Substrate Joining Hydrophilic Treatment for Strong Vacuum Bonding
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Solution Overview
Problem
Existing substrate joining methods, such as those using reactive ion etching and radical irradiation, often result in insufficient production of hydroxyl groups on joint surfaces, leading to inadequate joint strength between substrates, especially when joining in a vacuum environment.
Innovation Solution
A substrate joining method involving a hydrophilic treatment step that includes nitrogen gas reactive ion etching followed by nitrogen radical treatment, enhancing the formation of hydroxyl groups on the joint surfaces, which are then brought into contact and heated to form strong covalent bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If substrates are joined in the atmosphere with water molecules interposed, then joining can be achieved without vacuum equipment, but large voids occur due to air incorporation
Solution Approach 1:
The patent applies vacuum environment (inert environment) during the joining process to prevent air incorporation between substrates. By maintaining vacuum conditions during substrate approach and bonding, the method eliminates the harmful effect of air molecules that would otherwise form large voids, while still allowing water molecules to mediate the bonding process.
2Manufacturing precision
If substrates are joined in a vacuum, then voids are reduced by preventing air incorporation, but insufficient OH groups are produced on joint surfaces leading to inadequate joint strength
Solution Approach 1:
The patent applies preliminary hydrophilic treatment to the substrate surfaces before joining in vacuum. This pre-treatment introduces sufficient OH groups on the joint surfaces through exposure to water vapor or plasma treatment in the atmosphere prior to vacuum sealing, ensuring that when substrates are joined in vacuum, both void reduction and adequate joint strength are achieved.
Solution Approach 2:
The patent uses water molecules as an intermediary substance that mediates the bonding process. Water molecules serve dual functions: they provide OH groups for forming hydrogen bonds and covalent bonds between substrates, and they enable bonding to occur in vacuum environment without requiring air presence, thus resolving the contradiction between vacuum benefits and OH group production.
3Object-affected harmful factors
If substrates are joined while deflecting them in the center, then air incorporation is prevented, but distortion occurs in the substrates and alignment accuracy deteriorates
Solution Approach 1:
The patent uses vacuum environment as an inert atmosphere to prevent air incorporation between substrates during joining. By maintaining vacuum conditions, air molecules are excluded from the interface region, eliminating the need for mechanical deflection methods that would cause substrate distortion and alignment errors.
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 method effectively increases the number of hydroxyl groups on the substrates, improving joint strength and reducing voids by forming a large number of hydrogen bonds that convert to covalent bonds during heating, thereby enhancing the bonding quality between substrates.
Implementation Method 1
a first etching step of performing reactive ion etching using nitrogen gas on the joint surfaces of the substrates
Implementation Method 2
a radical treatment step of performing a radical treatment to irradiate the joint surfaces of the substrates with nitrogen radicals after the first etching step
Implementation Method 3
producing hydroxyl groups (OH groups) on the joint surfaces of the two substrates and bringing into mutual contact and pressurizing the joint surfaces of the two substrates to form the hydrogen bond between the joint surfaces
Implementation Method 4
the water molecules that are interposed between the joint surfaces of substrates can turn into OH groups and then turn into a strong covalent bond through heating
Data Source
AI summary
The substrate joining method is a substrate joining method for joying two substrates, including a hydrophilic treatment step of hydrophilizing at least one of respective joint surfaces of the two substrates that are to be joined to each other and a joining step of joining the two substrates after the hydrophilic treatment step. The hydrophilic treatment step includes a step of performing a N2 RIE treatment to perform reactive ion etching using N2 gas on the joint surfaces of the substrates and a step of performing a N2 radical treatment to irradiate the joint surfaces of the substrates with N2 radicals after the step of performing the N2 RIE treatment.