Substrate Freeze Cleaning with Supercooled Liquid Control
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Solution Overview
Problem
The existing freeze-cleaning methods for substrates, such as semiconductor wafers and photolithography masks, often damage fine uneven portions on the surface due to stress generated from ice film volume changes during the freezing process, and struggle to effectively remove contaminants while maintaining high removal ratios.
Innovation Solution
A substrate treatment device that includes a placement stand for rotating the substrate, a cooling part for supplying cooling gas, a liquid supplier for managing the liquid state, and a controller to set the substrate's liquid to a supercooled state, controlling the rotation speed, cooling gas flow rate, and liquid supply to optimize the freezing and thawing processes, thereby minimizing surface damage and enhancing contamination removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the liquid is frozen to form an ice film for contamination removal, then the removal ratio of contaminants is improved, but stress is generated between the ice film and substrate due to volume change, causing damage to the substrate surface and fine uneven portions
Solution Approach 1:
The patent applies parameter changes by controlling the liquid temperature to be in a supercooled state (below freezing point but not yet frozen) and precisely controlling the freezing process parameters. The controller adjusts the cooling gas flow rate and liquid supply amount to manage the phase transition, reducing thermal stress and volume change impact on the substrate while maintaining effective contamination removal.
Solution Approach 2:
The patent implements dynamics by continuously adjusting the cooling gas flow rate and liquid supply amount during the cleaning process. The controller dynamically modifies these parameters based on the cleaning stage, allowing the system to adapt to changing conditions and minimize stress on the substrate while maintaining cleaning effectiveness throughout the process.
2Manufacturing precision
If the cooling gas flow rate is increased to improve contamination removal, then the removal ratio of contaminants is improved, but the volume change of ice film increases, generating more stress on the substrate surface
Solution Approach 1:
The patent applies periodic action by alternating between liquid supply and cooling gas supply in controlled cycles. The controller periodically supplies liquid to the substrate, then supplies cooling gas to freeze the liquid, and subsequently supplies warm gas to melt the ice film. This periodic cycling allows contamination removal while managing ice film volume changes to reduce substrate stress.
Solution Approach 2:
The patent changes parameters by dynamically adjusting the cooling gas flow rate within optimal ranges rather than using constant high flow. The controller modulates the cooling gas flow rate to achieve effective freezing while controlling the rate and extent of ice film formation, thereby reducing thermal and mechanical stress on the substrate surface.
3Manufacturing precision
If the liquid supply amount is increased to enhance contamination removal, then the removal ratio of contaminants is improved, but the ice film thickness increases, causing greater stress and potential damage to fine uneven portions
Solution Approach 1:
The patent applies partial action by supplying liquid in controlled, moderate amounts rather than excessive quantities. The controller adjusts the liquid supply amount to form a thin liquid film that is sufficient for contamination removal but does not create overly thick ice films that would generate damaging stress. This partial action approach achieves effective cleaning while minimizing substrate damage.
Solution Approach 2:
The patent changes the liquid supply amount parameter to optimize the balance between cleaning effectiveness and substrate protection. The controller precisely controls the liquid supply amount to ensure adequate coverage for contamination removal while limiting ice film thickness to prevent excessive stress on fine uneven portions of the substrate surface.
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
The device effectively suppresses damage to surface uneven portions and improves the removal ratio of contaminants by controlling the supercooled state and phase transition of the liquid, allowing for repeated cleaning processes without excessive wear on the substrate.
Implementation Method 1
The controller sets the liquid on the surface of the substrate to be in a supercooled state
Implementation Method 2
the supply of pure water is stopped, and a part of the supplied pure water is discharged to form a water film on the surface of the substrate. The water film is frozen by the cooling gas supplied to the substrate
Implementation Method 3
stress is generated between the ice film and the substrate due to the volume change of the ice film
Implementation Method 4
pure water is supplied to the ice film to melt the ice film, and contaminations are removed from the surface of the substrate together with the pure water
Data Source
AI summary
According to one embodiment, a substrate treatment device includes a placement stand configured to rotate a substrate, a cooling part configured to supply a cooling gas into a space between the placement stand and the substrate, a liquid supplier configured to supply a liquid on a surface of the substrate opposite to the placement stand side, a detector configured to detect a state of the liquid on the surface of the substrate, and a controller controlling at least one of a rotation speed of the substrate, a flow rate of the cooling gas, or a supply amount of the liquid. The controller sets the liquid on the surface of the substrate to be in a supercooled state, obtains a temperature of the liquid in the supercooled state at a start of freezing, and is configured to calculate a removal ratio of a contamination.