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SEMI C3-0699 © SEMI 19 86, 1999 3 2.19 phys ical properties — physica l properties shall not us uall y be e mplo yed for sp ecific atio n pur po ses; fo r information, however, representative values for a particular g as…
SEMI C3-0699 © SEMI 1986, 1999 2
Abbreviation or
Symbol
Explanation
cc cubic centimeter(s)
CGA Compressed Gas Association
cm centimeter
DOT Department of Transportation (U.S.)
°F temperature, degrees Fahrenheit
ft foot, feet
ggram(s)
L liter(s)
lb pound(s)
max maximum
min minimum
mL milliliter(s)
mm millimeter(s)
MP melting point
mw molecular weight (g/mole)
ohm-cm ohm - centimeter
ppm
mole/mole x 10
6
ppb
mole/mole x 10
9
ppba
mole/mole x 10
9 atomic
ppbw
weight/weight x 10
9
psia pounds per square inch absolute
psig pounds per square inch gauge
SCF standard cubic foot (feet)
temp. temperature
vol volume
vol/vol volume/volume
wt. weight
w/v weight/volume
ww weight/weight
2.2 accuracy — (To Be Determined)
2.3 assay — determination of the content of a specific
component with no evaluation of other components.
2.4 comparison of analytical results with specific
limits — in the comparison of an analytical result for a
test with the numerical limit associated with that
specification, the result shall be rounded to the number
of significant figures indicated for that limit. (See
Rounding Numbers, SEMI C3, Section 2.22).
2.4.1 Consequently, a specification stated as 96%
minimum will be met by a result as small as 95.5%, and
that stated as 96.0% minimum will be met by a result as
small as 95.95%. A specification of 0.1% maximum
will be met as large as 0.14%, and that of 0.10%
maximum by a result as large as 0.104%.
2.5 cryogenic liquid — liquid with a normal boiling
point below –150°C.
2.6 cylinder pressure — pressure contained in a gas
cylinder prior to regulation.
2.7 cylinder tare weight — containers which are
stamped to denote the weight of the container or the
weight of the container and the valve less the product.
The weight does not include the weight of any
protective cylinder cap.
2.8 density — weight per unit volu me (w/v) is
expressed as grams per liter for gases at zero degrees
Celsius, one atmosphere.
2.9 detection limit — the detection limit for all the
analytical methods that appear in this section of the
BOSS must be established for each impurity defined.
The detection limit must be stated as well as the
statistical method used to establish that detection limit.
The analytical method should be chosen such that the
detection limit is at or below the specification.
2.10 dewpoint — the temperature at which liquid first
condenses when vapor is cooled.
2.11 expression of content and concentration —
unless otherwise stated, a specification limit and the
analytical result related to it shall be expressed in units
of mole per mole (mole/mole).
2.12 filtration — (To Be Determined)
2.13 Gas Purity Guideline — A Gas Purity Guideline
is a proposed specification recommended by one or
more users as needed in the future for the production of
semiconductor devices. They reflect future needs in
which test methods are not generally available at the
time of proposal. These guidelines are approved by the
Gases Committee for publication in the Standards
Book. Products meeting these guidelines are not
necessarily commercially available.
2.14 heavy metals — (To Be Determined)
2.15 liquified compressed gas — a gas which under
the charged pressure is partially liquid at a temperature
of 21.1°C (70°F).
2.16 metals — (To Be Determined)
2.17 molecular weight — the sum o f the atomic
weights of all the atoms in the molecule.
2.18 nonliquified compressed gas — a gas, other than
a gas in solution, which under the charging pressure is
entirely gaseous at a temperature of 21.1°C (70°F).
SEMI C3-0699 © SEMI 1986, 19993
2.19 physical properties — physical properties shall
not usually be employed for specification purposes; for
information, however, representative values for a
particular gas, as supplied, may be included as an item
in the monograph for that gas.
2.20 quality — the quality is determ ined by
subtracting the sum of the maximum acceptable gas
phase impurity levels, expressed in percent, from 100.
The result is truncated after the first significant figure
which is not a nine. The quality does not represent an
assay.
2.21 rare gas — any of the six gases, all noble,
comprising the extreme right-hand group of the
Periodic Table; namely helium, neon, argon, krypton,
xenon, and radon.
2.22 rounding numbers — the follo wing rules for
rounding of measured or calculated values shall be
employed:
2.22.1 When the figure next beyond t he last place to
be retained is less than 5, leave unchanged the figure in
the last place retained.
2.22.2 When the figure next beyond t he last place to
be retained is greater than 5, increase by 1 the figure in
the last place retained.
2.22.3 When the figure next beyond t he last place to
be retained is 5 and there are no figures beyond this 5 or
only zeroes, (a) increase by 1 the figure in the last place
retained if it is odd, or (b) leave the figure unchanged if
it is even.
2.22.4 When the figure next beyond t he last place to
be retained is 5 and there are figures other than zeroes
beyond this 5, increase by 1 the figure in the last place
retained.
2.22.5 Obtain the rounded value in on e step by direct
rounding and not in two or more steps of successive
rounding.
2.23 specific gravity — the ratio of the mass of a gas
to the mass of an equal volume of air at a specified
temperature. For liquids, it is the ratio of the mass of
the liquid to the mass of an equal volume of water.
2.24 specification and specification limits — the
specification limit should fall above or in the range of
the result and its uncertainty.
2.25 temperature — temperature va lues shall be
expressed in degrees Celsius.
2.26 tolerances in measurements — use the following
guidelines for mixture tolerances:
2.26.1 Mixtures should be specified b y the major
component and the concentration of the desired minor
component(s).
2.26.2 All component gases shall adhere to the
appropriate SEMI specification, if available.
2.26.3 The impurity levels in the mix ture shall not
exceed the algebraic sum of the impurities specified for
the designated components.
2.26.4 Mixtures shall be prepared according to the
following mixing tolerances:
Concentration of Minor
Component
Preparation Tolerance Level
10 - 99 ppm ± A 20%
100 - 999 ppm ± A 10%
0.1 - 50% ± A 5%
2.26.5 Standards used to verify mixin g tolerance
(henceforward called Certified Standards) shall meet
the following requirements:
Range Preparation
Tolerance of Each
Minor Component
Analytical
Accuracy of Each
Minor Component
0 - 9.9 ppm To Be Determined To Be Determined
10 - 99 ppm ± A 10% ± A 3%
100 - 999 ppm ± A 5% ± A 2%
0.1% - 50% ± A 4% ± A 2%
2.27 Calibration Standards — Calibration standards
shall be as close as practical to specification and may
not exceed ten times (10×) the specification unless
specifically excepted in procedure.
3 Samples
3.1 Sample Size — The quantity o f gas/liquid in a
single sample container shall be sufficient to perform
the analysis for all the listed specifications. If a single
sample does not contain a sufficient quantity of
gas/liquid to perform all of the required analyses,
additional samples from the same source shall be taken
under similar conditions.
3.2 Gaseous Samples — Gaseous samples shall be
representative of the gaseous supply. Sampling shall be
performed in accordance with one of the following:
3.2.1 By withdrawing a sample from the supply
container through a suitable connection into the sample
container. (For safety reasons, the sample container and
sampling system must have a rated service pressure at
least equal to the pressure in the supply container.)
SEMI C3-0699 © SEMI 1986, 1999 4
3.2.2 By connecting the container being sampled
directly to the analytical equipment.
3.2.3 By selecting a representative c ylinder from the
cylinders in the lot.
3.3 Liquid Sampling (Vaporized) — Vaporized liquid
samples shall be representative of the liquid supply.
Sampling shall be in accordance with one of the
following:
3.3.1 By vaporizing liquid from the supply container
in the sample tubing.
3.3.2 By flowing liquid from the sup ply container into,
or through, a suitable container in which a
representative sample is collected and then vaporized.
3.4 Liquid Samples (Liquified Compressed Gases) —
A direct connection between the liquid phase of
liquified compressed gas containers and the analytical
equipment can be achieved, provided suitable flash
vaporization is obtained.
3.5 Lot Acceptance Tests — These are analyses
performed on the gas/liquid in the shipping container,
or a sample thereof, which is representative of the lot.
(The terms “lot” and “batch” may be used
interchangeably.)
3.6 Lots — One of the following is to be used:
3.6.1 No specific quantity or any qu antity of product
agreed upon between the supplier and the customer.
3.6.2 All of the product supplied during the contract
period.
3.6.3 All of the product supplied or containers filled
during a calendar month.
3.6.4 All of the product supplied or containers filled
during seven consecutive days.
3.6.5 All of the product supplied or containers filled
during a consecutive 24-hour period.
3.6.6 All of the product supplied or containers filled
during one eight-hour shift.
3.6.7 All of the product supplied in one shipment.
3.6.8 All of the product supplied in one shipping
container.
3.6.9 All of the product supplied in the container(s)
filled on one manifold at the same time.
3.7 Number of Samples Per Lot — The number of
samples per lot shall be in accordance with one of the
following:
3.7.1 One sample per lot.
3.7.2 Any number of samples agreed upon by the
supplier and the customer.
4 Sampling
4.1 For gases provided in cylinder s, a sample can be
taken directly for analysis. For gases provided in bulk
quantities or cylinders where direct sampling is not
appropriate, a sample may be taken per SEMI sampling
procedures.
4.2 Sampling Procedures
4.2.1 Cryogenic Liquid Sample — Liquid Samples for
Oxygen, Nitrogen, and Argon, using the TTU-131/E
sampler.
WARNING: DO NOT USE THIS PROCEDURE
FOR THE SAMPLING OF LIQUID HYDROGEN.
4.2.2 Applicable Document — Military Specification
MIL-S-27626D 16 August 1979, Amendment 1, 24
April 1981.
4.2.3 General Description — The TTU-131/E
cryogenic sampler is a small, portable pressure vessel
used to receive, vaporize, and contain a representative
sample of cryogenic liquid from a supply source. The
vaporized sample is withdrawn as a gas for analytical
purposes.
4.2.4 Theory — The sampler is used to isolate a small
but representative quantity of cryogenic liquid and
vaporize the major component and all volatile
impurities to form a homogeneous gas sample suitable
for analysis. The cryogenic liquid is used to cool a
shielding space and sampling cup prior to admitting the
liquid to the sampling cup. The purpose of pre-cooling
the sampling cup is to prevent concentrating impurities
which could result when the warm cup causes the liquid
to vaporize, leaving behind impurities with higher
boiling points.
4.2.4.1 When the cup is adequately cooled, the
sampling valve is opened, allowing liquid to fill the
cup. When the sampling valve is closed, the liquid is
trapped in the cup and will vaporize as a result of
atmospheric heating. Once the sample is trapped, the
flow of liquid is stopped.
4.2.5 Preparation for Sampling
4.2.5.1 The sample should be kept in the same product
service to avoid sample contamination. If a product
change is required, always thoroughly purge the
sampler or evacuate to 100 microns prior to taking the
sample.
4.2.5.2 When taking the sample, the s ampler is to
remain secured to the bottom half of the case and
MUST be in an upright position.