Substrate Drying via Marangoni Convection for Particle Removal
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Solution Overview
Problem
Existing substrate drying methods risk leaving particles on the surface of substrates due to inadequate removal of processing liquids, which can contaminate the substrate's front surface.
Innovation Solution
A substrate processing method involving a substrate holding step, liquid film formation, vapor atmosphere filling, dry region formation, and expansion, utilizing a low surface tension vapor to create Marangoni convection that moves particles away from the substrate surface, ensuring complete drying without residual particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a vapor of a low surface tension liquid (IPA) is sprayed onto the liquid film of processing liquid to form a liquid film removal region and expand it over the whole area of the upper surface of the substrate, then the upper surface of the substrate is dried, but particles included in the processing liquid may appear on the upper surface of the substrate
Solution Approach 1:
The invention changes the physical parameters of the processing liquid by introducing a vapor atmosphere of a low surface tension liquid (IPA) with different surface tension properties. This parameter change triggers Marangoni convection, which fundamentally alters the liquid film's behavior and particle transport mechanisms, enabling particles to be moved toward the liquid film removal region rather than remaining on the substrate surface.
Solution Approach 2:
The invention replaces conventional mechanical drying methods with a chemically-driven convection system. Instead of relying solely on mechanical removal or evaporation, the system uses Marangoni convection induced by surface tension gradients to automatically transport particles away from the substrate surface, substituting mechanical particle removal with a self-organizing fluid dynamic system.
2Productivity
If a liquid film of processing liquid is formed on the upper surface of the substrate and then dried by spraying vapor, then the substrate can be processed, but particles in the processing liquid may be left on the substrate surface
Solution Approach 1:
The invention introduces a vapor atmosphere of low surface tension liquid as an intermediary medium between the processing liquid and the substrate surface. This intermediary vapor phase mediates the interaction by creating surface tension gradients that drive Marangoni convection, effectively transferring momentum and particles from the liquid film toward the removal region while maintaining processing efficiency.
Solution Approach 2:
The invention extracts particles from the processing liquid film by creating a directed flow through Marangoni convection. The vapor-induced surface tension gradients cause the liquid film to convect in a direction that carries particles toward the liquid film removal region, effectively extracting contaminants from the substrate surface area.
3Manufacturing precision
If conventional drying methods are used to remove processing liquid from the substrate, then the substrate can be dried, but particles may remain on the front surface of the substrate
Solution Approach 1:
The invention introduces dynamic convection flows into the drying process through Marangoni effects. Instead of static evaporation or simple mechanical removal, the system creates dynamic liquid film motion that actively transports particles away from the substrate surface. The vapor atmosphere continuously drives convective currents that maintain particle transport throughout the drying process.
Solution Approach 2:
The invention converts the harmful effect of surface tension differences into a beneficial force. The surface tension gradient, which could potentially cause uneven drying or defects, is instead harnessed to drive Marangoni convection that systematically transports particles away from the substrate surface. The potential harm of surface tension variations is transformed into the benefit of automated particle removal.
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
Effectively prevents particle deposition on the substrate surface by using Marangoni convection to incorporate particles into the processing liquid, which is then removed, ensuring a clean and dry substrate surface.
Implementation Method 1
a vapor atmosphere filling step of filling surroundings of the liquid film of the processing liquid with a vapor atmosphere containing a vapor of a low surface tension liquid... a dry region forming step of forming a dry region in the liquid film of the processing liquid by partially excluding the processing liquid while spraying a gas containing the vapor of the low surface tension liquid onto the liquid film
Data Source
AI summary
A substrate processing method includes a vapor atmosphere filling step of filling surroundings of a liquid film of a processing liquid with a vapor atmosphere containing a vapor of a low surface tension liquid that has a lower surface tension than the processing liquid, a dry region forming step of forming a dry region in the liquid film of the processing liquid by partially excluding the processing liquid while spraying a gas containing the vapor of the low surface tension liquid onto the liquid film of the processing liquid in parallel with the vapor atmosphere filling step, and a dry region expanding step of expanding the dry region toward an outer periphery of a substrate while rotating the substrate in parallel with the vapor atmosphere filling step.