SPM Solution Mixing Control With Oxygen Feedback and Preheating
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Solution Overview
Problem
Existing wafer cleaning processes using SPM-peroxy-sulfuric acid mixture solutions in tank-type devices face issues of uneven mixing, temperature control errors, and inadequate reaction, leading to decreased cleaning capability.
Innovation Solution
A multi-stage mixing and control method involving sulfuric acid and hydrogen peroxide mixing in a delivering pipe, with real-time monitoring and adjustment of oxygen concentration and temperature, using mixing screw rods and heating/cooling mechanisms to ensure full reaction and precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sulfuric acid and hydrogen peroxide are mixed in a single stage in the delivering pipe, then the mixing process is simple, but the mixing is uneven and the reaction is inadequate
Solution Approach 1:
The mixing process is divided into multiple stages within the delivering pipe. The first mixing stage combines sulfuric acid and hydrogen peroxide, followed by a second mixing stage that ensures complete mixing. This segmentation allows each stage to focus on specific mixing requirements, achieving both uniform mixing and complete reaction while maintaining system simplicity.
2Productivity
If the SPM solution is delivered without pre-mixing and heating, then the delivery process is fast, but the temperature control has large errors and the cleaning capability decreases
Solution Approach 1:
The system performs preliminary mixing and heating actions within the delivering pipe before the SPM solution reaches the cleaning chamber. The heating element pre-heats the mixed solution to the required temperature, and the multi-stage mixing ensures complete reaction. This preliminary action allows fast delivery without compromising temperature control precision or cleaning capability.
3Device complexity
If sulfuric acid and hydrogen peroxide are mixed without real-time monitoring, then the control system is simple, but the oxygen concentration and reaction completeness cannot be ensured
Solution Approach 1:
The system incorporates real-time monitoring of oxygen concentration in the mixed solution using oxygen concentration detection devices. The monitoring system provides feedback on the reaction progress, allowing the control system to adjust mixing parameters and ensure complete reaction. This feedback mechanism guarantees reaction completeness while maintaining reasonable control system complexity.
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
Ensures full reaction and precise temperature control of the SPM solution, improving the quality and efficiency of wafer cleaning by ensuring the mixed liquid meets cleaning requirements.
Implementation Method 1
mixing the sulfuric acid with the hydrogen peroxide at a specified volume ratio in a delivering pipe... heating the mixed liquid... oxygen concentration value of the mixed liquid
Implementation Method 2
heating the mixed liquid in the first stage
Implementation Method 3
mixing the sulfuric acid with the hydrogen peroxide at a specified volume ratio in a delivering pipe in a first stage and a second stage in turn
Implementation Method 4
heating the mixed liquid in the first stage
Implementation Method 5
monitoring in real time an oxygen concentration value of the mixed liquid flowing out after mixing in the first stage
Data Source
AI summary
A method of controlling mixed liquid to be delivered for SPM solution includes: before the SPM solution comes into an acid scouring tank, mixing the sulfuric acid with the hydrogen peroxide in a delivering pipe in a first stage and a second stage in turn, so as to make a mixed liquid after mixing in the first stage to further get mixed in the second stage; heating the mixed liquid in the first stage; monitoring an oxygen concentration value of the mixed liquid flowing out after mixing in the first stage; and if the oxygen concentration value is smaller than an oxygen concentration value at full reaction, adding supplementary sulfuric acid and hydrogen peroxide during mixing in the second stage, so as to enable the oxygen concentration value of the mixed liquid flowing out after mixing in the second stage monitored in real time to reach an oxygen concentration value.