Dielectric Endpoint Detection in Supercritical Substrate Drying
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Solution Overview
Problem
Conventional methods for detecting the progress and end point of a drying process using supercritical fluids in substrate processing are inefficient due to difficulties in accurately measuring organic solvents like isopropyl alcohol, especially under high pressure and temperature conditions, leading to challenges in real-time monitoring and high maintenance costs.
Innovation Solution
A process detecting unit that calculates the dielectric constant of the fluid discharged from the chamber by measuring capacitance, reflection coefficient, or resonance frequency, allowing for real-time monitoring of the process progress and end point by determining when the dielectric constant reaches a predetermined reference value, thereby accurately determining the completion of the substrate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sampling and analysis methods are used to detect process progress, then measurement of organic solvents can be performed, but real-time monitoring is difficult and maintenance costs are high
Solution Approach 1:
The patent replaces conventional mechanical sampling and analysis systems with an optical detection system that measures the refractive index of the fluid. This substitution enables continuous real-time monitoring without the time losses associated with sampling, transport, and laboratory analysis, while maintaining high measurement precision through optical refractometry.
Solution Approach 2:
The patent introduces the refractive index as an intermediary parameter that correlates with the concentration of organic solvents in the supercritical fluid. By measuring this intermediary optical property, the system indirectly detects solvent presence and process progress in real-time, avoiding direct sampling while maintaining detection accuracy.
2Reliability
If supercritical fluid drying process is used, then pattern collapse is prevented, but accurate detection of process progress becomes difficult due to high pressure conditions
Solution Approach 1:
The patent changes the measurement parameter from direct solvent concentration analysis to refractive index measurement. The refractive index of supercritical fluids changes predictably with solvent concentration, allowing accurate process monitoring under high pressure conditions without requiring complex high-pressure sampling equipment or disrupting the drying process.
3Ease of manufacture
If conventional drying methods are used, then processing can be performed, but capillary force causes pattern collapse
Solution Approach 1:
The patent utilizes the phase transition properties of supercritical fluids to eliminate capillary forces during drying. By maintaining the fluid in a supercritical state (above critical temperature and pressure) throughout the drying process and avoiding passage through the gas-liquid equilibrium line, the system prevents meniscus formation and associated capillary forces that cause pattern collapse, while still achieving effective solvent removal.
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
Enables real-time monitoring and accurate detection of the process end point, reducing processing time and increasing efficiency by using a dielectric constant-based method that is less prone to the limitations of conventional sampling and analysis techniques.
Implementation Method 1
calculates at least one parameter of the fluid discharged from the chamber and detect at least one of a progress of a process and an end point of the process
Implementation Method 2
calculates the dielectric constant of the fluid by measuring at least one of a capacitance, reflection coefficient, and resonance frequency of the fluid
Implementation Method 3
calculates the dielectric constant of the fluid by measuring at least one of a capacitance, reflection coefficient, and resonance frequency of the fluid
Implementation Method 4
a processing method of drying the processing liquid using a fluid in a supercritical state (hereinafter referred to as 'supercritical fluid') that does not form an interface between gas or liquid
Implementation Method 5
when the pressure of a liquid is raised from A to B and the temperature is then raised from B to C, the liquid is converted into a supercritical state C without passing the vapor-liquid equilibrium line
Data Source
AI summary
Provided is a substrate processing apparatus, more particularly, a substrate processing apparatus for detecting a progress and end point of a process for a substrate when a process such as a drying process is performed for a substrate using a supercritical fluid.