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SEMI C3.40-10 00 © SEMI 1989 , 2000 1 SEMI C3.40-1000 STANDARD FOR CARBON TETRAFLUORIDE (CF 4 ), VLSI GRA DE This s tandard w as technica lly approve d by the Global G a ses Committe e and is the dire ct responsi bility …

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SEMI C3.57-0600 © SEMI 2000 2
5.2.1 Detection Limit — 100 ppb.
5.2.2 Instrument Parameters
5.2.2.1 Flow requirements — Zero and span the
analyzer in accordance with the instrument
manufacturers instructions. Set the sample gas flow to
the rate specified by the manufacturer.
5.2.3 Calibration standard — The analyzer shall be
calibrated at the time of use by reference to a standard
gas calibration mixture containing a certified moisture
content close to the expected value of the gas under
test. If the analyzer indicates the certified moisture
content, within the overall measurement uncertainties
stated by the instrument and gas manufacturers, it may
be used without further adjustment or calibration.
NOTE 2: Further Experimental detail may be found in DIN
50450-1.
5.2.4 Sample system
5.2.4.1 Use insulated stainless steel sample lines to
prevent frosting during sampling.
5.2.4.2 Keep sample lines to a minimum length.
5.2.5 Operating Procedure
5.2.5.1 Follow the procedures specified in the
instrument manufacturer’s manual.
5.2.5.2 Allow the system to run until a stable reading
is obtained for 5 minutes.
5.2.5.3 Read and record the concentration of moisture,
in ppm, indicated on the moisture analyzer. The result
obtained shall not exceed the value specified in Section
2 of this standard.
NOTE 3: This specification applies to gaseous phase product
from a cylinder supply.
NOTE 4: It is recommended that the user discontinue use of
the cylinder prior to the complete consumption of the liquid
phase contents. The contents of cylinders containing liquefied
product should be determined by weight and not pressure.
NOTE 5: Adopt a replicate sampling protocol for both
calibration standard and unknown to achieve the required
measurement uncertainty.
NOTICE: SEMI makes no warranties or representa-
tions as to the suitability of the specification set forth
herein for any particular application. The determination
of the suitability of the specification is solely the
responsibility of the user. Users are cautioned to refer
to manufacturer’s instructions, product labels, product
data sheets, and other rele-vant literature respecting any
materials mentioned herein. These specifications are
subject to change without notice.
The user’s attention is called to the possibility that
compliance with this specification may require use of
copyrighted material or of an invention covered by
patent rights. By publication of this specification,
SEMI takes no position respecting the validity of any
patent rights or copyrights asserted in connection with
any item mentioned in this specification. Users of this
specification 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
f
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI C3.40-1000 © SEMI 1989, 20001
SEMI C3.40-1000
STANDARD FOR CARBON TETRAFLUORIDE (CF
4
), VLSI GRADE
This standard 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 July 11, 2000. Initially available at www.semi.org September 2000; to be published October
2000. Originally published in 1989; previously published in 1992.
1 Description
1.1 Carbon tetrafluoride is an odorless, colorless,
nonflammable gas. It is a simple asphyxiant. It is also
known as tetrafluoromethane.
2 Specifications
QUALITY: 99.997%
Impurities
Maximum Acceptable
Level (ppm) *
Carbon Dioxide (CO
2
)1
Carbon Monoxide (CO) 1
Nitrogen (N
2
)20
Other Halocarbons (CF
3
Cl,
CF
2
Cl
2
,CF
3
H)
1
Oxygen (O
2
)5
Sulfur Hexafluoride (SF
6
)1
Water (H
2
O) (v/v) 1
TOTAL IMPURITIES 30
* 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 Hydrolyzable Fluorides as HF 1 ppm max.
4 Physical Constants (for in formation only)
Metric Units US Units
Molecular weight 88.005 88.005
Boiling point at 1 atm -128.0°C -198.4°F
Density of gas at 0°C
(32°F) and 1 atm
3.946 kg/m
3
0.246 lb/ft
3
Specific gravity of gas at
0°C and 1 atm
3.05 3.05
Density of liquid at -80°C 1317 kg/m
3
82.22 lb/ft
3
5 Analytical Procedures (Se e Notes 1 and 2,
and Figures 1 and 2.)
5.1 Carbon Dioxide — This procedure is for the
determination of carbon dioxide in carbon tetrafluoride
using a gas chromatograph with an ultrasonic detector.
5.1.1 Detection Limit — 0.5 ppm (mole/mole).
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 OD ss or equivalent.
5.1.2.2 Carrier Flow: 16 mL/min helium.
5.1.2.3 Temperatures:
Detector 120°C
Column 50°C
Valve 90°C
5.1.2.4 Sample Volume: 1.0 mL
5.1.2.5 Time Table — Determine the times for valve
switching and signal changes, and enter into the run
table.
An example of a 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 carbon
dioxide and balance helium.
5.1.4 Operating Procedure
5.1.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record retention times and
peak areas. The retention time for carbon dioxide is
approximately 16 minutes.
5.1.4.2 Inject the sample to be tested in the same
manner as the calibration standard. Record the retention
times and peak areas.
5.1.4.3 Repeat 5.1.4.1.
5.1.4.4 Compare the average peak areas of the
calibration standard to those of the carbon tetrafluoride
SEMI C3.40-1000 © SEMI 1989, 2000 2
sample being tested. Calculate the concentration of
carbon dioxide in the sample, using the formula below.
The result may not exceed the specification in Section 2
of this Standard.
Sample Peak Area
Standard Peak Area
×
Concentration
of Standard
=
Concentration
of Sample
5.2 Oxygen, Nitrogen and Carbon Monoxide — This
procedure is for the determination of oxygen, nitrogen,
and carbon monoxide in carbon tetrafluoride using a
gas chromatograph with an ultrasonic detector.
5.2.1 Detection Limits — 0.5 ppm (mole/mole) for
each impurity.
5.2.2 Instrument Parameters
5.2.2.1 Columns:
Column 3: Porapak QS, 100/120 mesh, 3.6 m (12 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 OD ss or equivalent.
Column 5: Molecular Sieve 13X, 45/60 mesh, 2.1 m
(7 ft) by 3.2 mm OD ss or equivalent.
5.2.2.2 Carrier Flow: 16 mL/min helium.
5.2.2.3 Temperatures:
Detector 120°C
Column 50°C
Valve 90°C
5.2.2.4 Sample Volume: 2.0 mL
5.2.2.5 Time Table — Determine the times for valve
switching and signal changes, and enter into the run
table.
An example of a run table follows.
Valve On Off
10.01 *
29.20 *
3 0.01 12.00
* Valve left on until end of run.
5.2.3 Calibration Standard — 1–5 ppm (mole/mole)
each nitrogen, oxygen and carbon monoxide, balance
helium.
5.2.4 Operating Procedure
5.2.4.1 Inject 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 minutes, carbon
monoxide 14.5 minutes.
5.2.4.2 Inject the sample to be tested in the same
manner as the calibration standard. Record the retention
times and peak areas.
5.2.4.3 Repeat 5.2.4.1.
5.2.4.4 Compare the average peak areas of the
calibration standard to those of the carbon tetrafluoride
sample being tested. Calculate the concentrations of
oxygen, nitrogen and carbon monoxide in the sample,
using the formula below. The results may not exceed
the specifications in Section 2 of this Standard.
Sample Peak Area
Standard Peak Area
×
Concentration
of Standard
=
Concentration
of Sample
5.3 Fluorocarbon and Chlorofluorocarbon Impurities
— This procedure is for the determination of the
volatile organic impurities in carbon tetrafluoride using
a gas chromatograph with a flame ionization detector.
5.3.1 Detection Limits — 0.5 ppm (mole/mole) for
each impurity.
5.3.2 Instrument Parameters
5.3.2.1 Column: 1% SP-1000 on Carbopak B (60/80),
7.3 m (24 ft) by 3.2 mm (1/8 in) OD ss or equivalent.
5.3.2.2 Carrier Flow: 40 mL/min helium.
5.3.2.3 Support Gases: Set the flow rates as specified
by the instrument manufacturer.
5.3.2.4 Temperatures:
Injection Port 200°C
Detector 250°C
Initial Oven 35°C
Pre-Program Hold 7 min
Temperature Rise 10°C/min
Final Oven 150°C
Final Hold 10 min
5.3.2.5 Sample Volume: 2 mL.
5.3.3 Calibration Standard — 1–10 ppm (by volume)
desired impurities in helium. Practical impurities may
be trifluoromethane (CHF
3
), hexafluoroethane (C
2
F
6
),
dichlorodifluoromethane (CCl
2
F
2
), and chlorotrifluo-
romethane (CClF
3
).
5.3.4 Operating Procedure
5.3.4.1 Attach a stainless steel diaphragm two-stage
regulator to the standard cylinder. Connect the regulator
to the 6 port chromatographic sampling valve.