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SEMI E17-0600 © SEMI 1991 , 2000 5 4.2 Ev aluate t he transient characte r i s tics fro m “OFF” to a flowing condition at final set po int by using an auxiliar y input to an MFC designed for th e purpose. 4.2.1 Establish…
SEMI E17-0600 © SEMI 1991, 2000 4
Figure 3b
MFC Transient Characteristics Test Setup with Outlet at Vacuum
Figure 3c
VFC Transient Characteristics Test Setup with Rate of Rise (RoR) System
4 Test Procedure
4.1 Evaluate the transient characteristics from “OFF” to a flowing condition at final set point by a transition in set
point voltage only.
4.1.1 Apply a set point voltage sufficient to close the control valve following the manufacturer’s recommendation.
This may be a voltage other than zero, either positive or negative. Allow the output of the mass flow controller and
the actual flow, if any, to stabilize.
4.1.2 Apply the final set point value as shown in Table 1.
SEMI E17-0600 © SEMI 1991, 20005
4.2 Evaluate the transient characteristics from “OFF” to a flowing condition at final set point by using an auxiliary
input to an MFC designed for the purpose.
4.2.1 Establish an “OFF” condition following the manufacturer’s recommendation. The setpoint should be applied
as shown in Table 1. Allow the output of the mass flow controller and the actual flow, if any, to stabilize.
4.2.2 Change the state of the auxiliary input to achieve control.
4.3 Evaluate the testing transient characteristics between two non-zero set point controlled flows.
4.3.1 Adjust the command to the “initial set point” in Table 1, and allow the actual flow (as measured by the master
reference standard) to stabilize.
4.3.2 Apply final set point as shown in Table 1.
4.4 Refer to Figures 3 and 4 to determine the dead time, step response time, settling time, overshoot, and
undershoot. Record the results in Table 1.
5 Test Results
5.1 Transient characteristics test results shall be presented as follows:
(1) “OFF” means the MFC set point is zero or the lowest value permitted.
(2) The control valve leak rate at shut-off shall be recorded.
(3) Other initial and final set points may be tested and reported.
(4) The transient characteristics of the MFC electrical output signal shall also be recorded during the above testing
for purposes such as comparison with the actual flow.
Table 1
Initial Set Point
(% of Full Scale)
OFF
(1)
OFF
(1)
25 75
OTHER
(3)
Final Set Point
(% of Full Scale)
100 25 75 25 OTHER(3)
Dead Time
(Seconds)
Step Response Time
(Seconds)
Settling Time
(Seconds)
Transient Overshoot
(Percent of set point
step change)
Transient Undershoot
(Percent of set point
step change)
NOTICE: SEMI makes no warranties or representations as to the suitability of the guideline set forth herein for any
particular application. The determination of the suitability of the guideline 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 mentioned herein. These guidelines are subject to change without notice.
The user’s attention is called to the possibility that compliance with this guideline may require use of copyrighted
material or of an invention covered by patent rights. By publication of this guideline, SEMI takes no position
respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in this
guideline. Users of this guideline 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.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
f
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI E18-91 (Reapproved 1104)
GUIDELINE FOR TEMPERATURE SPECIFICATIONS OF THE MASS
FLOW CONTROLLER
This guideline 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 1991; last published February 1999.
1 Purpose
1.1 The purpose of this guideline is to establish a
uniform, worldwide means to describe the temperature
parameters which are characteristic of mass flow
controllers. It is intended to prevent confusion and
misunderstanding between manufacturers and users.
2 Scope
2.1 This guideline contains definitions of terms which
describe the effects of temperature upon mass flow
controllers as used in the semiconductor industry.
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 Referenced Standards
3.1 SEMI Standard
SEMI E12 — Standard for Standard Pressure,
Temperature, Density, and Flow Units Used in Mass
Flow Meters and Mass Flow Controllers
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
4 Terminology
4.1 Definitions (see Figure 1)
4.1.1 ambient temperature — the temperature of the
medium surrounding the device.
NOTE 1: The ambient temperature assumes that the
instrument is not exposed to significant radiant energy
sources.
4.1.2 calibration temperature — the ambient
temperature at which the mass flow controller was
calibrated.
4.1.2.1 Description Form: ___°C
CAUTION — Calibration Temperature is not to be
confused with Gas Temperature or Standard
Temperature.
4.1.3 gas temperature — the actual temperature of the
flowing gas at the primary flow standard.
4.1.4 maximum baking temperature — the highest
temperature to which the Mass Flow Controller or its
components in contact with the gas can be heated in
accordance with a specified baking procedure. The
specified baking process will not impair the
performance characteristics per the manufacturers
specifications. (“Baking” is a process whereby a device
is heated to accelerate the removal of adsorbed gases
and/or other volatile material).
4.1.4.1 Description Form: MAX. ___°C
4.1.5 normal operating temperature — the temperature
range within which the influence of ambient
temperature on the performance is stated.
4.1.5.1 Description Form: ___°C – ___°C
4.1.6 operating temperature limits — operation is
permitted within this range but performance is not
specified beyond the Normal Operating Temperature.
If the instrument is operated outside these limits
damage may occur.
4.1.6.1 Description Form: ___°C – ___°C
4.1.7 reference operating temperature — the range
within which accuracy statements apply without
requiring correction for Temperature Effects (see
Section 4.1.10).
4.1.7.1 Description Form: ___°C – ___°C
4.1.8 standard temperature — the temperature to
which a volumetric flow rate (measured at the Gas
Temperature) is referenced through the ideal gas law
(PV = nRT). SEMI E12 defines Standard Temperature
as 0.0°C.
CAUTION — Standard Temperature is not the same as
the Gas Temperature or Calibration Temperature.
4.1.9 storage temperature limits — the temperature
limits to which the mass flow controller may be
subjected in an unpowered condition. No permanent
impairment shall take place, however minor
adjustments may be needed to restore performance to
normal.
SEMI E18-91 © SEMI 1991, 2004 1