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SEMI F64-0701 © SEMI 2001 3 9.1.4 D ome-l oaded pressure control , o r other device capable of produ cing specified pres s ure transien t s. 9.1.5 Flo w s tandard, w ith time cons t a n t less tha n 20 msec a nd wi th fu…

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SEMI F64-0701 © SEMI 2001 2
5.2.10 P
1
— inlet pressure
5.2.11 P
2
— outlet pressure
5.2.12 PC
A
— pressure coefficient of actual flow per
pressure change at a set point.
5.2.13 PC
O
— pressure coefficient of indicated flow
per pressure change at zero flow.
5.2.14 PC
S
— pressure coefficient of span flow per
pressure change.
5.2.15 Psia — pounds per square inch absolute
5.2.16 Psig — pounds per square inch gauge
5.2.17 Q
A
— actual flow
5.2.18 Q
FS
— rated full scale flow
5.2.19 Q
I
— indicated flow
5.2.20 Q
N
— nominal actual flow dur ing steady state
conditions.
5.2.21 Q
R
— steady state actual flow while inlet
pressure is being ramped.
5.2.22 Q
SP
— set-point flow
5.2.23 T — time
5.2.24 t
f
— time when Q
A
is within 0 .5% of reading of
Q
N.
5.2.25 t
o
— time when pressure transi ent is initiated.
5.2.26 t
s
— settling time to Q
N
5.2.27 v — voltage
5.2.28 V
eq
— equivalent internal cont rol volume of the
DUT.
5.2.29 V
ip
— valve, pump isolation
6 Summary of Test Method
6.1 Inlet Pressure Step and Ramp Change — The
effects of fast-step and slow-ramp changes to the
pressure on actual flow out of the MFC is observed.
See Figures 6 and 7.
6.2 Inlet Pressure Effect Steady St ate — The effects of
a pressure increase/decrease on actual flow is observed
once the increase/decrease has reached steady state.
See Figure 8.
6.3 Outlet Pressure Step Change — The effects of an
outlet pressure change on actual flow is observed. See
Figure 9.
6.4 Crosstalk Pressure Effect – Th e effects of pressure
changes due to switching multiple flow devices on the
same gas line. See Figure 11.
7 Interferences
7.1 The accuracy rating of the mea suring equipment
shall be superior to that of the DUT. Preferably the
measuring equipment will have an accuracy that is four
times better than the DUT. Calibration equipment must
have a valid calibration certificate.
7.2 Take care when using test instruments with a
specified accuracy expressed in percent of full scale as
the accuracy is limited at lower percentages.
7.3 Installation effects on the flow should be
minimized.
7.4 Verify electrical signals directly at the DUT
connector to ensure that the signals at the DUT and
standard agree with the signals at the data recording
equipment.
7.5 All electrical measurements sh ould be read on
devices with at least 4.5 digits of resolution. These
devices must have valid calibration certifications.
7.6 The results of this test method depend on the
accuracy and repeatability of the pressure measurement
devices used in the test system. Take care to stay
within the specified pressure ranges of these devices
and verify their accuracy prior to and following MFC
evaluation activities.
7.7 The cleanliness level of the tes t gas should be
compatible with the DUT. The minimum requirement
placed on the test gas is that it be free of contamination
that could influence the operational characteristics of
the test article and instruments.
7.8 The test gas source and deliver y system must be
capable of satisfying the test volume flow rate at a
constant pressure ± 0.7 kPa (± 0.1 psi).
7.9 The ambient temperature shou ld be held to 22°C
±2°C for the duration of each analysis.
8 Significance and Use
8.1 The significance of the stabilit y calculations in this
method is to allow the MFC user to assess the transient
pressure effects on the DUT. In application, this
method will provide a consideration affecting gas
system designs and MFC selection.
9 Apparatus
9.1 Equipment Required for Methods A–1 and A–2
9.1.1 Inlet test gas filter
9.1.2 Shutoff valve (qty 2).
9.1.3 Pressure transducers, available range 0–446 kPa
(0–50 psig), with measurement accuracy of ± 0.2% and
time constant less than 20 msec (qty 2).
SEMI F64-0701 © SEMI 20013
9.1.4 Dome-loaded pressure control, or other device
capable of producing specified pressure transients.
9.1.5 Flow standard, with time constant less than 20
msec and with full scale that is 200% of the DUT’s full
scale, accurate to 1% of full scale, linear to 0.5% of full
scale, and capable of resolving to 0.2% of full scale.
9.1.6 Data acquisition system measu res the electrical
signals from the device under test. The data acquisition
system may also read the signals from the flow
standard, record test data and control the test sequence.
9.2 Equipment Required for Method B
9.2.1 Inlet test gas filter.
9.2.2 Shutoff valve (qty 2).
9.2.3 Pressure transducer, available range 0–791 kPa
(0–100 psig), with measurement accuracy of ± 0.1%
and time constant less than 20 msec.
9.2.4 Two-stage pressure regulator, capable of 0–690
kPa (100 psia) control.
9.2.5 Flow standard, with full scale that is at least
120% of the DUT’s full scale, accurate to 1% of full
scale, linear to 0.5% of full scale, and capable of
resolving to 0.2% of full scale.
9.2.6 Data acquisition system measu res the electrical
signals from the device under test. The data acquisition
system may also read the signals from the flow
standard, record test data and control the test sequence.
9.3 Equipment Required for Method C
9.3.1 Inlet test gas filter.
9.3.2 Manual metering valve.
9.3.3 Pressure transducer, available range 0–446 kPa
(0–50 psig), with measurement accuracy of ± 0.2% and
time constant less than 20 msec.
9.3.4 Pressure transducer, 0–101.325 kPa ± 1% and
with time constant less than 20 msec (qty 1).
9.3.5 Shutoff valves (qty 2).
9.3.6 Isolation valve (qty 1).
9.3.7 Vacuum pump, with pumping speed of at least
30 lpm, with throttling and isolation valve.
9.3.8 Flow standard, with time constant less than 20
msec and with full scale that is 200% of DUT full scale
accurate to 1% of full scale, linear to 0.5% of full scale,
and capable of resolving to 0.2% of full scale.
9.3.9 Data acquisition system measu res the electrical
signals from the device under test. The data acquisition
system may also read the signals from the flow
standard, record test data and control the test sequence.
9.4 Equipment Required for method D
9.4.1 Pressure transducer, available range 0–446 kPa
(0–50 psig), with measurement accuracy of ± 0.2% and
time constant less than 20 msec. (2)
9.4.2 Flow standard, with time constant less than 20
msec and with full scale that is 200% of DUT full scale
accurate to 1% of full scale, linear to 0.5% of full scale,
and capable of resolving to 0.2% of full scale.
9.4.3 Isolation valve (qty 1).
9.4.4 Data acquisition system measu res the electrical
signals from the device under test. The data acquisition
system may also read the signals from the flow
standard, record test data and control the test sequence.
9.4.5 MFC with time constant less th an 20 msec and a
full scale flow rate that is 10 times the full scale flow
rate of the DUT.
10 Materials
10.1 Clean, dry nitrogen, with a dew point less than or
equal to -40°C, at a delivery pressure of 791 kPa (100
psig).
11 Safety Precautions
11.1 This test method may involve hazardous
materials, operations, and equipment. This 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 to determine the applicability of regulatory
limitations before using this method.
12 Test Specimen
12.1 Allow all components in the te st apparatus to
warm up following the manufacturer’s specification.
12.2 Take necessary steps when switching gases to
ensure that only the desired gas is in the DUT and flow
standard at the time the test is performed.
13 Preparation of Apparatus
13.1 Setup and Schematic — See Figures 1, 2, and 10.
13.2 Plumbing Design Requirements for Methods A
and C
13.3 The test system must be highly conductive and
must have no changes in direction closer than 20 tubing
diameters upstream of the DUT.
SEMI F64-0701 © SEMI 2001 4
13.4 The pneumatic time constant for the system shall
be calculated as shown below:
τ = (Volume × Pressure Drop)/(Pressure × Volumetric
Flow)
where:
• Volume is measured between the flow standard and
the DUT
• Pressure drop is across the flow standard
• Pressure is the pressure in the defined volume
• Volumetric flow is as measured by the standard
13.5 The pneumatic time constant a dded to the flow
standard time constant should ideally be less than 100
msec and should be recorded if larger. For method C,
the volume between MV and V
ip
should be kept to a
minimum.
13.6 The system must be relatively leak free, i.e., the
maximum inboard leak rate should be 2 × 10
-7
atm cc/s
He.
13.7 The system must be supported and isolated in a
manner that keeps it from vibration, shock, and other
conditions that could influence the results of this test.
14 Procedure
14.1 Inlet Transient Pressure Effects (Method A-1)
14.1.1 Assemble the test MFC into th e test apparatus.
(See Figure 1.)
14.1.2 Satisfy the manufacturer’s war m-up
requirements for the MFC.
14.1.3 Set the inlet pressure (P
1
) to 274 kPa (25 psig).
14.1.4 Give the DUT a 50% set-point (Q
SP
= ½Q
FS
)
and wait for Q
I
to reach stability.
14.1.5 Adjust the pressure control device to initiate a
step in P
1
to 287 kPa (27 psig) with a time constant of
one second (see Figure 3c).
14.1.6 Wait until Q
I
and Q
A
have reac hed stability.
14.1.7 Using the pressure control device, initiate a step
in P
1
to 274 kPa (25 psig) with a time constant of one
second.
14.1.8 Give the DUT a 100% set-poin t (Q
SP
= Q
FS
)
and wait for stability.
14.1.9 Repeat Sections 14.1.5 through 14.1.7.
14.2 Process Side Effects (Method A-2)
14.2.1 Assemble the test MFC into th e test apparatus
(see Figure 1).
14.2.2 Satisfy the manufacturer’s war m-up
requirements for the MFC.
14.2.3 Set the inlet pressure (P
1
) to 274 kPa (25 psig).
14.2.4 Give the DUT a 50% set point (Q
SP
= ½Q
FS
)
and wait for Q
I
to reach stability.
14.2.5 Using the pressure control dev ice, initiate a
ramp in P
1
to 356 kPa (37 psig) (see graph in Figure
4c). Use a ramp rate between 0.7 kPa (0.1 psi) per
second and 21.0 kPa (3psi) per second. Record the
ramp rate used on the data sheet.
14.2.6 Wait until Q
I
and Q
A
have reac hed stability.
14.2.7 Using the pressure control dev ice, initiate a
ramp as in 14.2.5, initiate a ramp in P
1
to 274 kPa (25
psig) (see graph in Figure 4c).
14.2.8 Repeat Sections 14.2.5 through 14.2.7.
14.3 Inlet Pressure Effects, Steady S tate (Method B)
14.3.1 Assemble the DUT in the test apparatus (see
Figure 1).
14.3.2 Satisfy the manufacturer's war m-up
requirements for the DUT.
14.3.3 Set the inlet pressure (P
1
) to 205 kPa (15 psig).
14.3.4 Close V
io
, open DUT control valve.
14.3.5 Wait until Q
R
and Q
A
have rea ched stability.
Record P
1
, Q
I
and Q
A
(see Table A3.1).
14.3.6 Open V
io
and give the DUT a 50% set-point.
(Q
SP
= ½Q
FS
).
14.3.7 Wait until Q
I
and Q
A
have reac hed stability.
Record P
1
, Q
I
and Q
A
(see Table A3.1).
14.3.8 Give the DUT a 100% set-point (Q
SP
= Q
FS
).
14.3.9 Wait until Q
I
and Q
A
have reac hed stability.
Record P
1
, Q
I
and Q
A
(see Table A3.1).
14.3.10 Set inlet pressure (P
1
) to 446 kPa (50 psig) and
repeat Sections 14.3.4 through 14.3.9.
14.4 Outlet Pressure, Step Change (Method C)
14.4.1 Assemble the test MFC into th e test apparatus.
(See Figure 1.)
14.4.2 Satisfy the manufacturer's war m-up
requirements for the MFC.
14.4.3 Set the inlet pressure (P
1
) to 274 kPa (25 psig)
(see Figure 9).
14.4.4 Give the DUT a 50% set point (Q
SP
= ½Q
FS
).
14.4.5 Throttle the pump rate until P2 = 26.664 kPa.