Substrate Bonding With Nitrogen Activation and Timed Water Exposure
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Solution Overview
Problem
Conventional substrate bonding methods, particularly those involving hydrophilic bonding in a vacuum, often result in insufficient OH group generation on bonding surfaces, leading to weak bonding strength and potential substrate distortion due to air inclusion, which can cause microvoids and alignment issues.
Innovation Solution
A substrate bonding method and system that includes an activation treatment using nitrogen gas etching and nitrogen radical irradiation followed by exposure to water-containing gas within a controlled time frame to enhance OH group formation and subsequent heat treatment for converting hydrogen bonds to covalent bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrates are bonded in the air with water molecules interposed between bonding surfaces, then bonding can be achieved even without sufficient OH groups, but large voids occur due to air drawing-in and alignment precision deteriorates
Solution Approach 1:
The patent applies vacuum environment (inert atmosphere) to prevent air drawing-in during substrate bonding. By bonding substrates in a vacuum state, the harmful effect of air intrusion is eliminated, preventing void formation and maintaining alignment precision while achieving reliable bonding through water molecule mediation.
2Manufacturing precision
If substrates are bonded in a vacuum to prevent air drawing-in, then voids are prevented from occurring, but sufficient OH groups are not generated on bonding surfaces and bonding strength becomes insufficient
Solution Approach 1:
The patent applies preliminary activation treatment to generate sufficient OH groups on bonding surfaces before vacuum bonding. By pre-treating substrates with plasma or chemical methods to create hydroxyl groups, the bonding surfaces are prepared in advance to achieve strong bonding strength even when subsequent bonding occurs in vacuum conditions where air cannot provide additional OH groups.
3Ease of manufacture
If conventional RIE treatment and atmospheric air exposure are used to activate bonding surfaces, then processing is simple, but insufficient OH groups are generated and bonding strength becomes insufficient
Solution Approach 1:
The patent changes the activation method from conventional RIE with air exposure to plasma treatment or chemical treatment that generates sufficient OH groups. By modifying the activation parameters (using oxygen plasma, steam, or chemical solutions), the bonding surfaces acquire adequate hydroxyl groups to achieve strong bonding strength while maintaining process feasibility.
4Strength
If substrates are heated after bonding with water molecules interposed, then covalent bonds are formed, but microvoids occur
Solution Approach 1:
The patent applies preliminary removal of excess water molecules from bonding interfaces before heating. By pre-drying or evacuating the bonding surfaces to eliminate trapped water, the subsequent heating process can convert hydrogen bonds to covalent bonds without generating microvoids from vaporizing trapped water molecules.
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
This approach significantly increases bonding strength by forming a large number of covalent bonds between substrates, ensuring stable and robust adhesion without microvoids or distortion.
Implementation Method 1
subjecting at least one of bonding surfaces to be bonded to each other of respective ones of the two substrates to at least one of reactive ion etching using nitrogen gas
Implementation Method 2
irradiation of nitrogen radicals, activating the bonding surface
Implementation Method 3
exposing the bonding surfaces of the two substrates to gas containing water within a preset standard time
Implementation Method 4
causing hydrogen bonds to be formed between the bonding surfaces
Implementation Method 5
heating enabled bonds between the bonding surfaces to be converted to strong covalent bonds
Data Source
AI summary
A substrate bonding method for bonding two substrates includes an activation treatment step of, by subjecting at least one of bonding surfaces to be bonded to each other of respective ones of the two substrates to at least one of reactive ion etching using nitrogen gas and irradiation of nitrogen radicals, activating the bonding surface, a gas exposure step of, after the activation treatment step, exposing the bonding surfaces of the two substrates to gas containing water within a preset standard time, and a bonding step of bonding the two substrates that have the bonding surfaces activated in the activation treatment step.