation properties
Solution Approach 2:
The patent uses composite inorganic materials for the bonding layer, specifically silicon oxide-silicon nitride or silicon oxide-aluminum nitride composites. These composite materials combine the advantages of different inorganic materials to achieve both strong bonding and high insulation, eliminating the need to choose between bonding strength and electrical resistance
2Reliability
If the bonding layer is made thinner to improve insulation, then electrical resistance increases, but bonding strength decreases
Solution Approach 1:
The patent changes the material parameters of the bonding layer to inorganic materials with high intrinsic bonding strength. This allows the bonding layer to maintain sufficient bonding strength even at thin thicknesses (50-200 nm), thereby achieving both good insulation and adequate bonding strength simultaneously
Solution Approach 2:
The patent replaces the mechanical/chemical bonding mechanism of organic adhesives with the physical bonding mechanism of inorganic materials. This substitution enables the bonding layer to achieve high bonding strength through physical and chemical bonding at the atomic level, allowing thin layers to provide sufficient bonding while maintaining high electrical resistance
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 solution effectively improves the insulation and bonding strength of the bonding layer, preventing separation between the piezoelectric single crystal substrate and the supporting body, even after polishing, and maintains high electrical resistance within specified ranges.
Implementation Method 1
it is known direct bonding method of so-called FAB (Fast Atom Beam) system (patent document 4). According to this method, neutralized atomic beam is irradiated onto the respective bonding faces at ambient temperature to activate them, followed by direct bonding.
Data Source
AI summary
An object is to improve insulation in a bonding layer and to improve a bonding strength of a supporting body and piezoelectric single crystal substrate, in a bonded body having the supporting body made of a polycrystalline material or single crystal material, the piezoelectric single crystal substrate and the bonding layer provided between the supporting body and piezoelectric single crystal substrate, wherein the bonded body includes the supporting body, piezoelectric single crystal substrate and the bonding layer provided between the supporting body and piezoelectric single crystal substrate, and the bonding layer has a composition of Si(1-x)Ox (0.008≤x≤0.408).