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SEMI F70-0302 © SEMI 2002 2 5.2.7 partic le counts — a counted valu e from a laser particle coun t er (LP C) or cond ensatio n nucleus c ounter (CNC) show n for particles or larger than or equal to the m inimum counting …

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SEMI F70-0302 © SEMI 2002
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SEMI F70-0302
TEST METHOD FOR DETERMINATION OF PARTICLE CONTRIBUTION
OF GAS DELIVERY SYSTEM
This test method was technically approved by the Global Facilities Committee and is the direct responsibility
of the Japanese Facilities Committee. Current edition approved by the Japanese Regional Standards
Committee on January 11, 2002. Initially available at www.semi.org January 2002; to be published March
2002.
1 Purpose
1.1 The purpose of this document is to provide a
standardized methodology and procedure for measuring
the particle contribution performance of a gas delivery
system in terms of number of particles added to gas
flowing through the system. This standardized
procedure is intended to be used commonly by the
component suppliers, gas suppliers, equipment
suppliers, and users.
2 Scope
2.1 This test method applies to all types of surface
mount and conventional gas delivery systems used in
semiconductor manufacturing facilities and comparable
research and development areas.
2.2 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 All components must meet quality requirements as
established and controlled by manufacturers prior to
testing (e.g., dimensional, functional, etc.).
3.2 Care should be exercised in handling of
components to maintain manufacturer’s specifications.
4 Referenced Standards
NOTE 1: As listed or revised, all documents cited shall be
the latest publications of adopted standards.
4.1 ISO Standards
1
ISO 14644-1 — Cleanrooms and Associated Controlled
Environments – Part 1: Classification of air cleanliness
1 ISO Central Secretariat, 1, rue de Varembé, Case postale 56, CH-
1211 Genève 20, Switzerland, website: www.iso.ch
4.2 JIS Standards
2
JIS B 9921 — Light Scattering Automatic Particle
Counter
5 Terminology
5.1 Abbreviations and Acronyms
5.1.1 CNC — condensation nucleus counter
5.1.2 LPC — laser particle counter
5.1.3 MFC — mass flow controller
5.1.4 MFM — mass flow meter
5.1.5 slm — standard liters per minute, the gas
volumetric flow rate measured in liters per minute at
0°C and 1 atm.
5.2 Definitions
5.2.1 background counts — particle counts contributed
by the test apparatus (including false counts) with the
spool piece in the place of the test object as function of
particle size.
5.2.2 counting efficiency — the ratio of the particle
concentration calculated from the particle counts to the
actual particle concentration in the sampled gas for
particles equal to or larger than a given particle size.
5.2.3 design flow rate — flow rate normally applied to
the gas delivery system.
5.2.4 false counts — particle counts contributed by
electrical noise or by other events and not particles in
the sampled gas.
5.2.5 gas delivery system — a system installed in
semiconductor manufacturing equipment to supply
process and carrier gases to reactors, which typically
consists of tubing, fittings, valves, filters, mass flow
controllers and regulators; can be surface mount or
conventional system.
5.2.6 minimum counting particle diameter — a
predefined minimum diameter of particles to be
counted in this test method.
2 Japanese Standards Association, 1-24, Akasaka, 4-Chome, Minato-
ku, Tokyo 107 Japan
SEMI F70-0302 © SEMI 2002
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5.2.7 particle counts — a counted value from a laser particle counter (LPC) or condensation nucleus counter (CNC)
shown for particles or larger than or equal to the minimum counting particle diameter.
5.2.8 sample flow rate — the volumetric flow rate through the particle counter.
5.2.9 spool piece — a null component consisting of a straight piece of electropolished tubing or like object and
appropriate fittings used in place of the test system to establish the background.
5.2.10 test flow rate — the volumetric flow rate through the test systemRequired Apparatus
6 Required Apparatus
6.1 Filter — Filters with the following performance specified by the manufacturer.
Characteristic Performance Condition
Filtration Efficiency
9 log particle size: 0.02 µ m
Flow Rate
300 slm inlet pressure: 0.34 MPa
6.2 Tubing Material — 1/4 inch or 3/8 inch SUS 316L electropolished tubing or better.
6.3 Particle Counter — The particle counter may be either LPC or CNC of which the minimum counting particle
diameter is 0.1 µ m or smaller, and has the following performance as specified by JIS B 9921.
6.3.1 Counting Efficiency
Diameter of Polystyrene Latex Standard Particle Counting Efficiency
Minimum countable particle diameter of the counter (See NOTE 1.)
50 ± 20 %
1.5 to 2.0
×
Minimum countable particle diameter of the counter
100 ± 10 %
NOTE 1: For a CNC, the minimum countable diameter shall be defined as a diameter having counting efficiency of 50 ± 20%.
6.3.2 False Count — Equal to or less than 1 in 5 minutes.
6.3.3 Acceptable Error of Flow Rate — ± 5%
6.4 Sampler — A system used to perform partial sampling of the gas stream exiting the test system, that consists of
a diffuser equipped with a pressure reducing device in which gradual expansion to atmospheric pressure occurs and
a sample probe. It is desirable that the sampler is designed to obtain isokinetic sampling. The average velocity of
gas flowing through the sample probe should approximate the average velocity in the external tubing in which the
sample probe is inserted. The sample probe overlap with the external tube must be of appropriate length, and it must
be confirmed before use that the surrounding atmospheric gas is not drawn in the sample.
7 Test Condition
7.1 Test Gas — Liquid Nitrogen (LN
2
) or cleaner Nitrogen (N
2
) or Argon (Ar).
7.2 Temperature — Room temperature (between 18 and 26° C)
7.3 Environment — ISO/FDIS 14644-1 class 5 or better.
SEMI F70-0302 © SEMI 2002
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8 Preparation of Apparatus
8.1 Set up apparatus and the gas supply system as shown in Figure 1.
NV
RG F
N2
By-pass
MFM
System
Under
Test
Particle
Counter
Sampler
F
F
MFC
VENT
V
Legend, V: Valve MFC: Mass Flow Controller MFM: Mass Flow Meter
F: Filter RG: Regulator NV: Needle Valve
Figure 1
Test Set Up Basic Flow Diagram
8.2 If the test flow rate is equal to or less than the sample flow rate required by the particle counter, insert a filter in
place of the sampler to fulfill the sample flow rate. (See Figure 2.)
Test
Flow
Particle
Counter
Filter
Test Flow Rate
≤
Sample Flow Rate
Figure 2
Full Sampling
8.3 If the test flow rate is higher than the sample flow rate required by the particle counter, use the sampler for
partial sampling. (See Figure 3.) To establish the test flow rate and obtain an isokinetic condition, it is required to
adjust the MFC in the test set up and the NV on the by-pass line. The by-pass line is required to have a capability to
handle the maximum test flow when the valves in the system under test is closed position during the pulse test.
Sampler
Particle
Counter
Test
Flow
Vent
FNV
By-pass
Test Flow Rate
>
Sample Flow Rate
Figure 3
Partial Sampling