U.S. patent application number 10/500406 was filed with the patent office on 2005-07-28 for apparatus for the generation and supply of fluorine gas.
Invention is credited to Ino, Minoru, Kennedy, Colin, Kimura, Takako, Sonobe, Jun.
Application Number | 20050161321 10/500406 |
Document ID | / |
Family ID | 19189170 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050161321 |
Kind Code |
A1 |
Kennedy, Colin ; et
al. |
July 28, 2005 |
Apparatus for the generation and supply of fluorine gas
Abstract
To provide an apparatus for fluorine gas generation and supply
that is disposed in the gas supply system of a semiconductor
processing system and that in the event of abnormalities in the
apparatus enables back up by a safe and inexpensive structure. An
apparatus 30 for the generation and supply of gas is disposed in
the gas supply system of a semiconductor processing system. This
apparatus 30 contains an electrolytic cell 34 that generates
fluorine gas and a cylinder 62 that holds a substitute gas selected
from the group consisting of nitrogen fluoride, sulfur fluoride,
and chlorine fluoride. The electrolytic cell 34 and cylinder 62 are
connected to a gas switching section 56 that selectively supplies a
gas utilization section with fluorine gas from the electrolytic
cell 34 or with substitute gas from the cylinder 62. A controller
40 controls the gas switching section 56 in such a manner that,
upon detection of an abnormal state at the electrolytic cell 34 by
an electrolytic cell detector 36, substitute gas is supplied from
the cylinder 62 to the gas utilization section.
Inventors: |
Kennedy, Colin; (Tokyo,
JP) ; Kimura, Takako; (Tsukuba-Shi, Ibaraki-Ken,
JP) ; Ino, Minoru; (Tsukuba-Shi, Ibaraki-Ken, JP)
; Sonobe, Jun; (Tsukuba-Shi, Ibaraki-Ken, JP) |
Correspondence
Address: |
AIR LIQUIDE
2700 POST OAK BOULEVARD, SUITE 1800
HOUSTON
TX
77056
US
|
Family ID: |
19189170 |
Appl. No.: |
10/500406 |
Filed: |
March 21, 2005 |
PCT Filed: |
December 20, 2002 |
PCT NO: |
PCT/EP02/14909 |
Current U.S.
Class: |
204/277 |
Current CPC
Class: |
C25B 1/245 20130101;
C23C 16/4405 20130101; C25B 15/00 20130101 |
Class at
Publication: |
204/277 |
International
Class: |
C25B 001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2001 |
JP |
2001/397278 |
Claims
1-10. (canceled)
11. An apparatus which may be used to generate and supply fluorine
gas to a semiconductor processing system, said apparatus
comprising: a) a fluorine gas generating means comprising: 1) an
electrolytic cell for the electrolysis of hydrogen fluoride to
produce said fluorine gas, said cell further comprising: i) an
electrolytic bath, said bath further comprising hydrogen
fluoride-containing molten salt; b) a gas storage means comprising
a substitute gas, said substitute gas comprising at least one
member selected from the group consisting of: 1) nitrogen fluoride;
2) sulfur fluoride; and 3) chlorine fluoride; c) a gas switching
section connected to said electrolytic cell and said gas storage
means wherein said switching section selectively supplies said
semiconductor processing system with either: 1) said fluorine gas;
or 2) said substitute gas from said gas storage means; d) an
electrolytic cell detector, wherein said detector detects the state
of said cell; and e) a controller, wherein said controller acts on
said switching section to feed said substitute gas to said
semiconductor processing system.
12. The apparatus of claim 11, wherein said detector measures the
operating condition of said bath.
13. The apparatus of claim 12, wherein said detector detects a
parameter representative of said condition, said parameter
comprising at least one member selected from the group consisting
of: a) electrical current characteristics; b) liquid level; and c)
temperature.
14. The apparatus of claim 11, further comprising a path detector,
wherein said path detector detects an abnormal state in the gas
supply path from said cell to said semiconductor processing
system.
15. The apparatus of claim 14, wherein upon detection of an
abnormal parameter by either said cell detector or said path
detector, said controller feeds said substitute gas to said
semiconductor processing system.
16. An apparatus which may be used to generate and supply fluorine
gas to a semiconductor processing system, said apparatus
comprising: a) a fluorine gas generating means comprising: 1) an
electrolytic cell for the electrolysis of hydrogen fluoride to
produce said fluorine gas, said cell further comprising: i) an
electrolytic bath, said bath further comprising hydrogen
fluoride-containing molten salt; b) a gas storage means comprising
a substitute gas, said substitute gas comprising at least one
member selected from the group consisting of: 1) nitrogen fluoride;
2) sulfur fluoride; and 3) chlorine fluoride; c) a gas switching
section connected to said electrolytic cell and said gas storage
means wherein said switching section selectively supplies said
semiconductor processing system with either: 1) said fluorine gas;
or 2) said substitute gas from said gas storage means; d) a path
detector wherein said detector detects the state in the gas supply
path of said fluorine gas from said cell to said semiconductor
processing system; and e) a controller, wherein said controller
acts on said switching section to feed said substitute gas to said
semiconductor processing system.
17. The apparatus of claim 16, further comprising: a) a buffer
section on said gas supply path, wherein said buffer section
controls the pressure and flow rate of said fluorine gas produced
from said cell; and b) a buffer detector, wherein said buffer
detector: 1) is situated with said path detector; and 2) is able to
detect the status of said buffer section.
18. The apparatus of claim 17, further comprising a compressor
situated with said buffer section, wherein: a) said compressor
pressurizes said fluorine gas from said cell; and b) said buffer
detector detects the operational status of said compressor.
19. The apparatus of claim 17, further comprising a buffer tank
situated in said buffer section, wherein: a) said buffer tank
temporarily stores said fluorine gas from said cell; and b) said
buffer detector detects the pressure in said tank.
20. The apparatus of claim 17, further comprising a flow controller
situated in said buffer section, wherein: a) said flow controller
supplies fluorine gas to said switching section at a specified flow
rate; and b) said buffer detector detects the flow rate of said
fluorine gas at said flow controller.
21. The apparatus of claim 11, wherein said substitute gas
comprises chlorine fluoride.
22. The apparatus of claim 16, wherein said substitute gas
comprises chlorine fluoride.
23. A method for fluorine gas generation and supply to a
semiconductor processing system comprising generating and supplying
said fluorine with an apparatus, said apparatus further comprising:
a) a fluorine gas generating means comprising: 1) an electrolytic
cell for the electrolysis of hydrogen fluoride to produce said
fluorine gas, said cell further comprising: i) an electrolytic
bath, said bath further comprising hydrogen fluoride-containing
molten salt; b) a gas storage means comprising a substitute gas,
said substitute gas comprising at least one member selected from
the group consisting of: 1) nitrogen fluoride; 2) sulfur fluoride;
and 3) chlorine fluoride; c) a gas switching section connected to
said electrolytic cell and said gas storage means wherein said
switching section selectively supplies said semiconductor
processing system with either: 1) said fluorine gas from said cell;
or 2) said substitute gas from said gas storage means; d) a
detector comprising at least one member selected from the group
consisting of: 1) an electrolytic cell detector that detects the
status of said cell; and 2) a path detector that detects the status
of said gas supply path; and e) a controller, wherein said
controller acts on said switching section to feed said substitute
gas to said semiconductor processing system.
24. The method of claim 22, wherein said substitute gas comprises
chlorine fluoride.
Description
FIELD OF THE INVENTION
[0001] This invention relates to an apparatus that is disposed in
the gas supply system of a semiconductor processing system and that
generates and supplies fluorine gas. Semiconductor processing
refers in this context to the various processes carried out in
order to fabricate semiconductor devices and/or semiconductor
device-connecting structures (e.g., interconnects, electrodes) on
the substrate undergoing the processing (the target substrate) by
the formation of semiconductor, dielectric, and conductive layers
in specific patterns on the target substrate, such as a
semiconductor wafer or LCD substrate.
DESCRIPTION OF THE PRIOR ART
[0002] A variety of semiconductor processes, such as film
formation, etching, and diffusion, are carried out on the target
substrate, e.g., a semiconductor wafer or LCD substrate, during the
fabrication of semiconductor devices. The semiconductor processing
systems used to carry out these treatments employ fluorine-type
gases as process gases in a variety of applications, such as for
the etching of silicon films and silicon oxide films or to clean
the interior of process compartments, which are not necessarily
limited to semiconductor processes.
[0003] Fluorine-type process gases are generally made available to
the gas supply system of a semiconductor processing system as an
already prepared fluorine compound filled in a cylinder. Gases of
this type are seldom produced on-site from their essential
precursors, e.g., fluorine. The reasons for this relate not just to
problems with the reliability of the gas composition, but also to
the extreme danger associated with placing a cylinder filled to
high pressures (typically at least 5 kg/cm.sup.2) with a strong
oxidizer such as fluorine in the gas supply system of a
semiconductor processing system.
[0004] U.S. Pat. No. 5,688,384, on the other hand, discloses an
apparatus that automatically controls the on/off switching of
fluorine gas generation in response to demand. As its fluorine gas
generation module this apparatus uses an electrolytic cell that
generates fluorine gas by the electrolysis of hydrogen fluoride.
Since such electrolytic-type apparatuses can as necessary produce
fluorine gas at near atmospheric pressure, they can avoid the
safety problems associated with the installation of fluorine
cylinders.
[0005] Problems to Be Solved by the Invention
[0006] When a fluorine gas-generating and -supply apparatus as
described above is placed in the gas supply system of a
semiconductor processing system, it is also necessary to provide a
back-up means in order to prevent perturbations in the operation of
the main processing apparatus even when abnormalities occur in the
fluorine gas-generating and -supply apparatus. In a typical
strategy, two fluorine gas-generating and -supply apparatuses are
installed in a gas supply system and are operated in rotation as
the online apparatus and back-up apparatus. This back-up strategy,
however, causes high initial costs and high operating costs for the
gas supply system. Moreover, while fluorine cylinders can also be
used as a back-up means, safety problems are incurred by the
disposition of high-pressure fluorine cylinders in the gas supply
system of a semiconductor processing system.
[0007] This invention was developed in view of the problems
identified above for the prior art. The object of this invention is
to provide a fluorine gas-generating and -supply apparatus that is
disposed in the gas supply system of a semiconductor processing
system and that in the event of abnormalities in the apparatus
enables back up by a safe and inexpensive structure.
[0008] A particular object of this invention is to provide an
apparatus that can generate and supply fluorine gas both on-site
and on-demand. As used herein, on-site means that the mechanism for
generating and supplying the fluorine gas is combined or assembled
with the particular main process apparatus, for example, the main
process apparatus of a semiconductor processing system. On-demand
means that the gas can be supplied, with accompanying control of
its required components, with a timing that responds to the
requirements of the main process apparatus.
[0009] Means Solving the Problems
[0010] The first aspect of this invention is an apparatus that
generates and supplies fluorine gas and is disposed in the gas
supply system of a semiconductor processing system, said apparatus
being characteristically provided with
[0011] an electrolytic cell that generates fluorine gas by the
electrolysis of hydrogen fluoride in an electrolytic bath
comprising hydrogen fluoride-containing molten salt,
[0012] a cylinder that stores a substitute gas selected from the
group consisting of nitrogen fluoride, sulfur fluoride, and
chlorine fluoride,
[0013] a gas switching section that is connected to the
electrolytic cell and cylinder and that selectively supplies a gas
utilization section with fluorine gas from the electrolytic cell or
substitute gas from the cylinder,
[0014] an electrolytic cell detector that detects the state of the
electrolytic cell, and
[0015] a controller that, upon detection of an abnormal state at
the electrolytic cell by the electrolytic cell detector, exercises
control on the gas switching section so as to feed the substitute
gas from the cylinder to the gas utilization section.
[0016] The second aspect of this invention is an apparatus in
accordance with the first aspect with the additional characteristic
feature that the electrolytic cell detector detects a state that is
representative of the composition of the electrolytic bath.
[0017] The third aspect of this invention is an apparatus in
accordance with the second aspect with the additional
characteristic feature that the electrolytic cell detector detects
a state selected from the electrical current characteristics,
liquid level, and temperature of the electrolytic bath.
[0018] The fourth aspect of this invention is an apparatus in
accordance with any of the first to third aspects, characterized in
that the apparatus is additionally provided with a path detector
that can detect an abnormal state in the gas supply path that
supplies fluorine gas from the electrolytic cell to the gas
utilization section and in that the controller, upon detection of
an abnormal state at the electrolytic cell by the electrolytic cell
detector or upon detection of an abnormal state in the gas supply
path by the path detector, exercises control on the gas switching
section so as to feed the substitute gas from the cylinder to the
gas utilization section.
[0019] The fifth aspect of this invention is an apparatus that
generates and supplies fluorine gas and is disposed in the gas
supply system of a semiconductor processing system, said apparatus
being characteristically provided with
[0020] an electrolytic cell that generates fluorine gas by the
electrolysis of hydrogen fluoride in an electrolytic bath
comprising hydrogen fluoride-containing molten salt,
[0021] a cylinder that stores a substitute gas selected from the
group consisting of nitrogen fluoride, sulfur fluoride, and
chlorine fluoride,
[0022] a gas switching section that is connected to the
electrolytic cell and cylinder and that selectively supplies a gas
utilization section with fluorine gas from the electrolytic cell or
substitute gas from the cylinder,
[0023] a path detector that can detect an abnormal state in the gas
supply path that supplies fluorine gas from the electrolytic cell
to the gas utilization section, and
[0024] a controller that, upon detection of an abnormal state in
the gas supply path by the path detector, exercises control on the
gas switching section so as to feed the substitute gas from the
cylinder to the gas utilization section.
[0025] The sixth aspect of this invention is an apparatus in
accordance with the fourth or fifth aspect, characterized in that
the gas supply path is provided with a buffer section that controls
the pressure and flow rate of the fluorine gas that is supplied
from the electrolytic cell to the gas switching section and in that
the path detector is provided with a buffer detector that detects
the state of the buffer section.
[0026] The seventh aspect of this invention is an apparatus in
accordance with the sixth aspect, characterized in that the buffer
section is provided with a compressor that pressurizes the fluorine
gas from the electrolytic cell and in that the buffer detector
detects the operational status of the compressor.
[0027] The eighth aspect of this invention is an apparatus in
accordance with the sixth aspect, characterized in that the buffer
section is provided with a buffer tank that temporarily stores
fluorine gas from the electrolytic cell and in that the buffer
detector detects the pressure within the buffer tank.
[0028] The ninth aspect of this invention is an apparatus in
accordance with the sixth aspect, characterized in that the buffer
section is provided with a flow controller that supplies fluorine
gas from the electrolytic cell to the gas switching section at a
specified flow rate and in that the buffer detector detects the
fluorine gas flow rate at said flow controller.
[0029] The tenth aspect of this invention is an apparatus in
accordance with any of the first through ninth aspects,
characterized in that the substitute gas comprises chlorine
fluoride.
[0030] In addition, the embodiments of this invention explore a
variety of executions of this invention, and various embodiments of
this invention can be derived by suitable combination of the plural
number of disclosed constituent elements. For example, when an
embodiment of the invention has been derived in which some
constituent elements have been omitted from the overall set of
constituent elements presented for the embodiment, these omitted
elements can be suitably fulfilled by conventional well-known
technologies in the actual working of the derived inventive
embodiment.
EMBODIMENTS OF THE INVENTION
[0031] Embodiments of this invention are explained in the following
with reference to the drawings appended herewith. In the
explanation that follows, those constituent elements that have
approximately the same structure and function are assigned a common
reference symbol and their explanation will be repeated only when
necessary.
[0032] FIG. 1 contains a schematic drawing that illustrates a
semiconductor processing system that incorporates an embodiment of
the inventive apparatus for the generation and supply of fluorine
gas. This semiconductor processing system contains a semiconductor
processing apparatus 10 that executes a process, such as film
formation, etching, or diffusion, on a target substrate such as a
semiconductor wafer or LCD substrate.
[0033] The semiconductor processing apparatus 10 is provided with a
process chamber 12 that holds the target substrate and in which the
semiconductor process is implemented. Disposed within the process
chamber 12 is a mounting platform 14 (support member) that
functions both as a lower electrode and as a platform for mounting
the target substrate. An upper electrode 16 is also disposed within
the process chamber 12 facing the mounting platform 14. RF (high
frequency) power can be applied from an RF power source 15 across
the two electrodes 14 and 16 in order to form an RF field in the
process chamber 12 for the purpose of converting the process gas
into a plasma. An exhaust system 18 is connected to the lower
region of the process chamber 12 for the purpose of evacuating the
interior of the chamber and establishing a vacuum therein. A gas
supply system 20 is connected to the upper region of the process
chamber 12 for the purpose of supplying the process gas.
[0034] FIG. 2 contains a schematic drawing that illustrates a
modified example 10x of the semiconductor processing apparatus that
can be used in combination with the gas supply system 20
illustrated in FIG. 1. This semiconductor processing apparatus 10x
is provided with a process chamber 12 that holds the target
substrate and in which the semiconductor process is implemented. A
mounting platform 14 (support member) is disposed within the
process chamber 12 for the purpose of mounting the target
substrate. An exhaust system 18 is connected to the lower region of
the process chamber 12 for the purpose of evacuating the interior
of the chamber and establishing a vacuum therein. A remote plasma
chamber 13 is connected to the upper region of the process chamber
12 for the purpose of forming a plasma. The periphery of this
remote plasma chamber 13 is wrapped with a coil antenna 17. The
application of RF (high frequency) power from the RF power source
15 to the coil antenna 17 results in the formation in the remote
plasma chamber 13 of an induction field for the purpose of
converting the process gas to a plasma. A gas supply system 20 is
connected to the upper region of the remote plasma chamber 13 in
order to supply the process gas.
[0035] With reference again to FIG. 1, a flow management section 22
is disposed in the gas supply system 20; this flow management
section 22 can feed any designated gas, for example, process gas
for carrying out a semiconductor process or process gas for
cleaning the interior of the process chamber 12, into the process
chamber 12 at a specified flow rate and is also capable of
selective gas switching. A gas storage section 24 is connected to
the flow management section 22. This gas storage section 24
contains a plurality of gas sources and stores various active
and/or inert gases. Also connected to the flow management section
22 is a gas production section 26 that generates fluorine gas-type
process gas by a reaction process.
[0036] An inventive apparatus 30 for the generation and supply of
fluorine gas is connected in the embodiment under consideration to
the flow management section 22 and the gas production section 26.
More specifically, this generation and supply apparatus 30 either
directly supplies fluorine gas to the flow management section 22 or
is used to supply starting fluorine gas to the gas production
section 26 (switching valve not shown). The gas production section
26 can produce, for example, an interhalogen fluorine compound gas
by reacting the starting fluorine gas with another halogen gas such
as chlorine.
[0037] The generation and supply apparatus 30 contains an
electrolytic cell 34 that generates fluorine gas (F.sub.2) by the
electrolysis of hydrogen fluoride in an electrolytic bath
comprising hydrogen fluoride-containing molten salt. This molten
salt comprises a mixture (KF/2HF) of potassium fluoride (KF) and
hydrogen fluoride (HF) or a mixture of hydrogen fluoride and
Fremy's salt. The electrolytic cell 34 is connected to a hydrogen
fluoride source 32 that supplies hydrogen fluoride, the starting
material that undergoes depletion. A detector 36 is disposed within
the electrolytic cell 34 for the purpose of detecting, as a state
representative of changes in the composition of the electrolytic
bath, the electrical current characteristics, liquid level,
temperature, etc., of the electrolytic bath. The detection results
generated by the detector 36 are fed to a controller 40. The
electrolytic cell 34 is replenished with hydrogen fluoride--the
consumable starting material--from the hydrogen fluoride source 32
based on the detection result yielded by the detector 36 and under
control by the controller 40 using a quantitative threshold value
as the criterion.
[0038] The fluorine gas generated by the electrolytic cell 34 is
fed to a gas switching section 56 across a buffer section 42; the
purpose of the buffer section 42 is to control the pressure and
flow rate of the fluorine gas present in the supply conduit 38.
This buffer section 42 is provided with a compressor 44 in order to
pressurize the fluorine gas generated at substantially atmospheric
pressure at the electrolytic cell 34, a buffer tank 46 that
temporarily holds the fluorine gas, and a flow controller 48 that
feeds fluorine gas from the buffer tank 46 to the gas switching
section 56 at a specified flow rate. An operations detector 50 is
disposed at the compressor 44 in order to detect the operational
status of the compressor 44. A pressure detector 52 is disposed at
the buffer tank 46 in order to detect the pressure within the
buffer tank 46. A flow rate detector 54 is disposed at the flow
controller 48 in order to detect the flow rate of the fluorine gas
in the flow controller 48. The detection results generated by these
detectors 50, 52, and 54 are fed to the controller 40.
[0039] A back-up section 60 is provided against the contingency of
the appearance o-f abnormalities in the electrolytic cell 34
(fluorine gas generator), supply conduit that runs from the
electrolytic cell 34 to the gas utilization section, or fluorine
gas supply path (including the buffer section 42). This back-up
section 60 is provided with a cylinder 62 (or cylinder group) that
holds the substitute gas used as a fluorine gas substitute. The
substitute gas exiting the valve 64 of the cylinder 62 is supplied,
adjusted to a specified flow rate by the flow controller 66, to the
gas switching section 56.
[0040] The substitute gas is selected from the group consisting of
nitrogen fluoride, sulfur fluoride, and chlorine fluoride. Among
these, the use of nitrogen fluoride as the substitute gas is
particularly desirable due to its low reactivity at room
temperature and because it is a relatively safe gas. When nitrogen
fluoride (NF.sub.3) is used as the substitute gas, it will be
desirable to configure the flow controller to automatically bring
the nitrogen fluoride flow rate to approximately two-thirds the
fluorine flow rate when a switch is made from fluorine gas to
nitrogen fluoride. This configuration can maintain a constant
processing capacity at the location where the substitute gas is
used. The preferred substitute gas will also vary as a function of
the type of process and the nature of the semiconductor processing
apparatus. For example, nitrogen fluoride (NF.sub.3) is preferably
used as the substitute gas in the case of plasma cleaning while
chlorine fluoride is preferably used as the substitute gas in the
case of thermal cleaning.
[0041] The controller 40 controls the gas switching section 56 in
such a manner that substitute gas is supplied to the gas
utilization section (the main process facility) from the cylinder
62 when an abnormal state is detected in the electrolytic cell 34
and/or in the buffer section 42. Accompanying this gas switching at
the gas switching section 56, the controller 40 also adjusts the
status of the valve 64 on the cylinder 62 and adjusts the ON/OFF
status of the operation of the buffer section 42 (for example, the
operation of the compressor 44).
[0042] An abnormal state in the electrolytic cell 34 is sensed by
the electrolytic cell detector 36. In specific terms, the detector
36 detects, for example, the electric current characteristics,
liquid level, or temperature of the electrolytic bath as a state
representative of changes in the composition of the electrolytic
bath and transmits the result to the controller 40. The controller
40 then compares the detected value with a preliminarily set
threshold value and determines whether the electrolytic bath 34
resides in a normal state or has entered into an abnormal
state.
[0043] Likewise, an abnormal state at the buffer section 42 is
detected by means of three detectors making up the buffer detector,
i.e., the operations detector 50, the pressure detector 52, and the
flow rate detector 54. In specific terms, these detectors 50, 52,
and 54 detect, respectively, the operational status of the
compressor 44, the pressure within the buffer tank 46, and the
fluorine gas flow rate at the flow controller 48, and transmit
their results to the controller 40. The controller then compares
these detected values with preliminarily set threshold values and
determines whether the buffer section 42 resides in a normal state
or has entered into an abnormal state.
[0044] Thus, the detectors 36, 50, 52, and 54 are respectively
disposed in each of the main constituent members on the fluorine
gas generation and supply side, which enables the location and type
of an abnormal state on the generation and supply side to be
recognized by the controller 40. This enables the controller 40 to
carry out, in correspondence to the location and type of an
abnormal condition, a variety of information processing in
connection with control of the gas switching section 56, including,
for example, the decision on the timing of gas switching, the
execution prior to gas switching of a program that checks the
status of each main constituent member, transmission of an alarm
signal that alerts the operator of the location, etc., of the
abnormal state, and a manual operation indication.
[0045] The generation and supply apparatus 30 shown in FIG. 1 uses
a cylinder of the substitute gas as its back-up section rather than
providing an additional iteration of the fluorine gas generation
and supply structure that runs from the electrolytic cell 34 up to
and including the buffer section 42. This results in lower initial
costs and lower operating costs for the gas supply system. The
substitute gas selected from the group consisting of nitrogen
fluoride, sulfur fluoride, and chlorine fluoride, while supplied
filled in a cylinder, does not produce the problems associated with
high-pressure fluorine cylinders and is therefore preferred from a
safety standpoint.
[0046] FIG. 3 contains a schematic diagram of a fluorine gas
generation and supply apparatus that is another embodiment of this
invention. In this embodiment the controller 40 controls the gas
switching section 56 with reference only to the detectors that
detect an abnormal state in the gas supply path that supplies
fluorine gas from the electrolytic cell 34 to the gas utilization
section, and specifically only to the detection results for the
state of the buffer section 42 generated by the detectors 50, 52,
and 54. The detection results for the liquid level of the
electrolytic bath generated by the detector 36 are not transmitted
to the controller 40, but rather are used by a controller 70 for
replenishment of the electrolytic cell 34 with hydrogen fluoride
from the hydrogen fluoride source 32.
[0047] An abnormal state at the electrolytic cell 34 will generally
also cause an abnormality or perturbation in the status of the
generated fluorine gas. As a consequence, the basic information
necessary for controlling the gas switching section 56 can be
obtained by sensing an abnormal state in the gas supply path that
supplies fluorine gas from the electrolytic cell 34 to the gas
utilization section, for example, an abnormal state for the
fluorine gas in the downstream buffer section 42. However, in this
case it will be desirable to have enabled a separate sensing of any
abnormal state at the electrolytic cell 34 unrelated to control of
the gas switching section 56.
[0048] FIG. 4 contains a schematic diagram of a fluorine gas
generation and supply apparatus that is another embodiment of this
invention. This embodiment lacks detectors for detecting abnormal
conditions at the compressor 44, buffer tank 46, and flow
controller 48 in the buffer section 42. A detector 72 that detects
the pressure and flow rate in the gas supply conduit is provided
instead to function as a detector of abnormal conditions in the gas
supply path that feeds fluorine gas from the electrolytic cell 34
to the gas utilization section. The controller 40 exercises control
on the gas switching section 56 with reference not only to the
detection result for the status of the electrolytic cell 34
afforded by the detector 36, but also to the detection results
afforded by the detector 72 for the pressure and flow rate in the
fluorine gas supply conduit. As illustrated by the dash-and-dot
line in FIG. 4, the detector 72 can also be provided downstream
from the gas switching section 56.
[0049] An abnormal state in the buffer section 42 will generally
also cause an abnormal state or condition in the pressure and flow
rate in the fluorine gas supply conduit. As a consequence, the
basic information necessary for controlling the gas switching
section 56 can be obtained by sensing an abnormal state in the
pressure and flow rate within the fluorine gas supply conduit
downstream from the buffer section 42.
[0050] The gas switching section 56 may also be disposed between
the electrolytic cell 34 and the buffer section 42 in each of the
embodiments discussed above. In such a case the controller 40 will
exercise control on the gas switching section 56 with reference
only to the detection result afforded by the detector 36 for the
state of the electrolytic cell 34. Moreover, while the fluorine gas
is fed either to the flow management section 22 or to the gas
production section 26 in the embodiments discussed above, this gas
can be supplied directly to the process chamber 12 separately from
other process gases. The gas production section 26 can also be
configured to produce other fluorine-type process gases instead of
interhalogen fluorine compound gases. A cylinder of fluorine gas
can be used in each of the embodiments elaborated hereinabove in
place of the cylinder of substitute gas insofar as the
corresponding safety issues can be resolved.
[0051] While various modifications and alterations within the
technical sphere of the concept of this invention can be devised by
the individual skilled in the art, it should be understood that
such modifications and alterations also fall within the scope of
this invention.
[0052] Advantageous Effects of the Invention
[0053] As has been described in detail hereinabove, this invention
provides a fluorine gas-generation and -supply apparatus that is
disposed in the gas supply system of a semiconductor processing
system and that in the event of abnormalities in the apparatus
enables back up by a safe and inexpensive structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] FIG. 1 contains a schematic drawing that illustrates a
semiconductor processing system that incorporates an apparatus for
the generation and supply of fluorine gas that is an embodiment of
this invention.
[0055] FIG. 2 contains a schematic drawing that illustrates an
exemplary modification of the semiconductor processing apparatus
that is used in combination with the gas supply system shown in
FIG. 1.
[0056] FIG. 3 contains a schematic drawing that illustrates an
apparatus for the generation and supply of fluorine gas that is
another embodiment of this invention.
[0057] FIG. 4 contains a schematic drawing that illustrates an
apparatus for the generation and supply of fluorine gas that is yet
another embodiment of this invention.
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