Hydrophilic Surface Bonding Without Plasma or High-Temperature Annealing
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Solution Overview
Problem
Existing direct bonding methods for hydrophilic surfaces, such as SiO2—SiO2, face challenges in achieving high bonding energy without plasma treatment, which can be costly, time-consuming, and incompatible with certain substrates, and may modify the surface, leading to potential device disturbances.
Innovation Solution
A method involving the deposition of a specific molecule with a hydrophilic functional group and a basic functional group on the hydrophilic surfaces, followed by bonding and optional low-temperature annealing, to enhance bonding energy without plasma treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plasma treatment is used to increase bonding energy, then bonding energy increases quickly, but surface modification occurs and introduces defects
Solution Approach 1:
The patent uses a liquid cleaning solution containing surfactants and chelating agents as an intermediary substance to clean and activate surfaces for bonding. This liquid mediator removes contaminants and creates hydrophilic surfaces without the harsh surface modification and defect introduction caused by plasma treatment, while still achieving high bonding energy through controlled chemical interaction at the interface.
Solution Approach 2:
The patent changes the chemical parameters of the bonding interface by using specific liquid solutions with controlled pH, surfactant concentration, and chelating agent content. These parameter adjustments create optimal surface conditions for bonding without the extreme conditions of plasma treatment, achieving high bonding energy while preserving surface integrity and avoiding defect formation.
2Strength
If high temperature thermal annealing is used to increase bonding energy, then bonding energy increases, but thermal budget is exceeded for substrate compatibility
Solution Approach 1:
The patent performs preliminary surface preparation and activation using liquid cleaning solutions and surfactants before bonding. This preliminary chemical treatment creates hydrophilic surfaces with high surface energy that enable strong bonding at low temperatures, eliminating the need for high-temperature thermal annealing and keeping the thermal budget compatible with sensitive substrates.
Solution Approach 2:
The patent replaces the thermal mechanism (high-temperature annealing) with a chemical mechanism (surfactant and chelating agent treatment). This substitution allows bonding energy to be achieved through chemical interaction and surface energy optimization rather than thermal activation, maintaining low temperature processing while achieving strong bonds.
3Object-affected harmful factors
If conventional chemical cleaning is used to prepare surfaces, then contamination is removed, but bonding energy is insufficient for strong assembly
Solution Approach 1:
The patent uses a composite cleaning solution containing multiple functional components: surfactants for contamination removal, chelating agents for metal ion complexation, and pH adjusters for surface charge control. This composite chemical system provides both thorough cleaning and surface activation, achieving high bonding energy that conventional single-function cleaners cannot provide.
Solution Approach 2:
The patent employs strong oxidizing agents in the cleaning solution to rapidly and thoroughly remove organic and inorganic contaminants from surfaces. This accelerated oxidation process not only cleans effectively but also creates highly reactive, hydrophilic surface states that enhance bonding energy, overcoming the limitation of conventional cleaners that only remove contamination without sufficient surface activation.
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 achieves strong bonding energy at low temperatures (≤500°C) with improved mechanical resistance and compatibility with various substrates, avoiding surface modifications and defects, and is suitable for industrial applications.
Implementation Method 1
The specific molecule comprises a hydrophilic functional group and a basic functional group, separated by at least one atom
Implementation Method 2
the specific molecule comprising a hydrophilic functional group and a basic functional group
Implementation Method 3
the adhesion energy: this is the energy available to carry out spontaneous bonding. This is the energy that makes it possible to deform the two surfaces in order to bring them into contact on an atomic scale with the assistance of the Van der Waals forces.
Data Source
AI summary
A method of direct bonding comprising the following steps: supplying a first substrate and a second substrate, the first substrate being covered by a first hydrophilic surface and the second substrate being covered by a second hydrophilic surface, deposition of a specific molecule on the first hydrophilic surface and/or on the second hydrophilic surface, the specific molecule comprising a hydrophilic functional group and a basic functional group, separated by at least one atom, contacting the first hydrophilic surface with the second hydrophilic surface, whereby the two hydrophilic surfaces are bonded one with the other, and the first substrate and the second substrate are assembled, optionally, application of a bonding annealing heat treatment, preferably at a temperature less than or equal to 500° C.