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SEMI F43-0699 © SEMI 1999 2 5.2.3 cont rol product — a sam ple co m p o nent that gives consistent, s tabilized counts at or below t he expected cou nts from the test components. The produ ct is run periodically i n acco…
SEMI F43-0699 © SEMI 19991
SEMI F43-0699
TEST METHOD FOR DETERMINATION OF PARTICLE CONTRIBUTION
BY POINT-OF-USE PURIFIERS
This Test Method 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 December 18, 1998. Initially available on www.semi.org February 1999;
to be published June 1999.
1 Purpose
1.1 The purpose of this document is to define a
method for testing POU purifiers intended for
installation into a high-purity gas distribution system
and semiconductor manufacturing process equipment.
Application of this test method is expected to yield
comparable data among POU purifiers tested for the
purposes of qualification for its installation.
2 Scope
2.1 This document describes a test method designed to
draw comparisons of particulate generation
performance of POU purifiers tested under standard
conditions. The procedure utilizes a condensation
nucleus counter (CNC) applied to in-line gas purifiers
typically used in semiconductor applications. It applies
to purifiers of various media and up to 5 cm (~ 2 in.)
i.d. in size and for room temperature operation. The
purifier’s rated flow should be in the range of 0-50
standard liter per minute (slpm). For applications of this
method to larger purifiers, the testing flow rate should be
higher than specified in this method.
2.2 The experimental set up described in this method
can be used for testing either POU purifiers or stand-
alone POU filters.
3 Limitations
3.1 This procedure addresses total particle count
greater than the minimum detection limit (MDL) of the
condensation nucleus particle counter and does not
consider classifying data into various size ranges.
3.2 This methodology specifies flow and mechanical
stress conditions in excess of those considered typical.
These conditions shall not exceed those recommended
by the manufacturer. Actual performance under normal
operating conditions may differ.
3.3 The test medium is limited to nitrogen and argon.
Performance with other gases may vary.
3.4 This method does not include extended particle
count testing or testing under challenging conditions.
3.5 The accuracy of the data generated by this method
is limited to the accuracy of the particle measuring
instruments utilized.
3.6 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.
4 Referenced Documents
4.1 FED-STD-209. Federal Standard Airborne
Particulate Cleanliness Classes in Cleanrooms and
Clean Zones. General Services Administration.
5 Terminology
5.1 Acronyms
CNC – condensation nucleus counter
DUT – device under test
EP – electropolished
kPa – kiloPascal
LPC – laser particle counter
POU – point of use
psi – pounds per square inch
psia – pounds per square inch absolute
psid – pounds per square inch differential
psig – pounds per square inch guage
Ra – roughness average
Rmax – roughness maximum
scfm – standard cubic feet per minute
slpm – standard liters per minute
5.2 Definitions
5.2.1 background counts — counts contributed by the
test apparatus (including counter electrical noise) with
the spool piece in place of the test object.
5.2.2 CNC — condensation nucleus counter. A light
scattering instrument that detects particles in a gaseous
stream by condensing supersaturated vapor on the
particles.
SEMI F43-0699 © SEMI 1999 2
5.2.3 control product — a sample component that
gives consistent, stabilized counts at or below the
expected counts from the test components. The product
is run periodically in accordance with the test protocol
to assure that the system is not contributing particles
significantly different from expected levels. In the
absence of a control product, a spool piece can be used
as a control product of low particle emission rate.
NOTE 1: The control product may have to be changed
periodically if its performance degrades with testing.
Between tests, the control product must be bagged in
accordance with the original manufacturer's packaging and
stored in a clean manner. The control product is used to allow
the system to consider the disruption caused by changes in
flow due to the actuation of any valve, such as significant
fluctuations in flow, pressure, turbulence, and vibration.
5.2.4 dynamic test — a test performed to determine
particle contribution as a result of pulsing flow through
the DUT.
5.2.5 impact test — a test performed to determine
particle contribution as a result of mechanical shock
applied to the DUT.
5.2.6 Nine–log retention — number of particles
upstream of the purifier or filter are 1,000,000,000;
number of particles down-stream of the purifier or filter
is 1.
5.2.7 sample flow rate — the volumetric flow rate
drawn by the counter for particle detection. The
counter may draw higher flow for other purposes (e.g.,
sheath gas).
5.2.8 sampling time — the time increment over which
counts are recorded.
5.2.9 spool piece — a null component consisting of a
straight piece of electropolished tubing and appropriate
fittings used in place of the DUT to establish the
baseline.
5.2.10 static test — a test performed to determine
particle contribution under steady flow condition
through the DUT.
5.2.11 test duration — total time required to complete
the test procedure. (See Section 7.3)
5.2.12 test flow rate — mass flow through device
under test.
5.2.13 test pressure — pressure immediately
downstream of the test component. (See Figure 1.)
5.2.14 test temperature - ambient temperature at
which the experiment is being conducted.
6 Safety Precautions
6.1 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.
6.2 Exhaust from the CNC may contain hazardous
and/or flammable vapors and should be properly
vented.
6.2.1 Only inert gases like nitrogen and argon should
be used for purifier testing. No air is allowed in the
purifier testing procedure described in this
document.
6.3 Care should be taken to minimize the purifier’s
exposure to room air during and after testing.
7 Test Protocol
7.1 Test Conditions
7.1.1 The test is to be conducted at a normal indoor
temperature of between 18°C (64°F) and 26°C (78°F).
Environmental temperature within this range is not
expected to have any measurable effect on particle
detection. Follow manufacturer’s recommended
handling procedures.
7.1.2 Test apparatus must be enclosed in a Class 100
environment (per current revision of Federal Standard
209). If a clean hood is used, the hood should be
located within a clean environment. Use procedures
necessary to maintain Class 100 when handling test
apparatus and test component.
7.1.3 Care should be taken to protect the test apparatus
from excessive vibration. For example, vacuum pumps
and compressors should be isolated from the system.
7.2 Apparatus
7.2.1 Materials
7.2.1.1 Test gas — Nitrogen of minimum dryness of
<10 PPM moisture at 790.57 kPa (100psig) with <10
ppm of total hydrocarbons.
7.2.1.2 Filters — Electronics grade filters are required
to provide "particle-free" test gas. Each filter must be
nine-log retentive per manufacturer's specifications to
0.02 µm. The filter must be capable of achieving less
than 2 particles ≥=0.02 µm per cubic foot of test gas
under test conditions.
7.2.1.3 Pressure regulator — Made of electropolished
316L with an internal surface finish of 0.18 µm (7 µin.)
Ra and 0.25 µm (10 µin.) Rmax to maintain system
pressure.
SEMI F43-0699 © SEMI 19993
7.2.1.4 Pressure gauge — made of electropolished
316L stainless steel, with an internal surface finish of
0.18 µm (7 µin.) Ra and 0.25 µm (10 µin.) Rmax, to
monitor system test pressure.
7.2.1.5 Standard testing flow control device — Use
flow meters with ranges appropriate for testing from 0-
50 slpm.
7.2.1.6 Tubing — Made of electropolished 316L
stainless steel, with and internal surface finish of 0.18
µm (7 µin.) Ra and 0.25 µm (10 µin.) Rmax.
7.2.1.7 Sampler — The sampler is to be constructed
according to the drawing and sampler design criteria
given in Appendix 1 Sampler Design Criteria. The
sampler collects gas from the stream exiting the test
device, where the sample is near-isokinetic in design.
7.2.1.8 Upstream adapter — The upstream adapter
piece connects 12.7 mm (1/2–in.) tubing to the test
device. For 12.7 mm (1/2–in.) test devices, the adapter
is a simple face-seal connector. For 6.35 mm (1/4–in.)
test devices, the adapter is a tapered cone between 6.35
mm and 12.7 mm (1/4– and 1/2–in.) face-seal
connections.
7.2.1.9 Downstream adapter — The downstream
adapter piece connects 12.7 mm (1/2–in.) tubing of the
sampler to the test device. For 12.7 mm (1/2–in.) test
devices, the adapter is a simple face seal connector. For
6.35 mm (1/4–in.) test devices, the adapter is a tapered
cone between 6.35 mm (1/4–in.) and 12.7 mm (1/2–in.)
face-seal connections.
7.2.1.10 Spool Pieces — Spool pieces shall be the
same diameter as the fittings on the test piece and be 15
cm (6 in.) in length. The spool piece is to be installed
in the system in place of the DUT while obtaining
background counts for the system.
7.2.1.11 Fittings — Face seal connectors or
compression fittings dependent on test component end
connections. The end connection fittings of each DUT
being compared must be of the same type.
7.2.1.12 Gaskets — Use metal gaskets for attaching
the test device and adapter pieces. New gaskets should
be used for each new connection. The use of metal
gaskets is recommended in order to minimize the
particles that may be generated by installation of the
test piece. The use of silver plated metal gaskets should
be avoided because they shed particles after installation.
7.2.1.13 Mechanical shock device — To provide
mechanical shock by impact to the test device (see
Figure 2).
7.2.1.14 Actuator — A gas (compressed air or
nitrogen) operated device connected to the valve stem
to open and close the valve.
7.2.1.15 Actuator pressure — Minimum actuator gas
line pressure required to fully open and close the valve
during the dynamic test.
7.2.2 Instrumentation
7.2.2.1 A CNC whose counting efficiency
characteristics fall within the envelope defined in FED
STD 209 for counting ultrafine particles is to be used
for particle counting. Test durations in this test method
have been established based on a sampling flow rate of
0.05 scfm.
7.2.2.2 Instruments should be calibrated regularly,
according to manufacturer's recommendations. For the
CNC, this includes routine checks of instrument
operation as specified by the manufacturer.
7.2.2.3 The CNC and data collection equipment must
have power surge suppression.
7.2.3 Setup and Schematic
7.2.3.1 Assemble the test apparatus according to the
schematic drawing of the test apparatus used shown in
Figure 1. Install the test apparatus inside a class 100
clean room. Adjust the inlet gas pressure to the
required pressure of 30 psig using the pressure regulator
R1 as indicated by an electronics grade pressure gauge
P1. The filtered gas flow is then diverted to flow
through either of the two flowmeters located
downstream of the valve V1.
7.2.3.1.1 The test gas delivered from the flow meters
is filtered again by an electronics grade filter F2. The
test gas pressure at this point is measured by another
electronics grade pressure gauge P2 installed upstream
of filter F2. A pneumatic valve PV1 is installed
downstream of the filter F2 for obtaining the particle
counts for the dynamic test portion (including the
background) of the test method. The test gas is filtered
once again by another electronics grade filter F3 before
it is delivered to the spool piece and the test component.
7.2.3.1.2 Particles released from the spool piece and
the test component are measured by a CNC located
downstream of these components. A representative
sample of the gas flow is sampled by the CNC through
an isokinetic sampler located downstream of the test
devices. The CNC measures particle concentration
every minute, sampling at a flow rate of 0.05 scfm, to
provide a continuous measurement of particle counts
for the static, dynamic, and impact tests on the test
pieces. The particle data can also be collected and
stored in a computer using a data acquisition program.
7.2.3.1.3 A schematic drawing of a recommended test
apparatus is given in Figure 1. A list of parts used in
the construction of the recommended test stand is
presented in Table 1. The dimensions of the tubing and