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Description  |
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FIELD OF THE INVENTION
This invention relates to process gas distribution systems and methods.
BACKGROUND OF THE INVENTION
Systems and methods presently are used for the automatic or semi-automatic
control of process gas distribution in semi-conductor manufacturing. One
such system and method which is highly advantageous is shown in U.S.
patent application Ser. No. 194,828, filed May 17, 1988, now U.S. Pat. No.
4,989,160, which is assigned to the assignee of this patent application.
Despite its excellence, further improvements are needed to solve several
remaining problems.
Some prior systems provide for remote control at a single computer console
of a large number of remote gas flow control units or "cabinets". Each
control unit controls the delivery of process gas to one or more locations
where the gas is used to make semiconductor devices. These locations are
called "tool" locations. Most control units are located relatively far
from the tool locations. It is desired to provide communication links
between the tool locations and the flow control cabinets and to provide
means for monitoring and controlling the units at a central location. The
problem is how to do this without excessive cost.
Another problem with prior systems and methods has been caused by the need
to re-calibrate transducers in the gas flow control cabinets at periodic
intervals. For example, it has been customary to zero-calibrate pressure
transducers once every three to six months or so. The process used in the
past often has required up to a full day of labor by one worker for each
cabinet. This creates relatively high labor costs and shuts the control
unit down for a substantial time during which it cannot be used for
production.
A further problem has been created by the expansion of the capabilities of
each of the gas flow control cabinets so that it can deliver gas to any
one or more of several different tool locations upon demand. This has
created problems in purging the gas lines of toxic gas for worker safety
during local maintenance of the flow control units. If the "flow-through"
process is used, where a purge gas such as nitrogen simply is pumped in
one direction through the delivery conduit, it must flow through the long
conduit from the cabinet to the tool. This is wasteful of expensive gas,
and wastes time. Furthermore, sometimes it is not possible to use the
flow-through process, in which case maintenance work on the long delivery
conduit can be hazardous. The problems, then, are how to achieve safe
local purging without incurring excessive costs, and how to purge the long
delivery conduit when flow-through purging is not available.
A similar problem in purging the conduits has been created by the addition
of means for delivering gas selectively from two different supply tanks
and switching back and forth between the two tanks.
Each of the gas flow control cabinets has an exhaust outlet which is
connected to an exhaust duct and from which air and gas from the inside of
the cabinet is exhausted at a relatively high flow rate in order to avoid
the accumulation of toxic gas in the cabinet due to leaks, etc. Flow
measurement means are provided to measure the flow rate of the exhaust
gas. If the flow rate falls below a pre-determined safe level, an alarm is
activated so that the low flow condition can be remedied. Usually, each
duct and fan is in place in the plant before the cabinet is installed. If
the diameter of the duct is not the same as that of the exhaust outlet,
the flow rate measurement will be erroneous. A tedious and expensive
firmware program adjustment then is required in order to avoid this source
of error. The labor cost and time to do this constitute another problem to
be solved.
A further problem in prior gas distribution systems is that sometimes it is
necessary to change the association between a tool location and the gas
distribution conduits. For example, it may become necessary to supply a
given tool with a different gas or mix of gases, and it may be necessary
or expedient to change the connection of different gas distribution
conduits to the tool. In the past, this has required re-wiring of the
electrical connections so that the tool is correctly connected to the
proper control unit or units corresponding to the new gas conduit
connections. The inventors have recognized that the re-wiring requirement
is costly and time-consuming; it increases equipment down-time and reduces
productivity.
OBJECTS OF THE INVENTION
In accordance with the foregoing, it is an object of the present invention
to provide a process gas distribution system and method which overcome or
greatly alleviate the foregoing problems.
In particular, it is an object of the invention to provide such a system
and method with simple centralized monitoring and control of a number of
widely-spaced gas flow control cabinets and connection of the cabinets to
the tools, but without excessive installation, modification and equipment
costs. It is an object to provide such a system and method in which each
cabinet also is "smart" and can be used for automatic control of gas
delivery and other functions independently of one another and
independently of the central control computer.
It is another object of the invention to provide such a system and method
in which various transducers which convert process gas distribution
parameters into electrical signals can be re-calibrated very quickly and
at a relatively low cost.
Another object of the invention is to provide means for automatically
purging gas flow lines in a multiple-distribution-leg gas distribution
control cabinet quickly and easily, without the cost of other purging
means.
It is a further object to provide for purging of the gas delivery conduits
from the cabinets to the tools when flow-through purging is not available.
A further object of the invention is to provide such a system and method in
which multiple gas sources are used alternatingly to provide a continuous
source of gas to the tool locations, and to provide rapid, efficient and
flexible purging of the gas flow lines used for that purpose.
A further object of the invention is to provide such a system and method in
which the error in the exhaust flow measurement caused by the use of an
exhaust duct of a different diameter from that of the cabinet exhaust
outlet can be corrected quickly and easily.
Still further, it is an object to provide such a system and method in which
the electrical communications between the tools and the flow control
cabinets can be changed to correspond to gas flow re-routing changes,
without the time and cost of re-wiring the communications connections.
SUMMARY OF THE INVENTION
In accordance with the present invention, the foregoing objects are met by
the provision of a process gas distribution system and method in which the
remote gas control units are connected sequentially to one another and by
a single communication cable to a tool interface controller, which also
receives signals from various tool locations and communicates them to the
respective cabinets.
A supervisory control computer, preferably a simple and relatively
inexpensive personal computer, communicates with the tool interface
controller to provide monitoring of the operations of the various cabinets
and to control the flow of gases to the tools. A separate data processor
is provided in each of the cabinets to control its functions independently
from the supervisory control computer. Preferably, direct control by use
of the data processor in the cabinet will override control from the
central supervisory control computer.
The cost of this system is further minimized by the use of the interface
unit to enable communications between the tools and the cabinets, instead
of separate cables connected from each tool to each of several cabinets,
as in some prior systems. The cable and installation costs thus are
reduced significantly.
Zero calibration is provided, advantageously, by automatically subjecting
each transducer to a reference standard having a known parameter value. A
computer routine is used to compute the difference between the ideal
output of the transducer and its actual output. That difference, called an
"offset", is stored in computer memory. Later, the offset is used to
correct each reading of the transducer. Advantageously, components of the
system which are used for other purposes also are used to provide a zero
reference for each of the transducers. By this means, re-calibration is
performed simply and quickly, at a relatively low labor cost and with
relatively little downtime.
In accordance with another feature of the invention, the multiple
distribution legs of each gas flow control unit, and the delivery conduits
to the tools, are purged by the alternating connection of an evacuation
source and a source of purge gas to the distribution legs, with a number
of such cycles being selectable, and the duration of each of such cycles
being selectable. This provides variable and adjustable cost-saving local
purging for the multiple distribution legs, and also provides purging of
the delivery conduits to the tools when flow-through purging is not
possible, thus providing improved safety.
Purging of toxic gas from conduits from plural selectable gas sources also
is provided by purge control means similar to that described above for the
distribution legs.
In accordance with another feature of the invention, the exhaust duct
diameter can be compensated for, if it is different from that of the
exhaust outlet from the cabinet, by storing different constants for
different outlet duct sizes, and utilizing a computer routine and the
stored constants to compute the flow rate. Thus, the measurement
corrections are made by means of a few simple keystrokes of the gas
cabinet controls.
Another advantageous feature of the invention is the provision of
programmable interface means for enabling the control of gas delivery
through selected gas distribution conduits. Preferably, communications
lines from the tool locations are terminated in a centrally located
interface unit. Each tool is identified by a number. The responsiveness of
each gas delivery leg to gas demand signals from a given tool is stored in
programmable memory, and the association between tool signals and gas
delivery legs is stored in computer memory means. A change of the
associations can be made by relatively simple software procedures for
changing the data stored in memory, thus avoiding expensive re-wiring.
Other objects and advantages of the invention will be set forth in or
apparent from the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a process gas distribution system
constructed in accordance with the present invention;
FIG. 2 is a schematic circuit diagram of a connection between the tool
interface controller and one of the tool locations shown in FIG. i;
FIG. 3 is a schematic circuit diagram of an alternative embodiment of the
system shown in FIG. 1;
FIG. 4 is a schematic circuit diagram of a portion of the system shown in
FIG. 1, showing in some detail the electrical components of the tool
interface controller and one of the gas flow control cabinets of FIG. 1;
FIG. 5 is a side-elevation view partially broken away of one of the gas
cabinets shown in FIG. 1, with the side panel removed to show the internal
components;
FIG. 6 is a front-elevation view of the cabinets shown in FIG. 5, with the
front doors open and part of the components broken away for the sake of
clarity. FIG. 6 is also partially schematic in showing the exhaust system
in the upper portion of the figure;
FIG. 7 is a front-elevation view of the control and display portion of the
gas cabinet shown in FIGS. 5 and 6;
FIG. 8 is a schematic gas flow control diagram showing the distribution of
gas by means of the gas cabinet of FIGS. 5 and 6;
FIGS. 9 and 10 are generalized flow diagrams for the computer programs used
for automatic zero calibration of transducers used in the gas flow control
units;
FIG. 11 is a flow diagram for a computer program used for zero calibration
of a weighing scale used to measure the contents of one of the gas bottles
in the cabinet of FIGS. 5 and 6;
FIG. 12 is a flow diagram of a computer program used to zero-calibrate the
gas pressure transducers in the distribution gas flow legs of the cabinet
shown in FIGS. 5 and 6;
FIG. 13 is a flow diagram of a computer program used for zero calibration
of the transducers in the gas flow lines leading from the gas bottles in
the gas cabinet of FIGS. 5 and 6;
FIG. 14 is a schematic diagram of a data packet used in communications
between the cabinets and the tool interface controller of FIG. 1; and
FIG. 15 is an enlarged view of the control panel and display shown in FIG.
7, and
FIGS. 16-25 are displays which appear on the display screen of the
supervisory control computer of the system shown in FIG. 1.
GENERAL DESCRIPTION
FIG. 1 shows a process gas distribution system 20 as it is used in a
semi-conductor manufacturing plant. The semiconductors are manufactured
using equipment such as diffusion ovens, etc. at various different
locations in the plant, each of which is referred to as a "tool" location.
Located in one or more locations remote from the tool locations are a
plurality of gas flow control units 22, 24, 26, 28, etc. which are used to
store process gases, which often are highly toxic, and to control the
distribution of those gases to the various tool locations. Each of the
cabinets is "smart"; that is, it contains its own CPU, memory, and other
digital and analog interface circuitry, together with its own control
panel, to enable it to operate alone, without a remote computer. Each
cabinet can be operated separately and independently of every other
cabinet, and independently of other equipment in the system. The circuitry
of each cabinet is described in some detail below, and in the
aforementioned pending U.S. Pat. No. 4,989,160. The disclosure of that
patent application hereby is incorporated herein so as to avoid
unnecessary duplication of the detailed description given therein.
The control circuitry of each cabinet 22, 24, etc. is connected to the next
cabinet by means of a plug-connectable shielded communications cable 30.
Each cable 30 is connected to its neighbor and to the circuitry of one
cabinets through a plug receptacle 31, 33, 35, 37, etc. All of the
cabinets are connected in the same manner so that the cabinets are
connected together sequentially in "daisy-chain" fashion. They are
connected through a plug receptacle and a communications cable link 40 to
a tool interface controller 42.
Tool interface controller 42 is connected by a communications cable 53 to a
supervisory control computer 44 which includes a keyboard 46, a disk drive
48, and a video display screen 50, and has a printer 51 connected to it.
Advantageously, the supervisory control computer is a relatively
inexpensive personal computer such as the IBM PS/2, model 80.
Advantageously, the tool interface controller is connected by the shielded
cable 40 to the first cabinet 22 ("cabinet 1"), which is then connected in
sequence to cabinets 2, 3 and 4 and as many other cabinets as there are in
the system, up to 120 units, as the system presently is configured. Of
course, larger or smaller numbers of cabinets can be incorporated in the
system. For this reason, the number of the last cabinet in the sequence is
cabinet "n".
Additional cabinets can be added into the system simply by plugging in a
new cabinet to its nearest neighbor, and re-configuring the system in
software. Re-wiring is not needed.
The tool interface controller is adapted to sequentially poll each of the
cabinets to send and receive messages to and from each of the cabinets so
as to enable monitoring of the cabinet operation at the supervisory
control computer 44 and control of the functions of the cabinets from that
computer. By the use of this polling technique, the necessity of using
separate cables from each of the cabinets to the interface controller 42
is avoided, and a significant cost saving is achieved. Furthermore, since
only a relatively low baud rate is used in the communications signal
transmissions, the cable can be relatively inexpensive shielded cable
rather than the more expensive cable which otherwise might be required.
In accordance with one of the advantageous features of the invention,
signals are conducted between the controller 42 and the tools on lines 52,
54, 56, 58 etc. The number of tools which can be connected is relatively
large--e.g., up to 120 tools in a system which has been built and
successfully tested. Larger numbers are possible.
Turning now to FIG. 2, one of the lines 52 actually is shown to have six
separate conductors connected at the controller end to a terminal block
55, and at the tool end to a terminal block 57.
When an operator at a tool location desires to start the flow of process
gas to the tool, the operator closes a switch 60 and momentarily closes a
gas reset switch 68 to initiate the flow of gas from an appropriate one of
the gas cabinets. 24 volts DC is sent from terminal 61 at the tool
location to terminal 59 at the controller location over line 76 to enable
switches 77 and 78 to operate. Switch 77 closes and lights an indicator
lamp 72 at the tool when gas is flowing.
Switch 78 closes to energize an indicator lamp 74 at the tool location to
indicate when a purge is in process.
The "ready for gas" and "gas reset" signals sent over terminals 62, 63, 64,
65, and 70 and 71, are delivered by the tool interface controller 42 to
the appropriate gas cabinet to cause the opening of various valves to
start the gas flow. When the gas flow is to be shut off, the switch 60 is
opened, and the controller 42 sends a signal to the gas cabinet and causes
it to shut off the gas flow.
ALTERNATIVE TOOL COMMUNICATION
FIG. 3 shows an alternative arrangement for communication with each of the
tool locations. Instead of a separate six-conductor cable connected from
each of the tool locations to the controller 42, a single communications
cable 80, like the cable 40, is connected to the controller, and a
separate tool termination unit 92, 94, 96, 98, etc. is located at each of
the tool locations. Each unit 92, 94, etc. contains its own memory and
CPU, such as that provided by a microprocessor, together with programming
sufficient to enable it to communicate with the controller 42 in response
to polling.
Each of the tool termination units is connected to its neighbor by means of
a plug-in connector 39, 41, 43 and 45, etc., through cables 84, 86, 88,
90, etc. and cable section 82 in "daisy-chain" fashion, in the same way
that the cabinets 22, 24 etc. are connected together, and all are
connected to the interface controller. By this means, a great deal of
wiring, labor and materials cost is saved.
Each of the embodiments shown in FIGS. 1-3 gives considerable savings of
installation and wiring costs, as well as further savings of re-wiring
costs when the tools are later connected to receive gas from different
cabinets. For example, in one typical prior system, if four different
gases are delivered to a single tool, each from a separate cabinet, four
different cables are used to connect the tool electrically directly to the
four cabinets. With the embodiment of FIGS. 1-2, only one cable from each
tool to the TIC is used, and in the FIG. 3 embodiment, only one cable is
used for all tools.
Further saving are gained by both embodiments in avoiding the cost of
re-wiring the tools to the cabinets when the association of a tool with
the cabinets is changed.
CABINET CIRCUITRY AND CONTROLLER DETAILS
FIG. 4 is a schematic circuit diagram of the control circuit 300 for a
single gas flow control unit or cabinet, and shows some of the details of
the controller 42. The controller 42 communicates with the gas cabinets
and the supervisory computer 44 through a standard communications board
320.
The controller 42 is the sole connection between the tool locations and the
gas flow control cabinets. Therefore, it is important that it be as
fail-safe as possible. To this end, a certain amount of redundancy is
provided. Instead of one, there are two CPUs; a first CPU 322 and a second
CPU 324, each of which has a random-access memory ("RAM") 323 or 325.
An arbitrator circuit 326 is provided to determine when one of the CPUs is
not operating and automatically switch in the other CPU. Alarms 328 are
provided to indicate if either or both of the CPUs is inoperative; to
indicate if the arbitrator circuit 326 is inoperative; to indicate whether
power is not being supplied to the controller; to determine whether the
communication link 40 is not operating, etc., all in order to maximize
chances that the terminal controller is operating at substantially all
times, or that an alarm will call attention to any problems so they can be
corrected quickly. The construction and operation of the arbitrator
circuit and its control of the CPUs is conventional and will not be
described further herein.
The controller 42 also has several interface terminal units ("ITU") 327,
329, 331, etc, to which the tool cables 52, 54, 56, 58, etc. are
connected. The number of ITU's used depends on the number of tools in the
system. Each tool and its cable is identified by the simple expedient of
connecting it to a single terminal in one of the ITUs, and giving each
terminal (and thus, each tool) an identifying number. Each ITU comprises a
circuit board with six connection terminals, each terminal connected to a
specific tool.
The ITU arrangement is modular. The number of ITU units can be changed
easily to accommodate a greater or lesser number of tools in a system.
As it will be described below in greater detail, when the start or stop of
gas flow is requested by signals from the tool location, the interface
controller broadcasts the signals to the gas flow control cabinets, and
each cabinet which controls gas conduits connected to the tool recognizes
the tool number and starts or stops the flow of gas to the tool.
In the embodiment of the invention shown in FIG. 3, each tool is identified
by a uniquely coded signal which is transmitted to the tool interface
controller 42 periodically, by polling, along with gas flow start and stop
signals, and is broadcast to the cabinets.
The cabinet control circuit 300 shown in the upper left-hand portion of
FIG. 4 includes an analog input circuit 302, which receives analog inputs
on lines 304 from various transducers and other sources and amplifies
those signals and converts them from analog to digital signals. It
delivers the digital signals over a bus 318 to a CPU 306 which has a
memory 308. The memory 308 contains both volatile RAM storage chips, as
well as electrically erasable programmable read-only memory ("EEPROM").
The identity of the signal supplied on each analog input line 304 is marked
to the left of the line. Those markings are shown in FIGS. 6 and 8 to
indicate their source.
Also provided in the circuit 300 is a digital input/output unit 314 which
receives digital signals and transmits them over a bus 316 to the CPU 306.
The operator panel 138 which is shown in FIGS. 7 and 15, and the display
panels 310 also receive signals over the bus 316 to display the various
warning lights and indicators to be described below.
A set of DIP switches 307 is provided to set a code number to uniquely
identify the cabinet to the rest of the system.
Further description of this circuitry and its operation will be given
below.
CABINET CONSTRUCTION
FIGS. 5 and 6, show the construction of one of the cabinets 22. The cabinet
22 includes a rear wall 106, a bottom wall 112, and front doors 108 and
110. FIG. 5 is a left-side elevation view, with the front doors 108 and
110 open and the side-panel of the cabinet removed to show the inside
components, with some of the components broken away.
The cabinet 22 includes a control housing 92 with a display panel 94 having
a handle 96 for opening it. As it is shown in FIG. 5, the panel 94 is
angled downwardly so as to be readily viewable by an operator standing in
front of the unit.
The cabinet 22 has an upwardly-sloping upper wall 98 (FIG. 6) which ends in
a centrally-located exhaust outlet conduit 100. Connected to the exhaust
outlet is an exhaust duct 102 whose diameter "d" is less than the diameter
of the exhaust conduit 100.
An exhaust fan 104, shown in FIG. 6 normally is located on the roof of the
building in which the gas distribution system is located. It connects with
the conduit 102, as indicated at 136, to exhaust air and other gases from
the interior of the cabinet 122 to the atmosphere, where they can do no
harm. Thus, the exhaust fan minimizes danger to operating personnel by
removing process gases which might accumulate in the cabinet.
The cabinet 22 also includes a shelf 120 (FIG. 6) supporting a scale 118
and a cylinder 116 of process gas. A second cylinder 114 of process gas
rests on a second scale 107 resting on the floor 112 of the cabinet. The
scales 107 and 118 contain transducers which convert the weight of the gas
bottles into analog signals which are among the analog inputs to the
control cabinet circuitry shown in FIG. 4, labeled "SCALE A" and "SCALE
B". The weight of the gas cylinders indicates the amount of gas left in
them.
Gas is distributed from either bottle 114 or 116, as needed, so as to
ensure an uninterrupted supply of process gas.
Various gas flow lines in the cabinet 22 include sections 126 and 128 which
form a "cylinder manifold" 136 (FIG. 8) which conducts gas from the bottle
114 or 116 to a "cross-over" manifold 124 (FIGS. 6 and 8) which changes
the bottle from which gas is supplied.
A gas distribution conduit system, called a "distribution manifold" is
shown at 134 (also see FIG. 8). It includes four vertically aligned
distribution "legs", which will be described in greater detail below, to
distribute gas to 1, 2, 3 or 4 different tool locations simultaneously.
Also shown in FIG. 6 is an inlet 130 through Which nitrogen from a "house"
supply of nitrogen is supplied to the cabinet. An inlet 132 is provided
for bottled nitrogen from a local supply.
At the top of FIG. 6, inside the duct 102, a pitot tube transducer 105 is
mounted. The transducer 105 is used to measure the velocity of exhaust gas
flow through the conduit for purposes of determining whether the exhaust
flow is above predetermined safe level. The output of transducer 105 is
labeled "EXHAUST" in FIGS. 4 and 6, and is one of the analog inputs to the
data processing system of the cabinet.
GAS DISTRIBUTION SYSTEM IN CABINETS
FIG. 7 is an enlarged View of the front panel 94 of the cabinet 22.
Displayed on the panel is an operator panel 138, and schematic diagrams of
the distribution manifold 134 and the cylinder manifold 136.
FIG. 8 is a schematic diagram showing the piping and other flow control
elements in a single one of the gas flow control cabinets. FIG. 8 is an
enlarged reproduction of the two diagrams 134 and 136 which appear on the
panel 94 of FIG. 7, except that the two diagrams have been joined together
and modified, for the sake of clarity.
The distribution system shown in FIG. 8 consists of the three sections
shown in FIGS. 5 and 6; the distribution manifold 134, the cylinder
manifold 136 and the cross-over manifold 124.
In the diagram heavy lines indicate process gas distribution lines, whereas
lighter lines indicate purge gas lines which are used only during purge
and maintenance operations.
The cylinder manifold 136 consists of two halves, an "A" section 126 and a
"B" section 128. The "A" section on the left side includes equipment for
delivering process gas from a first source or cylinder A (cylinder 114 in
FIGS. 5 and 6), and a right half, which is a mirror image of the left
half, for delivering process gas from a second source "B" (cylinder 116 in
FIG. 6).
The distribution manifold 134 includes four distribution "legs" 158 and
160, 162 and 164 ("A", "B", "C" and "D") each of which delivers process
gas to a remote tool location 140, 142, 144 or 146, respectively.
The cross-over manifold 124 consists of a pair of valves "XA" and "XB",
which are connected to a common conduit 55 which distributes gas from
either source A or source B to any one or any combination of the four
distribution legs.
In general, all of the valves shown in FIG. 8 are pneumatically operated
with the exception of hand-operated valves 157, 159, 161 and 163 shown at
the top of FIG. 8. Circles made with heavy lines are located in FIG. 8
next to various valves and are designated by the letter "G". Green LED's
are located behind the transparent or translucent panel material in the
circles. When the valve is open, the LED is on. Thus, each of these
circles glows green to indicate when the valve next to it is open.
Other heavy circles marked with the letter "Y" glow yellow when a
predetermined condition exists. Those in the distribution manifold marked
"RFG A", "RFG B" etc. indicate when either leg A, B, C or D (158, 160, 162
or 164) is Ready For Gas; that is, ready for the delivery of process gas.
In the cylinder manifold 136, yellow indicator circles labeled "Change A"
and "Change B" indicate when either gas cylinder A or gas cylinder B is
empty and should be changed.
The smaller circles formed with lighter lines in FIG. 8 are gas pressure
transducers.
The delivery of gas from source A to Tool 1, for example, is accomplished
by the opening of valves A1, A2 and A7 in the cylinder manifold 136, valve
XA in the cross-over manifold 124; and the opening of valves Al, A7 and
157 in the distribution leg 158 in the distribution manifold 134. It
should be understood of course, that the delivery line between the end of
a distribution leg and the tool to which it is connected can be relatively
long; that is, the cabinet 22 often is up to several hundred feet from the
tool location.
If process gas is to be delivered to Tool 2, the foregoing procedure is
altered by opening valves B1, B7 and 159 in the distribution manifold.
Similarly, process gas will be delivered to Tool 3 by opening valves C1,
C7 and 161, and to Tool 4 by opening valves D1, D7 and 163 are opened.
If it is desired to | | |
