Substrate Freeze Cleaning with Gap Control to Prevent Dew
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Solution Overview
Problem
The existing freeze-cleaning methods for substrates with fine uneven portions are prone to damaging these features and often result in dew condensation, which can lead to contamination and watermarks due to the cooling of the stage and surrounding air.
Innovation Solution
A substrate processing apparatus with a rotatable stage, liquid supply, cooling unit, and moving unit, controlled by a controller to manage the distance between the stage and substrate, which includes a supercooling process, freezing process, and thawing process, along with a liquid-repellent film on the stage and holders to prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cooling gas is supplied to the opposite surface of the substrate to freeze the water film, then the freezing process can be improved, but the stage and surrounding air are cooled causing dew condensation on the substrate
Solution Approach 1:
The cooling gas supply is segmented into two separate nozzles: one facing the substrate surface and another facing the stage surface. This allows independent control of cooling zones, enabling the substrate to be frozen while the stage remains relatively warm to prevent dew condensation.
Solution Approach 2:
Different regions of the system are given different thermal properties - the substrate surface is locally cooled for freezing, while the stage surface is kept warmer to avoid dew condensation. This localized thermal management resolves the contradiction between effective freezing and preventing harmful condensation.
2Reliability
If cooling gas is supplied to freeze the water film on the substrate surface, then contaminants can be removed, but the substrate may be over-cooled causing dew condensation
Solution Approach 1:
The cooling system is segmented into substrate-directed cooling and stage-directed cooling. The substrate cooling ensures effective contaminant removal through freezing, while the stage cooling is controlled separately to prevent excessive cooling that would cause dew condensation.
Solution Approach 2:
The stage acts as an intermediary thermal element - it is cooled enough to support the freezing process but not so much that it causes dew condensation on the substrate. The stage temperature serves as a mediator between the cooling gas supply and the substrate thermal state.
3Manufacturing precision
If the stage temperature is maintained low for effective freezing, then the freezing process is improved, but heat transfer from substrate to stage increases cooling the substrate excessively
Solution Approach 1:
The thermal management is segmented into substrate cooling (for freezing) and stage cooling (controlled to prevent excessive heat transfer). This allows the stage to maintain a temperature that supports freezing without causing excessive substrate cooling.
Solution Approach 2:
The stage temperature parameter is optimized to a specific range that enables effective freezing of the water film while preventing excessive heat transfer that would over-cool the substrate and cause dew condensation.
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 approach effectively suppresses dew condensation on the substrate, reduces heat transfer, and prevents contamination by maintaining a controlled distance and using a liquid-repellent film to separate the substrate and stage, ensuring efficient cleaning without damaging the substrate's fine features.
Implementation Method 1
the amount of heat transferred from the substrate to the stage may increase due to a radiation
Implementation Method 2
a supercooling process of bringing the liquid on the substrate into a supercooled state from the temperature higher than the freezing point
Implementation Method 3
a freezing process (solid-liquid phase) progressed from the supercooled state until a completion of a freezing
Implementation Method 4
the amount of heat transferred from the substrate to the stage may increase due to a radiation
Implementation Method 5
a liquid-repellent film on the stage and holders to prevent contamination
Data Source
AI summary
A substrate processing apparatus according to an embodiment of the present disclosure includes: a stage; a plurality of holders configured to hold a substrate; a liquid supply configured to supply a liquid to a surface of the substrate opposite to the stage; a cooler configured to supply a cooling gas to a space between the stage and the substrate; a mover configured to change a distance between the stage and the substrate; and a controller configured to control the cooler and the mover. The controller performs a cooling process that at least includes a supercooling process and a freezing process (solid-liquid phase), and a thawing process after the cooling process. In the cooling process, the controller controls the mover to set the distance to a first distance, and in the thawing process, the controller controls the mover to set the distance to a second distance longer than the first distance.