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SEMI C3.12-1102 © SEMI 1983, 2002 4 Figure 1 Figure 2 Electronic Ammonia Wate r Measurement NOTICE: These standards do not purport to address sa fety issues, if any, associated w ith their use. It is the responsibility o…

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SEMI C3.12-1102 © SEMI 1983, 2002 3
4.2.4.8 Compare the average peak areas for at least
three runs each of the calibration standard to that of the
ammonia sample being tested. Calculate the
concentration of hydrocarbons C
1
– C
3
, using the
formula below. The result may not exceed the
specification in Section 2 of this standard.
Sample Pea
k
Area
Standard Peak
Area
×
Concentration
of Standard
=
Concentration
of Sample
4.3 Water — The method for the determination of
water in ammonia is based on its decomposition by the
reaction 2NH
3
→ N
2
+ 3H
2
, which occurs completely
and irreversibly when ammonia is passed over a nickel
catalyst at 1000°C. Water passes through the catalyst
unchanged. Therefore, the water content of ammonia
may be determined by measuring the dewpoint of the
stream of hydrogen and nitrogen produced by
decomposition of ammonia.
NOTE 12: The system should be checked for leaks prior to
use to preclude atmospheric contamination of the sample.
NOTE 13: The moisture analyzer must be calibrated
according to the manufacturer’s specified method prior to use.
4.3.1 Apparatus (shown in Figure 2)
4.3.1.1 The nitrogen and ammonia are connected to a
tee with 3.2 mm (1/8 in.) OD stainless steel tubing,
keeping the lines as short as is practical.
4.3.1.2 The nitrogen may be fed from a regulator.
4.3.1.3 The ammonia should be fed through a stainless
steel needle valve.
4.3.1.4 The furnace is a Lindberg Model 54032 or
equivalent, with an Inconel reaction tube. The reaction
tube is 0.6 m (24 in.) long by 25 cm (1 in.) OD and
terminates in 3.2 mm (1/8 in.) swaged tubing
connectors.
4.3.1.5 The reaction tube is filled with nickel lumps,
MCB Catalog number NX305 or equivalent.
4.3.1.6 The outlet of the furnace is connected by a 1.2
m (4 ft) by 3.2 mm (1/8 in.) OD stainless steel tubing to
a moisture analyzer suitable for determining the
concentration of water should be a mixture of hydrogen
and nitrogen at the specified concentration. This length
of tubing is required to permit adequate cooling of the
gas between the furnace and the moisture analyzer.
4.3.1.7 The outlet of the moisture analyzer is connected
to the inlet of a 0-10 CFH flowmeter.
4.3.1.8 The outlet of the flow meter is connected to an
appropriate vent for the disposal of ammonia, nitrogen
and hydrogen.
4.3.2 Operating Procedure
4.3.2.1 Start a nitrogen purge flow of approximately 5
CFH.
4.3.2.2 Set furnace to 950°C and allow to equilibrate
(approximately 1.5 to 2 hours).
4.3.2.3 With the ammonia cylinder valve closed,
disconnect the tubing from the cylinder outlet and open
the ammonia inlet needle valve to allow the ammonia
sample line to purge with nitrogen. Reconnect the
tubing to the cylinder outlet and close the needle valve.
4.3.2.4 Shut off the nitrogen flow.
4.3.2.5 Open the ammonia cylinder valve and adjust
the needle valve to obtain a flow of approximately 5
CFH.
4.3.2.6 Gradually increase the furnace temperature,
periodically testing the gas for the presence of ammonia
by placing a piece of wet red litmus paper in the vent
stream. If ammonia is present, the paper will turn blue.
When ammonia is no longer found, the appropriate
catalyst temperature has been reached.
4.3.2.7 Measure the concentration of water in the
nitrogen and hydrogen stream, following the
instructions of the moisture analyzer manufacturer.
Periodically test the vent stream for the presence of
ammonia, as described in Section 4.3.2.6, and adjust the
furnace temperature as necessary.
4.3.3 Reporting of Measurement
4.3.3.1 Double the water concentration obtained in
Section 4.3.2.7 to correct for the doubling of gas
volume by the decomposition of the ammonia.
4.3.3.2 Subtract twice the concentration of oxygen (as
measured by the procedure specified in Section 4.3) in
the sample from the concentration of water calculated
in Section 4.3.3.1. This is necessary because oxygen in
the ammonia reacts with the hydrogen formed by
decomposition to produce additional water.
4.3.3.3 The concentration of water calculated in Section
4.3.3.2 in the ammonia may not exceed the limit
specified in Section 3.
SEMI C3.12-1102 © SEMI 1983, 2002 4
Figure 1
Figure 2
Electronic Ammonia Water Measurement
NOTICE: These standards do not purport to address safety issues, if any, associated with their use. It is the
responsibility of the user of these standards to establish appropriate safety and health practices and determine the
applicability of regulatory limitations prior to use. SEMI makes no warranties or representations as to the suitability
of the standards set forth herein for any particular application. The determination of the suitability of the standard is
solely the responsibility of the user. Users are cautioned to refer to manufacturer’s instructions, product labels,
product data sheets, and other relevant literature respecting any materials mentioned herein. These standards are
subject to change without notice.
The user’s attention is called to the possibility that compliance with this standard may require use of copyrighted
material or of an invention covered by patent rights. By publication of this standard, SEMI takes no position
respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in this
standard. Users of this standard are expressly advised that determination of any such patent rights or copyrights, and
the risk of infringement of such rights, are entirely their own responsibility.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI C3.2-0301 © SEMI 1981, 20011
SEMI C3.2-0301
SPECIFICATION FOR ARSINE (AsH
3
) IN CYLINDERS, 99.94% QUALITY
This specification was technically approved by the Global Gases Committee and is the direct responsibility of
the North American Gases Committee. Current edition approved by the North American Regional Standards
Committee on October 17, 2000. Initially available at www.semi.org January 2001; to be published March
2001. Originally published in 1981; previously published in 1992.
1 Description
1.1 Arsine is a highly toxic, flammable, colorless gas
with a disagreeable garlic-like odor. It is a hemolytic
poison.
2 Specifications
QUALITY: 99.94%
Impurities
Maximum Acceptable
Level (ppm)
(See NOTE 1.)
Carbon monoxide and carbon dioxide
(CO + CO
2
)
2
Hydrocarbons (methane (CH
4
),
ethane (C
2
H
6
), ethylene (C
2
H
4
), and
acetylene (C
2
H
2
))
1
Hydrogen (H
2
) 500
Hydrogen Sulfide (H
2
S) 1
Nitrogen (N
2
)10
Oxygen (O
2
) + Argon (Ar) 5
Phosphine (PH
3
)10
Water (H
2
O) 4
TOTAL LISTED IMPURITIES 533
Metals — See NOTE 2.
Particles — See NOTE 2.
NOTE 1: An analysis of significant figures has not been considered.
The number of significant figures will be based on analytical
accuracy and the precision of the provided procedure.
NOTE 2: To be determined between supplier and user.
3 Physical Constants (for in formation only)
Metric Units US Units
Molecular weight 77.946 77.946
Boiling point at 1 atm -62.48°C -80.46°F
Density of gas at 20°C
(68°F) and 1 atm
3.243 kg/m
3
0.202 lb/ft
3
Specific gravity of gas at
21.1°C (70°F) and 1 atm
(air = 1)
2.695 2.695
Density of liquid at B.P. 1653 kg/m
3
103.96 lb/ft
3
4 Analytical Procedures
4.1 Carbon Monoxide, Carbon Dioxide, and
Hydrocarbons (methane, ethane, ethylene, acetylene)
— This procedure is for the determination of carbon
monoxide, carbon dioxide, and hydrocarbons in arsine
using a gas chromatograph with a methanizer and a
flame ionization detector. (See Note 1 and Figure 1.)
4.1.1 Detection Limit — 0.1 ppm each impurity.
4.1.2 Instrument Parameters
4.1.2.1 Column: Porapak QS, 3.5 m (12 ft) by 2 mm
ID (1/8 in OD) ss or equivalent.
4.1.2.2 Carrier Flow: 35 mL/min helium.
4.1.2.3 Support Gases: Set the flow rates as specified
by the instrument manufacturer.
Hydrogen: 30 mL/min added to the carrier gas
between the column outlet and the
methanizer inlet.
Air: 500 mL/min.
4.1.2.4 Temperatures:
Detector 110°C
Injector 40°C
Oven 40°C
Methanizer 370–400°C
4.1.2.5 Sample Volume: 3 mL.
4.1.3 Calibration Standards — 1–10 ppm each:
carbon monoxide, carbon dioxide, methane, ethane,
ethylene, and acetylene; balance helium.
4.1.4 Operating Procedure
4.1.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record retention times and
peak areas. Order of elution is carbon monoxide,
methane, carbon dioxide, acetylene, ethylene, ethane.
4.1.4.2 Inject the sample to be tested in same manner
as the calibration standard. Vent the arsine after the
ethane peak. Record the retention times and peak areas.
4.1.4.3 Repeat 4.1.4.1.