Plasma-Assisted Hydrophilic Alignment for Glass Microchips
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Solution Overview
Problem
Current methods for bonding glass or quartz microchips face low success rates due to the use of hazardous chemicals like Piranha solution, which complicates the alignment process and increases the risk of microchip bursting during thermal bonding, leading to inefficient and unsafe manufacturing.
Innovation Solution
A plasma-assisted method for precise alignment and pre-bonding of glass or quartz microchips, where plasma cleaning forms a high hydrophilic surface, allowing for flexible alignment and capillary penetration of ultra-pure water, followed by vacuum drying to remove water completely, eliminating the need for Piranha solution and enhancing bonding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Piranha solution is used for cleaning glass or quartz microchips, then superficial cleaning and activation effect is improved, but manufacturing safety deteriorates and manufacturing efficiency decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the cleaning solution, replacing the highly aggressive Piranha solution (concentrated H2SO4 and H2O2) with a milder alternative cleaning solution that achieves effective cleaning and activation without the severe safety hazards. This parameter change maintains cleaning effectiveness while eliminating the harmful factors associated with Piranha solution.
Solution Approach 2:
The patent employs a disposable-like approach by using a simple, safe, and easily preparable alternative cleaning solution that can be used without the need for specialized handling equipment required for Piranha solution. The alternative solution can be prepared fresh and disposed of safely, eliminating the need for complex safety infrastructure.
2Manufacturing precision
If Piranha solution is used for cleaning glass or quartz microchips, then superficial cleaning and activation effect is improved, but manufacturing efficiency deteriorates
Solution Approach 1:
The alternative cleaning solution can be prepared quickly and used immediately without the need for complex safety protocols, storage infrastructure, or specialized handling procedures. This disposable-like approach eliminates time-consuming safety preparation and handling steps, thereby improving manufacturing efficiency while maintaining cleaning effectiveness.
3Ease of operation
If water is present in inter-chip during thermal bonding, then alignment is facilitated, but microchips bursting occurs
Solution Approach 1:
The patent applies preliminary plasma treatment to the microchip surfaces before bonding. This preliminary action creates a hydrophilic surface that facilitates controlled water management during alignment, and simultaneously prepares the surface for subsequent complete water removal during thermal bonding, preventing bursting while maintaining alignment ease.
Solution Approach 2:
The patent utilizes the phase transition of water from liquid to vapor during thermal bonding. By controlling the heating process and using plasma-prepared surfaces, the remaining water in the inter-chip region is gradually evaporated in a controlled manner, preventing sudden vaporization that would cause microchip bursting while allowing water to be present during the alignment phase.
4Manufacturing precision
If substrate and cover plate are washed by Piranha solution, then cleaning is improved, but alignment difficulty increases due to close fitting
Solution Approach 1:
The patent changes the surface energy parameters of the substrates through plasma treatment, creating a hydrophilic surface that allows controlled interaction with water during alignment. This parameter change enables the substrates to be cleaned effectively while maintaining sufficient surface properties that prevent excessive close-fitting during the alignment process, thereby improving alignment ease.
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 significantly improves the success rate of thermal bonding to nearly 100%, reduces manufacturing time to under 30 minutes, and ensures safety by avoiding hazardous chemicals, while preventing microchip bursting and defects.
Implementation Method 1
superficial cleaning and activation of substrate and cover plate performed by plasma cleaning device
Implementation Method 2
The high hydrophilic surface, playing an assistant role in the following alignment and pre-bonding of microstructure of microchips, is formed because of superficial cleaning and activation of substrate and cover plate performed by plasma cleaning device
Implementation Method 3
the fitness of both microchips is realized under hydrophilic interaction through capillary penetration
Implementation Method 4
pre-bonding of glass or quartz microchips are carried out by complete removal of water in microchips with vacuum drying
Data Source
Figure 1~2
Figure 3
AI summary
The plasma-assisted method of precise alignment and pre-bonding for microstructure of glass and quartz microchip belongs to micromachining and bonding technologies of the microchip. The steps of which are as follows: photoresist and chromium layers on glass or quartz microchip are completely removed followed by sufficient cleaning of the surface with nonionic surfactant and quantities of ultra-pure water. Then the surface treatment is proceeded for an equipping surface with high hydrophily with the usage of plasma cleaning device. Under the drying condition, the precise alignment is accomplished through moving substrate and cover plate after being washed with the help of microscope observation. Further on, to achieve precise alignment and pre-bonding of the microstructure of glass and quartz microchip, a minute quantity of ultrapure water is instilled into a limbic crevice for adhesion, and entire water is completely wiped out by vacuum drying following sufficient squeezing. Based on the steps above, it is available to achieve permanent bonding by further adopting thermal bonding method. In summary, it takes within 30 min to finish the whole operation of precise alignment and pre-bonding by this method. Besides, this method is of great promise because of its speediness, efficiency, easy maneuverability, operational safety and wide applications.