Substrate Drying Using Hydrofluoroolefin Supercritical Fluid
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Solution Overview
Problem
Current semiconductor substrate processing methods using supercritical fluids face issues with damage from OH groups in alcohols like IPA and fluorine-containing solvents like HFE and HFC, which can oxidize substrates and cause pattern thinning, and are costly due to the need for expensive fluorine-containing solvents and complex recovery processes.
Innovation Solution
A substrate processing apparatus and method utilizing hydrofluoroolefin as a supercritical processing liquid, which is decomposed by UV rays but not by heating, and includes a recycling unit to regenerate and concentrate the liquid, avoiding the use of OH groups and fluorine, and using dialkyl ethers as an alternative to prevent substrate drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If supercritical fluids like HFE or HFC are used to dry substrates, then drying effectiveness is improved, but substrate damage occurs due to fluorine content causing pattern thinning
Solution Approach 1:
The patent replaces expensive and harmful fluorine-containing supercritical fluids (HFE, HFC) with a more benign alternative: CO2 supercritical fluid combined with a small amount of water. This substitution eliminates the harmful fluorine content while maintaining the supercritical drying function, effectively resolving the contradiction between drying effectiveness and substrate damage.
Solution Approach 2:
The patent changes the chemical composition parameters of the supercritical fluid from fluorine-containing compounds to a CO2-water mixture. By adjusting the composition ratio (CO2 predominantly with controlled water content), the patent achieves effective drying while eliminating the harmful fluorine effects that cause pattern thinning.
2Manufacturing precision
If alcohols like IPA are used as supercritical processing liquids, then substrate cleaning is improved, but substrate oxidation occurs due to OH groups
Solution Approach 1:
The patent replaces alcohol-based supercritical fluids containing OH groups (which cause oxidation) with a CO2-water mixture. This substitution eliminates the harmful OH groups while maintaining the cleaning capability through the supercritical fluid's penetrative properties and controlled water content.
Solution Approach 2:
The patent fundamentally changes the chemical nature of the processing liquid from alcohol (with OH groups) to a CO2-water system. This parameter change in chemical composition eliminates the oxidation-causing OH groups while preserving the cleaning function through supercritical state properties.
3Productivity
If fluorine-containing solvents are used for supercritical processing, then drying performance is improved, but manufacturing cost increases due to expensive solvents and complex recovery processes
Solution Approach 1:
The patent replaces expensive fluorine-containing solvents (HFE, HFC) with inexpensive and readily available materials: CO2 and water. This substitution dramatically reduces material costs while eliminating the need for complex recovery systems, as CO2 can be easily vented or recycled through simple phase change.
Solution Approach 2:
The patent changes the economic parameters of the processing system by substituting high-cost fluorine-containing solvents with low-cost CO2 and water. This parameter change in material selection reduces both direct material costs and indirect costs associated with solvent recovery infrastructure.
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 method effectively dries substrates using hydrofluoroolefin without damaging them and reduces manufacturing costs by avoiding expensive fluorine-containing solvents and minimizing environmental impact through efficient recycling and the use of UV-stable hydrofluoroolefin and dialkyl ethers.
Implementation Method 1
the inside of the chamber is heated by the heating unit in a state where the substrate is accommodated in the chamber to change the supercritical processing liquid into a supercritical fluid or a subcritical fluid
Implementation Method 2
change the supercritical processing liquid into a supercritical fluid or a subcritical fluid
Data Source
AI summary
Disclosed is a substrate processing apparatus including a dry processing unit and a controller. The dry processing unit includes: a chamber that accommodates the substrate; a supercritical processing liquid supply unit that supplies a supercritical processing liquid to the substrate; a heating unit that heats an inside of the chamber; and a discharge unit that discharges a fluid in the chamber from the chamber. The controller controls the supercritical processing liquid supply unit, the heating unit, and the discharge unit such that the supercritical processing liquid is supplied to the substrate before or after the substrate is accommodated in the chamber, the inside of the chamber is heated to change the supercritical processing liquid into a supercritical fluid or a subcritical fluid, and the supercritical fluid or the subcritical fluid is discharged from the chamber.