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SEMI F1-96 © SEMI 19 90, 1996 2 with oth er pieces or components . The t y pical compon e nts ref erred to by this specification are valv es, fittings, regulators, pressure gauges, pressure a nd flow sensors, and tubing …

SEMI F1-96 © SEMI 1990, 19961

SEMI F1-96

SPECIFICATION FOR LEAK INTEGRITY OF HIGH-PURITY GAS PIPING

SYSTEMS AND COMPONENTS

NOTE: This entire document was revised in 1995.

1 Purpose

This specification defines the leak testing requirements

and leakage rates for high-purity gas piping systems

and components used in semiconductor manufacturing.

It is also intended as an aid in the procurement and

installation of equipment, materials, and services.

2 Scope

2.1 This specification applies to high-purity gas piping

systems and components used in semiconductor

manufacturing facilities and comparable research and

development areas.

2.2 It includes testing methods for complete systems,

subsystems, and individual components.

2.3 It states requirements for both the user and

manufacturer and establishes leak rate limits for

acceptance testing and qualification testing.

3 Limitations

3.1 This specification is not a replacement for safety

regulations. It is the responsibility of the user to ensure

that piping systems and components comply with all

applicable safety regulations.

3.2 Interferences

3.2.1 Mass spectrometer leak testing with helium can

result in misleading indications due to high

permeability of polymeric materials by helium.

Permeation is often indicated by a delayed leakage

indication and a continually rising apparent leakage

rate. Helium tracer gas under pressure is absorbed by

permeable materials, and subsequent desorption can

inhibit later testing at sensitive levels. Therefore,

perform the tests in this order: inboard, internal, and

outboard.

3.2.2 For low pressure tests, 1 MPa (147 psig) or less,

the space to be filled with tracer gas must be purged or

evacuated to avoid dilution. This applies both to

enclosures and to the interiors of test objects.

3.2.3 Long tubing lines or small diameter tubing at an

inlet may require purging to ensure that the tracer gas

reaches the test object.

3.2.4 Conductance between the test object and the leak

detector must be adequate to ensure test sensitivity.

Restrictions such as regulators or check valves between

the test object and the leak detector may require testing

the test object before installing the downstream

components.

3.2.5 Air flow can severely hinder capture of leaking

gas by a detector probe. If possible, such air flow

should be reduced to a minimum during testing. If

testing must be performed in an area with substantial air

flow, a protective film, such as is described in ASTM E

499, Method B, should be placed around the probe tip

when examining each joint.

3.2.6 Temperature variations may affect leak

performance. However, this specification does not

address this effect.

4 Referenced Documents

All documents cited shall be the latest published

revisions.

4.1 SEMI Document

SEMI S2 — Safety Guidelines for Semiconductor

Manufacturing Equipment

4.2 ASTM Standards

E 493 — Standard Test Methods for Leaks Using the

Mass Spectrometer Leak Detector in the Inside-Out

Testing Mode

E 498 — Standard Methods of Testing for Leaks Using

the Mass Spectrometer Leak Detector or Residual Gas

Analyzer in the Tracer Probe Mode

E 499 — Standard Methods of Testing Leaks Using the

Mass Spectrometer Leak Detector in the Detector Probe

Mode

5 Terminology

5.1 acceptance test — A test conducted on each

component, subsystem, or system produced. It is the

basis for acceptance or rejection by the purchaser. The

purpose of acceptance testing is to provide a check to

ensure that the component, subsystem, or system has

been properly assembled or manufactured.

5.2 component — An individual piece or a complete

assembly of individual pieces capable of being joined

1 American Society for Testing and Materials, 100 Barr Harbor

Drive, West Conshohoken, PA 19428-2959

SEMI F1-96 © SEMI 1990, 1996 2

with other pieces or components. The typical

components referred to by this specification are valves,

fittings, regulators, pressure gauges, pressure and flow

sensors, and tubing welded to fittings.

5.3 design pressure — Of a system or subsystem, the

pressure at the most severe condition of internal and

external pressure expected during normal service. The

maximum pressure expected in any portion of a system

or subsystem is typically determined by the maximum

adjustable setting of the last pressure regulator that

supplies it, the supply pressure to the regulator, or the

actuation pressure of any relief device incorporated.

5.4 high-purity — Of a system, subsystem, or

component used for the control of chemicals (gases or

liquids), designed and constructed in such a manner that

it does not introduce significant impurities, particulate

or molecular, into the flow stream it controls or

regulates.

NOTE: Such systems, subsystems, or components are

designed and constructed such that, if an impurity is

introduced into the flow path, it can be readily purged to an

insignificant level.

5.5 leak — A path (or paths) in a sealed system that

will pass tracer gas when a pressure differential or

diffusion path exists. There are two leak mechanisms: a

mechanical passage and a material through which gas

can diffuse or permeate. A leak may have both

mechanisms operating in parallel.

5.6 leakage, inboard — Leakage from outside to

inside occurring when the internal pressure is less than

the external pressure acting on a component. Inboard

leakage is typically determined by introducing a tracer

gas around the exterior of the piping system or

component under test.

NOTE: Inboard leak tests are easier tests to conduct to high

sensitivity levels, but are typically not indicative of

pressurized operating conditions. It is difficult to correlate an

inboard leak test to the performance of a component,

subsystem, or system when under internal pressure. Also, the

internal collapsing forces created by external pressure may

mask leaks which may exist under pressurized operating

conditions.

5.7 leakage, internal — Leakage occurring within a

component across a flow barrier, such as the seat of a

closed valve.

5.8 leakage, outboard — Leakage from inside to

outside occurring when the internal pressure is greater

than the external pressure acting on a component.

Outboard leakage is typically determined by

introducing a tracer gas into the interior of the piping

system or component under test.

5.9 may — A term indicating that a provision is

neither required nor prohibited by this specification.

5.10 measured leak rate — The rate of leakage of a

given component, subsystem, or system measured

under specific conditions and employing a tracer gas.

NOTE: When testing with high-pressure 100% helium on a

mass spectrometer leak detector, measured leak rates must be

converted to equivalent standard leak rates.

5.11 qualification test — A test conducted on samples

of production articles manufactured to a single design

to establish the performance rating of a product. The

tests are extensive and closely controlled and

completely analyze the characteristics of a component

for use in a high-purity installation.

5.12 rated pressure — The manufacturer’s

recommended maximum allowable operating pressure

at the manufacturer’s rated temperature.

5.13 shall — A term indicating that a provision is a

requirement of this specification.

5.14 should — A term indicating that a provision is

recommended as good practice but is not a requirement

of this specification.

5.15 shutoff valve — A valve designed for, and

capable of, positive closure to prevent flow within a

system. Typical shutoff valves include manually

actuated, power-actuated, or spring-actuated, fail-safe

shutoff valves. Generally excluded are self-actuated

valves such as check valves, pressure regulators, flow

controllers, and other devices not intended to provide

positive shutoff.

5.16 standard leak rate — The flow of helium at

21.1°C (70°F) and 101.3 kPa (1 atm) through a leak

when the partial pressure of helium on the high side is

101.3 kPa and the partial pressure on the low side is

below 133 Pa (1 torr).

NOTE: Express leak rates in kiloPascal-liters per second

(kPa-L/sec). Calculate the standard leak rate of helium from

the measured leak rate by multiplying by the ratio of 101.3

kPa to the partial pressure of helium, as follows:

Standard

101.3 kPa(1 atm)

measured leak rate

actual He partial pressure

≠

5.17 subsystem — An assembly of two or more

components manufactured as a single entity. A

subsystem must be combined with one or more

additional components or subsystems to form a

complete system. The typical subsystems referred to by

this specification are gas source manifolds, gas

distribution manifolds, and gas control manifolds

within the process equipment.

5.18 system — An integrated structure of components

and subsystems capable of performing, in aggregate,

one or more specific functions. For the purpose of this

specification, a system includes the gas source

manifold, its connection to the gas source, the

distribution piping, and the gas control manifold within

the process equipment.

6 Ordering Information

Orders for equipment or services requiring leak testing

in accordance with this specification shall include:

a. This specification number and date of issue.

b. Acceptance test requirements and applicable test

paragraphs of this specification for the specific

product being purchased.

c. Qualification test requirements, if any, and

applicable test paragraphs of this specification for

the specific product being purchased.

d. The design pressure to be used for internal and

outboard leakage testing of systems, subsystems, or

components.

e. Whether certification of the qualification or

acceptance tests and a report of test results is

required.

7 Requirements

7.1 Personnel Qualifications — Personnel performing

tests in accordance with this specification shall have

suitable training and experience. Such personnel

should, as a minimum:

a. be trained and experienced in the use of mass

spectrometer leak detectors,

b. be familiar with the use of the ASTM test methods

referenced by this specification, and

c. be familiar with the operation and calibration of the

specific equipment used in performing the tests.

7.2 Tests

7.2.1 Prior to initial operation, test each component,

subsystem, and system in accordance with this

specification.

7.2.2 If repairs or additions are made after the leakage

tests, retest the affected portions of the component,

subsystem, or system.

7.3 Test Conditions

7.3.1 All joints, including welds, shall be uninsulated,

unpainted, and exposed for examination during the test.

7.3.2 Isolate portions of a system that are not being

tested during the test.

7.3.3 Tracer gas pressure shall not exceed the

manufacturer’s pressure rating.

7.3.4 Conduct leakage tests at a temperature between

18°C (64°F) and 26°C (78°F).