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SEMI E10-0304 E © SEMI 1986, 2004 27 R1-7 Intended Process-Flo w and Multi-Path Cluster-Tool Metrics R1-7.1 Once the IPF and multi-path cluster tool state histories have been prepared, evaluatio n of metrics m ay be perf…

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R1-6.3 Example 3 — A simplified example with a
discrete timeline is shown in Figure R1-12. In this
example there are three modules (i.e., M1, M2, M3) and
three IPFs (i.e., IPF1, IPF2, IPF3). IPF1 uses all three
modules, whereas IPF2 does not use M3, and IPF3 does
not use M2. The state value functions for the IPFs are
IPF1 = M1 × M2 × M3, IPF2 = M1 × M2, and IPF3
= M1 × M3, respectively. Temporal mapping of the
IPFs and the multi-path cluster tool is described in
Table R1-4.
NOTE 12: The condition between time t = 4 and t = 5, where
the multi-path cluster tool is productive but all of its IPFs are
down, is expected only as a transient condition in actual
practice. Once the productive module finishes its task in
progress, the multi-path cluster tool would be expected to go
down. However, while the module is productive, it also is
accruing theoretical processing time used in the SEMI E79
metric, rate efficiency. The allocation of this transient
condition to productive time is necessary in order to guarantee
that rate efficiency evaluated over any interval is never
greater than 100%.
5
100
M1
M2
M3
IPF2
IPF3
IPF1
time
Cluster Tool
Module
S
EMI E10
States
Process
Flow
Up/Down
States
=
P
roductive = Unscheduled Down =
N
ot-Productive
Figure R1-12
Mapping Cluster-Tool States, Example 3
Table R1-4 Temporal Mapping of Example 3
Time Module Events IPF Events Cluster Tool State
t = 0 M1 is productive. All IPFs are up. Productive
t = 2 M2 goes down.
M1 is still productive.
IPF1 and IPF2 go to unscheduled
downtime.
Productive
t = 4 M3 goes down.
M1 is still productive.
All IPFs are in unscheduled downtime. Productive
t = 5 M1 exits productive state.
No modules are productive.
All IPFs are still in unscheduled downtime. Unscheduled Downtime
t = 7 M2 come back up.
M3 transitions into scheduled
downtime.
IPF2 is up. At least one IPF is up.
IPF1 and IPF3 are down, but not in
unscheduled downtime
Neutral
t = 9 M3 comes back up.
All modules are up.
All IPFs are up. Neutral
SEMI E10-0304
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R1-7 Intended Process-Flow and Multi-Path
Cluster-Tool Metrics
R1-7.1 Once the IPF and multi-path cluster tool state
histories have been prepared, evaluation of metrics may
be performed in a similar manner to that used for
evaluating non-cluster or single-path cluster tools or
modules. The metrics are defined below with sample
calculations based on Example 3 from Section R1-6.
NOTE 13: The multi-path cluster tool metrics presented here
reflect the reliability of the multi-path cluster tool against total
failure rather than partial failure. It is recognized that these
metrics proposed here will reflect more favorably on systems
with higher levels of redundancy at each process step. The
cost or “trade-off” of this redundancy may be evaluated using
other metrics from SEMI E10, SEMI E79, SEMI E35, or from
non-standard evaluations. It also is recognized that these
metrics will not reflect the partial loss of throughput for an
IPF that is “up,” but some of its alternative modules are
“down.” Once again the analyst is encouraged to consult other
metrics from SEMI E10, SEMI E79, or from non-standard
evaluations.
R1-7.2 Multi-Path Cluster Tool Reliability
R1-7.2.1 Multi-Path Cluster Tool Mean Productive
Time Between Failure (MTBF
p-CT
) — mean productive
time between failure where productive time occurs
when at least one module is in the productive state, and
a failure occurs when there are no available IPFs
through the multi-path cluster tool due to module-level
unscheduled downtime.
M
TB
F
p-CT
=
=
=
5 hours
N
umber of Multi–Path Cluster Tool Failures
M
ulti
–
Path Cluster Tool Productive Time
5 hours
1 failure
R1-7.2.2 Multi-Path Cluster Tool Failure Time
(MFT
CT
) — mean time when there are no available IPFs
through the multi-path cluster tool due to module-level
unscheduled downtime.
M
F
T
CT
=
=
=
2 hours
N
umber of Multi–Path Cluster Tool Failures
M
ulti
–
Path Cluster Tool Unscheduled Downtime
2 hours
1 failure
NOTE 14: Since multi-path cluster tool productive time and
multi-path cluster tool unscheduled downtime are mutually
exclusive; they may be compatible with approaches based on
renewal cycle models. Other renewal cycle results (e.g., the
limiting probability of finding the cluster-tool productive or
failed when approaching it at random) similarly may apply, as
determined by the analyst.
R1-7.3 Multi-Path Cluster Tool Availability
R1-7.3.1 Multi-Path Cluster Tool Aggregate IPF
Uptime (Uptime
CT-IPF
) — availability of the multi-path
cluster tool as a function of module
“up/downtime/unscheduled downtime” states and is
evaluated as the aggregate uptimes of all IPFs.
43.3%
10 + 10 + 10
3 + 5 + 5
13
30
×
100
×
100
Σ
all IPFs
IPF Uptime
Uptime
CT-IPF
=
=
=
≈
Σ
all IPFs
IPF Operations Time
×
100
NOTE 15: For reference, the value of the aggregate
availability efficiency metric from SEMI E79 for the same
example is 20/30 or 66.7%. This difference clearly
demonstrates that depending on which combination of
modules is “down,” the effect on the multi-path cluster tool’s
availability may be substantially different than the aggregate
module availability.
NOTICE: SEMI makes no warranties or
representations as to the suitability of the standards set
forth herein for any particular application. The
determination of the suitability of the standard 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
standards are subject to change without notice.
The user’s attention is called to the possibility that
compliance with this standard may require use of
copyrighted material or of an invention covered by
patent rights. By publication of this standard, SEMI
takes no position respecting the validity of any patent
rights or copyrights asserted in connection with any
item mentioned in this standard. Users of this standard
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 E12-0303 © SEMI 1986, 2003 1
SEMI E12-0303
STANDARD FOR STANDARD PRESSURE, TEMPERATURE, DENSITY,
AND FLOW UNITS USED IN MASS FLOW METERS AND MASS FLOW
CONTROLLERS
This standard 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 October 25, 2002. Initially available at www.semi.org December 2002; to be published March
2003. Originally published in 1986, previously published in 1996.
1 Purpose
1.1 In the past, confusion has existed in the values of
standard temperature and standard pressure when gas
flow is expressed in “standard” volumetric units. To
eliminate this confusion, the Mass Flow Controllers
Committee has established this standard.
2 Scope
2.1 This standard provides a common basis for
communication between manufacturers and users.
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 Standard
3.1 ASTM Standard
1
E 380-89a — Standard Practice for Use of the
International System of Units (the Modernized Metric
System)
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
4 Terminology
None.
5 Standard Temperature
5.1 Standard temperature is defined as 273.15 K
(0.0° C).
1 American Society for Testing and Materials, 100 Barr Harbor
Drive, West Conshohocken, Pennsylvania 19428-2959, USA.
Telephone: 610.832.9585, Fax: 610.832.9555 Website:
www.astm.org
6 Standard Pressure
6.1 Standard pressure is defined as 101,325 pascals (1
atm, 760 Torr).
7 Standard Density
7.1 The standard density is defined as Mw/22,413.6
grams per standard cubic centimeter (g/scc), where Mw
is the molecular weight of the gas in grams per mole
(g/mol), and 22,413.6 is the standard molar volume in
cubic centimeters (scc/mol) (i.e., the volume of one
mole of a perfect gas at standard temperature and
standard pressure).
8 Standard Flow Rate
8.1 Standard flow rate is the volumetric flow rate of the
gas at the standard density defined in Section 7.1.
9 Units
9.1 Units for standard flow rate may be expressed as
standard cubic centimeters per minute (sccm), standard
liters per minute (slm), standard cubic decimeters per
minute (scdm), or as standard cubic meters per minute
(scmm).
1 sccm = 1 × 10
-3
* slm
= 1 × 10
-3
* scdm
= 1 × 10
-6
* scmm
NOTE 1: Units in this document have been editorially
changed to sccm, slm, scdm, and scmm in line with
international standards which require all units to be expressed
in SI terms. While neither “minute” nor “liter” is a primary SI
unit, each is acceptable under the system, and eliminating the
use of these units in this standard would seriously diminish its
acceptability.
10 Background
10.1 In the absence of this specification, there has been
confusion in the definition of standard conditions.
“Standard” temperature in particular has been variously
defined as 59° F, 68° F, 70° F, 20° C, 22° C, etc. to reflect
“normal” test conditions. The scientific community has