Supercritical Fluid Density Monitoring for Substrate Drying Timing
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Solution Overview
Problem
The existing techniques for replacing a liquid with a supercritical fluid in a chamber lack a method to determine the completion timing of the liquid's discharge, leading to potential drying failures and increased processing time and fluid consumption.
Innovation Solution
A method involving obtaining density profiles of the processing fluid with and without the liquid present, comparing these profiles to determine the end time of the liquid's replacement, ensuring accurate determination of the discharge completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supercritical state is maintained longer to ensure complete discharge of the liquid to be replaced, then the reliability of drying is improved, but the processing time and fluid consumption increase
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the density of the processing fluid during the replacement process. The density detection provides real-time information about the presence of liquid to be replaced, allowing the system to automatically determine when replacement is complete and terminate the process, thereby preventing both premature termination and excessive duration
Solution Approach 2:
The patent utilizes density as a critical parameter to monitor and control the replacement process. By detecting changes in fluid density, the system can accurately determine the completion of liquid discharge without relying on fixed time intervals, thus optimizing both reliability and processing time
2Reliability
If the supercritical state is maintained longer to ensure complete discharge of the liquid to be replaced, then the reliability of drying is improved, but the fluid consumption increases
Solution Approach 1:
The density detection system provides feedback that enables precise control of fluid consumption by terminating the supercritical state maintenance exactly when replacement is complete, avoiding unnecessary fluid usage while ensuring complete liquid discharge
Solution Approach 2:
The patent replaces time-based control with density-based control, substituting a mechanical/temporal process with a sensor-based detection system that optimizes fluid consumption through accurate real-time monitoring
3Reliability
If a fixed time longer than required is used for replacement, then the risk of drying failure is reduced, but the processing efficiency decreases
Solution Approach 1:
The continuous density monitoring provides feedback that allows dynamic adjustment of process duration, enabling the system to achieve reliable drying outcomes while minimizing processing time through accurate detection of replacement completion
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 allows for precise determination of the liquid's removal, reducing processing time and fluid consumption by avoiding unnecessary maintenance of the supercritical state and preventing drying failures.
Implementation Method 1
a density detector for detecting a density of the processing fluid in the chamber
Implementation Method 2
processing using supercritical fluids has been put into practical use in recent years
Implementation Method 3
the evaporation of the supercritical fluid is started after the liquid to be replaced is completely discharged from the chamber
Implementation Method 4
the substrate is dried by decompressing the chamber and evaporating the supercritical fluid
Data Source
AI summary
This invention relates to a replacement end time determination method in a process of replacing a liquid to be replaced by a processing fluid in a supercritical state and a substrate. In the invention, a density profile is obtained at each of a dry state where the liquid to be replaced is not present in a chamber and a wet state where the liquid to be replaced is present in the chamber by supplying and discharging the processing fluid into and from the chamber in accordance with a predetermined supply/discharge recipe while maintaining the processing fluid in a supercritical state. When both densities become substantially equal to each other after the density at the wet state becomes larger than the density at the dry state, the replacement of the liquid to be replaced by the processing liquid is regarded to be finished.