Substrate Drying via Dynamic IPA Nozzle and Inert Gas Opening
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Solution Overview
Problem
Existing substrate processing methods face challenges in swiftly drying the front surface of substrates while preventing low-surface-tension liquids from remaining, which can lead to pattern collapse due to uneven evaporation and surface tension effects.
Innovation Solution
A substrate processing apparatus and method that includes a substrate holding unit, a rotating unit, a processing liquid supply unit, a low-surface-tension liquid supply unit, an inert gas supply unit, and a controller to form and enlarge an opening in the liquid film, changing the landing position of the low-surface-tension liquid to prevent tearing and ensure even evaporation, using inert gas to dry the substrate surface efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IPA is supplied onto the substrate and nitrogen gas is sprayed to remove IPA, then the drying speed is improved, but the liquid film may tear and liquid droplets remain on the substrate due to uneven evaporation
Solution Approach 1:
The patent applies dynamics by making the nozzle position movable rather than fixed. The nozzle head moves in the radial direction of the substrate during rotation, allowing the IPA supply position to dynamically adjust. This enables the liquid film to be uniformly removed across different radial positions where evaporation rates differ, preventing film tearing while maintaining efficient drying speed.
Solution Approach 2:
The patent implements feedback control by monitoring the substrate rotation state and adjusting the nozzle position accordingly. The control unit coordinates the nozzle movement with substrate rotation to ensure IPA is supplied at optimal positions, and adjusts nitrogen gas spray timing based on liquid film state, preventing over-drying in some areas while under-drying others.
2Productivity
If the nozzle head is moved from center to peripheral edge while discharging IPA, then the liquid film is pushed outward by centrifugal force, but the spraying force becomes uneven causing liquid film tearing
Solution Approach 1:
The patent makes the nozzle position dynamic by moving it in the radial direction during substrate rotation. Instead of a fixed scanning path, the nozzle continuously adjusts its radial position to maintain optimal spacing from the substrate center, ensuring uniform IPA distribution and preventing localized over-spraying that would cause film tearing.
Solution Approach 2:
The patent applies local quality by adjusting the IPA supply and nitrogen spray parameters according to the local radial position on the substrate. Different regions receive different amounts of IPA and nitrogen based on their distance from the center, where peripheral regions with higher centrifugal forces receive less aggressive treatment compared to central regions.
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 method effectively prevents liquid film tearing and rapid evaporation, allowing for swift drying of the substrate surface while minimizing the time surface tension acts on the pattern, thus reducing the risk of pattern collapse.
Implementation Method 1
an inert gas is supplied from the inert gas supply unit toward the rotational center position that is a position existing on the rotational axis on the front surface of the substrate, thereby forming an opening spreading from the rotational center position in the liquid film of the low-surface-tension liquid
Implementation Method 2
enlarging the opening in a direction away from the rotational center position
Implementation Method 3
a low-surface-tension liquid whose surface tension is smaller than water to the front surface of the substrate held by the substrate holding unit... replacing the processing liquid with the low-surface-tension liquid
Implementation Method 4
IPA does not evenly evaporate from the liquid film of IPA... a part of the liquid film of IPA completely evaporates
Data Source
AI summary
The controller is programmed to cause a low-surface-tension liquid supply unit to supply a liquid film of a low-surface-tension liquid to a front surface of a substrate so as to form a liquid film of the low-surface-tension liquid. The controller is programmed to control the substrate rotating unit and the inert gas supply unit so that an inert gas is supplied toward the rotational center position while rotating the substrate, thereby forming an opening spreading from the rotational center position to be formed in the liquid film, and enlarging the opening in a direction away from the rotational center position, and to control the landing-position changing unit to change the landing position of the low-surface-tension liquid to at least two positions except the rotational center position in accordance with enlargement of the opening so that the landing position is placed outside the peripheral edge of the opening.