Supercritical Substrate Drying With Mixed-Fluid Density Detection
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Solution Overview
Problem
Existing substrate processing apparatuses face challenges in efficiently drying substrates using supercritical fluids, particularly in preventing the collapse of concave-convex patterns due to surface tension and liquid-gas interface formation.
Innovation Solution
The apparatus includes a processing container that supplies a supercritical fluid to replace the drying liquid on the substrate, a discharge line to remove the mixed fluid containing the supercritical fluid and the drying liquid, and a density detector to monitor the density of the mixed fluid, allowing for precise control of the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a drying liquid is used to dry a substrate, then the substrate can be dried, but surface tension causes liquid-gas interface formation that collapses concave-convex patterns
Solution Approach 1:
The patent changes the physical state of the drying fluid from liquid to supercritical state. By controlling temperature and pressure parameters to reach the supercritical region, the fluid eliminates surface tension while maintaining liquid-like density, thus preventing pattern collapse during drying
Solution Approach 2:
The patent utilizes the phase transition of the drying fluid from liquid to supercritical state. This phase transition occurs at specific temperature and pressure conditions, transforming the fluid properties to eliminate surface tension effects that cause pattern collapse
2Productivity
If the circulation of supercritical fluid is stopped early to improve throughput, then productivity increases, but incomplete drying occurs
Solution Approach 1:
The patent implements a feedback control system using a density detector to monitor the drying process. The detector measures the density of the drying fluid, and when the density reaches a predetermined threshold indicating complete drying, the system automatically stops the circulation, ensuring both complete drying and optimal throughput
Solution Approach 2:
The patent replaces mechanical timing-based control with a sensor-based density detection system. Instead of using fixed time intervals or mechanical switches to control circulation duration, the system uses optical or other detection methods to sense fluid density changes and control the process accordingly
3Measurement precision
If the density of mixed fluid is monitored to detect drying completion, then drying precision improves, but device complexity increases
Solution Approach 1:
The patent uses fluid density as an intermediary parameter to indirectly detect drying completion. Instead of directly measuring substrate moisture content, the system monitors the density of the circulating supercritical fluid, which changes predictably as drying progresses, providing a simple and effective detection method
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 solution effectively suppresses the generation of surface tension and prevents the collapse of concave-convex patterns, achieving efficient and reliable drying of substrates while improving throughput by allowing earlier initiation of depressurization.
Implementation Method 1
a processing container to which a supercritical fluid is supplied, the processing container being configured to dry a substrate by replacing a drying liquid collected on the substrate with the supercritical fluid
Implementation Method 2
effectively suppresses the generation of surface tension and prevents the collapse of concave-convex patterns
Implementation Method 3
a density detector configured to detect a density of the mixed fluid flowing through the discharge line
Data Source
AI summary
A substrate processing apparatus includes: a processing container to which a supercritical fluid is supplied, the processing container being configured to dry a substrate by replacing a drying liquid collected on the substrate with the supercritical fluid; a discharge line configured to discharge a mixed fluid containing the supercritical fluid and the drying liquid from an interior of the processing container; and a density detector configured to detect a density of the mixed fluid flowing through the discharge line.