Supercritical CO2 Drying With Multi-Level Pressure Control
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Solution Overview
Problem
Existing substrate drying methods using supercritical CO2 cause defects such as photo resist collapse, leaning, bridge, lifting, and local annular shape due to inadequate pressure control during the drying process.
Innovation Solution
A substrate processing apparatus and method that controls the flow rate of CO2 injected into a supercritical drying vessel through multi-level pressure control, using a system of valves to manage the supply and discharge of CO2 in multiple stages, ensuring uniform drying and preventing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-pressure CO2 supply device system is used to substitute and dry developing solution on a wafer, then drying effectiveness is improved, but local annular shape and clustered cluster defects are generated due to inadequate pressure control
Solution Approach 1:
The pressure control system is segmented into multiple levels with different pressure ranges. A first pressure control valve controls a first pressure range (e.g., 0-70 bar) while a second pressure control valve controls a second pressure range (e.g., 70-300 bar). This segmentation allows precise control at each pressure stage, preventing defects caused by inadequate pressure control while maintaining drying uniformity.
Solution Approach 2:
The system changes pressure parameters dynamically during the drying process. By adjusting pressure from low to high in stages through multi-level control, the system optimizes CO2 flow rate and drying effectiveness at different phases, preventing defects while achieving uniform drying results.
2Manufacturing precision
If multi-level pressure control is implemented to prevent drying defects, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The control system is divided into discrete pressure levels with dedicated control valves for each level. This segmentation enables independent optimization of each pressure stage, achieving defect prevention through precise control while managing complexity through modular valve architecture.
Solution Approach 2:
The multi-level pressure control system serves multiple functions: it controls CO2 flow rate, maintains supercritical conditions, prevents pressure shocks, and ensures uniform drying. By designing the valve system to handle multiple functions, the patent reduces overall system complexity despite the multi-level architecture.
3Productivity
If CO2 is supplied at high flow rate to ensure efficient drying, then productivity is improved, but photo resist collapse and lifting defects occur
Solution Approach 1:
The CO2 supply is implemented in periodic stages with different pressure levels. The system alternates between lower pressure stages (protecting photo resist) and higher pressure stages (accelerating drying). This periodic action allows efficient drying while preventing photo resist collapse and lifting defects.
Solution Approach 2:
The system performs preliminary drying at lower pressure levels before transitioning to high pressure. This preliminary action removes excess developing solution gently, preparing the photo resist for subsequent high-pressure drying without causing collapse or lifting defects.
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
The multi-level pressure control system effectively prevents defects like photo resist collapse and clustered clusters, ensuring uniform drying and maintaining substrate integrity.
Implementation Method 1
supplying a fluid into a process chamber to pressurize the fluid to be in a supercritical phase in the process chamber
Implementation Method 2
a method of substituting and drying a developing solution on a wafer by using supercritical CO2
Data Source
AI summary
A substrate processing apparatus and a substrate processing method are provided, in which a flow rate of CO2 injected into a supercritical drying vessel is controlled through multi-level pressure control. The substrate processing method includes disposing a substrate coated with a chemical liquid in a process chamber, that includes a space in which the substrate is processed; drying the substrate by using a supercritical fluid; and taking the substrate out of the process chamber when the substrate is dried.