Substrate Drying via Marangoni Convection to Suppress Particle Generation
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Solution Overview
Problem
Existing substrate drying methods using low surface tension vapors, such as rotagoni drying, often result in particle generation on the substrate surface due to thermal convection, which can lead to particles being left on the substrate after drying.
Innovation Solution
A substrate processing method involving the use of a first gas with a low surface tension vapor sprayed intersectingly to form a liquid film removal region, and a second gas with a low surface tension vapor discharged laterally and radially to maintain a rich vapor atmosphere, inducing Marangoni convection that prevents particles from reaching the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the liquid film removal region is enlarged to dry the entire substrate surface, then drying coverage is improved, but particles are generated and left on the substrate surface
Solution Approach 1:
The invention changes the physical parameters of the gas by introducing a carrier gas (nitrogen or air) mixed with IPA vapor, creating a gas stream with controlled composition and flow characteristics. This parameter change enables the gas to effectively remove liquid film while suppressing particle generation through modified convective patterns
Solution Approach 2:
The invention uses a carrier gas (nitrogen or air) as an intermediary substance to transport IPA vapor to the liquid film. This intermediary gas stream serves as a medium that facilitates liquid film removal while controlling the convective forces that would otherwise cause particle generation and deposition on the substrate
2Manufacturing precision
If vapor of low surface tension liquid is sprayed to form liquid film removal region, then liquid film is removed from substrate, but thermal convection generates particles that move to substrate surface
Solution Approach 1:
The invention modifies the temperature and composition parameters of the gas stream by mixing carrier gas with IPA vapor, creating a controlled gas environment that suppresses thermal convection while maintaining effective liquid film removal, thereby preventing particle generation and movement to the substrate surface
Solution Approach 2:
The carrier gas acts as an intermediary that modulates the convective patterns in the liquid film. By introducing this intermediary gas stream, the invention controls the flow dynamics to prevent thermal convection-driven particle movement toward the substrate while still achieving effective drying
3Productivity
If conventional drying method is used, then substrate surface is dried, but particles are left on the surface requiring rework
Solution Approach 1:
The invention maintains continuous supply of the modified gas stream (carrier gas + IPA vapor) throughout the drying process, ensuring uninterrupted suppression of particle generation and continuous removal of liquid film. This continuous action prevents particle deposition while maintaining high drying efficiency
Solution Approach 2:
The invention continuously adjusts the gas stream parameters (flow rate, composition, temperature) to optimize both drying efficiency and particle suppression. By dynamically controlling these parameters, the system maintains high productivity while ensuring surface quality free from particles
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 generation on the substrate surface by ensuring particles are removed with the liquid film, reducing the consumption of low surface tension liquid and maintaining a rich vapor atmosphere to enhance drying efficiency.
Implementation Method 1
within the boundary portion of the liquid film of the processing liquid, Marangoni convection flowing in a direction (that is, a direction opposite to the thermal convection) apart from the boundary between the liquid film of the processing liquid, the upper surface of the substrate and the gas phase is generated
Implementation Method 2
the vapor of isopropyl alcohol (IPA) whose boiling point is lower than that of water to the front surface of the substrate being rotated
Data Source
AI summary
A substrate processing method includes a first gas discharge step of discharging, from a first discharge port, a first gas containing a vapor of a low surface tension liquid having a lower surface tension than a processing liquid and spraying, to a liquid film of the processing liquid, the first gas from a direction intersecting the upper surface such that a liquid film removal region where the liquid film is removed from the liquid film of the processing liquid is formed, a second gas discharge step of discharging a second gas containing a vapor of a low surface tension liquid having a lower surface tension than the processing liquid from an annular second discharge port different from the first discharge port laterally and radially and a liquid film removal region enlargement step of enlarging the liquid film removal region.