Piezoelectric Substrate Bonding with Graded Amorphous Layer
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Solution Overview
Problem
Acoustic wave devices using piezoelectric single crystal substrates face warping issues due to thermal expansion differences between the substrate and supporting materials, leading to stress and potential failure at elevated temperatures.
Innovation Solution
A bonded body comprising a piezoelectric single crystal substrate, a supporting substrate with a polycrystalline or single crystal material, a bonding layer with a specific Si(1-x)Ox composition, and an amorphous layer with varying oxygen and argon concentrations, where the oxygen concentration is higher at the central part of the amorphous layer, reducing stress and warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a piezoelectric single crystal substrate is bonded with a supporting substrate, then heat dissipation is improved, but warping occurs due to thermal expansion difference
Solution Approach 1:
The patent applies local quality by creating a non-uniform amorphous layer with varying oxygen concentration across the bonding interface. The oxygen concentration is specifically higher at the central part and lower at the peripheral part of the amorphous layer, which locally adjusts the stress distribution to counteract warping while maintaining overall heat dissipation functionality.
Solution Approach 2:
The patent changes the compositional parameter of the amorphous layer by controlling the oxygen concentration distribution. The oxygen concentration is adjusted to be higher at the central part and lower at the peripheral part, which modifies the physical properties of the amorphous layer to reduce thermal stress and prevent warping during heating.
2Reliability
If a bonding layer with specific Si(1-x)Ox composition is used, then insulating property is improved, but manufacturing precision is required
Solution Approach 1:
The patent defines a specific compositional range for the bonding layer as Si(1-x)Ox where 0.008≤x≤0.408. This parameter specification balances the insulating property requirement with manufacturability, allowing sufficient insulation while providing a practical composition window that is achievable through standard fabrication processes.
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 reduces warping and stress on the piezoelectric single crystal substrate during heating by adjusting the in-plane distribution of the amorphous layer's thickness and oxygen concentration, enhancing the insulating properties and bonding strength.
Implementation Method 1
an amorphous layer provided between said supporting substrate and said bonding layer, said amorphous layer comprising oxygen atoms and argon atoms, wherein a concentration of said oxygen atoms at a central part of said amorphous layer is higher than a concentration of said oxygen atoms at a peripheral part of said amorphous layer
Implementation Method 2
a bonding layer provided on said piezoelectric single crystal substrate and having a composition of Si(1-x)Ox (0.008≤x≤0.408)
Implementation Method 3
a concentration of said oxygen atoms at a central part of said amorphous layer is higher than a concentration of said oxygen atoms at a peripheral part of said amorphous layer
Data Source
AI summary
A bonded body includes a piezoelectric single crystal substrate; a supporting substrate composed of a polycrystalline ceramic material or a single crystal material; a bonding layer provided on the 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, the amorphous layer containing oxygen atoms and argon atoms. A concentration of the oxygen atoms at a central part of the amorphous layer is higher than a concentration of the oxygen atoms at a peripheral part of the amorphous layer.