Substrate Drying Sequence Using Dual Supercritical Fluids
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Solution Overview
Problem
The challenge is to prevent fine patterns on semiconductor substrates from collapsing during the drying process, which is exacerbated by the use of supercritical fluids in EUV lithography.
Innovation Solution
A substrate drying apparatus and method utilizing a process chamber with a first fluid supply to increase pressure and a second fluid supply in a supercritical state to dissolve residual liquids, where the solubility of the residual liquid in the second fluid is higher than in the first fluid, combined with an exhaust system to remove waste fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a supercritical fluid is used to dry residual liquid on substrate, then drying efficiency is improved, but fine patterns may collapse due to high solubility and surface tension effects
Solution Approach 1:
The drying process is segmented into multiple stages using different fluids: first a low-solubility fluid (supercritical CO2) to remove bulk residual liquid, then a high-solubility fluid (supercritical HFE) to dissolve remaining residues without causing pattern collapse. This segmentation allows each fluid to perform its specific function optimally.
Solution Approach 2:
The patent changes the solubility parameter by switching between different supercritical fluids with distinct solubility characteristics. The first fluid (CO2) has low solubility for photoresist residues, while the second fluid (HFE) has high solubility, allowing controlled removal of residues at different process stages to prevent pattern collapse.
2Quantity of substance
If pressure is increased to maintain supercritical state, then fluid solubility increases for better cleaning, but fine patterns become more susceptible to collapse
Solution Approach 1:
The patent applies different fluid properties to different stages of the drying process. The first fluid (supercritical CO2) provides gentle drying with low solubility, while the second fluid (supercritical HFE) provides high solubility for residue dissolution. Each fluid's local properties are optimized for its specific function in the sequence.
Solution Approach 2:
The first fluid treatment is performed as a preliminary action to remove the bulk of residual liquid before the second fluid is applied. This preliminary removal reduces the total residue amount, allowing the second high-solubility fluid to work more effectively with less risk of pattern collapse.
3Device complexity
If a single supercritical fluid is used for drying, then process simplicity is maintained, but drying effectiveness is insufficient for preventing pattern collapse
Solution Approach 1:
The drying process is segmented into multiple stages using different fluids: first a low-solubility fluid (supercritical CO2) to remove bulk residual liquid, then a high-solubility fluid (supercritical HFE) to dissolve remaining residues without causing pattern collapse. This segmentation allows each fluid to perform its specific function optimally.
Solution Approach 2:
The patent uses a composite fluid approach, combining two different supercritical fluids (CO2 and HFE) with complementary properties. The first fluid provides gentle drying, while the second fluid provides enhanced solubility for complete residue removal, creating a composite drying system that overcomes the limitations of single-fluid approaches.
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 collapse of fine patterns by using fluids with varying solubilities to manage residual liquids, ensuring efficient and controlled drying without damaging the substrate.
Implementation Method 1
supplying a first fluid in a supercritical state to a processing space within a process chamber and increasing the pressure of the processing space
Implementation Method 2
supplying a second fluid in a supercritical state to the processing space and dissolving the residual liquid located on the surface of the substrate
Implementation Method 3
dissolving the residual liquid located on the surface of the substrate in the second fluid
Implementation Method 4
discharging a waste fluid within the processing space to the outside of the process chamber
Data Source
AI summary
A substrate drying apparatus includes a process chamber including a processing space for drying a residual liquid remaining on a surface of a substrate, a first fluid supply device configured to supply a first fluid to the processing space, wherein the solubility of the residual liquid in the first fluid is a first solubility, a second fluid supply device configured to supply a second fluid in a supercritical state to the processing space, wherein the solubility of the residual liquid in the second fluid is a second solubility that is greater than the first solubility, and an exhaust device configured to discharge a waste fluid within the processing space of the process chamber to the outside of the process chamber.