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SEMI F28-1103 © SEMI 1997, 2003 2 ISO 14644-2 — Cleanrooms an d associated controlled environm ents Part 2: Specifications for testing and monitoring t o prove continued com pliance with ISO 14644-1. NOTICE: Unless ot he…

SEMI F28-1103 © SEMI 1997, 2003 1

SEMI F28-1103

TEST METHOD FOR MEASURING PARTICLE GENERATION FROM

PROCESS PANELS

This test method was technically approved by the Global GasesCommittee and is the direct responsibility of

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

Committee on September 25, 2003. Initially available at www.semi.org October 2003; to be published

November 2003. Originally published September 1997.

1 Purpose

1.1 The purpose of this document is to define a method

for testing process panels intended for installation in

high-purity gas distribution systems. Application of this

test method is expected to yield comparable data among

process panels tested for the purposes of qualification

for this installation.

1.2 This document describes a test method designed to

draw comparisons of particulate generation

performance of process panels. This test method

evaluates the cleanliness of process panels in the “as

received” condition as well as under normal operating

conditions. The “as received” test is intended to enable

the user to evaluate the fabrication, cleaning, and

packaging techniques of the manufacturer of the

process panel. The test under actual operating

conditions is intended to allow the user to evaluate the

manufacturer’s component selection as well as the

quality of the panel design. The specific flow rates

described in both test methods are representative of

relatively high flow conditions for a typical process

panel.

2 Scope

2.1 This test method addresses total particle counts

greater than the minimum detection limit (MDL) of the

particle counter and does not consider classifying data

into various size ranges.

2.2 This procedure utilizes a particle counter applied to

process panels typically used in semiconductor

applications. It applies to process gas supply systems

(e.g., gas cabinets) which include a process panel, an

inert purge panel, and a system vent. Both automatic

and manual process panels are within the scope of this

test procedure. Panels, as defined in this test method,

are considered to consist of 6.35 mm O. D. × 0.89 mm

wall (1/4" O.D. × 0.035" wall) tubing and components.

NOTICE: 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 or other limitations prior

to use.

3 Limitations

3.1 This test method specifies flow and mechanical

stress conditions considered typical of conditions which

would be expected under moderately aggressive

operating conditions. These conditions should not

exceed those recommended by the manufacturer.

Actual performance under operating conditions at lower

flow rates or less aggressive conditions may differ. This

test method does not address particle generation under

vibrating conditions.

3.2 The test medium is limited to nitrogen, argon, or

clean dry air (CDA). Performance with other gases may

differ.

3.3 The accuracy of the data generated by this method

is limited to the accuracy of the particle measuring

instruments utilized.

3.4 This method is written with the assumption that the

operator understands the use of the apparatus at a level

equivalent to six months of experience.

3.5 This document is not intended as a methodology

for monitoring on-going particulate performance once a

particular process panel has been tested. Also, this

method does not include extended dynamic particle

count testing (particle generation after thousands of

cycles).

3.6 Auto-crossover systems are not within the scope of

this test procedure.

NOTE 1: It should be mentioned that test results from panels

equipped with final outlet filters can differ significantly from

test results from panels without filters.

4 Referenced Standards

4.1 ISO Standards

ISO 14644-1 — Cleanrooms and associated controlled

environments Part 1: Classification of air cleanliness.

1 International Organization for Standardization, ISO Central

Secretariat, 1, rue de Varembé, Case postale 56, CH-1211 Geneva 20,

Switzerland. Telephone: 41.22.749.01.11; Fax: 41.22.733.34.30,

Website: www.iso.ch

SEMI F28-1103 © SEMI 1997, 2003 2

ISO 14644-2 — Cleanrooms and associated controlled

environments Part 2: Specifications for testing and

monitoring to prove continued compliance with ISO

14644-1.

NOTICE: Unless otherwise indicated, all documents

cited shall be the latest published versions.

5 Terminology

5.1 Abbreviations and Acronyms

5.1.1 CDA — Clean, dry air

5.1.2 EP — Electropolished

5.1.3 LPC — Laser particle counter

5.1.4 psi — Pounds per square inch

5.1.5 psia — Pounds per square inch absolute

5.1.6 psid — Pounds per square inch differential

5.1.7 psig — Pounds per square inch gauge

5.1.8 scfm — Standard cubic feet per minute

5.1.9 slpm — Standard liters per minute

5.1.10 SL — Standard liters

5.2 Definitions

5.2.1 background counts — counts contributed by the

test apparatus (including counter electrical noise) with a

spool piece in place of the test object.

5.2.2 Compressed Gas Association (CGA) — also

frequently used to refer to a fitting, as defined and

specified by the Compressed Gas Association, which is

used to connect a gas source cylinder to a panel inlet.

5.2.3 condensation nucleus counter (CNC) — a

discrete particle counting instrument that detects

particles, in a gaseous stream, by measuring light

scattered from droplets grown to measurable size by

condensation of supersaturated vapor upon the

particles.

5.2.4 dynamic test — a test performed to determine

particle contribution as a result of valve actuation or

regulator adjustment in a process panel during normal

operation.

5.2.5 process panels — a gas source control piping

system for delivering process gases as defined in SEMI

F13.

5.2.6 sample flow rate — the volumetric flow rate

drawn by the particle counter for particle detection.

5.2.7 sampling time — the time increment over which

counts are recorded.

5.2.8 source pressure — pressure of the source gas

applied to the cylinder connection at the panel inlet.

5.2.9 spool piece — a null component consisting of a

straight piece of electropolished tubing and appropriate

fittings used in place of the test component to establish

the baseline.

5.2.10 standard conditions — 101.3 kPa, 0.0°C (14.73

psia, 32°F).

5.2.11 static test — a test performed on an as-received

process panel with all valves in the fully-open position.

5.2.12 test duration — total time required to complete

the test procedure.

5.2.13 test flow rate — volumetric flow rate of the test

gas at standard conditions as defined in Section 5.2.10.

5.2.14 test pressure — pressure immediately

downstream of the test panel.

6 Test Procedure

6.1 Test Conditions

6.1.1 Precautions — This test method may involve

hazardous materials, operations, and equipment. This

test method does not purport to address the safety

considerations associated with its use. It is the

responsibility of the user to establish appropriate safety

and health practices and determine the applicability of

regulatory limitations before using this method.

6.1.1.1 Exhaust from the CNC may contain hazardous

and/or flammable vapors and should be properly treated

before being released to atmosphere.

6.1.2 The test is to be conducted at a normal indoor

temperature of between 18°C (64°F) and 26°C (78°F).

6.1.3 Test apparatus must be enclosed in a Class 100

environment (per ISO 14644). Use procedures

necessary to maintain Class 100 when handling test

apparatus and test components.

6.1.4 Care should be taken to protect the test apparatus

from excessive vibration. For example, vacuum pumps

and compressors should be isolated from the system.

6.2 Apparatus and Materials

6.2.1 Test Gas — Clean, dry nitrogen or air is to be

used [minimum dryness −60°C dew point at 790 kPa

(100 psig) and < 10 ppm total hydrocarbons]

6.2.2 Filters — Filters are required to provide

“particle-free” test gas. Each filter must be nine-log

retentive, per manufacturer’s specifications, to 0.02 µm

particles and have a pressure drop of less than 6.9 kPa

(1 psid) at the specified test pressure and flow rate. The

filter must be capable of achieving less than 1 particle

(≥ 0.02 µm) per cubic foot of test gas under test

conditions.

6.2.3 Pressure Regulator — Pressure regulators are

required to maintain system test pressures.

6.2.4 Pressure Gauge — Pressure transducers or

gauges are required to monitor system test pressures.

6.2.5 Flow Control Device — A 0–100 slpm flow

control device is required for controlling the test flow

rate.

6.2.6 Tubing — A 6.35 mm O.D. × 0.89 mm wall (1/4"

O.D. × 0.035" wall) tubing is required. The tubing

shall have an average surface roughness of 0.25

micrometer (10 microinch) Ra or less. Electropolished

tubing (as defined in SEMI F16) is recommended.

6.2.7 Sampler — The sampling system consists of a

diffuser equipped with a pressure reducing device (e.g.,

critical orifice) and a sample probe. All parts of the

sampling system are to be electropolished with a

surface roughness of 0.25 micrometer (10 microinch)

Ra or less. If a critical orifice is to be used for pressure

reduction, it is not required to be electropolished. The

diffuser and sample probe must be sized to obtain

isokinetic sampling at the specified test conditions. The

critical orifice must be sized to obtain the specified

panel pressure at the specified test flow rate.

6.2.8 Spool Piece — Spool pieces shall be electro-

polished 316L stainless steel tubing with a surface

finish of 0.25 micrometer (10 microinch) Ra or better.

The spool piece is to be installed in the system in place

of the test device while obtaining background counts

for the system.

6.2.9 Fittings — Use face seal connectors or

compression fittings depending on test panel end

connections.

6.2.10 Gaskets — Use non-plated metal gaskets where

required.

6.2.11 A CNC capable of detecting particles at least as

small as 0.02 µm at a 50% efficiency envelope as

defined by ISO 14644, with a sampling flow rate of

1.23 SLPM (0.05 scfm) or greater, is to be used for

particle counting. A laser particle counter, capable of

detecting particles at least as small as 0.1 micro meters,

may be used in addition to, or in place of, the CNC.

Test durations in this test method have been established

based on a sampling flow rate of 1.23 SLPM (0.05

scfm).

6.2.11.1 Instruments should be calibrated regularly,

according to manufacturer’s recommendations. For the

CNC, this includes routine checks of sample flow rate,

working fluid level, and zero.

6.2.11.2 The CNC and data collection equipment

should have power surge suppression.

6.2.11.3 Setup and Schematic — See Figure 1.