Supercritical Fluid Density Detection for Liquid Replacement End Time
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Solution Overview
Problem
Existing methods for determining the end time of replacing a liquid with a supercritical processing fluid in a chamber are prone to errors due to fluctuations in fluid flow and detection issues, leading to potential drying failures and inefficiencies in substrate processing.
Innovation Solution
A method that involves detecting the density of the processing fluid discharged from the chamber, accumulating differences between detection values and a reference density profile, and using a threshold value to determine when the liquid replacement is complete, ensuring accurate timing and reducing processing time and fluid consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the end time of liquid replacement is determined based on simple density detection, then the determination process is simple, but the accuracy is low due to flow fluctuations and detection errors
Solution Approach 1:
The patent applies preliminary action by establishing a reference density profile beforehand through experiments or simulations under known dry conditions. This reference profile serves as a benchmark for comparing real-time density measurements, enabling accurate end time determination without complex real-time analysis algorithms.
Solution Approach 2:
The patent implements feedback by continuously monitoring the density of discharged processing fluid and comparing it against the pre-established reference density profile. The system adjusts the replacement process based on the comparison results, providing closed-loop control that improves accuracy while maintaining simple operation.
2Reliability
If the replacement process continues until complete liquid removal is confirmed, then drying quality is improved, but processing time and fluid consumption increase
Solution Approach 1:
The patent replaces mechanical timing methods with density-based detection to determine replacement end time. By using density measurements and comparison with reference profiles, the system accurately identifies when liquid removal is complete, preventing both premature termination (affecting quality) and excessive continuation (affecting efficiency).
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 replacement end time, reducing errors and improving the efficiency of substrate processing by ensuring complete removal of the liquid before drying, thereby preventing re-adhesion and optimizing processing fluid usage.
Implementation Method 1
a density of the processing fluid discharged from the chamber is detected
Implementation Method 2
processing using supercritical fluids has been put into practical use in recent years. In particular, in the processing of a substrate having a fine pattern formed on its surface, a supercritical fluid having a lower surface tension than a liquid penetrates deep into gaps among the pattern
Implementation Method 3
the substrate is dried by decompressing the chamber and vaporizing the supercritical fluid
Data Source
AI summary
In a replacement end time determination method in accordance with the present invention, in a dry state where a liquid to be replaced is not present in a chamber, a processing fluid is supplied and discharged in accordance with a predetermined supply/discharge recipe, and while the processing fluid is maintained in a supercritical state, a density profile is acquired to be used as a reference profile. A difference between the density profile acquired in a wet state where the liquid to be replaced is present in the chamber and the reference profile is accumulated, and on the basis of a comparison between the accumulated value and a threshold value set for the accumulated value, a replacement end time is determined.