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SEMI F31-0698 © SEMI 1998 2 chemical until it is transferred to the m anufacturing process. 5.2.6 decont amination — Clean ing u p o f a BCD Syst e m , or any su bsystems th ereof, by introdu cing chemical s ol uti ons i…

SEMI F31-0698 © SEMI 19981

SEMI F31-0698

GUIDE FOR BULK CHEMICAL DISTRIBUTION SYSTEMS

1 Purpose

1.1 This guide defines components of Bulk Chemical

Distribution Systems and sets forth Basic Design

Elements and optional design features common to BCD

Systems.

2 Scope

2.1 This guide applies to BCD Systems used in

semiconductor manufacturing facilities for supplying

liquid chemicals to wafer cleaning and other

manufacturing processes.

3 Limitations

3.1 This guide is not intended to be applicable to every

possible use and type of chemical dispensing system

but only to those systems that originate with sources of

single lots of liquid materials of 55 gallons or more, and

which operate in a way that splits a single liquid stream

into multiple streams. This guide excludes slurry

systems, small liquid chemical dispensing systems,

chemical waste systems, and many other types of

systems that dispense fluids.

3.2 This guide excludes construction protocols for

BCD Systems, such as clean manufacturing practices,

integrity of fabrication, and prequalification of

materials.

3.3 This guide does not intend to cover all the

important safety considerations which relate to Bulk

Chemical Distribution Systems.

3.4 References to “containers” in this document are

not limited to “Bulk Containers” as defined in the Code

of Federal Regulations (CFR) Section 49 or Department

of Transportation (DOT) Regulations.

4 Referenced Documents

NOTE: As listed or revised, all documents cited shall be the

latest publications of adopted standards.

4.1 SEMI Standards

SEMI E49 — Guide for Standard Performance,

Practices, and Sub-Assembly for High Purity Piping

Systems and Final Assembly for Semiconductor

Manufacturing Equipment

SEMI S2 — Environmental, Health, and Safety

Guideline for Semiconductor Manufacturing Equipment

4.2 DOT

Department of Transportation

4.3 Federal Regulations

49 CFR — Title 49 of the Code of Federal Regulations

5 Terminology

5.1 Acronyms

5.1.1 CDM — Chemical Dispensing Module

5.1.2 CDU — Chemical Dispensing Unit

5.1.3 DIW — Deionized Water

5.1.4 MDU — Modular Dispensing Unit

5.2 Definitions

5.2.1 blending — Combination of two or more

chemicals to create a mixture which contains a desired

ratio of constituents.

5.2.2 chemical dispense system — The module used

for filtering and for dispensing chemical into the

distribution piping network which may be referred to by

a number of manufacturer’s specific designations:

CDM, CDU, and MDU.

5.2.3 chemical reprocessing unit — A subsystem

which purifies or recycles a chemical.

5.2.4 chemical transfer — The technique used to

move chemical between different points in the

distribution system.

5.2.4.1 pressurization — The use of high purity

nitrogen or other appropriate gas to displace liquid

through the distribution system.

5.2.4.2 pumping — A mechanical or pneumatically

operated technique used to create hydraulic force in the

system.

5.2.4.3 hybrid system — A combination of

pressurization and pumping techniques used to transfer

chemical.

5.2.5 day tank — A vessel that stores that amount of

chemical which may be consumed within one or more

days. This holding vessel usually stores prefiltered

1 Department of Transportation, 400 Seventh Street, SW,

Washington, D.C. 20590

2 United States Government Printing Office, Washington, D.C. 20402

SEMI F31-0698 © SEMI 1998 2

chemical until it is transferred to the manufacturing

process.

5.2.6 decontamination — Cleaning up of a BCD

System, or any subsystems thereof, by introducing

chemical solutions into the piping systems. This

procedure occurs during qualification and prior to

commissioning the system.

5.2.7 dilution — Combination of a concentrated

chemical and DIW to create a lower concentration of

the aqueous chemical.

5.2.8 on-site gas-to-chemical generation — The

contacting of a liquid and gas phase to create a stable

liquid solution. The chemical is generated on-site in a

form suitable for distribution through a dispense

system.

5.2.9 pickling — Conditioning of the system by filling

it with the actual chemical or another chemical for

which the system is designed. This chemical will stay in

the system for a specified period of time. The purpose

of this conditioning is to leach out impurities prior to

actually using any chemical in the manufacturing

process.

5.2.10 polishing — The process of flowing chemical

through a filter one or more times to reduce the

particulate levels of the chemical.

5.2.11 primary containment — Tubing, piping, or

components whose wetted surface is directly in contact

with the chemical. These components are generally

made from fluoropolymer materials such as

Perfluoroalkoxy (PFA).

5.2.12 secondary containment — Tubing or piping

which contains the primary piping or tubing. The

purpose of this configuration is to control leaks and to

protect against spills. Secondary containment of solvent

systems generally uses stainless steel material, and acid

or base systems generally use Schedule 40

Polyvinylchloride (PVC) material boxes such as VMB.

This may also be used as secondary containment.

5.2.13 stabilized filtration — A design feature that

provides for the continuous flow of chemical through

filters to minimize shocking and pulsating of the filters.

5.2.14 surge suppression — Use of a device or in-line

chamber that minimizes flow pulsations caused by a

pump. This may also be referred to as pulsation

dampener.

5.2.15 valve manifold box (VMB) — A chemical-

resistant enclosure which houses manual and/or

pnuematically actuated valves, tees, and fittings.

5.2.16 vessel — A vessel fabricated from or

containing an inner lining of chemically inert and

resistant materials which is specifically designed to

maintain the purity level of the chemical for a long

period of time. All containers are fabricated from or at

least contain an inner lining of chemically inert and

resistant materials and are specifically designed to

maintain the purity level of the chemical for long

periods of time. The larger containers are generally

designed in conformance to Department of

Transportation Regulations (DOT) and may be

transported by ground. These containers have fittings

which are compatible to this purpose so that they may

be hooked up to the BCD Systems directly. Such

containers include:

5.2.16.1 drum — A container for storing chemicals,

generally with a cylindrical shape and not more than 55

gallons or 200 liters in size.

5.2.16.2 tote — A container for storing chemicals,

generally 110, 220, or 330 gallons in size and requiring

an outer shell to provide structural support to the vessel.

5.2.16.3 ISO container — A container for storing

chemicals, usually large in size, able to be transported

directly, and designed in compliance with criteria from

the International Standards Organization.

5.2.17 wetted surface — Any surface which comes

into contact with the chemical.

6 General Requirements

6.1 Materials — Components of the BCD Systems

must be appropriate to the application and conform to

electrical, mechanical, and chemical requirements as

defined by the physical installation environment, local

and national code interpretations, process requirements,

and delivery specifications.

6.2 System Installation — The Bulk Chemical

Distribution System is installed according to a protocol

which ensures mechanical integrity, leakproof

operation, and minimal contamination to any liquids

being distributed throughout the system.

6.2.1 System Installation procedures include a

rinsedown protocol which may include any of the

following: (1) a flushing procedure with DIW; (2) a

sanitization step using hydrogen peroxide; (3) a drying

step using nitrogen gas; and (4) a “pickling” process

using the actual chemical, or a less concentrated form

of the chemical. For solvent systems, the rinse-down

chemicals introduced are generally the same as the

solvent that is designated to be used in the system,

whereas for acid systems, the rinse down solutions may

include DIW, ozonated water, or a dilute form of

hydrogen peroxide.

6.2.2 The protocol for System Installation and start-up

follows a predefined sequence of events which

incorporates all of the physical activities and testing

parameters and establishes check points for approvals at

each stage.

6.3 Acceptance Tests — Acceptance tests are

conducted on each subsystem or system produced. They

are the basis for acceptance or rejection by the

purchaser.

6.3.1 Acceptance testing may include performance

demonstrations, demonstration of reliability criteria,

and achievement of purity standards. Safety

considerations are addressed elsewhere.

6.4 Qualification Testing — Qualification testing is

performed on the liquid chemicals being transported

through each chemical piping subsystem.

6.4.1 Qualification testing may include tests for trace

metals, anions, particles, and total organic carbon.

Assay analysis is recommended for blending or dilution

operations.

6.5 Chemical Specifications — Particulate BCD

Systems are specified as to the level of impurities at the

point of use as compared to the quality of the incoming

chemical. Impurities in the chemical are generally

specified in terms of particles per ml; metallic

impurities are specified for each element and for total

adders; and organic impurities are specified for total

added.

7 Basic Design Elements

7.1 General — Each Bulk Chemical Distribution

System contains certain basic components and a variety

of design options to meet particular customer and

facility needs. A simple example system is shown in

Figure 1.

Figure 1

Schematic of Basic Bulk Chemical Distribution System