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SEMI C3.20-92 © SE MI 1982, 1999 3 4.5.4.2 In troduce the zero hel i um with k no wn quantity of hy drocarbons and, using the 0-10 ppm rang e, set the needle (or output) to read the correct level using the zero adjust kn…

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SEMI C3.20-92 © SEMI 1982, 1999 2
4.2.1 Detection Limit — 500 ppb.
4.2.2 Instrument Parameters
4.2.2.1 Column: 5A molecular sieve, 1.9 m (6 ft) by
3.2 mm (1/8 in) ss, or equivalent.
4.2.2.2 Carrier Flow: 30 mL/min helium.
4.2.2.3 Sample Volume: 3.0 mL.
4.2.2.4 Temperatures:
Detector
125°C
Column Temperature
65°C
4.2.3 Calibration Standard — 5-15 ppm nitrogen in
helium.
4.2.4 Operating Procedure
4.2.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record the retention time
and peak area.
4.2.4.2 Inject the sample to be tested in same manner
as the calibration standard. Record the retention time
and peak area.
4.2.4.3 Repeat 4.2.4.1.
4.2.4.4 Compare the average peak area of the
calibration standard to that of the helium sample being
tested. Calculate the concentration of nitrogen, using
the formula below. The result may not exceed the
specification in Section 2 of this Standard.
Sample Peak Are
a
Standard Peak Area
×
C
oncentrat
i
on
of Standard
=
C
oncentrat
i
on
of Sample
4.3 Oxygen — This procedure is for the determination
of oxygen in helium using a continuous flow analyzer
using an electrochemical method.
4.3.1 Detection Limit — 100 ppb (mole/mole).
4.3.2 Flow Rate — Set sample flow rates in
accordance with the instrument manufacturer's
instructions.
4.3.3 Calibration Standard — 1-10 ppm (mole/mole)
oxygen in helium or in accordance with the instrument
manufacturer's instructions.
4.3.4 Operating Procedure
4.3.4.1 Do not change the initial sample flow setting
once established.
4.3.4.2 Introduce helium sample and record oxygen
reading. The result may not exceed the specification in
Section 2 of this Standard.
4.4 Water — This procedure is for the determination
of trace moisture (water) in helium using a continuous
flowing piezoelectric hygrometer. (See Note 3.)
4.4.1 Detection Limit — 0.1 ppm (vol / vol) or -90°C
(-130°F).
4.4.2 Flow Requirements — Set the sample pressure
and flow rate in accordance with the instrument
manufacturer's instructions.
4.4.3 Calibration Standards — Construct a calibration
curve which contains at least three points covering the
range of interest. Verify the standards employed
independently by another analytical method.
4.4.4 Operating Procedure
4.4.4.1 Obtain a continuous flow of sample gas from
the source using a clean and passivated 316 stainless
steel line which has been purged dry after exposure to
ambient moisture.
4.4.4.2 After prepurging with a dry gas, allow the
sample gas to flow through the sampling system and the
piezoelectric hygrometer until a stable reading is
obtained. Determine the concentration of moisture by
comparing the reading to the calibration curve obtained
in 4.4.3. The result may not exceed the specification in
Section 2 of this Standard.
4.5 Total Hydrocarbons — This procedure is for the
determination of total hydrocarbons in helium using a
continuous flow flame ionization detector-equipped
total hydrocarbon analyzer. (See Notes 4, 5, 6.)
4.5.1 Detection Limit — 0.1 ppm (mole/mole).
4.5.2 Flow Requirements
4.5.2.1 High purity, hydrocarbon-free (less than 1.0
ppm) hydrogen: 35-40 mL/min or 40% hydrogen in
either helium or nitrogen matrix at 75-80 mL/min.
4.5.2.2 Dry, hydrocarbon-free (less than 1.0 ppm) air:
350-400 mL/min.
4.5.2.3 Set sample flow rates in accordance with
instrument manufacturer's instructions.
4.5.3 Calibration Standards
4.5.3.1 Helium with known quantity of hydrocarbons
at 0.5 ppm level.
4.5.3.2 The span gas not exceeding 5 times the
concentration of the specification.
4.5.4 Operating Procedure
4.5.4.1 Do not change the initial flow settings for
hydrogen, air and sample once established.
SEMI C3.20-92 © SEMI 1982, 19993
4.5.4.2 Introduce the zero helium with known quantity
of hydrocarbons and, using the 0-10 ppm range, set the
needle (or output) to read the correct level using the
zero adjust knob.
4.5.4.3 Introduce the span gas standard in helium and,
using the span adjust knob, set the needle (or output
reading) to match the level of hydrocarbons in the span
gas.
4.5.4.4 Introduce helium sample into the analyzer and
read the quantity of hydrocarbons on the analyzer. The
result may not exceed the specification in Section 2 of
this Standard.
4.6 Notes
NOTE 1: Introduce the calibration standard as many times as
necessary to achieve the desired precision.
NOTE 2: All gases used in the analysis of the sample should
contain not more than 10% of the specified value of the
component of interest unless otherwise specified.
NOTE 3: The sampling system and hygrometer must be
designed to operate under the sample pressure, or the sample
pressure must be reduced (by a regulator with a diaphragm of
stainless steel or other suitable material) to accommodate the
pressure restrictions of the analytical hygrometer.
NOTE 4: The 0-1 range may be used provided that zero and
span gas standards in helium with known levels of
hydrocarbons between 0-1 ppm are used in the calibration of
the analyzer.
NOTE 5: As the flow rate and heat capacity of the matrix gas
affect the instrument output, the zero gas matrices must
coincide with that of the sample gas.
NOTE 6: The effective response of a flame ionization
detector-equipped total hydrocarbon analyzer to different
hydrocarbons can vary and must be approximated. However,
the response of the most common hydrocarbon impurities in
helium can be accurately totaled and compared to methane.
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
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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
f
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI C3.37-0701 © SEMI 1989, 20011
SEMI C3.37-0701
SPECIFICATION FOR HEXAFLUOROETHANE (C
2
F
6
), 99.97% 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 April 30, 2001. Initially available at www.semi.org May 2001; to be published July 2001.
Originally published in 1989; previously published in 1993.
1 Description
1.1 Hexafluoroethane is one of the most stable of all
organic compounds. It is inert, colorless,
nonflammable, odorless and tasteless.
2 Specifications
QUALITY: 99.97%
Impurities
Maximum Impurities
Acceptable (ppm)*
Carbon Dioxide (CO
2
)1
Carbon Monoxide (CO) 1
Nitrogen (N
2
) 100
Other Halogenated Hydrocarbons
(CF
3
Cl, CF
3
H, CF
2
HCl, C
2
F
5
Cl)
50
Oxygen (O
2
)25
Water (H
2
O) (v/v) 40
TOTAL LISTED IMPURITIES 217
*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.
3 Chemical Specification
Total Acidity 0.1 ppmw max.
4 Physical Constants (for in formation only)
Metric Units US Units
Molecular weight 138.01 138.01
Boiling point at 1 atm -78.2°C -108.8°F
Density of gas at 24°C
(75°F) and 1 atm
5.734 kg/m
3
0.357 lb/ft
3
Specific gravity of gas
at 24°C and 1 atm
4.823 4.823
Density of liquid at -
80.0°C
1611 kg/m
3
100.6 lb/ft
3
5 Analytical Procedures (Se e Notes 1, 2, 3,
and Figure 1)
5.1 Oxygen, Nitrogen, Carbon Monoxide, and Carbon
Dioxide — This procedure is for the determination of
oxygen, nitrogen, carbon monoxide, and carbon dioxide
in hexafluoroethane using a gas chromatograph with an
ultrasonic detector.
5.1.1 Detection Limit — 0.5 ppm (mol/mol) for each
impurity.
5.1.2 Instrument Parameters
5.1.2.1 Columns:
Column 1: Haysep D, 100/120 mesh, 4.6 m (15 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 2: Porapak QS, 100/120 mesh, 2.1 m (7 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 3: Porapak QS, 100/120 mesh, 3.6 m (2 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 4: Haysep D, 100/120 mesh, 4.6 m (15 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 5: Molecular Sieve 13×, 45/60 menh, 2.1 m (7 ft)
by 3.2 mm (1/8 in) OD ss, or equivalent.
5.1.2.2 Carrier Flow: 16 mL/min helium
5.1.2.3 Sample Volume: 1.0 and 2.0 mL
5.1.2.4 Temperatures:
Detector 120°C
Column 1, 2 and 5 50°C
Column 3 and 4 90°C
Valve 90°C
5.1.2.5 Time Table — Determine the times for valve
switching and signal changes, and enter into the run
table.
An example run table follows:
Valve
On Off
10.01*
29.20*
3 0.01 12.00
* Valve left on until end of run.
5.1.3 Calibration Standard — 1–5 ppm (mol/mol)
each carbon dioxide, nitrogen, oxygen and carbon
monoxide, balance helium.
5.1.4 Operating Procedure
5.1.4.1 Inject a sample of the calibration standard into
the column using a gas sampling valve. Record
retention times and peak areas. The approximate
retention times are: oxygen 11.1 minutes, nitrogen 11.6