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SEMI F61-0301 © SEMI 2001 2 4.2.9 dissolved solid s  contaminan t s in water that are so small that they are unifor m ly distributed, includ- ing ions and the smallest T OC and silica co m pound s. 4.2.10 dual -beds  a…

SEMI F61-0301 © SEMI 20011

SEMI F61-0301

GUIDE FOR ULTRAPURE WATER SYSTEM USED IN

SEMICONDUCTOR PROCESSING

This guide was technically approved by the Global Facilities Committee and is the direct responsibility of the

North American Facilities Committee. Current edition approved by the North American Regional Standards

Committee on November 22, 2000. Initially available at www.semi.org December 2000; to be published

March 2001.

1 Purpose

1.1 This guide establishes the typical definitional

requirements for an ultrapure water (UPW) system used

in semiconductor manufacturing. It is intended to

establish a common basis for developing detailed

specifications in subsequent documents concerning

design, performance and certification and monitoring of

UPW systems.

1.2 This document may be used by users and suppliers

as a basis for developing site-specific UPW

specifications and performance criteria.

2 Scope

2.1 This guide applies to ultrapure water systems used

in semiconductor manufacturing facilities for supplying

high purity water for chemical dilutions, wafer

processing and other manufacturing processes.

2.2 This guide can be used to understand the design

elements and functionality of all UPW systems, which

includes a Reverse Osmosis (RO) and a Deionization

(DI) process. However, it is most applicable to newer

designed UPW systems that support submicron

linewidth device manufacturing.

2.3 This standard does not purport to address safety

issues, if any, associated with its use. It is the

responsibility of the users of this standard to establish

appropriate safety and health practices and determine

the applicability of regulatory limitations prior to use.

3 Limitations

3.1 This guide does not define the actual specifications

generally negotiated between the user and the

manufacturer of the UPW system, against which water

samples are tested and qualification is passed.

3.2 This guide does not address the testing and

prequalification of materials, subassemblies, or

components used in a UPW system.

3.3 This guide does not address the protocols and

requirements defined by the manufacturer concerning

the installation of the UPW system.

3.4 This guide does not address the type, level, or

frequency of testing necessary and appropriate for

ongoing monitoring of a UPW system.

3.5 This guide does not address the frequency or scope

of ongoing maintenance for UPW systems including

change out of resin beds and replacement of filters.

3.6 This guide does not intend to cover any of the

important safety considerations that relate to the proper

installation, operation, or maintenance of a UPW

system.

4 Terminology

4.1 Acronyms and Abbreviations

4.1.1 TOC  Total organic carbon, also Total

Oxidizable Carbon. Refers to organic compounds.

4.1.2 UPW — Ultrapure Water System consisting of

multiple components including a Reverse Osmosis

(RO) and a Deionization (DI) process.

4.2 Definitions

4.2.1 activated Carbon  a media filter used to

remove oxidizing agents, like chlorine and chloramines,

and remove (adsorb) certain TOC compounds.

4.2.2 anion  a negatively charged ion.

4.2.3 cation  a positively charged ion.

4.2.4 clarifier  a piece of water treatment

equipment, typically used at municipal drinking water

plants, to remove suspended solids from surface water

and/or to soften surface water.

4.2.5 degasification  the removal of a certain

amount of volatile compounds dissolved in water.

4.2.6 deionization (DI)  the removal of undesirable

ions from water.

4.2.7 DI storage  generally refers to a storage tank

that contains DI water, located between the primary and

polishing ion exchange subsystems.

4.2.8 DI (deionized) water  generally refers to water

that has passed through a full-train ion exchange system

or RO water that has been polished by ion exchange.

SEMI F61-0301 © SEMI 2001 2

4.2.9 dissolved solids  contaminants in water that

are so small that they are uniformly distributed, includ-

ing ions and the smallest TOC and silica compounds.

4.2.10 dual-beds  an ion exchange scheme where a

cation exchange unit is followed by an anion exchange

unit.

4.2.11 electrodeionization (EDI)  a water treatment

technology that utilizes mixed-bed ion exchange plus

an electrical potential to remove undesirable dissolved

solids. Also referred to in the industry as CDI

(Continuous Deionization).

4.2.12 filtration  the removal of suspended solids by

passing water through some form of solid or semi-solid

medium.

4.2.13 final filter  generally the final treatment step

in a UPW system; used to remove suspended solids.

4.2.14 full-train DI  an ion exchange scheme where

a cation exchange unit is followed by an anion

exchange unit and a mixed-bed ion exchange unit.

4.2.15 ground water  water located below the

surface of the earth, also called well water.

4.2.16 heat exchanger  a piece of equipment used to

control the temperature of a water stream.

4.2.17 ion exchange  a water treatment technology

used in a high-purity water treatment application to

exchange undesirable cations for hydrogen ions and

undesirable anions for hydroxide ions.

4.2.18 loop  the distribution system that includes the

continuous circulation of UPW from the Final Filter

back to the DI storage tank. End users draw off of the

loop.

4.2.19 low-pressure UV units  units that use UV

lamps that have a slight vacuum within. Typically,

low-pressure lamps are called 254 nm for ozone

destruction and bacterial inactivation or 185 nm for

TOC reduction.

4.2.20 medium-pressure UV units  units that use UV

lamps that have a positive pressure within. Used with

bacterial inactivation/ozone destruction lamps or TOC

reduction lamps.

4.2.21 microfiltration  generally refers to filters

designed to remove suspended solids less then one

micron in size but greater than 0.1 micron in size.

4.2.22 mixed-beds  ion exchange vessels used to

polish already purified water, in which both cation and

anion exchange occurs.

4.2.23 multimedia filter  generally refers to a

suspended-solids removal piece of equipment that

contains two or more filtering media such as anthracite

and sand, or anthracite, sand and garnet.

4.2.24 Ozone  Ozone (O

) may be injected into the

Supply and/or Return line to control microbiological

contaminants and also to enhance the action of TOC

breakdown in downstream TOC reducing UV units.

4.2.25 polishing ion exchange  a cation/anion

exchange step located downstream of primary ion

exchange.

4.2.26 pretreated water  generally refers to treated

water that is fed to reverse osmosis (RO) units.

4.2.27 primary ion exchange  the first cation/anion

exchange step in a high purity water treatment scheme.

4.2.28 raw water  any untreated natural water like

river water, lake water, ground water, or seawater.

May also refer to the treated feed water that enters a

plant from a municipal drinking water source or other

source.

4.2.29 return  the UPW sent to but not used by end

users that returns to the DI storage tank.

4.2.30 reverse osmosis (RO)  a filtration technology

that utilizes a semi-permeable membrane to remove

essentially all suspended solids and the vast majority of

all dissolved solids. Generally refers to water

(permeate) that has passed through a reverse osmosis

(RO) membrane.

4.2.31 RO storage  generally refers to a storage tank

that contains RO water.

4.2.32 scale inhibitor  a chemical used to minimize

or eliminate the precipitation of slightly-soluble salts,

like calcium carbonate (limestone) or calcium sulfate

(gypsum), within water treatment equipment

4.2.33 supply  the UPW sent to end users.

4.2.34 surface water  water located on the surface

of the earth, such as river water, lake water, and

seawater.

4.2.35 TOC  total organic carbon, also Total

Oxidizable Carbon. Refers to organic compounds.

4.2.36 treated water  water that has passed through

water treatment equipment and/or received chemical

injections in order to modify the dissolved and/or

suspended solids content of the water.

4.2.37 ultrafiltration  generally refers to filters

designed to remove all submicron suspended solids.

4.2.38 ultraviolet (UV)  electromagnetic energy

with around a 100–400 nm (nanometer) wavelength.

SEMI F61-0301 © SEMI 20013

4.2.39 UPW (ultra pure water)  the highest purity

water produced by a semiconductor water treatment

system, which is sent to the end users for use in

manufacturing.

5 General Requirements

5.1 Materials



Components of the UPW system

must be appropriate to the application and conform to

electrical, mechanical, and purity requirements, as well

as the corrosive properties of the UPW chemistry.

These requirements are defined by the physical

installation environment, local and national code

interpretations, process requirements, and delivery

specifications.

5.2 System Installation  The UPW system is

installed according to a protocol that ensures

mechanical integrity, leakproof operation, and no or

minimal contamination being added from distribution

throughout the system.

5.3 Acceptance Tests  Acceptance tests are

conducted on each subsystem or system produced. Such

tests may include performance demonstrations,

demonstrations of reliability criteria, and achievement

of purity standards. Such tests are the basis for

acceptance or rejection by the purchaser against a pre-

negotiated set of criteria for the performance of the

system.

5.4 Qualification Testing  Qualification testing may

include tests for resistivity, temperature, pressure, TOC,

dissolved oxygen, particle levels, bacteria, total silica,

dissolved silica, non-volatile residue, ions, and metals.

5.5 Monitoring  UPW systems are monitored for

continuing performance against desired and achievable

levels of quality. Action limits are generally set to

determine when system performance suggests that

corrective action is required.

5.6 UPW specifications  UPW systems are generally

guaranteed to deliver a certain quality of water on an

ongoing basis. The guaranteed performance is

established in advance between the UPW equipment

manufacturer and the system owner. Both qualification

testing and monitoring testing use the guaranteed

specifications to determine the parameters and levels of

purity to be tested.

5.7 Recycle/Reclaim Opportunitie s



There can be

several opportunities for using water within a UPW

system, and should be recognized during the design

phase when possible. Examples are; use of 1

pass

reject for cooling tower make-up water, returning UF

reject to Primary or Feed water Tank, re-use of last

stage rinse waters as UPW for lower grade use areas,

i.e., CMP, isolation of CMP waste stream, for possible

reclaim/reuse.

6 Source Water

6.1 Raw Water



is the raw material from which

UPW is made. Untreated raw water is natural water

that is obtained from a surface source such as a lake or

river, or from a ground water source. The raw water to

a UPW system is most frequently treated Municipal

Drinking Water.

6.2 Municipal Drinking Water  Most natural raw

waters must be treated in order to produce drinking

water that meets federal and state requirements. There

are upper limits for inorganic contaminants (e.g.,

asbestos, arsenic, copper, and lead), pesticides, volatile

organic chemicals (e.g., benzene, trichloroethylene,

toluene, and xylene), turbidity, microbiological

contaminants, and radiological contaminants (e.g.,

radon 226, radon 228, tritium, and strontium 90).

Municipal Water Treatment may utilize only

chlorination, or filtration and chlorination for certain

ground water sources. For many surface water sources,

coagulation (injection of aluminum or iron salts),

flocculation (injection of a long-chain polymer),

sedimentation, lime or lime/soda ash softening,

filtration, chlorination or chloramination (chlorine plus

ammonia) and other steps may be required.

7 Major Treatment Processe s

7.1 Pretreatment includes all of the water treatment

steps ahead of the Reverse Osmosis Membrane

Treatment step. These steps are primarily required to

protect the membrane units from scaling with sparingly

soluble salts, fouling with living or non-living

suspended particles, or chemical attack by pH,

oxidizing agents or other dissolved contaminants.

Pretreatment equipment may include media filtration,

micro filtration, or ultrafiltration (bulk suspended solids

removal), 1–5 micron cartridge filtration (polishing step

for suspended solids removal), sodium-cycle cation

exchange (softening, to remove scale-forming cations),

acid injection (to minimize cellulose acetate membrane

damage and/or to control carbonate scales), scale

inhibitor injection (to control scaling), activated carbon

filtration (to remove oxidizing agents and certain

organic molecules), and sulfite ion injection (to remove

oxidizing agents).

7.2 Reverse osmosis Membrane Treatment provides

extremely high rejection of dissolved ions (charged

atoms and molecules), organic (carbon containing)

compounds, silica (silicon containing) compounds, and

virtually complete rejection of suspended contaminants,

but will not reject dissolved gases and volatile organic

compounds as well. Reverse osmosis (RO) units may