U.S. patent application number 11/123174 was filed with the patent office on 2005-09-01 for gas processing apparatus and method and computer storage medium storing program for controlling same.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Ishibashi, Seiji, Kasai, Shigeru, Tanaka, Sumi, Yamamoto, Kaoru, Yanagitani, Kenichi.
Application Number | 20050189074 11/123174 |
Document ID | / |
Family ID | 34890857 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050189074 |
Kind Code |
A1 |
Kasai, Shigeru ; et
al. |
September 1, 2005 |
Gas processing apparatus and method and computer storage medium
storing program for controlling same
Abstract
A processing apparatus includes a processing vessel, a gas
introduction unit, a processing gas supply unit, a nonreactive gas
supply unit, a vacuum pumping unit, a pressure gauge and a control
unit. The control unit controls a valve opening ratio of a pressure
control valve based on a detection value of the pressure gauge
while making a processing gas flow to a flow rate controller of the
processing gas supply unit at a constant flow rate when performing
a process in which a partial pressure of the processing gas is
important. Meanwhile, when performing a process wherein the partial
pressure of the processing gas is relatively unimportant, the
control unit fixes the valve opening ratio of the pressure control
valve at a predetermined value, and operating a flow rate
controller of the nonreactive gas supply unit to control a flow
rate based on the detection value.
Inventors: |
Kasai, Shigeru;
(Nirasaka-shi, JP) ; Ishibashi, Seiji;
(Nirasaka-shi, JP) ; Yamamoto, Kaoru;
(Nirasaka-shi, JP) ; Tanaka, Sumi; (Nirasaka-shi,
JP) ; Yanagitani, Kenichi; (Nirasaka-shi,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TOKYO ELECTRON LIMITED
Tokyo
JP
|
Family ID: |
34890857 |
Appl. No.: |
11/123174 |
Filed: |
May 6, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11123174 |
May 6, 2005 |
|
|
|
PCT/JP03/14266 |
Nov 10, 2003 |
|
|
|
Current U.S.
Class: |
156/345.33 ;
216/59 |
Current CPC
Class: |
H01L 21/67109 20130101;
H01L 21/6831 20130101; G05D 16/2026 20130101; H01L 21/67253
20130101 |
Class at
Publication: |
156/345.33 ;
216/059 |
International
Class: |
C23F 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2002 |
JP |
2002-326128 |
Mar 26, 2003 |
JP |
2003-086504 |
Claims
1. A processing apparatus comprising: a processing vessel having
therein a mounting table for mounting an object to be processed; a
gas introduction unit for introducing a gas towards the mounting
table inside the processing vessel; a processing gas supply unit,
connected to the gas introduction unit and provided with a flow
rate controller, for supplying a processing gas; a nonreactive gas
supply unit, connected to the gas introduction unit and provided a
flow rate controller, for supplying a nonreactive gas; a vacuum
pumping unit connected to the processing vessel and provided with a
pressure control valve having a variable valve opening ratio and a
vacuum pump; a pressure gauge installed at the processing vessel;
and a control unit for controlling the valve opening ratio of the
pressure control valve based on a detection value of the pressure
gauge while making the processing gas flow to the flow rate
controller of the processing gas supply unit at a constant flow
rate when performing a process wherein a partial pressure of the
processing gas is important; and for fixing the valve opening ratio
of the pressure control valve at a predetermined value, and at the
same time, operating the flow rate controller of the nonreactive
gas supply unit to control a flow rate based on the detection value
of the pressure gauge when performing a process wherein the partial
pressure of the processing gas is relatively unimportant.
2. The processing apparatus of claim 1, further comprising one or
more additional processing gas supply units, wherein the control
unit is configured to set the valve opening ratio of the pressure
control valve at a fully opened state during a predetermined
process; and in that state, to let the flow rate controller of each
processing gas supply unit control each flow rate based on the
detection value of the pressure gauge while maintaining a flow rate
ratio at a substantially constant state.
3. The processing apparatus of claim 1, wherein the vacuum pumping
unit is provided with an additional vacuum pump; and a bypass
exhaust path bypassing the pressure control valve of the vacuum
pumping unit and the second vacuum pump, wherein a converting
opening/closing valve is installed in the bypass exhaust path.
4. A processing method for performing a process on an object by
using a processing apparatus, which includes a processing vessel
having therein a mounting table for mounting the object to be
processed; a gas introduction unit for introducing a gas towards
the mounting table inside the processing vessel; a processing gas
supply unit, connected to the gas introduction unit and provided
with a flow rate controller, for supplying a processing gas; a
nonreactive gas supply unit, connected to the gas introduction unit
and provided with a flow rate controller, for supplying a
nonreactive gas; a vacuum pumping unit connected to the processing
vessel and provided with a pressure control valve having a variable
valve opening ratio and a vacuum pump; and a pressure gauge
installed at the processing vessel, wherein the valve opening ratio
of the pressure control valve is controlled based on a detection
value of the pressure gauge while a flow rate of the processing gas
flowing to the processing gas supply unit is maintained constant
when performing a first process in which a partial pressure of the
processing gas is important; and wherein the valve opening ratio of
the pressure control valve is fixed at a predetermined value, and
at the same time, a flow rate of the nonreactive gas flowing to the
nonreactive gas supply unit is controlled based on the detection
value of the pressure gauge when performing a second process in
which the partial pressure of the processing gas is relatively
unimportant.
5. The processing method of claim 4, wherein the processing
apparatus includes one or more additional processing gas supply
units; and wherein the valve opening ratio of the pressure control
valve is set at a fully opened state during a predetermined
process; and in that state, each flow rate is controlled based on
the detection value of the pressure gauge while a flow rate ratio
of the processing gas flowing through each processing gas supply
unit is maintained at a substantially constant state.
6. The processing method of claim 4, wherein the number of
revolutions in the process wherein the partial pressure of the
processing gas is important is controlled by the vacuum pump to be
different from that in the process in which the partial pressure of
the processing gas is unimportant.
7. The processing method of claim 4, wherein the process in which
the partial pressure of the processing gas is important is a film
forming process, and the process in which the partial pressure of
the processing gas is relatively unimportant is a cleaning
process.
8. The processing method of claim 4, wherein the processing vessel
is pumped during the first and the second process by the vacuum
pumping unit.
9. A processing apparatus comprising: a processing vessel having
therein a mounting table for mounting an object to be processed; a
gas introduction unit for introducing a gas towards the mounting
table inside the processing vessel; a processing gas supply unit,
connected to the gas introduction unit and provided with a flow
rate controller, for supplying a processing gas; a nonreactive gas
supply unit, connected to the gas introduction unit and provided
with a flow rate controller, for supplying a nonreactive gas; a
vacuum pumping unit connected to the processing vessel and provided
with a pressure control valve having a variable valve opening ratio
and a first vacuum pump; a pressure gauge installed at the
processing vessel; and a control unit for fixing the valve opening
ratio of the pressure control valve at a predetermined value, and
at the same time, performing a first control for controlling a flow
rate by using the flow rate controller of the nonreactive gas
supply unit based on a detection value of the pressure gauge.
10. The processing apparatus of claim 9, wherein the control unit
performs a second control for controlling the valve opening ratio
of the pressure control valve based on the detection value of the
pressure gauge while making the processing gas flow to the flow
rate controller of the processing gas supply unit at a constant
flow rate, and wherein the second control is used for a process
wherein a partial pressure of the processing gas is important.
11. The processing apparatus of claim 9, wherein the first control
is used for a process in which a partial pressure of the processing
gas is relatively unimportant.
12. The processing apparatus of claim 9, wherein the first control
is used for a case when a process is performed at a low pressure
where a passing flow rate is not substantially changed even though
the valve opening ratio of the pressure control valve is
changed.
13. A processing method for performing a process on an object by
using a processing apparatus, which includes a processing vessel
having therein a mounting table for mounting the object to be
processed; a gas introduction unit for introducing a gas towards
the mounting table inside the processing vessel; a processing gas
supply unit, connected to the gas introduction unit and provided
with a flow rate controller, for supplying a processing gas; a
nonreactive gas supply unit, connected to the gas introduction unit
and provided with a flow rate controller, for supplying a
nonreactive gas; a vacuum pumping unit connected to the processing
vessel and a pressure control valve having a variable valve opening
ratio and a first vacuum pump; and a pressure gauge installed at
the processing vessel, wherein the valve opening ratio of the
pressure control valve is fixed at a predetermined value; and
wherein a first control for controlling a flow rate is performed by
using the flow rate controller of the nonreactive gas supply unit
based on a detection value of the pressure gauge.
14. The processing method of claim 13, wherein a second control for
controlling the valve opening ratio of the pressure control valve
is further performed based on the detection value of the pressure
gauge while making the processing gas flow to the flow rate
controller of the processing gas supply unit at a constant flow
rate, the second control being used for a process in which a
partial pressure of the processing gas is important.
15. The processing method of claim 13, wherein the first control is
used for a process in which a partial pressure of the processing
gas is relatively unimportant.
16. The processing method of claim 15, wherein the process in which
the partial pressure of the processing gas is relatively
unimportant is a cleaning process.
17. The processing method of claim 13, wherein the first control is
used for a case when a process is performed at a low pressure where
a passing flow rate is not substantially changed even though the
valve opening ratio of the pressure control valve is changed.
18. The processing method of claim 17, wherein the low pressure
process where the passing flow rate is not substantially changed
even though the valve opening ratio of the pressure control valve
is changed is a plasma etching process.
19. The processing method of claim 14, wherein the process in which
the partial pressure of the processing gas is important is a film
forming process.
20. A processing apparatus including a processing vessel having
therein a mounting table for mounting an object to be processed; a
gas introduction unit for introducing a gas towards the mounting
table inside the processing vessel; a gas supply unit, connected to
the gas introduction unit and provided with a flow rate controller,
for supplying a predetermined gas; a vacuum pumping unit connected
to the processing vessel and provided with a first vacuum pump, a
second vacuum pump and a pressure control valve having a variable
valve opening ratio; and a pressure gauge for detecting a pressure
of the processing vessel, the processing apparatus comprising: a
bypass exhaust path installed to bypass the pressure control valve
and the second vacuum pump; a soft start valve mechanism installed
in the bypass exhaust path, the soft start valve mechanism having a
function of buffering an impact of a vacuum exhaust when exhausting
an inside of the processing vessel from an atmospheric pressure to
vacuum; and a control unit installed to control an inner pressure
of the processing vessel by adjusting the valve opening ratio of
the pressure control valve based on a detection value of the
pressure gauge during a relatively low processing pressure process;
and to stop an exhaust toward the pressure control valve, and at
the same time, to flow an exhaust gas to the bypass exhaust path
while maintaining the soft start valve mechanism at a low pumping
conductance state during a relatively high processing pressure
process.
21. The processing apparatus of claim 20, wherein the control unit
adjusts a flow rate by using the flow rate controller based on the
detection value of the pressure gauge during the relatively high
processing pressure process, to thereby control the inner pressure
of the processing vessel.
22. The processing apparatus of claim 20, wherein the soft start
valve mechanism includes: a first bypass opening/closing valve
installed in a bypass exhaust line of the bypass exhaust path; an
auxiliary bypass exhaust line installed to bypass the first bypass
opening/closing valve; a second bypass opening/closing valve
installed in the auxiliary bypass exhaust line; and an orifice
mechanism installed in the auxiliary bypass exhaust line.
23. The processing apparatus of claim 22, wherein the control unit
turns the first bypass opening/closing valve into a closed state
and turns the second bypass opening/closing valve into an opened
state, in order to realize the low pumping conductance state.
24. The processing apparatus of claim 20, wherein the soft start
valve mechanism is formed of a soft start valve.
25. A processing method for performing a process on an object by
using a processing apparatus, which includes a processing vessel
having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a gas towards
the mounting table inside the processing vessel; a gas supply unit,
connected to the gas introduction unit and provided with a flow
rate controller, for supplying a predetermined gas; a vacuum
pumping unit connected to the processing vessel and provided with a
first vacuum pump, a second vacuum pump and a pressure control
valve having a variable valve opening ratio; and a pressure gauge
for detecting a pressure of the processing vessel, wherein a bypass
exhaust path bypassing the pressure control valve and the second
vacuum pump is installed; wherein a soft start valve mechanism in
the bypass exhaust path is installed, the soft start valve
mechanism having a function of buffering an impact of a vacuum
exhaust when exhausting an inside of the processing vessel from an
atmospheric pressure to vacuum; and wherein an inner pressure of
the processing vessel is controlled by adjusting the valve opening
ratio of the pressure control valve based on a detection value of
the pressure gauge during a relatively low processing pressure
process; and an exhaust toward the pressure control valve is
stopped, and at the same time, an exhaust gas flows to the bypass
exhaust path while the soft start valve mechanism is maintained at
a low pumping conductance state during a relatively high processing
pressure process.
26. A computer readable storage medium storing therein a program
for controlling the processing method of claim 4, 13 or 25.
Description
[0001] This application is a Continuation-In-Part of PCT
International Application No. PCT/JP03/014266 filed on Nov. 10,
2003, which designated the United States.
FIELD OF THE INVENTION
[0002] The present invention relates to a processing apparatus and
method for performing specific processes on, e.g., a semiconductor
wafer and the like, and a computer readable storage medium storing
therein a program for controlling same.
BACKGROUND OF THE INVENTION
[0003] Generally, for fabricating a semiconductor integrated
circuit, various processes, such as a film forming process, an
etching process, a thermal oxidation process, a diffusion process,
a reforming process, a crystallization process and the like, are
performed repeatedly on an object to be processed such as a
semiconductor wafer to form a desired integrated circuit. Further,
in order to remove unnecessary films or particles deposited to a
processing vessel and the like, a cleaning process for removing the
above-mentioned unnecessary films and the like by flowing with an
etching gas is also performed suitably.
[0004] However, in some cases, a single processing apparatus is
used in performing different kinds of processes as described above
or plural processes that are of the same kind but differ in
processing conditions. Conventionally, a pumping system installed
in the processing apparatus is designed by taking a pressure range
applied during a process wherein this processing apparatus is used
into consideration; a diameter of an exhaust line is set to
optimize a pumping conductance in the employed pressure range; and
a type of the vacuum pump is also determined to be suitable for the
employed pressure range.
[0005] Moreover, in case a single processing apparatus is to be
used for different kinds of processes or plural processes which are
of the same kind but differ in processing conditions as described
above and there are included processes performed under a relatively
low processing pressure and performed under a relatively high
processing pressure, it is required to control an inner pressure of
the processing vessel stably within each pressure range. For this,
when employing a conventional processing apparatus, an inner
pressure of a processing vessel is detected to control a pressure
control valve of a pumping system based on the detected pressure
value or a ballast gas is introduced to a pumping system while a
flow rate thereof is controlled as shown in reference 1 [Japanese
Patent Laid-open Application No. H10-11152 (Pages 2 to 4, and FIGS.
1 to 5)].
[0006] Further, another conventional apparatus wherein a bypass
line is installed in a pumping system to be used alternatively
depending on the employed pressure range has been also known. An
example of this conventional apparatus will now be described with
reference to FIG. 8. FIG. 8 is a schematic diagram illustrating an
exemplary conventional processing apparatus.
[0007] As is shown, a processing apparatus 2 includes a
barrel-shaped processing vessel 4 made of, e.g., aluminum, wherein
the processing vessel 4 is designed to be vacuum-exhausted. In the
processing vessel 4, there is installed a mounting table 8 having a
heating unit 6, e.g., a heater and the like, wherein the mounting
table 8 is configured to mount a semiconductor wafer W to be fixed
thereon. Further, in a ceiling portion of the processing vessel 4,
there is installed as a gas introduction unit, e.g., a shower head
unit 10, for introducing various processing gases towards the
mounting table 8 inside the processing vessel 4. Gases are injected
downward from multiple gas injection holes 10A installed on a lower
surface of the shower head unit 10.
[0008] Further, to the shower head unit 10, there are connected a
nonreactive gas supply unit 12 for providing nonreactive gases such
as Ar, He, N.sub.2 and the like; and plural, i.e., three in this
example, processing gas supply units 14, 16 and 18. For example, a
first processing gas supply unit 14 provides a WF.sub.6 gas as a
processing gas for a film formation; a second processing gas supply
unit 16 provides a H.sub.2 gas as a processing gas for a film
formation; and a third processing gas supply unit 18 provides a
ClF.sub.3 gas as a processing gas (cleaning gas) for a cleaning
process. Further, for controlling flow rates of gases flowing
through the nonreactive gas supply unit 12 and the processing gas
supply units 14, 16 and 18, flow rate controllers 12A, 14A, 16A and
18A formed of, e.g., mass flow controller and the like, are
installed, respectively. Moreover, in upstream sides and downstream
sides of the respective flow rate controllers 12A to 18A, there are
installed opening/closing valves 22, 24, 26 and 28, respectively,
and they are configured to be opened or closed if necessary.
[0009] Meanwhile, a gas exhaust port 30 is installed on a bottom
portion of the processing vessel 4 and a vacuum pumping unit 32 is
connected to the exhaust port 30. The vacuum pumping unit 32
contains a main exhaust line 34 having a large inner diameter and
thus having a high pumping conductance. In the main exhaust line
34, there are installed a first pressure control valve 36 such as a
throttle valve capable of controlling a valve opening ratio, and a
vacuum pump 38 in this order from the upstream side to the
downstream side thereof. Also, the first pressure control valve 36
is disposed between opening/closing valves 40.
[0010] Further, a bypass exhaust line 42 having a smaller inner
diameter than that of the main exhaust line 34 and thus having a
lower pumping conductance is connected such that it bypasses the
first pressure control valve 36 and the respective opening/closing
valves 40. In the bypass exhaust line 42, there is installed a
second pressure control valve 44 such as a throttle valve capable
of controlling a valve opening ratio. Also, the second pressure
control valve 44 is disposed between opening/closing valves 46.
[0011] Still further, a pressure gauge 48 is installed in the
processing vessel 4 for detecting an inner pressure thereof, and a
control unit 50 comprising, e.g., a microcomputer and the like, is
configured to control the first and the second pressure control
valve 36 and 44, the vacuum pump 38 and opening/closing operations
of the respective opening/closing valves 40 and 46, based on a
detection value of the pressure gauge 48. The control unit 50 also
controls the whole operation of the processing apparatus 2, and
control operations are performed based on plural processing
programs (also referred to as recipes) inputted therein in
advance.
[0012] For example, when performing a film forming process on a
tungsten film by applying a low pressure process at a low
processing pressure, only a WF.sub.6 gas and a H.sub.2 gas are
provided while flow rates thereof are controlled to have specific
values, respectively (a nonreactive gas may be provided, if
necessary), and at the same time, the opening/closing valves 46 of
the bypass exhaust line 42 are closed to prevent the gases from
flowing through the bypass exhaust line 42. Further, the
opening/closing valves 40 of the main exhaust line 34 are opened,
and a valve opening ratio of the first pressure control valve 36 is
controlled to keep an inner pressure of the processing vessel 4
constant.
[0013] Contrary to this, when performing, e.g., a cleaning process
as a high pressure process under a high processing pressure, only a
ClF.sub.6 is provided while a flow rate thereof is controlled to
have a specified value (a nonreactive gas may be provided, if
necessary), and at the same time, the opening/closing valves 40 of
the main exhaust line 34 are closed to prevent the gas from flowing
through the first pressure control valve 36. Further, the
opening/closing valves 46 of the bypass exhaust line 42 are opened
to flow the gas through the bypass exhaust line 42, and a valve
opening ratio of the second pressure control valve 44 is controlled
to keep an inner pressure of the processing vessel 4 constant.
[0014] As described above, by alternatively using the main exhaust
line 34 and the bypass exhaust line 42 in cases of the high
processing pressure and the low processing pressure, it is possible
to deal with many kinds of processes wherein there are big
differences in the employed pressure ranges. Meanwhile, as for
examples of high processing pressure processes, there are an
oxidation processing, a diffusion processing and the like in
addition to the cleaning process.
[0015] Further, as a technology related to the present invention,
there has been known a processing apparatus described in reference
2 [Japanese Patent Laid-open Application No. H8-290050 (Pages 4 and
5 and FIG. 1)] wherein a bypass exhaust line is installed to cope
with a difference in an operation pressure range in case where a
multiplicity of vacuum pumps are installed.
[0016] However, in the conventional apparatus of the aforementioned
reference 1 [Japanese Patent Laid-open Application No. H10-11152
(Pages 2 to 4 and FIGS. 1 to 5)], the ballast gas whose flow rate
is controlled is to be introduced to the pumping system, so that it
cannot properly cope with a case where there is a big change in the
processing pressure. Further, a large amount of unnecessary
nonreactive gas is employed, resulting in an operation cost
increase for the apparatus.
[0017] Moreover, in the conventional apparatus shown in FIG. 8, the
bypass exhaust line 42 in which the second pressure control valve
44 is installed needs to be installed, resulting in a further cost
increase of the apparatus itself. In addition, since many
components are employed and it takes much time for maintenance
thereof, the maintenance becomes problematic.
SUMMARY OF THE INVENTION
[0018] It is, therefore, a primary object of the present invention
to provide a processing apparatus and method and a computer
readable storage medium storing therein a program for controlling
same, wherein a pressure control can be properly performed in each
processing without using a bypass line or multiple pressure control
valves, even in case when many kinds of processes of big
differences in processing pressure ranges are carried out.
[0019] Further, it is another object of the present invention to
provide a processing apparatus and method and a computer readable
storage medium storing therein a program for controlling same,
wherein a pressure control can be properly performed in each
processing without using multiple pressure control valves.
[0020] In accordance with one aspect of the present invention,
there is provided a processing apparatus including: a processing
vessel having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a processing gas
towards the mounting table inside the processing vessel; a
processing gas supply unit, connected to the gas introduction unit
and provided with a flow rate controller, for supplying a
processing gas; a nonreactive gas supply unit, connected to the gas
introduction unit and provided a flow rate controller, for
supplying a nonreactive gas; a vacuum pumping unit connected to the
processing vessel and provided with a pressure control valve having
a variable valve opening ratio and a vacuum pump; a pressure gauge
installed at the processing vessel; and a control unit for
controlling the valve opening ratio of the pressure control valve
based on a detection value of the pressure gauge while making the
processing gas flow to the flow rate controller of the processing
gas supply unit at a constant flow rate when performing a process
wherein a partial pressure of the processing gas is important and
for fixing the valve opening ratio of the pressure control valve at
a predetermined value, and at the same time, operating the flow
rate controller of the nonreactive gas supply unit to control a
flow rate based on the detection value of the pressure gauge when
performing a process wherein the partial pressure of the processing
gas is relatively unimportant.
[0021] As described above, in case when performing a process
wherein a processing pressure is low and the partial pressure of
the processing gas is important, the valve opening ratio of the
pressure control valve is adjusted to control an inner pressure of
the processing vessel while making the processing gas at a constant
flow rate, or in case when performing a process wherein the
processing pressure is high and the partial pressure of the
processing gas is relatively unimportant, the flow rate of the
nonreactive gas is adjusted to control the inner pressure of the
processing vessel while fixing the valve opening ratio of the
pressure control valve at a predetermined value. Therefore, a
pressure control can be properly performed in each process without
using a bypass line or multiple pressure control valves, even in
case when many kinds of processes of big differences in a
processing pressure ranges are carried out.
[0022] In accordance with another aspect of the present invention,
there are provided a processing method and a computer readable
storage medium storing therein a program for controlling same, the
processing method being used for performing a process on an object
by using a processing apparatus, which contains a processing vessel
having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a processing gas
towards the mounting table inside the processing vessel; a
processing gas supply unit, connected to the gas introduction unit
and provided with a flow rate controller, for supplying a
predetermined processing gas; a nonreactive gas supply unit,
connected to the gas introduction unit and provided with a flow
rate controller, for supplying a nonreactive gas; a vacuum pumping
unit connected to the processing vessel and provided with a
pressure control valve having a variable valve opening ratio and a
vacuum pump; and a pressure gauge installed at the processing
vessel, wherein the valve opening ratio of the pressure control
valve is controlled based on a detection value of the pressure
gauge while a flow rate of a processing gas flowing to the
processing gas supply unit is maintained constant when performing a
first process in which a partial pressure of the processing gas is
important; and wherein the valve opening ratio of the pressure
control valve is fixed at a predetermined value, and at the same
time, a flow rate of a nonreactive gas flowing to the nonreactive
gas supply unit is controlled based on the detection value of the
pressure gauge when performing a second process in which the
partial pressure of the processing gas is relatively
unimportant.
[0023] In accordance with further aspect the present invention,
there is provided a processing apparatus including: a processing
vessel having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a processing gas
towards the mounting table inside the processing vessel; a
processing gas supply unit, connected to the gas introduction unit
and provided with a flow rate controller, for supplying a
predetermined processing gas; a nonreactive gas supply unit,
connected to the gas introduction unit and provided with a flow
rate controller, for supplying a nonreactive gas; a vacuum pumping
unit connected to the processing vessel and provided with a
pressure control valve having a variable valve opening ratio and a
first vacuum pump; a pressure gauge installed at the processing
vessel; and a control unit for fixing the valve opening ratio of
the pressure control valve at a predetermined value, and at the
same time, performing a first control for controlling a flow rate
by using the flow rate controller of the nonreactive gas supply
unit based on a detection value of the pressure gauge.
[0024] In accordance with further aspect of the present invention,
there are provided a processing method and a computer readable
storage medium storing therein a program for controlling same, the
processing method being used for performing a process on an object
by using a processing apparatus, which contains a processing vessel
having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a processing gas
towards the mounting table inside the processing vessel; a
processing gas supply unit, connected to the gas introduction unit
and provided with a flow rate controller, for supplying a
predetermined processing gas; a nonreactive gas supply unit,
connected to the gas introduction unit and provided with a flow
rate controller, for supplying a nonreactive gas; a vacuum pumping
unit connected to the processing vessel and a pressure control
valve having a variable valve opening ratio and a first vacuum
pump; and a pressure gauge installed at the processing vessel,
wherein the valve opening ratio of the pressure control valve is
fixed at a predetermined value; and wherein a first control for
controlling a flow rate is performed by using the flow rate
controller of the nonreactive gas supply unit based on a detection
value of the pressure gauge.
[0025] In accordance with further aspect of the present invention,
there is provided a processing apparatus containing a processing
vessel having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a processing gas
towards the mounting table inside the processing vessel; a gas
supply unit, connected to the gas introduction unit and provided
with a flow rate controller, for supplying a predetermined gas; a
vacuum pumping unit connected to the processing vessel and provided
with a first vacuum pump, a second vacuum pump and a pressure
control valve having a variable valve opening ratio; and a pressure
gauge for detecting a pressure of the processing vessel, the
processing apparatus including: a bypass exhaust path installed to
bypass the pressure control valve and the second vacuum pump; a
soft start valve mechanism installed in the bypass exhaust path,
the soft start valve mechanism having a function of buffering an
impact of a vacuum exhaust when exhausting an inside of the
processing vessel from an atmospheric pressure to vacuum; and a
control unit installed to control an inner pressure of the
processing vessel by adjusting the valve opening ratio of the
pressure control valve based on a detection value of the pressure
gauge during a relatively low processing pressure process and to
stop an exhaust toward the pressure control valve, and at the same
time, to flow an exhaust gas to the bypass exhaust path while
maintaining the soft start valve mechanism at a low pumping
conductance state during a relatively high processing pressure
process.
[0026] As described above, the bypass exhaust path is installed in
the vacuum pumping unit, and at the same time, the soft start valve
mechanism is installed in the bypass exhaust path. Moreover, the
valve opening ratio of the pressure control valve is adjusted to
control the inner pressure of the processing vessel during the
relatively low processing pressure process; and the exhaust toward
the pressure control valve is stopped, and at the same time, the
exhaust gas flows to the bypass exhaust path to set the inner
pressure of the processing vessel while the soft start valve
mechanism is maintained at a low pumping conductance state during
the relatively high processing pressure process. Therefore, it is
unnecessary to install expensive and large scaled multiple pressure
control valves, and it is possible to make small a structure of the
pumping unit and to simplify it.
[0027] In accordance with further aspect of the present invention,
there are provided a processing method and a computer readable
storage medium storing therein a program for controlling same, the
processing method being used for performing a process on an object
by using a processing apparatus, which contains a processing vessel
having therein a mounting table for mounting an object to be
processed; a gas introduction unit for introducing a processing gas
towards the mounting table inside the processing vessel; a gas
supply unit, connected to the gas introduction unit and provided
with a flow rate controller, for supplying a predetermined gas; a
vacuum pumping unit connected to the processing vessel and provided
with a first vacuum pump, a second vacuum pump and a pressure
control valve having a variable valve opening ratio; and a pressure
gauge for detecting a pressure of the processing vessel, wherein a
bypass exhaust path bypassing the pressure control valve and the
second vacuum pump is installed; wherein a soft start valve
mechanism in the bypass exhaust path is installed, the soft start
valve mechanism having a function of buffering an impact of a
vacuum exhaust when exhausting an inside of the processing vessel
from an atmospheric pressure to vacuum; and wherein an inner
pressure of the processing vessel is controlled by adjusting the
valve opening ratio of the pressure control valve based on a
detection value of the pressure gauge during a relatively low
processing pressure process and an exhaust toward the pressure
control valve is stopped, and at the same time, an exhaust gas
flows to the bypass exhaust path while the valve mechanism is
maintained at a low pumping conductance state during a relatively
high processing pressure process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above and other objects and features of the present
invention will become apparent from the following description of
preferred embodiments given in conjunction with the accompanying
drawings, in which:
[0029] FIG. 1 describes a schematic diagram showing a first
embodiment of a processing apparatus in accordance with the present
invention;
[0030] FIG. 2 provides a flowchart showing an embodiment of process
in accordance with a first processing method;
[0031] FIG. 3 offers a flowchart showing an embodiment of process
in accordance with a second processing method;
[0032] FIG. 4 illustrates a schematic cross sectional view showing
an embodiment of mounting table used for a pre-cleaning process in
which a third processing method is applied;
[0033] FIG. 5 is a flowchart showing an embodiment of process in
accordance with the third processing method;
[0034] FIG. 6 sets forth to a schematic diagram showing a second
embodiment of a processing apparatus in accordance with the present
invention;
[0035] FIG. 7 provides a schematic diagram showing a third
embodiment of a processing apparatus in accordance with the present
invention; and
[0036] FIG. 8 is a schematic diagram of an exemplary conventional
processing apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] Hereinafter, preferred embodiments of the present invention
will be described in detail with reference to the accompanying
drawings.
First Embodiment
[0038] FIG. 1 is a schematic diagram showing a first embodiment of
a processing apparatus in accordance with the present invention;
FIG. 2 is a flowchart showing an embodiment of process in
accordance with a first processing method; FIG. 3 is a flowchart
showing an embodiment of process in accordance with a second
processing method; FIG. 4 is a cross sectional view showing an
embodiment of mounting table in case when a pre-cleaning process is
carried out; and FIG. 5 is a flowchart showing an embodiment of
process in accordance with a third processing method. Identical
reference numerals will be assigned and explained for corresponding
parts having substantially the same functions and configurations
with those in FIG. 8. Further, the term "a process wherein a
partial pressure of a processing gas is relatively important" to be
explained below means a low processing pressure process (low
pressure process), and the term "a process wherein a partial
pressure of a processing gas is relatively unimportant" to be
explained below means a high processing pressure process (high
pressure process), generally.
[0039] As is shown, a processing apparatus 52 includes a
barrel-shaped processing vessel 4 made of, e.g., aluminum, wherein
the processing vessel 4 is designed to be vacuum-exhausted. In the
processing vessel 4, there is installed a mounting table 8 having a
heating unit 6, e.g., a heater and the like, wherein the mounting
table 8 is configured to mount a semiconductor wafer W to be fixed
thereon. Further, in a ceiling portion of the processing vessel 4,
there is installed as a gas introduction unit, e.g., a shower head
unit 10, for introducing various processing gases towards the
mounting table 8 inside the processing vessel 4. Gases are injected
downward from multiple gas injection holes 10A installed on a lower
surface of the shower head unit 10.
[0040] Further, to the shower head unit 10, there are connected a
nonreactive gas supply unit 12 for supplying nonreactive gases such
as Ar, He, N.sub.2 and the like; and plural, i.e., three in this
example, processing gas supply units 14, 16 and 18. For example, a
first processing gas supply unit 14 supplies a WF.sub.6 gas as a
processing gas for a film formation; a second processing gas supply
unit 16 supplies a H.sub.2 gas as a processing gas for a film
formation; and a third processing gas supply unit 18 provides a
ClF.sub.3 gas as a processing gas (cleaning gas) for a cleaning
process. Here, the WF.sub.6 gas and the H.sub.2 gas are supplied
during a film formation of a tungsten film, and a nonreactive gas
may be supplied during the film formation, if necessary.
[0041] Still further, for controlling flow rates of gases flowing
through the nonreactive gas supply unit 12 and the first, the
second and the third processing gas supply units 14, 16 and 18,
flow rate controllers 12A, 14A, 16A and 18A formed of, e.g., mass
flow controller and the like, are installed, respectively.
Moreover, in upstream sides and downstream sides of the respective
flow rate controllers 12A to 18A, there are installed
opening/closing valves 22, 24, 26 and 28, respectively, and they
are configured to be opened or closed if necessary.
[0042] Meanwhile, a gas exhaust port 30 is installed on a bottom
portion of the processing vessel 4 and a vacuum pumping unit 32 is
connected to the exhaust port 30. The vacuum pumping unit 32
contains an exhaust line 34 having a large inner diameter and thus
having a high pumping conductance. The inner diameter of the
exhaust line 34 is in the range from about 100 to 150 mm, for
example. In the exhaust line 34, there are installed a pressure
control valve 36 such as a throttle valve capable of controlling a
valve opening ratio and a vacuum pump 38 in this order from the
upstream side to the downstream side thereof. Also, the pressure
control valve 36 is disposed between opening/closing valves 40.
Here, the inner diameter of the line or capacities of the pressure
control valve 36 and the vacuum pump 38 are set such that an
optimum pumping conductance required for the process in which a
partial pressure of a processing gas needs to be controlled with
high accuracy, i.e., the film forming process of the tungsten film,
can be realized in the vacuum pumping unit 32. Thus, in the present
embodiment, the bypass exhaust line 42 and the second pressure
control valve 44 used in the conventional apparatus (see FIG. 8)
are not installed.
[0043] Further, a pressure gauge 48 is installed in the processing
vessel 4 for detecting an inner pressure thereof based on a
detection value of the pressure gauge 48; and a control unit 54
including, e.g., a microcomputer and the like, controls the flow
rate controllers 12A to 18A, the pressure control valve 36, the
vacuum pump 38 and opening/closing operations of the respective
opening/closing valves 22 to 28 and 40. The control unit 54 also
controls the whole operation of the processing apparatus 52.
Various control operations of the control unit 54 are performed
under the control or based on corresponding processing programs
(recipes). A conventional personal computer may also be employed as
the control unit 54. Processing programs are prestored in a storage
unit (or computer storage medium) 55, such as a hard disc, ROM and
the like, of the control unit 54. The processing programs may be
programmed directly on the control unit 54 or can be made outside
the control unit 54 and then transferred thereto via network or by
using a CD or DVD for example.
[0044] As will be explained below, when a process, wherein a
partial pressure of a processing gas is important as in, e.g., a
film forming process of a tungsten film, is performed as a low
pressure process under a low processing pressure, only a WF.sub.6
gas and a H.sub.2 gas are provided while flow rates thereof are
controlled to be set at specified values respectively (a
nonreactive gas may be provided, if necessary), and at the same
time, a valve opening ratio of the pressure control valve 36 is
controlled to keep an inner pressure of the processing vessel 4
constant. It is preferable that the pressure control valve 36 is
the one selected to have operational characteristics offering a
highest operational accuracy within an operational pressure range
of the processing vessel 4.
[0045] Contrary to this, when a process, wherein a partial pressure
of a processing gas is relatively unimportant as in the case of,
e.g., a cleaning process, is performed as a high pressure process
under a high processing pressure, a ClF.sub.6 is provided while a
flow rate thereof is controlled to be set at a specified value, and
at the same time, a nonreactive gas is provided. Simultaneously, a
flow rate of the nonreactive gas is controlled to keep an inner
pressure of the processing vessel 4 substantially constant while a
valve opening ratio of the pressure control valve 36 is maintained
at a predetermined valve opening ratio. Meanwhile, as a high
pressure process performed under a high processing pressure, e.g.,
an oxidation process, a diffusion process and the like may be
included, for example.
[0046] Next, a processing method to be performed by using the
processing apparatus as configured above will be discussed.
[0047] In the processing apparatus 52, there are performed various
processes such as a process wherein a partial pressure of a
processing gas is important, e.g., a film forming process of a
tungsten film; and a process wherein a partial pressure of a
processing gas is relatively unimportant, e.g., a cleaning process.
The respective cases will now be explained. The term "process" used
herein includes a process performed in a case when a semiconductor
wafer W is present in the processing vessel 4 as well as a process
such as a cleaning process performed in a case when there is no
semiconductor wafer W present.
[0048] <A Process Wherein a Partial Pressure of a Processing Gas
is Important: a Film Forming Process of a Tungsten Film>
[0049] First, a process wherein a partial pressure of a processing
gas is important will now be discussed.
[0050] Here, the term "a process wherein a partial pressure of a
processing gas is important" refers to a film forming process for
depositing a tungsten film by using, e.g., a WF.sub.6 gas and a
H.sub.2 gas. For depositing the tungsten film of good electrical
characteristics with an appropriate film forming rate while
maintaining a high in-surface uniformity in a film thickness in an
in-surface of a wafer, flow rates of both gases, a flow rate ratio,
a processing pressure, a processing temperature and the like must
be kept with a high accuracy. Such a process is performed by
following steps as illustrated in, e.g., a flowchart described in
FIG. 2.
[0051] First, if an unprocessed semiconductor wafer W is mounted on
the mounting table 8 of the processing vessel 4, the vacuum pump 38
of the vacuum pumping unit 32 is operated to exhaust an inside of
the processing vessel 4 to vacuum, and the vacuum pump 38 is
maintained at the specified number of revolutions for the film
forming process (S1). The number of revolutions may be different
from that when performing a cleaning process. At the same time, the
wafer W is heated to be kept at a predetermined temperature (S2).
Then, a film forming process is started to deposit a tungsten film
by setting the WF.sub.6 gas and the H.sub.2 gas at specified flow
rates, respectively, and flowing them (S3). During the film forming
process, an inner pressure of the processing vessel 4 is detected
all the time by the pressure gauge 48 (S4). A pressure detection
value is compared with a set value preset in the control unit 54,
and an opening ratio of the pressure control valve 36 installed in
the exhaust line 34 is properly adjusted such that the detection
value becomes equal to the set value (NO of S5 and S6). The film
forming process is carried out for a predetermined time (YES of S5
and NO of S7). After the film forming process is carried out for
the predetermined time (YES of S7), the process is terminated. The
time required in adjusting the pressure control valve 36 (about
several seconds) is much shorter than the time required for the
film forming process, and thus negligibly offsets the film
thickness produced during the film forming process.
[0052] <A Process Wherein a Partial Pressure of a Processing Gas
is Relatively Unimportant: a Cleaning Process>
[0053] Next, a process wherein a partial pressure of a processing
gas is relatively unimportant will now be discussed.
[0054] Here, the term "a process wherein a partial pressure of a
processing gas is relatively unimportant" refers to a cleaning
process for removing residual deposition films and the like inside
the processing vessel by using, e.g., a cleaning gas. For keeping a
specified etching rate, a flow rate of the cleaning gas and a
processing pressure need to be maintained at preset values,
respectively. At this time, the processing pressure is set at a
much higher value than that for the case when performing the prior
film forming process. Such a processing is carried out as
illustrated in, e.g., a flowchart shown in FIG. 3.
[0055] First, the wafer W is unloaded from the processing vessel 4
to make an inside of the processing vessel 4 an airtight state, and
the vacuum pump 38 is set and maintained at the preset specific
number of revolutions for the cleaning (S11). Subsequently, a
cleaning process is started by flowing a nonreactive gas, e.g., Ar
or the like, and at the same time, flowing as a processing gas a
cleaning gas, e.g., ClF.sub.3 gas, at a preset flow rate (S12).
Simultaneously, the pressure control valve 36 is set at a preset
specific valve opening ratio, and this state is maintained
continuously (S13). The valve opening ratio has been experimentally
obtained in advance such that the pumping conductance of the vacuum
pumping unit 32 during the cleaning process is optimized.
[0056] Further, during the cleaning process, an inner pressure of
the processing vessel 4 is detected all the time by the pressure
gauge 48 (S14). A pressure detection value is compared with a set
value preset in the control unit 54, and the flow rate controller
12A installed in the nonreactive gas supply unit 12 is properly
adjusted such that the detection value becomes equal to the set
value (NO of S15 and S16). During this time, a flow rate of the
ClF.sub.3 gas is maintained at a constant value all the time. The
cleaning process is carried out for a predetermined time (YES of
S15 and NO of S17). After the cleaning process is carried out for
the predetermined time (YES of S17), the process is terminated.
[0057] As described above, even in case when many kinds of
processes having big differences in the employed pressure ranges,
such as the film forming process of the tungsten film or the
cleaning process for removing unnecessary depositions inside the
processing vessel 4, are performed, the pressure control in each
process can be properly carried out without using a bypass line or
multiple pressure control valves.
[0058] Further, the number of components to be used becomes small,
so that maintenance and repair can be carried out rapidly, thereby
improving the efficiency in the maintenance and repair.
[0059] Generally, since a response operation of the flow rate
controller 12A is much faster than that of the pressure control
valve 36, the processing pressure can be obtained faster by the
pressure control of the flow rate controller 12A; and, in
accordance with the present invention, the pressure controls are
conducted by using the flow rate controller having a rapid response
operation in some processes, in contrast with the conventional
apparatus in which the pressure controls are conducted by the
pressure control valve in all processes. As a result, the
processing time can be reduced in the present invention and thus
throughput can be improved.
[0060] Next, in case of using many kinds of processing gases
contrary to the respective processes as mentioned above, if
corresponding process can be performed within a specific partial
pressure range without deteriorating quality of the processing
result, the valve opening ratio (open angle) of the pressure
control valve 36 may be set large, e.g., 100%, during such a
process and an inner pressure of the processing vessel 4 is
controlled by adjusting flow rates of the respective processing
gases while keeping constant the flow rate ratio between the
processing gases. Thus, a predetermined process may be carried out
by only adjusting the flow rate.
[0061] Typical examples of such a process can be a PVD (Physical
Vapor Deposition) process, a plasma pre-cleaning process, a dry
etching process and the like, which can be performed in processing
apparatus using a mounting table having an electrostatic chuck.
[0062] FIG. 4 shows a cross sectional view of a mounting table in
case of performing a pre-cleaning process of one embodiment.
[0063] A mounting table 101 has an electrostatic chuck 107 on a
mounting table main body 103, and a DC electrode 102 is embedded in
the electrostatic chuck 107. A wafer is configured to be adsorbed
or separated by ON/OFF of currents flowing towards the DC electrode
102. The electrostatic chuck 107 is made of a dielectric insulation
member, and the wafer W is mounted on the electrostatic chuck 107.
Meanwhile, in the mounting table main body 103, there is formed a
heat exchange medium path 109 for cooling the electrode, and a
cooling fluid, e.g., a water or a fluorine-based fluid (galden
etc.), is supplied and circulated through a medium supply path 106
and a medium collection path 108. Further, the mounting table 103
is cooled by the cooling fluid and thus the wafer W is cooled. In
the electrostatic chuck 107, there is installed a gas introduction
path 117 supplying between the wafer W and the mounting table 101 a
backside gas, e.g., a He and the like, having a high thermal
conductivity. The backside gas is supplied through a gas supply
path 105 and flows between the wafer W and the dielectric
insulation member, to thereby make the heat transfer from a plasma
processed wafer W to the electrode easier and to facilitate a
cooling effect resulting in improvement of etching efficiency.
Further, the backside gas is discharged from the backside gas
introduction path 117 and passes through between the wafer W and
the dielectric insulation member, and thus it leaks from an outer
periphery of the wafer W to an inside of the processing vessel, as
indicated by an arrow R.
[0064] In case when a process is carried out by using such a
mounting table 101, the wafer temperature to be controlled for each
plasma process is changed, so that a supply amount of the backside
gas is minutely changed, or a supply amount of the backside gas
must be adjusted in accordance with this. Accordingly, the inner
pressure of the chamber is changed for each wafer process, but it
cannot be controlled by the pressure control valve 36 since the
pressure change inside the chamber is very small.
[0065] For preventing such a pressure change inside the chamber by
finely adjusting the supply of the nonreactive gas, a pre-cleaning
process is performed in accordance with a flowchart described in
FIG. 5.
[0066] First, the vacuum pump 38 of the vacuum pumping unit 32 is
operated to exhaust the inside of the processing vessel 4 to
vacuum, and is maintained at the predetermined number of
revolutions (S21). Subsequently, the wafer W is chucked (S22).
Then, the backside gas formed of Ar is provided between the wafer W
and the mounting table 101 (S23). Subsequently, the nonreactive gas
is supplied into the chamber, and the processing gas is set at a
specified flow rate (S24). Simultaneously, the pressure control
valve 36 is set at a specified valve opening ratio (S25). Further,
an inner pressure of the processing vessel is detected by the
pressure gauge 48 (S26). A pressure detection value is compared
with a set value preset in the control unit 54 (S27). If the
detection value is different from the set value, the flow rate
controller 12A installed in the nonreactive gas supply unit 12 is
properly adjusted by the control unit 54 such that the detection
value becomes equal to the set value (S28). Further, if the
detection value comes to be equal to the set value, plasma ignition
is conducted by the control unit 54 (S29). Then, it is determined
whether or not a predetermined processing time is elapsed (S30),
and the process is terminated after the predetermined time has
elapsed.
[0067] As described above, in such a control, a minor pressure
change of the chamber caused by the backside gas leakage can be
prevented by adjusting the supply amount of the nonreactive gas
with high accuracy. In this case, the processing pressure can be
controlled by using only a control operation of the flow rate
controller having a rapid response speed without adjusting the
valve opening ratio of the pressure control valve 36, so that
controllability is enhanced, thereby resulting in improvement of
throughput.
Second Embodiment
[0068] In the aforementioned embodiment, such a case has been
explained by using an example where an integrated exhaust line 34
is installed and one vacuum pump 38 is installed therein, as shown
in FIG. 1. However, in case when pumping capacity is insufficient
with one vacuum pump 38, a configuration of a second embodiment
shown in FIG. 6 may be adopted. Namely, in this case, a second
vacuum pump 60 formed of, e.g., a turbo molecular pump, is
installed in series with the pressure control valve 36, and a
bypass exhaust path 62 is connected to the exhaust line 34 such
that it bypasses the pressure control valve 36 and the second
vacuum pump 60. Further, a converting opening/closing valve 64 is
installed in the bypass exhaust path 62. An inner diameter of the
bypass exhaust path 62 is about in the range from 25 to 40 mm.
[0069] In this embodiment, the opening/closing valves 40 of the
exhaust line 34 are first closed in case when vacuum-exhausting the
inside of the processing vessel 4; instead, the converting
opening/closing valve 64 of the bypass exhaust path 62 is opened to
communicate with the bypass exhaust path 62; and the vacuum pump 38
is rotationally operated to roughly exhaust the processing vessel
4. After somewhat roughly exhausting it, if the inner pressure of
the processing vessel 4 is reduced to a specified vacuum level, the
opening/closing valves 40 of the exhaust line 34 are opened to
rotationally drive the second vacuum pump 60. And, the converting
opening/closing valve 64 of the bypass exhaust path 62 is closed.
In this way, the vacuum exhaust operation is continuously carried
out by two vacuum pumps of the prior vacuum pump 38 and the second
vacuum pump 60. Further, in case when a relatively high processing
pressure process, e.g., a cleaning process, is carried out, the
cleaning process may be performed while the vacuum exhaust
operation is performed by closing the opening/closing valves 40 of
the exhaust line 34 and only by using the bypass exhaust path 62.
In this embodiment, plural processes having big differences in the
processing pressure ranges are performed in the same manner with
reference to FIGS. 1 to 5.
Third Embodiment
[0070] Next, a third embodiment of the present invention will be
explained.
[0071] FIG. 7 is a schematic diagram showing a third embodiment of
a processing apparatus in accordance with the present invention.
Identical reference numerals will be assigned and explained for
corresponding parts having substantially the same functions and
configurations with those in FIGS. 1, 6 and 8. Further, the term "a
relatively low processing pressure process" explained herein means
a process wherein a partial pressure of a processing gas is
important as was explained before, and the term "a relatively high
processing pressure process" means a process wherein a partial
pressure of a processing gas is unimportant.
[0072] As shown in FIG. 7, in the main exhaust line 34, there are
installed the pressure control valve 36, the second vacuum pump 60
formed of, e.g., a turbo molecular pump and the first vacuum pump
38 formed of, e.g., a dry pump, in this order from the upstream
side to the downstream side thereof. Also, the pressure control
valve 36 and the second vacuum pump 60 are disposed between
opening/closing valves 40.
[0073] Further, the bypass exhaust path 62 is connected to the main
exhaust line 34 such that it bypasses the pressure control valve
36, the second vacuum pump 60 and both of the opening/closing
valves 40. As mentioned above, the inner diameter of the main
exhaust line 34 is large, e.g., in the range from about 100 to 150
mm, and that of the bypass exhaust path 62 is small, e.g., in the
range from about 25 to 40 mm.
[0074] Still further, in the bypass exhaust path 62, there is
installed a soft start valve mechanism 70 having a function of
buffering an impact of the vacuum exhaust when exhausting the
inside of the processing vessel 4 from an atmospheric pressure to
vacuum. Accordingly, the control unit 54 controls the inner
pressure of the processing vessel 4 by adjusting the valve opening
ratio of the pressure control valve 36 based on a detection value
obtained from the pressure gauge 48 installed in the processing
vessel 4, in case when performing a relatively low processing
pressure process (e.g., film forming process etc.). In case when
performing a relatively high processing pressure process (e.g.,
cleaning process, oxidation process, diffusion process etc.), the
exhaust operation through the pressure control valve 36 is stopped,
and at the same time, it is controlled such that the soft start
valve mechanism 70 is maintained at a low pumping conductance state
to flow the exhaust gas through the bypass exhaust path 62.
[0075] Specifically, the soft start valve mechanism 70 is formed of
a first bypass opening/closing valve 72 installed in the bypass
exhaust path 62; an auxiliary bypass exhaust line 74 of a small
inner diameter, which is connected to the bypass exhaust path 62
such that it bypasses the first bypass opening/closing valve 72;
and an orifice mechanism 76 and a second bypass opening/closing
valve 78 that are installed in the auxiliary bypass exhaust line 74
in order.
[0076] Here, as is generally known, the orifice mechanism 76 has an
orifice (not shown) for narrowing a flow path area, and the soft
start valve mechanism 70 can be maintained at a low pumping
conductance state by closing the first bypass opening/closing valve
72 and opening the second bypass opening/closing valve 78. Herein,
each of the inner diameters of the bypass exhaust path 62 and the
auxiliary bypass exhaust line 74, and the flow path area of the
orifice hole in the orifice mechanism 76 are preset and the pumping
conductance thereof is fixed, enabling a pressure substantially
identical to a required processing pressure to be obtained when a
relatively high processing pressure process is carried out.
[0077] In other words, there are many cases where the processing
pressure need not be controlled with high accuracy in a relatively
high processing pressure process. In these cases, it is configured
such that the pressure control of the processing vessel 4 is
conducted by a preset fixed pumping conductance, and operations
such as the adjustment of the valve opening ratio and the like are
not conducted actively.
[0078] Next, an operation of the embodiment as configured above
will be explained.
[0079] <A Case of Exhausting an Atmospheric State to
Vacuum>
[0080] In case when the inside of the processing vessel 4 is in the
atmospheric state and is exhausted to vacuum, both opening/closing
valves 40 of the main exhaust line 34 are first closed to isolate
the second vacuum pump 60 comprising a turbo molecular pump, which
cannot be used until the inner pressure of the processing vessel 4
reaches to a specified vacuum level. At the same time, the soft
start valve mechanism 70 is kept at a low pumping conductance state
by closing the first bypass opening/closing valve 72 installed in
the bypass exhaust path 62 and by opening the second bypass
opening/closing valve 78 installed in the auxiliary bypass exhaust
line 74. Under the condition, the first vacuum pump 38 is operated
to start the vacuum exhaust. In this case, since an atmosphere of
the processing vessel 4 is exhausted only through the auxiliary
bypass exhaust line 74 having therein the orifice hole of the
orifice mechanism 76, the pumping conductance becomes very low as
mentioned above. As a result, the impact of the vacuum exhaust
caused in the processing vessel 4 is eased to thereby become very
small, and structures or particles inside the processing vessel 4
can be prevented from being scattered in a moment. Further, an
unnecessary film attached to an inner wall surface of the
processing vessel 4 or a surface of the inner structure may not be
peeled off to fall down, so that the generation of the particles
can be prevented.
[0081] As a result of the vacuum exhaust, if a specific vacuum
level (e.g., about 1330 Pa) is reached, the first bypass
opening/closing valve 72 is turned to be opened to vacuum exhaust
the whole bypass exhaust path 62. At this time, the second bypass
opening/closing valve 78 may remain to be either opened or
closed.
[0082] If a predetermined vacuum level, e.g., about 133 Pa,
corresponding to an upper limit of the pressure value in the turbo
molecular pump, is reached by further vacuum exhausting it, both of
the opening/closing valves 40 installed in the main exhaust line 34
are turned open, and at the same time, the second vacuum pump 60
begins to be operated. At this time, the first pressure control
valve 36 becomes fully opened. Simultaneously, the first and the
second bypass opening/closing valve 72 and 78 are turned to be
closed. By doing this, the inside of the processing vessel 4 can be
vacuum exhausted to a low pressure atmosphere.
[0083] <A Low Processing Pressure Process: e.g., Film Forming
Process>
[0084] Next, the pressure control of the processing vessel 4 during
a low processing pressure process is substantially same as the case
where the partial pressure of the processing gas is important as
was explained in the first embodiment.
[0085] Namely, the first and the second bypass opening/closing
valve 72 and 78 of the soft start valve mechanism 70 are converted
into the closed state; both opening/closing valves 40 of the main
exhaust line 34 are maintained at the opened state; and the inner
pressure of the processing vessel 4 is controlled by adjusting the
valve opening ratio of the pressure control valve 36 based on a
detection value of the pressure gauge 48. At this time, the flow
rate of each gas is maintained at a constant value as determined in
a recipe. The processing pressure of a low processing pressure
process is in the range from about tens of Pa to hundreds of Pa,
for example.
[0086] <A High Processing Pressure Process: e.g., Cleaning
Process or Oxidation Process>
[0087] Next, the pressure control of the processing vessel 4 during
a high processing pressure process will be discussed.
[0088] In this case, the low pumping conductance state is kept same
as in the case where the inside of the processing vessel 4 begins
to be exhausted from the atmospheric pressure to vacuum. Namely,
contrary to the above-described film forming process, both of the
opening/closing valves 40 installed in the main exhaust line 34 are
maintained at the closed state to isolate the second vacuum pump
60. In the soft start valve mechanism 70, the first bypass
opening/closing valves 72 is maintained at the closed state, and at
the same time, the second bypass opening/closing valves 78 is
maintained at the opened state, so that the exhaust gas is vacuum
exhausted only through the auxiliary bypass exhaust line 74 via the
orifice mechanism 76. At this time, the pumping conductance of the
soft start valve mechanism 70 is substantially same as that of the
pressure control valve 36 in which a minimum gas is formed even in
case of the fully closed state.
[0089] Accordingly, the process can be performed while the
processing pressure inside the processing vessel 4 is kept high.
The processing pressure of the process whose processing pressure is
high as mentioned above is in the range from about thousands of Pa
to 20000 Pa, for example.
[0090] In the high processing pressure process, the inner pressure
of the processing vessel 4 could not be controlled actively, but it
may not be limited thereto. For example, it can be configured such
that the inner pressure of the processing vessel 4 is detected by
the pressure gauge 48 and the flow rate controller is controlled by
the control unit 54 to maintain the detection value at a
predetermined pressure, and thus a gas flow rate, e.g., a flow rate
of a nonreactive gas or a cleaning gas, or a flow rate of an
oxidation gas in case of performing an oxidation process, is
controlled.
[0091] By doing this, the processing pressure can be controlled
with high accuracy even in case of the high processing pressure
process.
[0092] Further, the soft start valve mechanism 70 is explained for
a case where it is formed of the auxiliary bypass exhaust line 74,
the first and the second bypass opening/closing valve 72 and 78 and
the orifice mechanism 76. However, as the soft start valve
mechanism 70, a soft start valve of SMC company (registered
trademark) may be used for example, which has three functions of:
setting the inside of the bypass exhaust path 62 at a completely
blocked state; setting the bypass exhaust path 62 at a low pumping
conductance state; and setting the inside of the bypass exhaust
path 62 at about middle pumping conductance state somewhat higher
than the low pumping conductance.
[0093] Further, in the respective embodiments, a case of the film
forming process of the tungsten film was explained as an example,
but the present invention may be applied for the case of forming
other film species.
[0094] Still further, a process wherein a partial pressure of the
processing gas is important is not limited to the film forming
process, and other processes may be used. In the same manner, a
processing wherein a partial pressure of the processing gas is
relatively unimportant is not limited to the cleaning process, and
other processes, e.g., the oxidation process, the diffusion
processing and the like as mentioned above, may be applied.
[0095] Still further, the supply type of each gas is nothing but an
example. If the kinds of the processing gases increase or decrease,
the number of gas supply units accordingly increases or decreases.
Further, with respect to the configuration of the shower head unit
10, the present invention may adopt any of a pre-mix type or a
post-mix type, wherein in the pre-mix type, the processing gas is
mixed before being injected towards the mounting table 8 inside the
processing vessel 4, and in the post-mix type, the processing gas
is mixed after being injected from the shower head unit 10. Still
further, a gas introduction unit not using the shower head unit 10
may be applied for the present invention.
[0096] Still further, a single wafer processing apparatus was
explained as an example, but the present invention may be applied
to a batch type processing apparatus in which plural objects are
processed at a time.
[0097] Sill further, the control by the mass flow controller is
mainly employed for the PVD process which is performed within a
specific partial pressure range, and the pressure control valve is
used for the CVD process. But, they can be applied for the case of
performing both of the PVD and the CVD processes in the same
apparatus.
[0098] Still further, in the aforementioned embodiments, the
semiconductor wafer was explained as an object to be processed.
However, it is not limited to this, and a glass substrate, an LCD
substrate or the like, may be used as well.
[0099] Still further, in the aforementioned embodiments, either the
temperature control unit or the pressure control valve was kept
constant during the pressure control, but the pressure control may
be conducted all the time by both operations thereof while the
temperature control unit and the pressure control valve are not
made constant.
[0100] While the invention has been shown and described with
respect to the preferred embodiments, it will be understood by
those skilled in the art that various changes and modifications may
be made without departing from the spirit and scope of the
invention as defined in the following claims.
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