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SEMI C59-1104 © SEMI 2002, 2004 2 7 Requirements 7.1 Purity an d other requirements fo r the various grades of nit r ogen are gi ven in Table 1. 8 Physical Constants 8.1 The physi cal constants of ni trogen are given in …
SEMI C59-1104 © SEMI 2002, 2004 1
SEMI C59-1104
SPECIFICATIONS AND GUIDELINES FOR NITROGEN
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 July 11, 2004. Initially available at www.semi.org September 2004; to be published
November 2004. Originally published in November 2002; previously published November 2003.
1 Purpose
1.1 The purpose of this document is to provide a series
of specifications for different grades of Nitrogen (N
2
)
that are used in the semiconductor industry.
2 Scope
2.1 This document covers requirements for all grades
of nitrogen used in the semiconductor industry.
2.2 If analytical methods are not complete, the
requirements are presented as a guideline.
NOTICE: This standard does not purport to address
safety issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish
appropriate safety and health practices and determine
the applicability of regulatory or other limitations prior
to use.
3 Description
3.1 Nitrogen is an odorless, tasteless, noncombustible
diatomic gas comprising approximately 78% of the
earth’s atmosphere; at cryogenic temperatures it is a
colorless liquid. Noncombustible; a cryogenic gas
derived from liquid air by fractional distillation.
4 Limitations
4.1 None.
5 Referenced Standards
5.1 SEMI Standards
SEMI C1 — Specifications for Reagents
SEMI C3 — Specifications for Gases
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
6 Terminology
6.1 Terminology appropriate to this standard is defined
in SEMI C3.
Table 1 Impurity and Other Requirements for Various Grades of Nitrogen
Previous SEMI Reference #
C3.5-93
(Specification)
C3.15-93
(Specification)
C3.48-0200
(Specification)
C3.29-96
(Specification)
C3.28-0200
(Guideline)
C3.49-94
(Specification)
Grade 4.8 5.2 5.4 5.5 5.6 7.0
Purity 99.998% 99.9992% 99.9994% 99.9995%
#1
99.9996% 99.99999%
Impurities Maximum Acceptable Level (ppm)
#2
Carbon Dioxide (CO
2
) 1 1 0.5 0.2 0.5 0.010
Carbon Monoxide (CO) 5 2 2 2 0.5 0.010
Hydrogen (H
2
) 2 2 2 2 1 0.010
Oxygen (O
2
) 3 1 0.5 0.2 0.5 0.010
Water (H
2
O) (ppmv) 1 1 0.5 0.2 0.5 0.050
Total Hydrocarbons expressed
as Methane (THC)
1
1
0.5 0.2 0.5 0.010
TOTAL SPECIFIED
IMPURITIES
13
8
6 4.8 3.5 0.100
Particles
#3
#3
#3
#3
#3
Max. 20/ft
3
>
0.02 m
#4
#1
A purifier is allowed to be used to meet this specification.
#2
An analysis of significant figures has not been considered. The number of significant figures is based on analytical accuracy and the precision
of the provided procedure.
#3
To be determined between supplier and user.
#4
May be determined after purifier/filter. Sampling point top be agreed between supplier and user.
SEMI C59-1104 © SEMI 2002, 2004 2
7 Requirements
7.1 Purity and other requirements for the various
grades of nitrogen are given in Table 1.
8 Physical Constants
8.1 The physical constants of nitrogen are given in
Table 2 (for information only).
Table 2 Physical Constants of Nitrogen (for
information only)
Metric Units US Units
Molecular weight 28.013 28.013
Boiling point at 1 atm
–195.8C –320.4F
Density of gas at 21.1C
(70F) and 1 atm
1.1605 kg/m
3
0.07245 lb/ft
3
Specific gravity of gas at
21.1C and 1 atm (air = 1)
0.967 0.967
Density of liquid at boiling
point
808.8 kg/m
3
50.49 lb/ft
3
9 Analytical Procedures for Grade 4.8 Nitrogen
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 no more than 10% of the sample value of the
component of interest unless otherwise specified.
9.1 Carbon Monoxide and Carbon Dioxide — This
procedure is for the determination of carbon monoxide
and carbon dioxide in nitrogen using a gas
chromatograph with a flame ionization detector and
methanizer.
NOTE 3: Carrier gases should contain less than 0.1 ppm
carbon monoxide and less than 0.1 ppm hydrogen.
9.1.1 Detection Limit — 100 ppb
9.1.2 Instrument Parameters
9.1.2.1 Column: Porapak T or Q, 3 m (9.8 ft) by 3.2
mm (1/8 in) OD by 2.2 mm (0.085 in) ID stainless
steel; or Chromosorb 102, 2 m (6.6 ft) by 3.2 mm (1/8
in) OD by 2.2 mm (0.085 in) ID stainless steel; or
equivalent.
9.1.2.2 Carrier Flow: 30 mL/min helium.
9.1.2.3 Sample Volume: 0.5 to 2.0 mL.
9.1.2.4 Temperatures:
Detector
280C
Column Oven
60C
Methanizer
350C
9.1.3 Calibration Standards — 1–5 ppm carbon
monoxide, 1–5 ppm carbon dioxide, balance nitrogen.
9.1.4 Operating Procedure
9.1.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record the retention times
and peak areas. Order of elution is carbon monoxide,
carbon dioxide.
9.1.4.2 Inject the sample to be tested in same manner
as the calibration standard. Record the retention times
and peak areas.
9.1.4.3 Repeat Section 9.1.4.1.
9.1.4.4 Compare the average peak area of the
calibration standard to that of the nitrogen sample being
tested. Calculate the concentrations of carbon
monoxide and carbon dioxide, using the formula:
Sample Peak Area
Concentration of Standard
Standard Peak Area
Concentration of Sample
9.1.4.5 The result may not exceed the specification in
Table 1.
9.2 Hydrogen — This procedure is for the
determination of hydrogen in nitrogen using a gas
chromatograph with a helium ionization detector.
9.2.1 Detection Limit — 500 ppb.
9.2.2 Instrument Parameters
9.2.2.1 Column — 5A molecular sieve, 1.9 m (6 ft) by
3.2 mm (1/8 in) OD by 2.2 mm (0.085 in) stainless steel
or equivalent.
9.2.2.2 Carrier Flow — 30 mL/min helium.
9.2.2.3 Sample Volume — 3.0 mL
9.2.2.4 Temperatures:
Detector
125C
Column Temperature
65C
9.2.3 Calibration Standard — 1–5 ppm hydrogen in
nitrogen.
9.2.4 Operating Procedure
9.2.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record the retention time
and peak area.
9.2.4.2 Inject the sample to be tested in same manner
as the calibration standard. Record the retention time
and peak area.
9.2.4.3 Repeat Section 9.2.4.1.
SEMI C59-1104 © SEMI 2002, 2004 3
9.2.4.4 Compare the average peak area of the
calibration standard to that of the nitrogen sample being
tested. Calculate the concentration of hydrogen, using
the formula:
Sample Peak Area
Concentration of Standard
Standard Peak Area
Concentration of Sample
9.2.4.5 The result may not exceed the specification in
Table 1.
9.3 Oxygen — This procedure is for the determination
of oxygen in nitrogen using a continuous flow analyzer
using an electrochemical method.
9.3.1 Detection Limit — 100 ppb.
9.3.2 Flow Rate — Set sample flow rates in
accordance with the instrument manufacturer's
instructions.
9.3.3 Calibration Standard — 3–15 ppm oxygen in
nitrogen or in accordance with the instrument
manufacturer's instructions.
9.3.4 Operating Procedure
9.3.4.1 Do not change the sample flow setting once
established.
9.3.4.2 Introduce nitrogen sample and record oxygen
reading. The result may not exceed the specification in
Table 1.
9.4 Total Hydrocarbons — This procedure is for the
determination of total hydrocarbons in nitrogen using a
continuous flow flame ionization detector equipped
total hydrocarbon analyzer.
NOTE 4: The 0–1 range can be used provided that zero and
span gas standards in nitrogen 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 and span 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
nitrogen can be accurately totaled and compared to methane.
9.4.1 Detection Limit — 0.1 ppm.
9.4.2 Flow Requirements
9.4.2.1 High purity, hydrocarbon-free (less than 0.1
ppm) hydrogen: 35–40 mL/min or 40% hydrogen in
either helium or nitrogen matrix at 75–80 mL/min.
9.4.2.2 Dry, hydrocarbon-free (less than 0.1 ppm) air:
350–400 mL/min.
9.4.2.3 Set sample flow rates in accordance with the
instrument manufacturer's instructions.
9.4.3 Calibration Standards
9.4.3.1 Nitrogen with known quantity of hydrocarbons
at 0.5 ppm level.
9.4.3.2 The upper level span gas not exceeding 5 times
the concentration of the specification.
9.4.4 Operating Procedure
9.4.4.1 Do not change the flow settings for hydrogen,
air and sample once established.
9.4.4.2 Introduce the nitrogen 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.
9.4.4.3 Introduce the span gas standard in nitrogen and,
using the span adjust knob, set the needle (or output
reading) to match the level of hydrocarbons in the span
gas.
9.4.4.4 Introduce nitrogen sample into the analyzer and
read the quantity of hydrocarbons on the analyzer
meter. The result may not exceed the specification in
Table 1.
9.5 Water — This procedure is for the determination of
trace moisture (water) in nitrogen using a continuous
flowing piezoelectric hygrometer.
NOTE 7: 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.
9.5.1 Detection Limit — 0.1 ppmv or 90C (130F).
9.5.2 Flow Requirements — Set the sample pressure
and flow rate in accordance with the instrument
manufacturer’s instructions.
9.5.3 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.
9.5.4 Operating Procedure
9.5.4.1 Obtain a continuous flow sample of gas from
the source using a clean and passivated stainless steel
line which has been purged dry after exposure to
ambient moisture.
9.5.4.2 After prepurging with a dry gas, allow the
sample gas to flow through the sampling system and the