Method and system for providing ultrapure water with flexible lamp configuration

Patent metadata

Field	Value
Publication number	US-11697607-B2
Application number	US-202117199092-A
Country	US
Kind code	B2
Filing date	Mar 11, 2021
Priority date	May 4, 2015
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

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. The free radical scavenging system can utilize actinic radiation with a free radical precursor compound, such as ammonium persulfate. The ultrapure water may be further treated by utilizing ion exchange media and degasification apparatus. A control system can be utilized to regulate a continuously variable intensity of the actinic radiation.

First claim

What is claimed is:

1. A method of treating water comprising:
Providing water to be treated;
Measuring a total organic carbon (TOC) value of the water to be treated;
Introducing persulfate anions to the water to be treated based in part on at least one input signal of the measured TOC value of the water to be treated;
Introducing the water containing persulfate anions to a primary reactor;
Exposing the persulfate anions in the water to ultraviolet light in the reactor to produce an irradiated water stream;
Providing an electronic ballast circuit including a resonant tank circuit having a power output operatively coupled to the ultraviolet light, the electronic ballast circuit operable to control the continuously variable intensity of the ultraviolet light over a continuous range of power levels by continuously measuring the current supplied to the ultraviolet light and adjusting a frequency of a drive voltage supplied to the resonant tank circuit responsive to at least one input signal from the measured TOC value;
Wherein the electronic ballast circuit controls the continuously variable intensity of the ultraviolet light to provide sufficient power to the ultraviolet light to remove a desired amount of TOC from fluid undergoing treatment while not producing more ultraviolet radiation than is necessary to remove the desired amount of TOC; and
Adjusting the continuously variable intensity of the ultraviolet light based in part on at least one of an input signal selected from the group consisting of a TOC value of the water to be treated, a persulfate value of the water downstream of the reactor, and a rate of addition of persulfate anions.

2. The method of claim 1 , further comprising exposing the irradiated water to ultraviolet light in a secondary reactor located downstream of the primary reactor.

3. The method of claim 1 , further comprising removing dissolved solids and dissolved gases from the water.

4. The method of claim 1 , further comprising treating the water to be treated prior to providing the water to be treated to the reactor vessel.

5. The method of claim 1 , further comprising introducing a reducing agent to the irradiated water.

6. The method of claim 5 , further comprising measuring a reducing agent concentration value of the irradiated water.

7. The method of claim 6 , further comprising introducing the reducing agent to the irradiated water based on the measured reducing agent concentration value.

8. The method of claim 5 , wherein the reducing agent is sulfur dioxide.

9. The method of claim 1 , wherein providing the water to be treated includes providing inlet water having a TOC value of less than about 25 ppb and treating the water includes reducing the TOC value of the water to less than 1 ppb.

10. A method of providing ultrapure water to a semiconductor fabrication unit, comprising:
Providing inlet water having a TOC value of less than about 25 ppb;
Introducing at least one free radical precursor compound into the water;
Converting the at least one free radical precursor compound into at least one free radical scavenging species by exposing the at least one free radical precursor to UV radiation from a source of UV radiation having a continuously variable UV radiation power output;
Providing an electronic ballast circuit including a resonant tank circuit having a power output operatively coupled to the source of UV radiation, the electronic ballast circuit operable to control the continuously variable intensity of the source of UV radiation over a continuous range of power levels by continuously measuring the current supplied to the source of UV radiation and adjusting a frequency of a drive voltage supplied to the resonant tank circuit responsive to at least one input signal based at least partially from a measured TOC value of the inlet water;
Wherein the electronic ballast circuit controls the continuously variable intensity of the source of UV radiation to provide sufficient power to said source of UV radiation to remove a desired amount of TOC from fluid undergoing treatment while not producing more ultraviolet radiation than is necessary to remove the desired amount of TOC;
Removing at least a portion of any particulates from the water to produce the ultrapure water; and
Delivering at least a portion of the ultrapure water to the semiconductor fabrication unit.

11. The method of claim 10 , further comprising regulating a rate of addition of the at least one precursor compound based at least partially on the TOC value of the inlet water.

Assignees

• Evoqua Water Tech Llc

Inventors

• Hall Christopher
• Coulter Bruce Lee

Classifications

• C02F2209/20

  Total organic carbon [TOC] · CPC title

• C02F1/70

  by reduction {(C02F1/4676 takes precedence)} · CPC title

• C02F2103/04

  for obtaining ultra-pure water · CPC title

• C02F1/004

  using large scale industrial sized filters · CPC title

• C02F1/008

  Control or steering systems not provided for elsewhere in subclass C02F · CPC title