UV-Activated Persulfate Process for Semiconductor Water TOC Reduction

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Solution Overview

Problem

Current methods for producing ultrapure water in semiconductor manufacturing lack a reliable, continuous source of low Total Organic Carbon (TOC) and are inefficient in purifying spent water for reuse, requiring high temperatures and pH adjustments.

Innovation Solution

A UV-activated persulfate process that decomposes organic compounds by converting persulfate into sulfate radicals at ambient temperature, using a photochemical reactor system with UV lamps, either in a continuous-stirred tank or plug flow configuration, to reduce TOC in both pure and spent water streams.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional TOC reduction methods (heating to 110-170°C with pH adjustment) are used, then organic compounds can be decomposed, but the process requires high energy consumption and complex pH control

Engineering Contradiction:

ImproveTOC reduction effectivenessVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental parameters of the oxidation process by using UV light activation at ambient temperature instead of thermal heating at 110-170°C. This parameter change eliminates the need for high temperature energy input while maintaining effective TOC decomposition through photochemical activation of persulfate salts.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal-mechanical system (heating equipment, pH control systems) with a photochemical system (UV light sources). This substitution eliminates complex mechanical control systems while achieving the same oxidation objective through light-induced chemical reactions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If batch processing methods are used for TOC reduction, then treatment can be achieved, but continuous production of ultrapure water cannot be reliably provided

Engineering Contradiction:

Improvecontinuous TOC reductionVSAvoidcontinuous ultrapure water production

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements continuous flow processing where water passes through a series of treatment stages including UV irradiation and oxidation in a continuous manner. This continuous action ensures reliable and consistent TOC reduction while maintaining high productivity for ultrapure water production, eliminating the interruptions inherent in batch processing.

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If spent water is discharged without treatment, then processing time is reduced, but environmental compliance and water reuse are compromised

Engineering Contradiction:

Improvewater processing throughputVSAvoidorganic carbon discharge

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful organic carbon content in spent water into beneficial outcomes by using UV-activated oxidation to decompose TOC into harmless substances. This approach simultaneously addresses environmental compliance requirements and enables water reuse, transforming a waste stream into a potentially reusable resource without significantly impacting processing throughput.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 process effectively reduces TOC to low levels (<5 ppb) in semiconductor process water, enabling continuous production of ultrapure water and allowing for the reuse of treated spent water, while being cost-effective and efficient by optimizing reactor design and UV light utilization.

Implementation Method 1

The process uses a standard photochemical reactor either a plug flow (PFR) or a stirred tank (CSTR) or a combination of both. The most cost-effective design is expected to be a CSTR with immersed UV lamps.

Methodology Applied

Scientific EffectPhotochemical activation: Photo-oxidation

Implementation Method 2

The ultraviolet light is absorbed by the persulfate—converting the persulfate into sulfate radicals.

Methodology Applied

Scientific EffectUV light absorption: Absorption (EM radiation)

Implementation Method 3

The sulfate radicals oxidize TOC, converting the contributing compounds into CO2 and mineral salts.

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS10550020B2Ultraviolet light activated oxidation process for the reduction of organic carbon in semiconductor process water

Publication Date: 2020.02.04 EVOQUA WATER TECHNOLOGIES LLC

AI summary

In a system for decomposing organic compounds in water for use in semiconductor manufacturing, a chemical reactor vessel having a fluid inlet and a fluid outlet, a persulfate anion addition system upstream of the reactor vessel, and a light emitting device contained within the reactor vessel. The light emitting device provides light capable of decomposing persulfate anions.