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SEMI C3.39-0304 © SEMI 1989, 2004 5 Figure 1 Configuration for the Analysis of CF 4 , CO 2 , N 2 O, SF 6 , and CO in NF 3 Figure 2 Configuration for the An alysis of O 2 /Ar and N 2 in NF 3

SEMI C3.39-0304 © SEMI 1989, 2004 4

Table 1 Calibration Concentrations

Added Volume of

Working Standard

(ml)

Total Volume

(ml)

Resulting F

Concentration (M)

0.2 100.2 1.0 × 10

-6

0.2 100.4 2.0 × 10

-6

0.4 100.8 4.0 × 10

-6

0.4 101.2 5.9 × 10

-6

0.8 102.0 9.8 × 10

-6

1.0 103.0 1.5 × 10

-5

2.0 105.0 2.4 × 10

-5

5.6.5.5 Put 50 ml 0.2 N NaOH into each of two

bubblers connected in series.

5.6.5.6 Establish a flow of < 1000 sccm of NF

through

the bubblers using a suitable flow controller or

flowmeter.

5.6.5.7 Sample approximately 15 liters of NF

. Record

flowrate and time of sampling to determine total

volume sampled (flowrate × time). A wet test meter

can also be used to measure total volume. The amount

of gas sample must be the volume at STP. If the

flowmeter or wet test meter is not reference to 0º and

760 torr, use the formula below to correct sample

volume.

K 273

273T

Torr 760

Liters Measured STPat Liters

××=

P: Pressure of sampled gas (mm Hg)

T: Temperature of sampled gas or reference

temperature of the flow controller or meter in ºC.

5.6.5.8 Transfer contents of each bubbler to individual

100 ml volumetric flasks and add 50 ml Buffer solution

to each. Then, if necessary, add deionized or distilled

water to bring the volume up to 100 ml.

5.6.5.9 Transfer contents to a plastic beaker.

5.6.5.10 While stirring, measure and record mV

readings for each sample.

5.6.5.11 Determine F

concentration in solution using

calibration curve generated in Section 5.6.5.4.

5.6.5.12 Calculate gas phase hydrolyzable fluoride

concentration using the equation below. Note that the

equation assumes the hydrolyzable fluoride is hydrogen

fluoride.

l/mole 22.4

0.11 C )(ppm HF Phase Gas ×××=

C: Measured hydrolyzable fluoride concentration (M)

determined in Section 5.6.5.11.

Vs: Volume of NF

sampled (liters at STP)

5.6.5.13 The HF concentration of the second bubbler

should be insignificant compared to the first bubbler. If

significant HF levels are found in the second bubbler,

resample with a lower flowrate.

5.7 Notes

NOTE 1: Pass the carrier gas through a trap (3 m (10 ft.) by

6.4 mm (1/4 in.) OD) containing 50% by volume molecular

sieve 5A and 50% by volume molecular sieve 13X submerged

in liquid nitrogen.

NOTE 2: The methanizer catalyst can be destroyed by

nitrogen trifluoride passing through to at high temperature.

After the carbon monoxide peak is detected, the bulk nitrogen

trifluoride is bypassed to vent by means of a four-port

switching valve installed downstream of the separating

column and before the methanizer (see Figure 1).

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: A passivation procedure is described in the Metals

Handbook, 8th ed., Vol. 2, American Society for Metals,

Metals Park, OH.

NOTE 5: Polytetrafluoroethlyene, polymethylpentene and

polypropylene are suitable plastic materials.

Figure 1

Configuration for the Analysis of CF

, CO

, N

O, SF

, and CO in NF

Figure 2

Configuration for the Analysis of O

/Ar and N

in NF

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