Piezoelectric Substrate Bonding via Argon Gradient Amorphous Layer
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Solution Overview
Problem
Piezoelectric single crystal substrates used in acoustic wave filters are susceptible to warping due to thermal expansion differences when bonded with supporting substrates, leading to heat dissipation issues and reduced performance in high-temperature communication devices.
Innovation Solution
A bonded body comprising a piezoelectric single crystal substrate and a supporting substrate with an amorphous layer containing niobium, tantalum, and argon, where the argon concentration is higher in the central part of the amorphous layer than the peripheral part, adjusting the in-plane distribution of the amorphous layer thickness to reduce stress and warping upon heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a piezoelectric single crystal substrate is bonded with a supporting substrate using conventional methods, then heat dissipation performance is improved, but warping occurs due to thermal expansion differences
Solution Approach 1:
The patent applies local quality by creating a non-uniform argon concentration distribution within the amorphous layer, with higher concentration at the center and lower concentration at the periphery. This localized compositional variation compensates for thermal expansion differences between the piezoelectric substrate and supporting substrate, reducing warping while maintaining heat dissipation performance.
Solution Approach 2:
The patent changes the compositional parameters of the amorphous layer by controlling the argon atom concentration gradient. By adjusting the argon concentration from center to periphery, the thermal stress distribution is optimized to minimize warping during heating processes while preserving the heat dissipation function.
2Ease of manufacture
If the argon concentration is uniformly distributed in the amorphous layer, then the bonding process is simple, but warping occurs upon heating
Solution Approach 1:
The patent implements local quality by establishing a non-uniform argon concentration profile in the amorphous layer, with higher concentration at the central region and lower concentration at the peripheral region. This spatially varying composition is specifically designed to counteract thermal expansion mismatches during heating, thereby suppressing warping while maintaining manufacturing feasibility through controlled deposition processes.
3Shape
If a thin amorphous layer is formed to reduce stress, then warping is reduced, but bonding strength may be insufficient
Solution Approach 1:
The patent optimizes the amorphous layer by controlling both its thickness and compositional gradient. The argon concentration is engineered to be higher at the center and lower at the periphery, which allows the layer to maintain adequate bonding strength while effectively reducing thermal stress-induced warping through controlled compositional variation rather than simply increasing thickness.
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 modified amorphous layer structure significantly reduces warping and stress on the piezoelectric single crystal substrate during heating, enhancing the thermal stability and performance of the bonded body.
Implementation Method 1
a large stress is applied on a crystal face of the piezoelectric single crystal substrate due to a difference of the thermal expansion between the piezoelectric single crystal substrate and supporting substrate
Implementation Method 2
it is possible to dissipate heat toward the side of the supporting substrate so that it is superior in a heat dissipating property than the acoustic wave filter composed of a single plate of a piezoelectric single crystal
Data Source
AI summary
A bonded body includes a supporting substrate; a piezoelectric single crystal substrate composed of a material selected from the group consisting of lithium niobate, lithium tantalate and lithium niobate-lithium tantalate; and an amorphous layer present between the supporting substrate and piezoelectric material substrate, and the amorphous layer contains one or more metal atoms selected from the group consisting of niobium and tantalum, an atom constituting the supporting substrate, and an argon atom. A concentration of the argon atom in a central part of the amorphous layer is higher than a concentration of the argon atom in a peripheral part of the amorphous layer.