Substrate Drying via Marangoni Effect and Localized Thermal Control
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Solution Overview
Problem
In the context of substrate processing, particularly for semiconductor devices with fine and high aspect-ratio patterns, existing drying techniques can cause pattern collapse due to the high integration and low strength of these patterns, leading to issues during the drying process.
Innovation Solution
A substrate processing method and apparatus that involves forming a liquid film on the substrate, creating a liquid film-removed region, and expanding it by supplying a gas with low surface tension vapor parallel to the liquid film-removed region expansion, while heating the liquid film-removed region above the boiling point of the low surface tension liquid and cooling the bulk portion below it, utilizing the Marangoni effect and evaporation to maintain a large contact angle and prevent pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gas containing low surface tension liquid vapor is sprayed onto the liquid film to expand the liquid film-removed region, then the drying speed is improved, but the patterns may collapse due to the high aspect ratio and low strength
Solution Approach 1:
The patent applies different treatments to different regions of the substrate: the liquid film-removed region is heated to promote evaporation and contact angle increase, while the bulk portion is cooled to prevent condensation and maintain pattern stability. This localized quality control allows fast drying where needed while protecting patterns where required.
Solution Approach 2:
The patent dynamically changes temperature parameters in different regions: heating the liquid film-removed region to accelerate evaporation and increasing contact angle, while cooling the bulk portion to prevent harmful condensation. This parameter control enables both fast drying and pattern protection.
2Productivity
If the liquid film is removed quickly to improve productivity, then drying efficiency is improved, but condensation may occur on the bulk portion causing pattern collapse
Solution Approach 1:
The patent applies preliminary cooling to the bulk portion of the substrate before and during the drying process. This pre-cooling prevents condensation from forming on the patterns in the bulk region, countering the harmful effect before it can occur.
Solution Approach 2:
The patent creates different thermal conditions in different regions: the liquid film-removed region is heated for evaporation, while the bulk portion is cooled to prevent condensation. This localized quality approach allows efficient drying without harmful condensation effects.
3Strength
If the contact angle is increased to suppress pattern collapse, then pattern protection is improved, but the drying time may be extended
Solution Approach 1:
The patent increases contact angle locally in the liquid film-removed region through heating, which promotes liquid retraction and pattern protection only where the liquid film boundary exists, without requiring extended drying time across the entire substrate.
Solution Approach 2:
The patent applies heating excessively to the liquid film-removed region to rapidly increase contact angle and promote liquid retraction, achieving pattern protection in a localized area without extending overall drying time.
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 method effectively suppresses pattern collapse by maintaining a large contact angle and preventing condensation, allowing for efficient drying of the substrate surface without damaging the patterns.
Implementation Method 1
a periphery of the edge portion of the liquid film is made into a gas atmosphere, thereby dissolving the low surface tension liquid into the processing liquid at the edge portion of the liquid film. Thereby, a difference in surface tension is generated between the edge portion of the liquid film and a portion excluding the edge portion
Implementation Method 2
the liquid film-removed region on the upper surface of the substrate is heated to a temperature not less than a boiling point of the low surface tension liquid... suppressing condensation by heating the liquid film-removed region to a temperature not less than the boiling point of the low surface tension liquid
Implementation Method 3
a bulk portion of the liquid film on the substrate is cooled to a temperature lower than the boiling point of the low surface tension liquid
Data Source
AI summary
In a substrate processing method, a liquid film 30 of a processing liquid is formed on an upper surface of a substrate W, a gas which comprising vapor of a low surface tension liquid is sprayed to the liquid film 30 to form a liquid film-removed region 31. The liquid film-removed region 31 is expanded. A coolant 29 is supplied to a lower surface of the substrate W, while the liquid film 30 is cooled to a temperature lower than the boiling point of the low surface tension liquid, a heated gas is sprayed to selectively remove the coolant 29, and a range 33 in which the coolant 29 is removed is heated by a heated gas, by which the liquid film-removed region 31 on the upper surface of the substrate W is selectively heated to a temperature not less than the boiling point of the low surface tension liquid, and also a range which heats the liquid film-removed region 31 is expanded in synchronization with expansion of the liquid film-removed region 31.