U.S. patent application number 09/765665 was filed with the patent office on 2001-08-16 for apparatus and method for feeding gases for use in semiconductor manufacturing.
Invention is credited to Ikeda, Nobukazu, Kitayama, Hirofumi, Kurono, Yoichi, Masuda, Naoya.
Application Number | 20010013363 09/765665 |
Document ID | / |
Family ID | 23140759 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013363 |
Kind Code |
A1 |
Kitayama, Hirofumi ; et
al. |
August 16, 2001 |
Apparatus and method for feeding gases for use in semiconductor
manufacturing
Abstract
An apparatus for feeding gases for use in semiconductor
manufacturing reduced in size and manufacturing costs and
facilitating maintenance and operation of the gas supply system.
The apparatus comprises a plurality of gas supply sources, gas
source valves provided on the gas lead-out pipes from the
respective gas supply sources, flow rate controllers provided on
main gas feed pipes into which the lead-out pipes converge, and gas
supply valves provided on the outlet side of the flow rate
controllers.
Inventors: |
Kitayama, Hirofumi;
(Kanagawa-ken, JP) ; Kurono, Yoichi; (Beverly,
MA) ; Ikeda, Nobukazu; (Osaka, JP) ; Masuda,
Naoya; (Osaka, JP) |
Correspondence
Address: |
Joerg-Uwe Szipl
Griffin & Szipl, P.C.
Suite PH-1
2300 Ninth Street, South
Arlington
VA
22204-2320
US
|
Family ID: |
23140759 |
Appl. No.: |
09/765665 |
Filed: |
January 22, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09765665 |
Jan 22, 2001 |
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09296136 |
Apr 22, 1999 |
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6210482 |
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Current U.S.
Class: |
137/7 ;
137/605 |
Current CPC
Class: |
C23C 16/455 20130101;
Y10T 137/87314 20150401; Y10T 137/87692 20150401; Y10T 137/86389
20150401; G05D 7/0641 20130101; C23C 16/44 20130101; Y10T 137/0318
20150401; Y10T 137/87676 20150401; Y10T 137/0352 20150401; F17D
1/04 20130101; C23C 16/45561 20130101; H01L 21/67017 20130101 |
Class at
Publication: |
137/7 ;
137/605 |
International
Class: |
F17D 003/00; F17D
001/04 |
Claims
What is claimed is:
1. An apparatus for feeding gases for use in semiconductor
manufacturing facilities comprising a plurality of gas supply
sources, gas source valves provided on gas lead-out pipes from said
respective gas supply sources, a flow rate controller provided on a
main gas feed pipe into which the lead-out pipes converge, and a
gas feed valve provided on an outlet side of the flow rate
controller.
2. An apparatus for feeding gases for use in semiconductor
manufacturing facilities comprising a plurality of gas feeders
arranged in parallel, each gas feeder to supply different gases
needed, each said gas feeder having a plurality of gas supply
sources, gas source valves provided on gas lead-out pipes from said
respective gas supply sources, a flow rate controller provided on a
main gas feed pipe into which said lead-out pipes are converged and
a gas feed valve provided on an outlet side of the flow rate
controller.
3. An apparatus for feeding gases for use in semiconductor
manufacturing facilities comprising a gas supply source, a flow
rate controller provided on a supply pipe from said gas supply
source, and a plurality of gas feed valves provided on an outlet
side of said flow rate controller in the shape of parallel
branches.
4. An apparatus for feeding gases for use in semiconductor
manufacturing facilities comprising a plurality of gas feeders
arranged in parallel, each gas feeder to supply a different gas
needed, each said gas feeder comprising a gas supply source, a flow
rate controller provided on a supply pipe from said gas supply
source, and a plurality of gas feed valves provided on an outlet
side of said flow rate controller in the shape of parallel
branches.
5. An apparatus for feeding gases for use in semiconductor
manufacturing facilities as defined in one of claims 1, 2, 3, and
4, wherein the flow rate controller is a mass flow controller.
6. An apparatus for feeding gases for use in semiconductor
manufacturing facilities as defined in one of claims 1, 2, 3, and
4, wherein the flow rate controller is a pressure-type flow
controller.
7. An apparatus for feeding gases for use in semiconductor
manufacturing facilities as defined in claim 6, wherein the
pressure-type flow control system comprises: a control valve
provided on the main gas feed pipe, a pressure detector provided on
a downstream side of the control valve, a plurality of orifices
provided on the downstream side of the pressure detector in
parallel, a flow rate calculation circuit for calculating the flow
rate Qc given by the equation Qc=KP1 from the pressure P1 found by
said pressure detector and the constant K, a flow rate setting
circuit for outputting a flow setting signal, and a calculation
control circuit for outputting to a drive of the control valve a
control signal comprising the difference between said calculation
flow rate and the flow rate setting signal, wherein the control
valve is operable to bring the control signal to zero, thereby to
control the flow rates on the downstream sides of orifices 2a, 2b .
. . and at the same time to select the orifice with the bore that
matches the gas flow rate out of said orifices 2a, 2b . . . and to
actuate the orifice so selected.
8. An apparatus for feeding gases for use in semiconductor
manufacturing facilities as defined in claim 6, wherein the
pressure-type flow control system is configured so that one or a
plurality of orifices are provided in the shape of branches on the
downstream side of the gas feed valve.
9. An apparatus for feeding gases for use in semiconductor
manufacturing facilities as defined in claim 8, configured so that
one or a plurality of orifices are provided in the shape of
branches at the inlet of or inside of the treatment reactor forming
a semiconductor manufacturing facilities.
10. A method for feeding gases for use in semiconductor
manufacturing facilities, which comprises providing a single flow
rate controller unit for gas supply in each semiconductor
manufacturing process or in a group of common steps in the
processes and supplying a single type or a plurality of types of
gases needed one after another by switching at specific time
intervals to each process or each group of common steps by
regulating the flow rate by said flow rate controller.
11. A method for feeding gases for use in semiconductor
manufacturing facilities as defined in claim 10, which comprises
supplying a single type or a plurality of types of gases needed
simultaneously to a treatment reactor unit from a plurality of feed
ports.
12. A method for feeding gases for use in semiconductor
manufacturing facilities as defined in one of claims 10 and 11,
which comprises working out the flow rate controller is a mass flow
controller and wherein the flow rate control characteristics for
each type of gas to supply and each flow rate in data form, storing
said data in the storage of a control computer in advance,
retrieving the flow rate characteristics matching with the type and
flow rate of a gas to be switched over to from said storage at the
time of switching, and controlling the flow rate on the basis of
said flow rate characteristics.
13. A method for feeding gases for use in semiconductor
manufacturing facilities are defined in one of claims 10 and 11
wherein the flow rate controller is a pressure-type flow
controller, which comprises working out and storing in advance the
flow factor against a reference gas for each of the gases to be
supplied, and adjusting the flow rate specifying signal Qs for the
gas to be switched over to kQe, that is, Qs=kQe where Qe is the set
flow rate signal against the reference gas and k is the flow rate
conversion rate, when the type of gas is changed.
14. A method for feeding gases for use in semiconductor
manufacturing facilities as defined in one of claims 10 and 11
wherein the flow rate controller is a pressure-type flow control
system, which comprises providing the pressure-type flow control
system with a plurality of orifices with different bores in
parallel and selectively actuating said orifices according to the
flow rate of the gas to which the system is to be switched over and
with which the system is to be supplied.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to improved apparatuses and
methods for feeding gases. More specifically, in one embodiment
this invention relates to feeding or supplying a plurality of
different types of gases one after another through a single gas
feed pipe by switching the gas type from one to another at specific
time intervals. In another embodiment, this invention relates to
feeding or supplying a single type of gas through one or a
plurality of pipes or any combination of pipes in any sequence of
switching pipes. With the flow rates controlled by means of a
single flow rate controller in semiconductor manufacturing
facilities, this offers such advantages as reduction in the size
and manufacturing costs of the gas feeder.
BACKGROUND OF THE INVENTION
[0002] In semiconductor manufacturing, many types of gases are used
in different ways. For example, a number of different types of
gases are drawn, not all at once but one after another in a series
fashion by switching the gas type from one to another at specific
time intervals. Also, one and the same type of gas is often used at
different flow rates simultaneously or in parallel. In those
applications, the flow rates must be controlled with high
accuracy.
[0003] In prior art gas feeding apparatuses for use in
semiconductor manufacturing, flow rate controllers such as mass
flow rate controllers are installed, one on each gas line, to
control the flow rate with high accuracy.
[0004] In etching, one of the important processes in semiconductor
manufacturing, for example, a plurality of insulating films are
etched. This process is made up of a number of etching steps. In
each step, 3 or 4 types of gases are used in combination. To supply
those gases, prior art gas feeders require a total of more than 10
gas and flow rate controllers in the etching process alone. A vast
number of such controllers have to be installed to serve an entire
semiconductor manufacturing plant.
[0005] In the Chemical Vapor Deposition (CVD) process, a type of
gas is supplied to a treatment reactor at one or different flow
rates through a plurality of outlets simultaneously to carry out a
CVD treatment. The prior art gas feeder has a flow rate controller
installed at every outlet line to regulate the flow rates. Here,
also, too many flow rate controllers are needed. To a single
treatment reactor for the CVD process, in addition, a plurality of
types of gases may also be supplied in a series fashion. That
likewise requires quite a number of flow rate controllers.
[0006] Heretofore, mass flow rate controllers had been the primary
flow rate controllers used. In recent years, so-called
pressure-type flow control systems have become more common.
[0007] The installation of a large number of flow rate controllers
not only increases the size of the gas feeder but also makes it
difficult to keep down the costs both of the feeder itself and of
facility maintenance and service costs. This also presents such
problems as increased labor in maintenance and the necessity of
keeping many replacement and spare parts in stock, which inevitable
raises the running costs of the gas feeder.
[0008] The present invention addresses those problems encountered
with the prior art apparatus and method for feeding gases in
semiconductor manufacturing plants, that is, the necessity of
installing too many flow rate controllers, one for each outlet
line, which has prohibited size reduction of the gas feeding
equipment and reduction of the costs of the equipment itself.
SUMMARY OF THE INVENTION
[0009] It is accordingly a primary object of the present invention
to provide an apparatus and method for feeding gases for use in
semiconductor manufacturing.
[0010] This novel apparatus and method, by means of only a few flow
rate controller units, controls many different types of gases or
different flow rates of the same gas in semiconductor manufacturing
with high accuracy. Moreover, the novel apparatus and method
permits a reduction in the size of the gas feeder itself and a
substantial reduction in the manufacturing costs of the
equipment.
[0011] The object of the invention is achieved by installing a
single flow rate controller in a single process consisting of a
number of steps or a group of common steps in the respective
processes, thereby controlling the gas flow rates so as to supply
one and the same type of gas or a plurality of different types of
gases to each process or step one after another, by switching the
gas flow path or gas type from one to another at specific time
intervals, and also by making arrangements so that many different
types of gases or significantly different flow rates of one and the
same gas are dealt with or controlled with high accuracy and
supplied through one or a plurality of feed ports.
[0012] In each semiconductor manufacturing process or in steps in
the process, many different types of gases are used. They are
generally used, however, not all at a time but one after another or
in a series fashion. That is, the flow of gases to a process is
switched from one type of gas to another type of gas at specific
time intervals. Even a single flow rate controller can control
different flow rates of one type of gas or the flow of a plurality
of gases with high accuracy, if the flow characteristics can be
automatically switched and compensated or switched and adjusted to
cope with the change in gas type or flow rate.
[0013] The apparatus for feeding gases for use in semiconductor
manufacturing as defined in one embodiment is basically constituted
of a plurality of gas supply sources, gas source valves provided on
the respective lead-out pipes, a flow rate controller provided on
the main gas feed pipe into which the lead-out pipes converge, and
a gas feed valve mounted on the outlet side of the flow rate
controller. Preferredly, a plurality of units of this apparatus for
feeding gas are arranged in parallel and each gas feeder supplies
different types of gases as needed to the semiconductor
manufacturing facilities.
[0014] The apparatus for feeding gases for use in semiconductor
manufacturing in another embodiment is basically constituted of a
unit of gas supply source, a flow rate controller installed on the
main gas feed pipe from the gas supply source, and a plurality of
gas feed valves provided on the outlet side of the flow rate
controller in the shape of a plurality of parallel branches.
Preferredly, a plurality of units of this apparatus too for feeding
gas are arranged in parallel and each gas feeder supplies different
types of gases as needed to the semiconductor manufacturing
facilities.
[0015] In both of the above embodiments of the invention, the flow
rate controller may be either a mass flow controller or a
pressure-type controller.
[0016] When a pressure-type controller is used in this invention,
the pressure-type flow control system may comprise a control valve
CV provided on the main gas feed pipe, a pressure detector 14
provided on the downstream side from the control valve CV, a
plurality of orifices 2a, 2b, . . . provided in parallel on the
downstream side from the pressure detector 14, a flow rate
calculation circuit 20 for calculating the flow rate Qc=KP1 (where
K is a constant) from the pressure P1 detected at the pressure
detector 14, a flow rate setting circuit 32 for outputting a flow
rate setting signal Qs, and a calculation control circuit 38 for
outputting the difference between the calculation flow rate signal
Qc and the flow rate setting signal Qs as control signal Qy to the
drive 8 of the control valve CV. The control valve CV is operated
to bring the control signal Qy to zero, thereby controlling the
flow rates on the downstream side from the orifices 2a, 2b . . .
and at the same time selecting the orifice with the bore matching
with the gas flow rate out of the plurality of orifice 2a, 2b . . .
and actuating the same.
[0017] In the above-described apparatuses, the pressure-type flow
control system may be configured so that one or a plurality of
orifices are provided in the shape of branches and installed on the
downstream side from the gas feed valve. In this case, a plurality
of units of the orifice may be provided in the shape of branches at
the inlet of or inside of the treatment reactor on the downstream
side from the gas feed valve.
[0018] Still another embodiment of the present invention is a
method for feeding gases for use in semiconductor manufacturing,
which method comprises providing a single flow rate controller for
gas supply in each semiconductor manufacturing process or in a
group of common steps in the processes and wherein, with the flow
rates regulated by the flow rate controller, one type or plurality
of types of gases are switched and supplied one after another to
each process or each common step group at specific time intervals.
In carrying out this method, a single type or a plurality of types
of gases may be supplied to a single treatment reactor from a
plurality of feed ports. Further, in implementing this method, one
may work out in advance the flow rate control characteristics of
the mass flow controller in the form of data for each type of gas
to be supplied and each flow rate, store those data in a storage of
a control computer, retrieve the flow rate characteristics matching
for the type of gas or flow rate to be switched over to from the
computer storage when the gas type or flow rate is switched, and
regulate the flow rate of gas according to the flow rate
characteristics.
[0019] In accordance with the method of the present invention in
which the flow rate controller is of the pressure-type, one may
work out in advance the flow factor FF in relation to a reference
gas (e.g., nitrogen gas) for each type of gas to be supplied and,
when the gas type is switched, bring the flow rate specifying
signal Qs after the switching to kQe, that is Qs=kQe in which Qe is
the flow rate setting signal for the reference gas and k is the
flow rate conversion rate.
[0020] When the flow rate controller herein is of the
pressure-type, it may be provided with a plurality of orifices with
different bores in parallel and those orifices may be selectively
activated according to the flow rate of the gas to be switched over
to.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic flow diagram of the configuration of
an apparatus for feeding gases for use in semiconductor
manufacturing of a first embodiment of the present invention, with
part of the apparatus omitted.
[0022] FIG. 2 is a schematic flow diagram of the configuration of
an apparatus for feeding gases for use in semiconductor
manufacturing of a second embodiment of the present invention, with
part of the apparatus omitted.
[0023] FIG. 3 is a schematic flow diagram of the configuration of
an apparatus for feeding gases for use in semiconductor
manufacturing of a third embodiment of the present invention, with
part of the apparatus omitted.
[0024] FIG. 4 is a schematic flow diagram of the basic
configuration of the pressure-type flow control system used in the
present invention.
[0025] FIG. 5 is a schematic flow diagram of the basic
configuration of an apparatus for feeding gases of a fourth
embodiment of the present invention in which a pressure-type flow
control system is used.
[0026] FIG. 6 is a schematic flow diagram of the basic
configuration of a pressure-type flow control system in another
embodiment of the present invention.
[0027] FIG. 7 is a schematic flow diagram of the configuration of
an apparatus for feeding gases for use in semiconductor
manufacturing of a fifth embodiment of the present invention.
[0028] FIG. 8 is a schematic flow diagram of the configuration of
an apparatus for feeding gases for use in semiconductor
manufacturing of a sixth embodiment of the present invention.
[0029] FIG. 9 is a schematic flow diagram of the basic
configuration of the pressure-type flow control system used in an
another embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Now, various illustrative embodiments of the present
invention will be described with reference to the drawings.
EXAMPLE 1
[0031] FIG. 1 shows a first embodiment of the present invention. In
FIG. 1, RR is a treatment reactor forming part of semiconductor
manufacturing facilities and A1, A2, A3 are individual apparatuses
for feeding gases to the treatment reactor RR. That is, the gas
feeders A1, A2, and A3 supply the gases needed for treatment steps
B1, B2, and B3 to be carried out in the treatment reactor RR. For
example, when the treatment step B1 is to be carried out in the
treatment reactor RR, the gas feed valve V1 will be opened while
the feed valves V2 and V3 will be closed. Then gases G1, G2, G3,
and G4 are switched and supplied one after another to the treatment
reactor RR at specific time intervals.
[0032] In FIG. 1, G1, G2, G3, and G4 are different supply gas
sources, each for a different type gas: G1 for oxygen, G2 for
hydrogen, G3 for nitrogen, and G4 for SiH.sub.4, for example.
[0033] MFC is a mass flow controller forming a flow rate controller
FRC. VG1, VG2, VG3, and VG4 are gas source valves. L1, L2, L3, and
L4 are gas lead-out pipes. Lo is a main gas feed pipe. F1, F2, and
F3 are gas take-off ports. And V1, V2, and V3 are gas feed
valves.
[0034] The mass flow controller MFC making up the flow rate
controller FRC itself is already known and no detail will be
described. But it is noted that the mass flow controller MFR used
in the present invention has lots of prepared flow rate control
characteristic curves on every type of gas and every gas flow rate
stored in the storage of a control computer attached thereto. When
the type of gas or the flow rate is switched from one to another,
the flow rate control is automatically retrieved from the storage
in the computer (not shown). On the basis of the retrieved flow
rate control characteristics, the flow rate of the gas to be
switched over to is controlled with adjustment made to such
functions as linear riser in the mass flow controller MFC.
[0035] In the embodiment shown in FIG. 1, when the gas type or the
flow rate of gas is switched, the linear riser in the mass flow
controller MFC is so adjusted as to conform the flow rate
characteristics of the mass flow controller MFC to the flow rate
characteristics prepared in advance on every gas type. But another
procedure is also possible. It is this: The flow rate control
characteristic curves in the mass flow controller MFC are fixed on
only the gas types and the flow rates conforming to the standard.
For the gas types or flow rates outside the standard, their
conversion factors against the standard gases are worked out and
stored in advance so that when the gas type or the flow rate is
changed, an approximate control parameter corresponding to the
standard gas and the standard flow rate is calculated on the basis
of the measurements at that time and the conversion factors.
According to that approximate control parameter, the flow rate of
the non-standard gas is controlled.
[0036] In FIG. 1, three gas feeders A1, A2, and A3 are combined in
parallel to constitute a gas supply battery. In practice, a gas
supply battery is generally formed of three to ten gas feeders.
EXAMPLE 2
[0037] FIG. 2 shows a second embodiment of the present invention.
It is so configured that one gas supply source G1 supplies one and
the same type of gas at specific rates simultaneously to a
plurality of gas feed ports provided on the treatment reactor RR
through a flow rate controller FRC, a main gas feed pipe Lo and a
plurality of gas feed valves V1 to V4 on branch pipes. The feed
path may be switched from a specific port or ports to another at
specific time intervals, too.
[0038] In FIG. 2, three gas feeders A1, A2, and A3 are installed in
parallel. In practice, five to ten feeders are arranged in parallel
to form a battery of gas feeders as in FIG. 1.
EXAMPLE 3
[0039] FIG. 3 shows a third embodiment of the present invention. In
this embodiment, a pressure-type flow control system FCS is used as
flow rate controller FRC instead of the mass flow controller MFC
used in FIG. 1.
[0040] The gas feeder A in FIG. 3 is exactly the same as that in
FIG. 1 except that the flow rate controller FRC installed is a
pressure-type flow control system FCS, and not the mass flow
controller MFC, and so there will be no detailed description of the
gas feeder.
[0041] FIG. 4 is a schematic flow diagram of the configuration of
the pressure-type flow control system FCS which is used in the gas
feeders shown in FIG. 3.
[0042] In FIG. 4, if the ratio between the gas pressures before and
after an orifice 2, that is, the ratio of the downstream gas
pressure P2 to the upstream gas pressure P1, falls below the
critical gas pressure ration (in the case of air, nitrogen, etc.,
about 0.5), the flow velocity of the gas passing the orifice will
reach sonic velocity. As a result, the fluctuation in pressure on
the downstream side of the orifice 2 will be difficult to convey to
the upstream side, and that will bring about a stable mass flow
rate on the downstream side matching with the state on the upstream
side of the orifice 2.
[0043] That is, if, with a fixed bore of the orifice 2, the
upstream pressure P1 is set at about twice or more than twice the
downstream pressure P2, the downstream flow rate Qc of the gas
passing the orifice 2 will depend on only the upstream pressure P1
and the linear relationship Qc=KP1 will hold good to the highest
degree. If the bore of the orifice is fixed, the constant K will be
fixed.
[0044] The flow path 4 on the upstream side of the orifice 2 is
connected to a control valve CV which is operated by a drive 8,
while the flow path 6 on the downstream side is connected to the
treatment reactor (not shown) via an orifice-responding valve 10
and a gas take-off joint 12.
[0045] The pressure P1 on the upstream side of the orifice 2 is
detected by the pressure detector 14, and amplified by an
amplification circuit 16 and displayed on a pressure display 22.
The output is passed on to an analog-digital (A-D) converter to be
digitalized, from which the flow rate Q on the downstream side of
orifice, that is, Q-KP1 (K:constant) is calculated by a calculation
circuit 20.
[0046] On the other hand, the temperature T1 on the upstream side
is detected by a temperature detector 24 and output through an
amplification circuit 26 and an A-D converter 28 to a temperature
compensation circuit 30, where the flow rate Q is
temperature-compensated. The calculated flow rate Qc is output to a
comparison circuit 36. Here, the calculation circuit 20, the
temperature compensation circuit 30 and the comparison circuit 36
make up a calculation control circuit 38.
[0047] A flow rate setting circuit 32 outputs a flow rate Qs
through an A-D converter 34 to the comparison circuit 36. The
comparison circuit 36 calculates a difference signal Qy between the
calculated flow rate Qc and the set flow rate Qs, that is,
Qy=Qc-Qs, and outputs the result to the drive 8 through an
amplification circuit 40.
[0048] The drive 8 so operates the control valve CV as to bring the
difference signal Qy to zero so that the flow rate on the
downstream side of the orifice is equal to the set flow rate.
[0049] This pressure-type flow control system FCS is so designed
that the flow rate on the secondary side of the orifice 2 is
controlled through adjustment of the pressure P1 on the upstream
side thereof. That permits control of the flow rate on the
downstream side of the orifice 2 without being influenced by the
gas pressure on the upstream side of the control valve CV and gives
flow rate characteristics with a relatively high linearity.
[0050] For different types of gases or flow rates, the so-called
flow factors against the standard gases and standard flow rates are
prepared and stored. With that, the pressure-type flow control
system FCS can also exercise flow rate control on different types
of gases or flow rates with relative ease and high accuracy.
EXAMPLE 4
[0051] FIG. 5 shows a fourth embodiment of the present invention.
In this embodiment, a pressure-type flow control system FCS is used
as flow rate controller FRC and it is so configured that the
orifice 2, an component of the pressure-type flow control system,
is provided at the inlet of or inside of the treatment reactor RR
on the downstream side of the gas feed valve V1.
[0052] One orifice 2 or more may be provided at the inlet of or
inside of the treatment reactor RR, but two or more orifices would
be convenient, for that would permit adjustment to any flow rate of
the flow of gas to be discharged into the respective regions within
the treatment reactor RR.
[0053] Two or more orifice, each with a different bore, would make
it possible to control different flow rates of gas with one
pressure-type flow control system FCS.
[0054] FIG. 6 is a schematic flow diagram of the configuration of
the pressure-type flow control system FCS used in the fourth
embodiment of the present invention shown in FIG. 5. It is
different from the one in FIG. 4 in that the orifice 2 in FIG. 6 is
provided at the inlet of or inside of the treatment reactor RR on
the downstream side of the orifice-responding valve 10. In other
points, the controller FCS in FIG. 6 is identical with that in FIG.
4. In case the cross-sectional area of the treatment reactor is so
large as to require facilitation of the distribution of the flow
rate of the discharge gas, the pressure-type flow control system
FCS configured as FIGS. 4 and 6 is used as mentioned.
EXAMPLE 5
[0055] FIG. 7 shows a fifth embodiment of the present invention. In
this embodiment, a pressure-type flow control system FCS is used as
flow rate controller FRC and it is so configured that the gas type
is switched among G1, G2, G3, and G4 to supply each gas at a
different flow rate to the treatment reactor RR.
[0056] In FIG. 7, the same component parts as those in FIGS. 3 and
4 are indicated by the common reference numbers.
[0057] That is, 2a, 2b, 2c, and 2d in FIG. 7 are orifices. Those
four orifices are different in bore and ranked in that order with
2a being the largest and 2d the smallest. 10a,10b, 10c, and 10d are
orifice-responding valves. F1a, F1b, F1c, and F1d are gas take-off
ports. V1a to V1d are gas feed valves. While it is so configured in
FIG. 7 that orifices 2a, 2b, 2c, and 2d are different from each
other in bore, two or more of them, needless to say, may be
identical in bore.
[0058] In case a gas, nitrogen for example, is to be supplied from
a gas source array consisting of G1, G2, G3, and G4 to the
treatment reactor RR at a high flow rate, the gas flow rate is
controlled this way: the orifice-responding valve 10a and the gas
feed valve V1a are opened while the orifice-responding values 10b,
10c, and 10d and the gas feed valves V1b, V1c, and V1d are closed
to actuate the orifice 2a so as to bring the flow rate of the gas
supply to the set flow rate Qsa (maximum flow rate).
[0059] Similarly, when a gas, say, 02 is supplied from the gas
source array consisting of G1, G2, G3, and G4 to the treatment
reactor RR for the minimum flow rate of a gas at the minimum flow
rate, the orifice-responding valve 10d and the gas feed valve V1d
are opened while the orifice-responding values 10a, 10b, and 10c
and the gas feed valves V1a, V1b, and V1c are closed to actuate the
orifice 2d so as to bring the flow rate of the gas supply from the
02 source G4 to the set flow rate Qsd (minimum flow rate).
[0060] The set flow rates Qsa, Qsb, Qsc, and Qsd for the gases from
G1 to G4 are freely set according to the needs at the treatment
reactor RR. The full scale on the pressure-type flow control system
FCS is switched as by properly adjusting the amplification degree
of the output amplifier 16 for the pressure detector 14, for
example, according to the sizes of the set flow rate Qsa to
Qsd.
EXAMPLE 6
[0061] FIG. 8 shows a sixth embodiment of the present invention.
This embodiment is provided with four groups of gas sources, each
group consisting of four different type gas sources, for example,
G1 for hydrogen, G2 for oxygen, G3 for nitrogen and G4 for
SiH.sub.4 and is so configured that those gases are supplied to the
treatment reactor RR at different flow rates.
[0062] That is, in FIG. 8, four units of the gas feeder shown in
FIG. 6 which is provided with four different gas sources G1, G2,
G3, and G4 are arranged in parallel and are each equipped with
three orifices 2a, 2b, and 2c, each with a different bore, for
setting the flow rates.
[0063] As in FIG. 1, any two of the orifices 2a, 2b and 2c can be
identical in bore.
[0064] In the embodiment shown in FIG. 8, furthermore, it is
possible to supply to the treatment reactor RR different gases from
the different gas sources G1, G2, G3, and G4 simultaneously by
actuating all the pressure-type flow control systems FCS1, FCS2,
FCS3, and FCS4 or in a series fashion by repeating selection and
actuation of one or more from those flow control systems. Needless
to say, the respective pressure-type flow control systems FCS1,
FCS2, FCS3, and FCS4 select the orifice 2a, 2b, or 2c having the
bore which matches for the gas flow rate required.
[0065] The full scale on the pressure-type flow control systems
FCS1, FCS2, FCS3 and FCS4 can be freely switched according to the
selected orifice bore, that is, the gas flow rate just the same way
as in FIG. 3 and FIG. 7.
EXAMPLE 7
[0066] FIG. 9 shows a further embodiment of the pressure-type flow
control system used in the present invention. This embodiment is
the same as the pressure-type flow control system shown in FIG. 4
except that a flow rate conversion circuit 39 is provided between
the flow rate-setting circuit 32 and the comparison circuit 36.
[0067] The flow rate conversion circuit 39 is to make the full
scale flow rate variable.
[0068] In case the conversion rate k of the flow rate conversion
circuit 39 is 1, that is, the full scale flow rate is not switched
yet, the calculation circuit 20 calculates the flow rate Q from the
pressure signal P1 by the equation Q=KP1. At the same, the flow
rate Q is temperature-compensated by a compensation signal from the
temperature compensation circuit 30, and the calculated flow rate
Qc is output to the comparison circuit 36.
[0069] In case the conversion rate K in the flow rate conversion
circuit 39 is set at the constant K, the signal Qe is converted
into the flow rate specifying signal Qs (Qs=kQe) through the flow
rate conversion circuit 39, and this flow rate specifying signal Qs
is inputted in the calculation control circuit 38.
[0070] The constant K represents the flow rate conversion rate and
is provided to make the full scale flow rate variable. Therefore,
the flow rate conversion circuit 39 can vary the flow rate
conversion rate k continuously or in stages. For the variation in
stages, a dip switch, for example, can be used.
[0071] The flow rate conversion rate k set by the flow rate
conversion circuit 39 for nitrogen gas, helium gas, CF.sub.4 gas,
etc. is varied in stages and is related to the flow factor FF of
each gas which will be described later.
[0072] That is, the flow factor FF indicates how many times the
flow rate of nitrogen gas the flow rate of such working gases as
helium and CF.sub.4 represents with the same bore of the orifice 2
and the same pressure P1 on the upstream side. It can be defined as
FF=flow rate of working gas/that of nitrogen.
[0073] To be concrete, here are some examples of the factor FF:
N.sub.2=1, Ar=0.887, He=2.804, CF.sub.4=0.556,
C.sub.4F.sub.8=0.344.
[0074] If the orifice 2 in the pressure-type flow control system of
the present invention is 90 microns, for example, and the control
pressure, that is, P1 is 1.8 (kgf/cm2abs), the flow rate of
nitrogen gas is 125.9 SCCM according to the results of experiments.
This means that with the nitrogen gas, the full scale flow rate is
125.9 SCCM. This is set as 100% of the flow rate setting signal Qe
with the voltage at 5 V. Since the flow rate conversion rate k is
set at 1 (k=1) for nitrogen gas, the flow rate specifying signal Qs
is 100% with the full scale at 125.9 SCCM, because Qs=kQe.
[0075] Now, there will be considered the switching of supply gases
from nitrogen gas to helium gas with that orifice 2 and under the
pressure P1. Suppose that the flow rate of helium gas to supply is
300 SCCM, for example, the flow factor FF of helium is 300
SCCM/2.804=107.0 SCCM.
[0076] Meantime, since 125.9 of SCCM of nitrogen gas is the full
scale range in the present embodiment as mentioned earlier, the
flow rate conversion rate K for helium is set as follows: 107.0
SCCM/125.9 SCCM=0.850.
[0077] As a result, the flow rate specifying signal Qs is
Qs=0.850.times.Qe=0.850.times.300 SCCM, and the voltage is 5
B.times.0.850.
[0078] In the embodiment shown in FIG. 9, the flow factor FF of
each supply gas against the reference gas nitrogen is worked out
and stored, on the basis of which the flow rate conversion rate k
is calculated for the type and the flow rate of the supply gas to
be switched over to as mentioned. Setting the flow rate conversion
rate in the flow rate conversion circuit at the calculated value K
makes it possible to regulate the flow rate of the gas to be
switched over to at the set flow rate Qe to continue the flow of
gas.
[0079] In the embodiments shown in FIGS. 1 to 9, the mass flow
controller MFC or the pressure-type flow control system FCS is used
as flow rate controller FRC. The flow rate controller FRC is not
limited to those two types but may be of any configuration such as,
for example, the general-use flow rate controller made up of a
combination of valves, orifices and detection sensors to detect the
difference between the pressures before and after the orifice.
[0080] Also, the embodiments shown in FIGS. 4 to 9 are provided
with orifice-responding valves 10a to 10d and gas feed valves V1a
to V1c. But the orifice-responding valves 10a to 10d may be
omitted, and the orifices 2a to 2d, a pressure detector P or the
like may be properly incorporated in the valve bodies of the gas
feed valves V1a to V1d.
EFFECT OF THE INVENTION
[0081] The apparatuses or a method for feeding gases for use at
semiconductor manufacturing facilities as disclosed and claimed
herein are configured so that a plurality of types of gases are
grouped and the gases within the group are supplied through a flow
rate controller one after another to a semiconductor treatment
reactor, or so that one type of gas is controlled by a flow rate
controller and supplied through different flow paths either
simultaneously or in a series fashion. This is to be compared with
prior art gas feeders provided with a flow rate controller on every
gas line to the semiconductor manufacturing facility. Thus, the
present invention permits size reduction and cost reduction of the
gas feeder and besides substantially cuts down the maintenance
costs of the equipment.
[0082] The present invention can cope with a change of gas types
and major change in gas flow rate with one and the same flow rate
controller with relative ease and thus allow continuation of flow
rate control with high accuracy. Likewise, the present invention
can respond to not only a change of gas types but also to a major
change in gas flow rate very easily, and can maintain high accuracy
flow rate control even when there is a change of gas types and gas
flow rates.
[0083] This invention additionally permits free adjustment of the
distribution of the gas discharge flow rate within the treatment
reactor, and thus enables processing steps to proceed in a
semiconductor manufacturing facility with high accuracy.
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