Actinic Radiation Reactor for Ultrapure Water TOC Reduction
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Solution Overview
Problem
Current methods for providing ultrapure water to semiconductor fabrication units face challenges in maintaining low total organic carbon (TOC) levels and removing particulates, which are essential for preventing contamination and ensuring the quality of the water used in these sensitive processes.
Innovation Solution
A system and method that involve introducing a free radical precursor compound into the water, converting it into free radical scavenging species, and removing particulates using actinic radiation reactors and filtration systems, with a control system regulating the process based on TOC values and other parameters to maintain ultrapure water quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional water treatment methods are used, then basic purification is achieved, but TOC levels remain high and particulate removal is insufficient
Solution Approach 1:
The water purification system is divided into multiple specialized stages: a first actinic radiation reactor for TOC reduction, a second actinic radiation reactor for residual oxidant reduction, and intermediate filtration systems. Each stage targets specific contaminants, allowing precise control of TOC levels through segmented functional modules rather than a single complex unit.
Solution Approach 2:
Free radical precursor compounds are introduced as intermediaries between the inlet water and the actinic radiation reactors. These precursors convert to free radicals under UV irradiation, which then oxidize organic contaminants. The intermediaries enable indirect oxidation that is more effective for TOC removal while allowing controlled reaction conditions.
2Manufacturing precision
If strong oxidizing agents are added to remove organic contaminants, then TOC levels decrease, but residual oxidants contaminate the ultrapure water
Solution Approach 1:
The system converts the harmful residual oxidants into a beneficial secondary treatment step. The second actinic radiation reactor uses the same UV technology to reduce residual oxidants and free radicals to harmless byproducts. This transforms the potential contamination problem into an opportunity for further purification, ensuring ultrapure water quality without adding chemical contaminants.
Solution Approach 2:
The system discards residual oxidants and free radicals through the second actinic radiation reactor, converting them into harmless substances. This two-stage approach first uses oxidation to remove TOC, then discards the harmful residuals, achieving both TOC reduction and water purity without introducing new contaminants.
3Manufacturing precision
If multiple treatment stages are implemented to ensure ultrapure water quality, then water purity increases, but system complexity and operational difficulty increase
Solution Approach 1:
The control system continuously monitors water quality parameters including TOC levels, residual oxidant concentrations, and flow rates. Based on this feedback, the system automatically adjusts the dosing rates of free radical precursors, UV lamp intensity, and pump speeds. This closed-loop control maintains ultrapure water quality while simplifying operation, as the system self-regulates without requiring manual intervention for each parameter.
Solution Approach 2:
The system incorporates automatic control that allows it to regulate its own operation. The control system monitors output water quality and automatically adjusts treatment parameters, eliminating the need for constant operator attention. The system serves itself by maintaining optimal treatment conditions through automated feedback loops, reducing operational complexity despite multiple treatment stages.
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 system effectively reduces TOC levels and removes particulates, ensuring the delivery of ultrapure water to semiconductor fabrication units, thereby maintaining the required water quality and preventing contamination, as demonstrated by the ability to maintain low TOC levels even during fluctuations in inlet water quality.
Implementation Method 1
converting the at least one free radical precursor compound into at least one free radical scavenging species
Implementation Method 2
removing at least a portion of any particulates from the water
Data Source
AI summary
A method and system of providing ultrapure water for semiconductor fabrication operations is provided. The water is treated by utilizing a free radical scavenging system and a free radical removal system. The free radical scavenging system can utilize actinic radiation with a free radical precursor compound, such as ammonium persulfate. The free radical removal system can comprise use of a reducing agent. The ultrapure water may be further treated by utilizing ion exchange media and degasification apparatus. A control system can be utilized to regulate addition of the precursor compound, the intensity of the actinic radiation, and addition of the reducing agent to the water.