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SEMI C3.24-03 01 © SEMI 1984 , 2001 3 NOTICE: T hese standards do n ot purport to address safety issues, if any, as sociated with their use. It is the responsibility of the user of these sta ndards to establish appropria…

SEMI C3.24-0301 © SEMI 1984, 2001 2

50 mL high-density polyethylene bottles

Assorted Class A volumetric flasks

Ion chromatograph

Anion column which separates:

, Cl

, Br

, SO

-2

, PO

-3

4.2.2 Ion Chromatograph Parameters:

Instrument: Dionex 2000 (or equivalent)

Integrator: Dionex 4270 (or equivalent)

Column: HDIC AS4A (or equivalent)

Eluent: 0.001 M Na

+ 0.001 M NaHCO

Flow Rate: 2 mL/minute

Pressure: 960 psia

Detector

Conductivity

Range:

3.0 microsiemens for less than 10 ppm

Sample: 100 microliters

4.2.3 Calibration — Calibrate the ion chromatograph

by dissolving a weighed amount of ammonium fluoride

(NH

F) in deionized water and sequentially diluting it

to a fluoride concentration of 0.1 ppmw in Class A

volumetric flasks and analyzing it as specified by the

instrument manufacturer.

4.2.4 Operating Procedure

4.2.4.1 Prepare a fresh solution of 1.7 mM sodium

bicarbonate in deionized water.

4.2.4.2 Pipet 200 mL of the solution into a 500 mL

Greenburgh impinger.

4.2.4.3 Bubble approximately 20 L of sulfur

hexafluoride (SF

) through the solution, using the

delivery system shown in Figure 1.

4.2.4.4 Analyze the solution as specified by the

instrument manufacturer.

4.2.4.5 Calculation — Calculate the concentration of

hydrogen fluoride (HF) using the following formula:

ppmv HFg =

ppmw)×Vg

19.00×mg

Where:

ppm = Fluoride concentration in trapped solution.

Vg = Volume of collection solution (mL).

mg = Moles of SF

bubbled through the collecting

solution.

19.00 = Molecular weight of F

The result may not exceed the specification in Section 2

of this Standard.

4.3

Water — This procedure is for the determination

of trace moisture (water) in sulfur hexafluoride using a

continuous flowing electrolytic hygrometer. (See Notes

4, and 5.)

4.3.1

Detection Limit — 1.0 ppm (vol/vol) or -76°C

(-105°F).

4.3.2 Sample Pressure and Flow — Set in accordance

with instrument manufacturer’s instructions.

4.3.3 Operation Check — Check the instrument

periodically for correct operation. A gas containing a

known amount of moisture should be passed through

the instrument. Agreement between the hygrometer and

the standard should be within their relative accuracies.

4.3.4

Operating Procedure

4.3.4.1 Obtain a continuous flow samp le of sulfur

hexafluoride source, using a clean, electropolished or

passivated stainless steel line which has been purged

dry after exposure to ambient moisture. (See Note 5.)

4.3.4.2

After prepurging with a dry gas, allow the

sample gas to flow through the sampling system and

hygrometer until a stable reading is obtained. The

reading may not exceed the specification in Section 2 of

this Standard.

4.4

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

not contain more than 10% of the specified value of the

component of interest, unless otherwise stated.

NOTE 3: Observe proper safety procedures for handling and

disposing of sulfur hexafluoride (SF

NOTE 4: The sampling system and hygrometer must be

designed to operate at 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 hygrometer.

NOTE 5: A passivation procedure is described in Metals

Handbook, Eighth Edition, Volume 2, ASM International,

Metals Park, Ohio.

Figure 1

SEMI C3.24-0301 © SEMI 1984, 20013

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 or

equipment 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.

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 C3.26-0301 © SEMI 1984, 20011

SEMI C3.26-0301

SPECIFICATION FOR TUNGSTEN HEXAFLUORIDE (WF

) IN

CYLINDERS, 99.8% 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 November 22, 2000. Initially available at www.semi.org January 2001; to be published March

2001. Originally published in 1984; previously published in 1994.

1 Description

1.1 Tungsten hexafluoride is a colorless gas or

colorless liquid. It is shipped as a liquefied gas under

its own vapor pressure.

2 Specifications

QUALITY: 99.8%

Impurities

Maximum Acceptable

Level (ppm) (See NOTE 1.)

Carbon Tetrafluoride (CF

)10

Hydrogen Fluoride (HF) 1000

Nitrogen (N

)50

Oxygen (O

) + Argon (Ar) 50

Sulfur Hexafluoride 10

Silicon Tetrafluoride 10

TOTAL LISTED IMPURITIES 1130

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.

3 Physical Constants (for in formation only)

Metric Units US Units

Molecular weight 297.85 297.85

Boiling point at 1 atm 17.1°C 62.8°F

Density of gas at 22.8°C

(73°F) and 1 atm

12.9 kg/m

0.805 lb/ft

Specific gravity of gas 10.8 10.8

Density of liquid at boiling

point

3440 kg/m

214.8 lb/ft

4 Analytical Procedures (Se e Notes 1, 2, 3, 4,

5, 6, 7)

4.1 Nitrogen and Oxygen + Argon — This procedure

is for the determination of nitrogen and oxygen + argon

in tungsten hexafluoride using a gas chromatograph

with a thermal conductivity detector.

4.1.1 Detection Limits — 10 ppm (mol/mol) nitrogen,

and 10 ppm (mol/mol) oxygen + argon.

4.1.2 Instrument Parameters

4.1.2.1 Columns: (See Figures 1, 2)

Column 1: Porapak S, 80/100 mesh, 1.5 m (5 ft) by

6.4 mm (1/4 in) OD, 5.1 mm (0.2 in) ID, ss

or equivalent.

Column 2: Molecular sieve 5A, 80/100 mesh, 1.8 m

(6 ft) by 4.8 mm (3/16 in) OD, 3.7 mm

(0.147 in) ID, ss or equivalent.

4.1.2.2 Column Flow: 30 mL/min helium.

4.1.2.3 Sample Volume: 2 mL

4.1.2.4 Temperatures

Detector 70°C

Column 40°C

4.1.3 Calibration Standard — 50 ppm (mol/mol)

nitrogen, 50 ppm (mol/mol) oxygen, balance helium.

4.1.4 Operating Procedures

4.1.4.1 Determine the times for valve switching and

signal changes, and enter into the run table. An example

of a run table follows.

Time Position Function

0 min. 1 Purge sample through loop. Backflush

Porapak column. Connect MS column

to the TCD.

1 min. 2 Inject sample onto Porapak column.

Allow oxygen + argon and nitrogen to

elute from the Porapak column to the

MS column. Sequentially elute the

oxygen + argon and nitrogen from the

MS column to the TCD.

4 min. 1 Backflush Porapak column to vent for

8 minutes.

4.1.4.2 Set the valves in Position 1 (Figure 1).

4.1.4.3 Flow the calibration standard through the 10-

port valve. Analyze standard using the conditions

described above. Record retention times and peak areas.