Supercritical Substrate Treatment for Complete IPA Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing supercritical fluid drying process for semiconductor substrates faces issues with rapid phase changes of carbon dioxide, leading to incomplete removal of isopropyl alcohol (IPA) due to changes in pressure and temperature, resulting in residual IPA and pattern leaning phenomena, which increases production costs and reduces yields.
Innovation Solution
The method involves using two supercritical fluids with different densities, where the first fluid dissolves the residue and the second fluid, with higher diffusivity, is used to discharge the remaining first fluid from between patterns, and the process includes sequential supply and evacuation steps to manage pressure and temperature effectively, preventing rapid phase changes and ensuring efficient IPA removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the chamber is evacuated to reduce pressure after substrate treatment, then the supercritical fluid can be discharged from the chamber, but the temperature drops below the critical temperature of carbon dioxide causing phase change and incomplete IPA removal
Solution Approach 1:
The patent changes the physical parameters (temperature and pressure) of the supercritical fluid in a controlled manner. During evacuation, the pressure is reduced while simultaneously heating the chamber to maintain temperature above the critical temperature of carbon dioxide (31°C), preventing phase change and ensuring complete IPA removal. This parameter control resolves the contradiction between discharging the fluid and maintaining treatment effectiveness.
Solution Approach 2:
The patent applies prior cushioning by pre-heating the chamber and supercritical fluid before evacuation begins. This ensures that when pressure drops during evacuation, the temperature remains sufficiently high to prevent condensation of the supercritical fluid, thus cushioning against the harmful effect of premature phase change and ensuring complete residue removal.
2Productivity
If the chamber is opened immediately after treatment to increase productivity, then the processing time is reduced, but rapid phase change occurs causing IPA to remain on the substrate
Solution Approach 1:
The patent performs preliminary actions before opening the chamber: the supercritical fluid is fully discharged through evacuation, and the chamber is maintained at elevated temperature to prevent phase change. Only after these preliminary steps are complete is the chamber opened, ensuring that no IPA remains on the substrate. This preliminary preparation resolves the contradiction between fast processing and high cleaning quality.
Solution Approach 2:
The patent maintains continuous heating during the evacuation process to ensure the supercritical fluid remains in the supercritical state until completely discharged. This continuous thermal action prevents any interruption in the cleaning effectiveness, allowing the chamber to be opened immediately afterward without risk of IPA condensation, thus achieving both high productivity and reliable cleaning quality.
3Reliability
If process time is increased to ensure complete IPA removal, then cleaning quality improves, but production costs increase and yields decrease
Solution Approach 1:
The patent utilizes controlled phase transitions of the supercritical fluid. By maintaining the fluid in the supercritical state through temperature control during pressure reduction, the cleaning action is maximized and completed rapidly. The fluid then transitions to a gaseous state for easy discharge, avoiding condensation that would require extended processing time. This controlled phase transition enables high cleaning quality with reduced process time.
Solution Approach 2:
The patent employs dynamic control of temperature and pressure parameters throughout the treatment and evacuation process. The system actively adjusts heating power and evacuation rate to maintain optimal conditions, ensuring complete IPA removal in the minimum necessary time. This dynamic optimization resolves the contradiction between cleaning quality and process time by adapting parameters in real-time rather than using fixed, overly conservative settings.
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 enhances the efficiency of substrate treatment by preventing contamination and minimizing IPA residues, thereby improving the cleaning process and reducing production costs while maintaining high yields.
Implementation Method 1
the first fluid in the supercritical state and the second fluid in the supercritical state have different densities... the first fluid dissolves the residue
Implementation Method 2
the second fluid, with higher diffusivity, is used to discharge the remaining first fluid from between patterns
Implementation Method 3
the temperature in the chamber is lowered to less than 31 degrees Celsius, which is the critical temperature of the carbon dioxide, by adiabatic expansion
Data Source
AI summary
The inventive concept provides a method for treating a substrate. In an embodiment, the substrate treating method includes a treatment step of treating a residue on the substrate with a first fluid in a supercritical state and a second fluid in a supercritical state in a process space of a chamber, and the first fluid in the supercritical state and the second fluid in the supercritical state have different densities.