Supercritical Fluid Flow Control for Pattern-Safe Substrate Drying
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Solution Overview
Problem
The rotary drying method for semiconductor substrates risks pattern collapse due to inefficiencies in removing treatment liquids, and existing supercritical drying processes face challenges in accurately measuring and controlling the flow rate of supercritical fluids.
Innovation Solution
A substrate processing apparatus and method that maintain a single phase of supercritical fluid throughout the supply line, using a flow rate measuring member and controller to accurately control the flow rate of supercritical fluids, ensuring precise delivery and removal of treatment fluids during the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotary drying method is used to remove rinsing liquid from the substrate, then the drying speed is improved, but the pattern on the substrate may collapse
Solution Approach 1:
The patent uses supercritical drying which involves phase transition of the drying fluid from liquid to supercritical state and then to gas. The substrate is first treated with liquid drying fluid, then CO2 is supplied in supercritical state to replace the liquid, and finally the supercritical CO2 is depressurized to gas for removal. This phase transition process allows effective drying without the mechanical stress that causes pattern collapse in rotary drying.
2Ease of operation
If a flow rate control valve is installed downstream of the flow rate measuring member, then the flow rate can be controlled, but flow rate measurement errors occur due to pressure changes across the valve
Solution Approach 1:
The patent applies preliminary action by positioning the flow rate measuring member upstream of the flow rate control valve. This allows the flow rate to be measured before it is affected by pressure changes across the valve, ensuring accurate measurement. The valve then adjusts the flow based on this pre-measurement, resolving the contradiction between flow control and measurement accuracy.
3Measurement precision
If the flow rate measuring member is positioned downstream of the flow rate control valve, then the measured flow rate reflects the controlled flow, but the pressure drop across the valve causes measurement errors
Solution Approach 1:
By positioning the flow rate measuring member upstream of the flow rate control valve, the system performs preliminary measurement of the flow rate before the valve-induced pressure drop affects the measurement. This ensures both accurate measurement and reliable flow control, as the valve can then adjust the flow based on the accurate pre-measurement without compromising measurement reliability.
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 effectively corrects flow rate errors and prevents pattern collapse by maintaining a stable supercritical state, ensuring accurate and efficient drying of semiconductor substrates without compromising the formed patterns.
Implementation Method 1
a flow rate measuring member installed in the supply line and positioned between the fluid supply source and the flow rate control valve
Implementation Method 2
a flow rate control valve installed in the supply line, and a controller configured to control the flow rate control valve to supply the supercritical fluid based on a flow rate of the supercritical fluid measured by the flow rate measuring member
Implementation Method 3
a supercritical drying process is used for supplying an organic solvent such as isopropyl alcohol (IPA) onto a substrate to replace a rinsing liquid remaining on the substrate with the organic solvent having a low surface tension, and then supplying a drying gas (e.g., carbon dioxide) in a supercritical state onto the substrate to remove the organic solvent remaining on the substrate
Data Source
AI summary
Provided is a substrate processing apparatus including a chamber including an inner space, a fluid supply unit configured to supply a supercritical fluid to the inner space, a fluid exhaust unit configured to exhaust the supercritical fluid from the inner space, and a controller configured to control the fluid supply unit and the fluid exhaust unit, wherein the fluid supply unit includes a fluid supply source, a supply line connecting the fluid supply source and the chamber to each other, a flow rate control valve installed in the supply line, and a flow rate measuring member installed in the supply line and positioned between the fluid supply source and the flow rate control valve, and the controller is further configured to control the flow rate control valve to supply the supercritical fluid, based on a flow rate of the supercritical fluid measured by the flow rate measuring member.