Substrate Drying via Gas Phase Layer and Directed Gas Stream
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Solution Overview
Problem
Existing substrate processing methods face challenges in efficiently drying substrates with fine patterns without causing pattern collapse, due to the prolonged heating time required and the subsequent prolonged exposure of the pattern to surface tension, which can lead to instability and collapse of the pattern.
Innovation Solution
A method involving the formation of a gas phase layer above the substrate by evaporating a processing liquid, followed by blowing a gas to open a hole in the liquid film and changing the direction of the gas stream to promote the movement of the liquid film outward, ensuring it is removed without stagnating at the substrate's periphery, while maintaining the gas phase layer until the entire liquid film is expelled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the substrate is rotated during heating to promote liquid film removal, then the liquid film can be moved by centrifugal force, but an interval must be secured between the substrate and heater causing prolonged heating time
Solution Approach 1:
The gas phase layer is formed in advance before liquid film removal begins. This preliminary action allows the liquid film to be removed more efficiently once formation is complete, reducing the overall time required for the drying process while maintaining effective liquid film removal.
Solution Approach 2:
The heating process continues continuously without interruption during liquid film removal. By maintaining continuous heating while the liquid film is being removed, the process eliminates idle time and ensures that the substrate remains at the optimal temperature for efficient liquid film removal throughout the entire process.
2Loss of time
If the substrate is not rotated to maintain heating efficiency, then heating time is reduced, but centrifugal force cannot be used to remove the liquid film causing prolonged exposure to surface tension
Solution Approach 1:
A gas stream is introduced as an intermediary force to remove the liquid film from the substrate surface. This gas stream acts as a mediator that can efficiently remove the liquid film without requiring substrate rotation, thereby maintaining heating efficiency while still preventing pattern collapse by quickly removing the liquid film that causes surface tension issues.
Solution Approach 2:
The mechanical centrifugal force method (substrate rotation) is replaced with a gas stream-based liquid film removal method. This substitution allows liquid film removal to occur without rotating the substrate, maintaining continuous heating and reducing overall processing time while still effectively preventing pattern collapse.
3Speed
If the liquid film is removed by high flow rate inert gas blowing, then the liquid film can be swept off quickly, but substrate and liquid film temperature decreases causing gas phase layer loss
Solution Approach 1:
The gas phase layer is formed in advance before high flow rate gas blowing begins. This preliminary formation creates a protective layer that insulates the substrate and liquid film from the cooling effect of the incoming gas stream, allowing rapid liquid film removal while maintaining substrate temperature.
Solution Approach 2:
Heating continues continuously throughout the liquid film removal process. By maintaining continuous heating while the high flow rate gas stream removes the liquid film, the substrate and liquid film temperature is compensated for the cooling effect, preventing gas phase layer loss while still achieving rapid liquid film removal.
4Speed
If the heater is separated from the substrate to allow rotation, then liquid film movement is promoted by centrifugal force, but heat is taken away by atmosphere causing temperature decrease and gas phase layer loss
Solution Approach 1:
The mechanical centrifugal force system (substrate rotation) is replaced with a gas stream-based liquid film removal system. This substitution eliminates heat loss to the atmosphere that occurs during rotation while still achieving effective liquid film removal, thereby preventing energy loss and gas phase layer loss.
Solution Approach 2:
A gas stream is used as an intermediary to remove the liquid film without requiring substrate rotation. This intermediary approach allows liquid film removal to occur while the substrate remains stationary and in contact with the heater, preventing atmospheric heat loss while still achieving the desired liquid film removal effect.
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 the influence of surface tension on the fine pattern, preventing collapse and improving productivity by shortening the heating time and ensuring reliable removal of the liquid film without splitting or stopping at the substrate's periphery.
Implementation Method 1
heating the substrate by a substrate heating unit to evaporate the processing liquid in contact with the upper surface of the substrate, to forma gas phase layer
Implementation Method 2
blowing a gas onto the liquid film at the upper surface of the substrate after the forming of the gas phase layer to partially remove the processing liquid to open a hole in the liquid film and further spread the hole to an outer periphery of the substrate, and to move the liquid film on the gas phase layer
Data Source
AI summary
A processing liquid is supplied to an upper surface of a horizontally-held substrate to form a liquid film of the processing liquid that covers an entirety of the substrate upper surface. The substrate is heated to evaporate the processing liquid in contact with the upper surface of the substrate to form a gas phase layer between the upper surface of the substrate and the liquid film of the processing liquid. After the gas phase layer has been formed, a gas is blown onto the liquid film above the substrate to open a hole in the liquid film. The gas is blown onto a region inside the hole in the liquid film to move the liquid film on the gas phase layer. A direction of a gas stream at a substrate outer peripheral portion is changed to remove the liquid film at the substrate outer peripheral portion.