Plasma-Modified Bonded Substrates for Void-Free Strong Interfaces
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Solution Overview
Problem
The formation of voids and poor bonding strength are issues in bonded substrates composed of quartz and lithium tantalate or lithium niobate, which affect the performance of surface acoustic wave elements and optical modulators.
Innovation Solution
A method involving plasma treatment to form modified layers on the surfaces of substrates, followed by temporary bonding and annealing, to achieve a bonded substrate with high bonding strength and suppressed void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If substrates are bonded directly without surface modification, then the manufacturing process is simple, but voids are formed in the bonding surfaces and bonding strength is poor
Solution Approach 1:
The patent applies preliminary action by performing plasma treatment on substrate surfaces before bonding to modify surface properties. This pre-treatment creates a modified layer that enhances bonding strength and prevents void formation, resolving the contradiction between simple manufacturing and reliable bonding.
Solution Approach 2:
The patent changes physical parameters of the substrate surface through plasma treatment, modifying surface energy, roughness, and chemical composition. These parameter changes improve bonding strength and eliminate voids while maintaining process efficiency.
2Productivity
If substrates are bonded with conventional methods, then manufacturing time is short, but voids are formed and bonding quality is poor
Solution Approach 1:
By performing plasma treatment before bonding, the method prepares surfaces in advance to ensure high-quality bonding without requiring lengthy bonding processes. This preliminary modification enables both rapid bonding and high precision bonding surfaces.
Solution Approach 2:
The patent replaces conventional mechanical bonding methods with plasma-assisted bonding. The plasma treatment modifies surface properties to enable strong bonding without requiring high pressure or extended bonding time, thus maintaining productivity while improving precision.
3Device complexity
If no surface modification is applied, then the manufacturing process is simple and quick, but the bonding strength is insufficient and voids occur
Solution Approach 1:
The patent applies plasma treatment to change surface parameters such as energy, roughness, and chemical composition. This modification significantly improves bonding strength while adding minimal complexity to the manufacturing process.
Solution Approach 2:
Plasma treatment acts as a strong oxidizing environment that modifies substrate surfaces by introducing oxygen-containing groups and increasing surface energy. This acceleration of surface oxidation enhances bonding strength without requiring complex additional processing steps.
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 results in a bonded substrate with enhanced bonding strength and reduced voids, improving the performance of surface acoustic wave elements and optical modulators.
Implementation Method 1
a step of plasma-treating a surface of the first substrate and thereby forming a first modified layer over the surface of the first substrate
Implementation Method 2
a step of annealing the temporarily-bonded substrates and thereby bonding the first and second substrates to each other
Data Source
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AI summary
A bonded substrate having a high bonding strength in which the formation of voids is suppressed is provided. A bonded substrate according to an aspect of the present disclosure is a bonded substrate in which a first substrate and a second substrate are bonded to each other through their bonding surfaces. The first substrate includes a first modified layer on the side thereof on which its bonding surface is located, and the second substrate includes a second modified layer on the side thereof on which its bonding surface is located. A method for manufacturing a bonded substrate according to an aspect of the present disclosure is a method for manufacturing a bonded substrate in which a first substrate and a second substrate are bonded to each other, the method including: a step of plasma-treating a surface of the first substrate and thereby forming a first modified layer over the surface of the first substrate; a step of plasma-treating a surface of the second substrate and thereby forming a second modified layer over the surface of the second substrate; a step of temporarily bonding the first and second substrates to each other in a state where the first and second modified layers face each other; and a step of annealing the temporarily-bonded substrates and thereby bonding the first and second substrates to each other.