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SEMI F67-1101 © SEMI 2001 4 8.2.2.2 An impurity analyzer is used to measure high er concentrations of impu rit ies s uch as found in the test gas. 8.2.2.3 Electronically controlled mass flow controllers are used to accur…

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SEMI F67-1101 © SEMI 20013
measure all impurities of interest at the specified level
of the customer, the ppb or sub-ppb level.
5.2.21 zero gas — nitrogen, argon, helium or hydrogen
with an estimated level an order of magnitude, or more,
lower than the lowest calibration point for each
impurity of interest (as defined in SEMI F33).
6 Summary of Method
6.1 This method will allow a user to quantify the
impurity removal capacity of a given inert gas purifier
for that impurity.
7 Safety Precautions
7.1 This test method may involve hazardous materials,
operations, and equipment. The test method does not
purport to address the safety considerations associated
with its use. It is the responsibility of the user to
establish appropriate safety and health practices and
determine the applicability of regulatory limitations
before using this method.
7.2 Exhaust from the DUT should be properly vented.
7.3 Only the appropriate gas should be used for purifier
testing. Use of the inappropriate gas may cause
exothermic reactions and possible explosions.
7.4 Electric discharges or mechanical friction might
trigger combustion within a getter. Avoid situations
where there is an accumulation of electrostatic charge.
7.5 Purifiers are generally designed for use with
impurity levels less than 1% and should not be used to
purify air or other inappropriate gases. Contact the
manufacturer if there is any question as to the
suitability for a particular gas.
7.6 Care should be taken to minimize the purifier’s
exposure to room air (even filtered air). Room air may
chemically react with some purifiers shortening the
purifier lifetime. Follow manufacturer’s installation
procedures.
8 Test Protocol
8.1 Test Conditions
8.1.1 The test should be conducted following
manufacturers recommended handling procedures to
activate new media or regenerate existing purifier
media.
8.1.2 The test is to be conducted at a room temperature
maintained between 18°C (64°F) and 26°C (78°F).
Environmental temperature fluctuations within this
range are not expected to have any measurable effect on
the instrumentation used to detect the level of
impurities. Follow instrument manufacturer’s operating
procedures.
8.1.3 Testing performed at high impurity challenge
may alter test results, and may not be appropriate to do
for all types of purifiers. Any significant temperature
change during the test could have adverse or false
effects on the capacity results.
8.1.4 For a mixture of more than 1 impurity, competing
reactions may occur between impurities, which may
lead to different results.
8.2 Apparatus
8.2.1 Materials
8.2.1.1 Test Gas — a mixture of pure gas and
challenge gas. Select the appropriate concentration
level. For initial studies, a higher concentration range,
e.g., 500 ppm to 1% is suggested for each given
impurity. For more representative studies done over
longer time periods, 1–10 ppm for each given impurity
is suggested.
8.2.1.2 Pressure Regulators — all wetted internal
surfaces, where appropriate, should be made of
electropolished 316L stainless steel with an internal
surface finish of 0.18 µ m (7 µ in) R
a
and 0.25 µ m (10
µ in) R
a,max
, to control system pressures.
8.2.1.3 Pressure Gauge — all wetted internal surfaces,
where appropriate, should be made of electropolished
316L stainless steel with an internal surface finish of
0.18 µ m (7 µ in) R
a
and 0.25 µ m (10 µ in) R
a,max
, to
monitor system pressures.
8.2.1.4 Standard Test Flows — use appropriate mass
flow devices. One MFC with appropriate range of 0–50
slpm for the pure gas is suggested. Various MFCs with
appropriate ranges of 0–25 sccm, 0–100 sccm and 0–1
slpm for the challenge gas is suggested.
8.2.1.5 Tubing — made of electropolished 316L
stainless steel, with an internal surface finish of 0.18
µ m (7 µ in) R
a
and 0.25 µ m (10 µ in) R
a,max
, to transport
gas.
8.2.1.6 Fittings — the appropriate size face-seal fitting
is used.
8.2.1.7 Gaskets — use metal gaskets for all
connections. New gaskets should be used for each new
connection. Use of cleanroom gloves is required when
handling gaskets and fittings.
8.2.2 Instrumentation
8.2.2.1 An APIMS or other ultratrace analytical
instrumentation is used to determine the level of each
gaseous impurity exiting the DUT.
SEMI F67-1101 © SEMI 2001 4
8.2.2.2 An impurity analyzer is used to measure higher
concentrations of impurities such as found in the test
gas.
8.2.2.3 Electronically controlled mass flow controllers
are used to accurately blend the impurity challenge
level.
8.2.2.4 Data collection equipment is used to gather
output from the ultratrace analytical instrumentation.
8.2.2.5 All instruments used should be calibrated
regularly, according to manufacturer’s specifications.
8.2.3 Test Set-up and Schematic
8.2.3.1 Assemble the test setup according to Figure 1.
Do not install the DUT until a purge flow is established
through MFC1.
8.2.3.2 For the test set-up, pure gas is blended with
challenge gas to create a test gas mixture.
8.2.3.3 The DUT is connected, purged per the
manufacturer’s recommendation, positioned with the
appropriate attitude (if required by the manufacturer),
and heated (if required by manufacturer) under pure gas
flow.
8.2.3.4 Challenge gas flow is introduced and the
impurity analyzer measures the impurity levels. If
appropriate, the APIMS or other ultratrace analytical
instrumentation may be used to measure the test gas
while the test gas bypasses the DUT
. See Section 9 on
Exposure Precautions.
8.2.3.5 Measure and record the test gas concentration
for the desired impurity.
8.2.3.6 Following measurement of the test gas, the
bypass should be purged with pure gas to ensure
impurity removal from the section of the test set-up that
is downstream of the DUT.
8.3 Test Procedures — Refer to Figure 1.
8.3.1 Use of the impurity analyzer is recommended to
protect the APIMS or ultratrace analytical
instrumentation from high impurity concentrations
which may harm the instrument. The test may be
conducted without the impurity analyzer at the risk of
exposing the APIMS or ultratrace analytical
instrumentation to high impurity concentrations.
8.3.2 Analytical Instrumentation Setup
8.3.2.1 Set up and calibrate the analytical
instrumentation (APIMS or ultratrace analytical
instrumentation and impurity analyzer) according to
manufacturer specifications. This includes establishing
the appropriate flow rate to the instrument.
8.3.2.2 Acquire zero data to establish the analytical
instrumentation baseline and stability prior to starting
the test.
8.3.3 Establish flow of pure gas through the manifold
bypass:
8.3.3.1 Start with all valves closed except purge gas to
analytical instrumentation (V11 and V13 open).
8.3.3.2 Open V1 and adjust R1 to the suggested
operating pressure range of 275–415 kPa (40–60 psig).
8.3.3.3 Open V2, V8, V9 and adjust R3 to provide
appropriate backpressure for operation of the APIMS or
other ultratrace analytical instrumentation. R3 will vent
excess gas providing the volume challenge to the DUT.
Set MFC1 to the appropriate flow rate. Readjust R1
and R3 to obtain the proper operating conditions.
8.3.4 Monitor drydown of the manifold bypass:
8.3.4.1 Close V11 and Open V10.
8.3.4.2 Purge the bypass manifold until the impurity
level is in the range of the APIMS or ultratrace
analytical instrumentation.
8.3.4.3 Close V13 and Open V12. Close V10 and
Open V11.
8.3.4.4 Purge the bypass manifold until the moisture
impurity level at the APIMS or ultratrace analytical
instrumentation is below 1.0 ppb.
8.3.5 Re-isolate the APIMS or ultratrace analytical
instrumentation:
8.3.5.1 Close V12 and Open V13. Maintain a constant
purge to the analytical instrumentation.
8.3.6 Install the DUT, Purging with Pure Gas:
8.3.6.1 Open V6. Remove the DUT inlet face-seal
connection. Quickly install the DUT inlet. Remove the
DUT outlet face-seal connection and install the DUT
outlet. Open V7.
8.3.6.2 Isolate the manifold bypass, directing all flow
through the DUT, close V8 and V9.
8.3.6.3 Adjust R1 and R3 until P1 measures the stated
purifier operating pressure.
8.3.6.4 Purge the DUT per the manufacturer’s
recommendation. If required, heat the DUT per
manufacturer’s recommendation.
8.3.7 Monitor the impurity level at the outlet of the
DUT until stable:
8.3.7.1 Initial impurity monitoring may be done with
the impurity analyzer. Close V11, open V9 and V10.
SEMI F67-1101 © SEMI 20015
8.3.7.2 When the impurity level is in the range of the
APIMS or ultratrace analytical instrumentation, Close
V13 and Open V12. Close V9 and V10, Open V11.
8.3.7.3 Monitor impurity level until stable.
8.3.8 Initiate Impurity Challenge:
8.3.8.1 Isolate the DUT and APIMS or ultratrace
analytical instrumentation. Close V7 and V12, open
V13.
8.3.8.2 Open V3 and adjust R2 to the suggested
operating pressure range of 275–415 kPa (40–60 psig).
Open V5 and set MFC2 to the desired flow. (See
Appendix 1 to determine the desired flow for MFC2).
8.3.8.3 Verify test gas impurity. Open V4, V8, and
V10 and then close V5 and V11, supplying test gas to
the impurity analyzer. Adjust R2 as necessary to
maintain appropriate pressure for supplying MFC2.
Monitor test gas impurity until stable and verified to
theoretical impurity value (See Appendix 1).
8.3.8.4 Initiate test. Direct input test gas through the
DUT to the APIMS or ultratrace impurity analyzer,
Open V6 and V7. Open V12 and close V13. Isolate
impurity analyzer, Close V8 and V10. Open V11.
8.3.8.5 Zero test gas flow totalizers (Pure Gas MFC1
and challenge gas through MFC2) beginning Purifier
Capacity Test.
8.3.9 Determination of purifier capacity:
8.3.9.1 The test will require several weeks or months
depending on the purifier’s capacity for retention of and
the concentration of the impurity.
8.3.9.2 The test may be done on newly activated media
or may be done using existing media that has been
regenerated. The test may be destructive to the DUT.
8.3.9.3 Constant monitoring of the purifier effluent
over the duration of the test is preferred. However,
periodic monitoring, e.g. every few hours is sufficient.
8.3.9.4 The test gas can be periodically monitored at
the impurity analyzer by closing V11 and opening V8
and V10. If significant, ensure that flow volume to
impurity analyzer during this time is subtracted from
total volume input through DUT. In addition,
instrument calibration should be monitored as
recommended by the manufacturer.
8.3.9.5 Monitor trends in outlet purity until the
breakthrough point for the impurity is detected. Time,
liters of gas, and outlet purity should be recorded.
8.4 Repeat test for each new impurity to be analyzed
using a new or regenerated DUT.
9 Exposure Precautions
9.1 The APIMS or ultratrace analytical instrument
should not be exposed to high levels of impurities.
After installation of the purifier, it should be purged
well, per the manufacturer’s recommendation. A
typical recommendation might be to purge a minimum
of 150 bed volumes before directing the flow to the
APIMS.
10 Calculation of Purifier Capacity
10.1 Use the following formula to calculate Purifier
Capacity:
10.2 (Test Duration (min)) × (Test Flow Rate slpm) =
Total Liters Test Gas (TLTG)
10.3 Impurity(liters) = (TLTG) × ppm × 10
-6
10.4 Purifier Capacity = (Total Impurity
(liters)/(Purifier Volume(liters))
10.5 Purifier Capacity is reported as total liters of each
given impurity per liter purifier, and is a dimensionless
number.
11 Reporting Results
11.1 The following test conditions should be reported:
11.1.1 Date and time of test,
11.1.2 Operator,
11.1.3 Pure gas flow rate (slpm),
11.1.4 Challenge gas flow rate (sccm),
11.1.5 Test pressure kPa (psig or psia),
11.1.6 DUT operating temperature (° C),
11.1.7 Purifier manufacturer, model, and serial
number, and volume,
11.1.8 Ultratrace analytical instrumentation used,
11.1.9 Test gas impurities and levels, and
11.1.10 Calibration certificates for the mass flow
devices, pressure gauges and ultratrace analytical
instrumentation.
12 Related Documents
SEMI F30 — Start-up and Verification of Purifier
Performance Testing for Trace Gas Impurities and
Particles at an Installation Site
SEMI F43 — Test Method for Determination of
Particle Contribution by Point-Of-Use Purifiers
NOTE 3: Unless otherwise indicated, all documents cited
shall be the latest published versions.