Composite Piezoelectric Substrate Bonding With Low-Loss Intermediate Layers
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Solution Overview
Problem
Existing methods for bonding piezoelectric substrates like LiNbO3 and LiTaO3 with support substrates result in reduced bonding strength, leading to separation issues during processing, especially when intermediate layers like silicon nitride are used.
Innovation Solution
A composite substrate design incorporating intermediate layers of SiO2, MgF2, or CaF2, with specific layer structures and fast atom beam irradiation to form sputtered films, followed by heating to enhance bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bonding layer made of Si3N4 is provided between the piezoelectric substrate and support substrate, then the bonding strength is increased and separation is prevented, but the energy confinement capability is reduced due to the presence of the bonding layer
Solution Approach 1:
The patent introduces an intermediate layer made of SiO2, MgF2, or CaF2 between the piezoelectric substrate and support substrate. This intermediate layer serves as a mediator that enables strong bonding while having minimal impact on energy confinement, thus resolving the contradiction between bonding strength and energy loss.
Solution Approach 2:
The patent changes the material parameter of the intermediate layer from Si3N4 to materials with lower refractive index (SiO2, MgF2, or CaF2). This parameter change reduces the impact on energy confinement while maintaining bonding strength through the intermediate layer structure.
2Object-generated harmful factors
If the piezoelectric substrate and support substrate are directly bonded without an intermediate layer, then the energy confinement is improved, but the bonding strength is insufficient and separation occurs during processing
Solution Approach 1:
The patent introduces an intermediate layer made of SiO2, MgF2, or CaF2 between the piezoelectric substrate and support substrate. This intermediate layer serves as a mediator that enables strong bonding while having minimal impact on energy confinement, thus resolving the contradiction between bonding strength and energy loss.
3Device complexity
If fast atom beam irradiation is applied to both bonding surfaces for activation treatment, then the bonding process is simplified, but the bonding strength is reduced leading to separation during processing
Solution Approach 1:
The patent applies fast atom beam irradiation to the support substrate before forming the intermediate layer, preparing the surface in advance. This preliminary action ensures that the intermediate layer forms with strong adhesion to the support substrate, preventing separation during subsequent processing while maintaining process simplicity.
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 method increases bonding strength between piezoelectric and support substrates, preventing separation and improving optical propagation characteristics.
Implementation Method 1
irradiating a surface of the piezoelectric material substrate with a fast atom beam to form a sputtered film made of a material of the piezoelectric material substrate on the surface of the intermediate layer
Implementation Method 2
bonding the piezoelectric material substrate and the intermediate layer on which the sputtered film is formed to obtain a bonded body
Data Source
AI summary
A composite substrate includes a piezoelectric material substrate made of an LiNbO3 or LiTaO3 material, a support substrate that supports the piezoelectric material substrate, and an intermediate layer provided on the support substrate, in which the piezoelectric material substrate and the support substrate are bonded to each other via the intermediate layer, the intermediate layer contains at least one of SiO2, MgF2, and CaF2, and the piezoelectric material substrate includes a first layer that does not contain inert gas atoms, a second layer that is disposed on a side closer to the intermediate layer than the first layer and contains the inert gas, and a third layer that contacts the intermediate layer, and does not contain the inert gas or contains the inert gas with a lower content than the content in the second layer.