Electrolytic Sulfuric Acid Cleaning for Semiconductor Photoresist Stripping
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Solution Overview
Problem
Conventional methods for photoresist stripping using electrolytic sulfuric acid face inefficiencies due to low concentration of sulfuric acid, leading to prolonged processing times and opposing requirements for electrolytic and stripping properties.
Innovation Solution
A method involving a sulfuric acid electrolytic cell with a conductive diamond anode, where two sulfuric acid solutions of different concentrations are electrolyzed and mixed to form a cleaning solution, enhancing electrolytic current efficiency and stripping efficiency simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low concentration sulfuric acid (2-11 mol/L) is used for electrolysis to achieve high electrolytic current efficiency, then oxidizing agent formation efficiency is improved, but photoresist stripping efficiency deteriorates and processing time increases
Solution Approach 1:
The invention divides the sulfuric acid solution into two separate compartments: the first compartment contains low concentration sulfuric acid (2-11 mol/L) for efficient electrolytic oxidation, while the second compartment contains high concentration sulfuric acid (18-24 mol/L) for effective photoresist stripping. This spatial segmentation allows both contradictory requirements to be satisfied simultaneously in different locations.
Solution Approach 2:
A diaphragm is introduced as an intermediary component to separate the two sulfuric acid compartments while allowing controlled interaction. The diaphragm enables the system to maintain both low and high concentration zones, mediating between the conflicting requirements for electrolytic efficiency and stripping efficiency.
2Loss of time
If concentrated sulfuric acid is electrolyzed to reduce processing time, then photoresist stripping efficiency is improved, but oxidizing agent stability deteriorates due to moisture content
Solution Approach 1:
The system segments the sulfuric acid into two compartments with different concentrations and functions. The first compartment maintains low concentration for stable oxidizing agent formation, while the second compartment provides high concentration for rapid stripping, eliminating the trade-off between stability and speed.
Solution Approach 2:
The oxidizing agent is preliminarily formed in the first compartment under stable low concentration conditions, then the solution is transferred to the second compartment where high concentration sulfuric acid provides rapid stripping action. This preliminary formation ensures stability before the aggressive stripping phase.
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 stabilizes the production of oxidizing agents and significantly improves photoresist stripping efficiency, allowing for shorter processing times while maintaining high electrolytic current efficiency.
Implementation Method 1
electrolysis is performed to form electrolytic sulfuric acid containing oxidizing agent
Implementation Method 2
the treatment solution comprising the mixed solution is raised to 120 degree Celsius or more by the dilution heat generated when sulfuric acid of a higher concentration and a higher temperature is diluted
Data Source
AI summary
The cleaning method by electrolytic sulfuric acid and the manufacturing method of semiconductor device comprising:the process in which the first sulfuric acid solution is supplied from outside to the sulfuric acid electrolytic cell to form the first electrolytic sulfuric acid containing oxidizing agent in the sulfuric acid electrolytic cell;the process in which the second sulfuric acid solution, which is higher in concentration than said the first sulfuric acid solution previously supplied, is supplied from outside to said sulfuric acid electrolytic cell; said the second sulfuric acid solution and the first electrolytic sulfuric acid are mixed in said sulfuric acid electrolytic cell; and electrolysis is performed to form the cleaning solution comprising the second electrolytic sulfuric acid containing sulfuric acid and oxidation agent in said sulfuric acid electrolytic cell and the process in which cleaning treatment is performed for the cleaning object with said cleaning solution.