U.S. patent application number 15/541083 was filed with the patent office on 2017-12-07 for improvements in or relating to vacuum pumping arrangement.
The applicant listed for this patent is Edwards Limited. Invention is credited to Nigel Paul SCHOFIELD, Andrew SEELEY, Jack Raymond TATTERSALL, Neil TURNER.
Application Number | 20170350395 15/541083 |
Document ID | / |
Family ID | 55129989 |
Filed Date | 2017-12-07 |
United States Patent
Application |
20170350395 |
Kind Code |
A1 |
SCHOFIELD; Nigel Paul ; et
al. |
December 7, 2017 |
IMPROVEMENTS IN OR RELATING TO VACUUM PUMPING ARRANGEMENT
Abstract
A vacuum pumping arrangement includes a first primary pump
having an inlet and an outlet, and a first common pumping line
fluidly connected to the inlet, the first common pumping line
including a plurality of first common pumping line inlets each of
which is fluidly connectable to at least one vacuum process chamber
forming the semiconductor fabrication tool, the first primary pump
and the first common pumping line handling deposition process
flows. The pumping arrangement further including a second primary
pump having an inlet and an outlet, and a second common pumping
line fluidly connected to the inlet of the second primary pump, the
second common pumping line including a plurality of second pumping
line inlets each of which is fluidly connectable to at least one
process chamber forming the semiconductor fabrication tool, the
second primary pump and the second common pumping line handling
cleaning process flows.
Inventors: |
SCHOFIELD; Nigel Paul;
(Burgess Hill, Sussex, GB) ; SEELEY; Andrew;
(Clevedon, Somerset, GB) ; TATTERSALL; Jack Raymond;
(Bonbeach, Victoria, AU) ; TURNER; Neil; (Burgess
Hill, Sussex, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Edwards Limited |
Burgess Hill, Sussex |
|
GB |
|
|
Family ID: |
55129989 |
Appl. No.: |
15/541083 |
Filed: |
January 6, 2016 |
PCT Filed: |
January 6, 2016 |
PCT NO: |
PCT/GB2016/050018 |
371 Date: |
June 30, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 25/02 20130101;
C23C 16/4405 20130101; C23C 16/4412 20130101; F04C 2220/30
20130101; F04C 23/003 20130101; H01L 21/67155 20130101; F16K 15/00
20130101; H01L 21/205 20130101; F04C 23/001 20130101 |
International
Class: |
F04C 25/02 20060101
F04C025/02; H01L 21/67 20060101 H01L021/67 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 6, 2015 |
GB |
1500133.2 |
Jan 6, 2016 |
GB |
1600201.6 |
Claims
1. A vacuum pumping arrangement comprising: a first primary pump
having an inlet and an outlet, and a first common pumping line
fluidly connected to the inlet of the first primary pump, the first
common pumping line including a plurality of first common pumping
line inlets each of which is fluidly connectable to at least one
vacuum process chamber within the group of process chambers forming
the semiconductor fabrication tool, the first primary pump and the
first common pumping line, in use, handling deposition process
flows; and a second primary pump having an inlet and an outlet, and
a second common pumping line fluidly connected to the inlet of the
second primary pump, the second common pumping line including a
plurality of second pumping line inlets each of which is fluidly
connectable to at least one process chamber within the group of
process chambers forming the semiconductor fabrication tool, the
second primary pump and the second common pumping line, in use,
handling cleaning process flows.
2. The vacuum pumping arrangement according to claim 1 wherein each
of the first and second primary pumps has a respective abatement
module arranged in fluid communication therewith.
3. The vacuum pumping arrangement according to claim 1 wherein
respective pairs of first and second pumping line inlets are
fluidly interconnected by a valve module which in turn is fluidly
connectable to a said at least one process chamber.
4. The vacuum pumping arrangement according to claim 3 wherein at
least one valve module includes a fail-safe arrangement to prevent
mixing of deposition and cleaning process flows upstream of the
valve module.
5. The vacuum pumping arrangement according to claim 3 wherein at
least one valve module is located downstream of any booster pump
associated with the corresponding process chamber.
6. The vacuum pumping arrangement according to claim 1 wherein the
second common pumping line is selectively fluidly connectable with
the first primary pump.
7. The vacuum pumping arrangement according to claim 1 wherein at
least one common pumping line includes an interconnecting member
fluidly connectable to a common pumping line of at least one other
vacuum pumping arrangement.
8. The vacuum pumping arrangement according to claim 1 further
including one or more rough down pumping lines, each having a first
end arranged in fluid communication with a primary pump and a
second end including a bleed valve, the bleed valve being fluidly
connectable to a respective process chamber to initially evacuate
the said process chamber.
9. A semiconductor fabrication facility comprising a plurality of
semiconductor fabrication tools each of which includes: a plurality
of process chambers; and a vacuum pumping arrangement including a
primary pump having an inlet and an outlet, the inlet being fluidly
connected to a common pumping line, the common pumping line
including a plurality of pumping line inlets each of which is
fluidly connected to at least one corresponding process chamber,
the common pumping line of the vacuum pumping arrangement of one
semiconductor fabrication tool being fluidly connected to the
common pumping line of the vacuum pumping arrangement of at least
one other semiconductor fabrication tool.
10. A vacuum pumping arrangement for evacuating at least first and
second vacuum process chambers, said vacuum pumping arrangement
comprising: at least first and second vacuum pumps, said first
vacuum pump inlet in fluid communication with an outlet of the
first process chamber, said second vacuum pump inlet in fluid
communication with an outlet of the second process chamber; at
least first and second valve modules, said valve modules being at
least three way valve modules comprising an inlet, a first outlet
and a second outlet, said first valve module inlet in fluid
communication with an outlet of the first vacuum pump, said second
valve arrangement inlet in fluid communication with an outlet of
the second vacuum pump; at least first and second common pumping
lines, the first common pumping line in fluid communication with
the first outlets of both of the first and second valve modules,
the second common pumping line in fluid communication with the
second outlets of both the first and second valve modules, wherein
the first and second vacuum pumps are secondary vacuum pumps and
each of the first and second common pumping lines comprises at
least respective first and second primary vacuum pump to provide
sufficient pumping capacity for each of the at least first and
second vacuum pumps when in fluid communication via the first
and/or second valve modules; and wherein at least one of the common
pumping lines is in fluid communication with an abatement
device.
11-13. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This Application is a Section 371 National Stage Application
of International Application No. PCT/GB2016/050018, filed Jan. 6,
2016, which is incorporated by reference in its entirety and
published as WO 2016/110694 A1 on Jul. 14, 2016 and which claims
priority of British Application No. 1500133.2, filed Jan. 6, 2015
and British Application No. 1600201.6, filed Jan. 6, 2016.
FIELD
[0002] The various embodiments relate to a vacuum pumping
arrangement for use in a semiconductor fabrication facility, a
semiconductor fabrication tool including such a vacuum pumping
arrangement, and a semiconductor fabrication facility including a
plurality of semiconductor fabrication tools each of which includes
such a vacuum pumping arrangement.
BACKGROUND
[0003] Vacuum pumping arrangements are used extensively in
connection with semiconductor fabrication, e.g. the manufacture of
silicon chips, flat panel displays, solar panels and light emitting
diodes (LEDs). There is a need to improve the efficiency of such
pumping arrangements, particularly in relation to the manufacture
of silicon chips.
[0004] FIG. 4 illustrates schematically a known vacuum pumping
arrangement 1 for evacuating several process chambers 22a, 22b,
22c, 22d of a process tool 86. In the example illustrated in FIG.
4, each process chamber 22a, 22b, 22c, 22d is evacuated by both at
least one secondary pump 520a, 520b, 520c, 520d, for example a
roots booster pump and/or a turbomolecular pump; and a primary pump
12a, 12b, 12c, 12d, for example a multistage roots, claw or screw
type dry vacuum pump, respectively. For example, first process
chamber 22a is in fluid communication with and evacuated by first
secondary pump 520a and first primary vacuum pump 12a. It is common
for a plurality of similar or identical processing steps to be
carried out in each processing chamber 22a, 22b, 22c, 22d for
example a first processing step could be a deposition step, and a
second processing step could be a cleaning step. Any unused process
gases and process by-products pass through the respective secondary
520 and primary pumps 12 and are exhausted to a single type of
abatement module 3 which must be able to destroy all the exhaust
gases conveyed to it.
[0005] Another know vacuum pump arrangement 500 for evacuating
several process chambers 22a, 22b, 22c, 22d of a process tool 86 is
illustrated schematically in FIG. 5. The vacuum pump arrangement
500 comprises a primary pump 12 having an inlet 14 and an outlet
16, and further comprises a common pumping line 180 fluidly
connected to the primary pump inlet 14, the common pumping line 180
includes a plurality of pumping line inlets 20 each of which is
fluidly connectable to at least one process chamber 22a, 22b, 22c,
22d within a group of process chambers 22 forming said
semiconductor process tool 86. Each common pumping line inlet 20 is
arranged in fluid communication with at least one chamber
connecting line (foreline) which, in use, is fluidly connected to a
respective process chamber 22. Each chamber connecting line
includes at least one secondary pump 520(a-d), such as a roots
booster and/or turbomolecular pump fluidly connected therewith for
evacuating each respective chamber 22(a-d).
[0006] The provision of a common pumping line 180 which is fluidly
connectable to each of a plurality of vacuum process chambers 22
within a group of vacuum process chambers 22(a-d) that forms a
semiconductor fabrication tool 86, allows a single primary vacuum
pump 12 to service all of the process chambers of a given
fabrication tool, and thereby reduces both the capital cost of
installing the vacuum pumping arrangement 500, as well as the
on-going running costs, compared to those associated with the
conventional vacuum pumping arrangement as shown in FIG. 4. The
inclusion of at least one first secondary pump 520(a-d) in each
foreline, for example a roots booster pump and/or a turbomolecular
pump, helps to prevent pressure changes in one chamber 22 affecting
the pressure within a second chamber 22, and also buffers, or
protects, the pressure within a given chamber 22(a-d) from any
pressure changes in the common pumping line 180.
[0007] A reduction in the number of primary vacuum pumps 12
required to service the process chambers 22 of a given fabrication
tool 86 also reduces the space required to house the vacuum pumping
arrangement.
[0008] The vacuum pumping arrangement 500 further includes a first
abatement module (device) 3 arranged in fluid communication with
the primary pump 12. The first abatement module 3 within such an
arrangement 500 must also be able to treat the process flows from
all of the process chambers 22(a-d) of a given fabrication tool 86
simultaneously.
[0009] There is a need to improve the efficiency of such vacuum
pumping and abatement arrangements.
[0010] The discussion above is merely provided for general
background information and is not intended to be used as an aid in
determining the scope of the claimed subject matter. The claimed
subject matter is not limited to implementations that solve any or
all disadvantages noted in the background.
SUMMARY
[0011] A first aspect provides a vacuum pumping arrangement that
includes
[0012] a first primary pump having an inlet and an outlet, and a
first common pumping line fluidly connected to the inlet of the
first primary pump, the first common pumping line including a
plurality of first common pumping line inlets each of which is
fluidly connectable to at least one vacuum process chamber within
the group of process chambers forming the semiconductor fabrication
tool, the first primary pump and the first common pumping line, in
use, handling deposition process flows; and
[0013] a second primary pump having an inlet and an outlet, and a
second common pumping line fluidly connected to the inlet of the
second primary pump, the second common pumping line including a
plurality of second pumping line inlets each of which is fluidly
connectable to at least one process chamber within the group of
process chambers forming the semiconductor fabrication tool, the
second primary pump and the second common pumping line, in use,
handling cleaning process flows.
[0014] The inclusion of first and second primary pumps and
associated first and second common pumping lines still provides an
improved cost and space utilisation efficiency compared to the
process tool illustrated in FIG. 4, while permitting optimisation
of the respective primary pump according to the nature of the
process flow passing therethrough. The various embodiments thereby
provides further efficiency savings. For example primary pumps
required to pump deposition gases are often required to operate at
temperatures above, for example, 100.degree. C. to 80.degree. C. to
prevent deposition exhaust gases, such as tetraethylorthosilicate
(TEOS), collecting within the pumping mechanism, whereas primary
pumps evacuating halogenated etch/chamber cleaning gases are often
required to run cooler than, for example, 1000.degree. C.
-80.degree. C. to reduce the rate of corrosion in the pumping
mechanism.
[0015] Preferably each of the first and second primary pumps has a
respective abatement module arranged in fluid communication
therewith. Such an arrangement permits optimisation of each
abatement module according to the process flow, i.e. deposition or
etch/cleaning, passing therethrough, thereby helping to ensure
maximum efficiency of each abatement module compared to a single
abatement module provided to abate all the unused process gases
(precursors) and process by products exhausted from a chamber, or
group of chambers. With this arrangement each abatement module can
be chosen to be specifically designed for the abatement of, for
example, fluorine, or (TEOS).
[0016] Optionally the abatement modules are or includes one of:
[0017] a plasma-based device;
[0018] a flame-based device; and
[0019] an oxidizer.
[0020] Plasma- and flame-based devices, especially in the presence
of water and/or oxygen provide a desired breakdown of
perfluorocarbons (PFCs), such as CF.sub.4, NF.sub.3, SF.sub.6 etc.,
following, e.g. an etch process in a process chamber or a process
chamber cleaning process, and also produce fine dry powders from
deposition gases such as silane and tetraethylorthosilicate (TEOS).
However, the addition of water and/or oxygen to a plasma based
device for the destruction of deposition gases is undesirable. An
oxidizer usefully burns process gas flows with reduced NO.sub.x
emissions.
[0021] The abatement modules may be located:
[0022] upstream of a primary pump;
[0023] downstream of a primary pump; and
[0024] at an interstage of a primary pump.
[0025] Mounting the abatement module upstream, or at an interstage,
of one of the primary pumps means exhaust gases comprising etch
gases such as PFCs are destroyed before they are substantially
diluted with nitrogen purge, thus reducing the power requirements
of the abatement module. It is well known that the power
requirements of an abatement module increases with increasing gas
dilution.
[0026] In addition to the reduced dilution of a process flow
afforded by having the abatement module arranged at an interstage
of the primary pump, it also permits sub-atmospheric abatement at
approximately 200 mbar, which provides an increase in safety when
handling flammable fluids (SiH.sub.4, TEOS etc.) exhausted from the
process chambers because any potential explosive fluid would have
lower pressure limits. Furthermore, arrangement at an interstage of
the primary pump provides a very integrated primary pump and
abatement arrangement which is readily installable in a compact and
efficient manner.
[0027] Arranging the abatement module downstream of the primary
pump has the benefit of avoiding the need for a heat exchanger
immediately following, e.g. an oxidizer.
[0028] Preferably respective pairs of first and second common
pumping line inlets are fluidly interconnected by a valve module
which in turn is fluidly connectable to a said at least one process
chamber.
[0029] The inclusion of a valve module enables a particular process
chamber exhaust to be directed to either the first or second common
pumping lines depending on the composition of the fluid being
exhausted from the process chamber at a given time, namely
dependent on what processing step is being carried out in said
chamber. In some respect it also reduces the amount of pipeline
required between the common pumping line and each corresponding
process chamber, compared to the installation of two forelines from
each chamber, and so provides a commensurate installation cost
saving.
[0030] In another embodiment at least one valve module includes a
fail-safe arrangement, for example a one way valve, to prevent the
accidental mixing of deposition and cleaning process flows upstream
of the valve module. Such an arrangement helps to ensure safe
operation of the vacuum pumping arrangement.
[0031] At least one valve module may be located downstream of any
of the at least one first or second secondary pump associated with
the corresponding process chamber. For example the valve module
could be located downstream of a turbomolecular pump, but upstream
of a roots booster pump in a given chamber connecting foreline. The
at least one valve module is preferably located downstream of the
roots booster to ensure the process tool is protected from pressure
variations and back migration of process gases.
[0032] Such location of a valve module helps to minimise the size
and cost of the valve module.
[0033] Preferably the second common pumping line is selectively
fluidly connectable with the first primary pump in isolation from
the first common pumping line.
[0034] The ability to, as required, fluidly connect the second
common pumping line with the first primary pump permits selective
cleaning of the first primary pump, i.e. removal of any deposition
process by-products from the first primary pump. By selectively
passing etch, or clean process by-product exhaust gases
(halogenated gases) through the first primary pump it is possible
to periodically clean the internal vacuum pump mechanism. Thus
improving the time between service intervals for the first primary
pump.
[0035] The second primary pump, primarily designed to pump the
cleaning step gases and their corrosive by-products, will
preferably utilise corrosion resistant materials for one or more
parts of the or each pump. This will increases the cost of the pump
to a certain degree despite the advantages of providing a dedicated
cleaning gas primary pump.
[0036] However, it is also possible to selectively fluidly connect
the first common pumping line (used for pumping deposition process
by-product gases for example) with the second primary pump in
isolation from the second common pumping line to allow small
amounts of "protective" deposits build up on and accumulation
member such as the internal vacuum pump mechanisms to reduce the
effect of the corrosive gases. Thus providing for a less corrosion
resistant pump to be required for the second primary pump.
[0037] Thus an exemplary embodiment also provides a vacuum pumping
arrangement, for use in a semiconductor fabrication assembly that
includes:
[0038] a primary pump configured principally to handle cleaning
process flows, the pump having arranged therein an accumulation
member lying in fluid communication with the internal swept volume
of the pump; and
[0039] a control module configured to operate the pump during a
deposition step and a subsequent cleaning step which together
define a deposition-clean cycle, the control module during the
deposition step selectively diverting a deposition process flow
through the internal swept volume of the pump whereby a deposition
residue accumulates on the accumulation member, the control module
during the cleaning step allowing a cleaning process flow to flow
through the internal swept volume of the pump whereby the cleaning
process flow reacts with the deposition residue and removes at
least a portion of the deposition residue from the accumulation
member, and the control module monitoring at least one of the
accumulation and the removal of deposition residue from the
accumulation member and controlling a characteristic of at least
one of the deposition process residue accumulation step and the
cleaning process deposition reaction step in response to said
monitoring to control the level of deposition residue remaining at
the end of a deposition-clean cycle.
[0040] Having the control module selectively divert a deposition
process flow through the internal swept volume of the pump whereby
a deposition residue accumulates on the accumulation member means
that during the cleaning step, i.e. essentially normal operation of
the pump, any aggressive constituents of the cleaning process flow,
e.g. any un-reacted cleaning gas, preferentially attacks the
deposition residue rather than attacking the interior of the
pump.
[0041] In addition, having the control module monitor at least one
of the accumulation and the removal of deposition residue from the
accumulation member helps to avoid one or both of either the
accumulation of too much deposition residue (which might otherwise
fill pumping clearances and thereby reduce the reliability of the
pump), or the complete removal of the deposition residue before the
cleaning step is complete (which might otherwise allow any
un-reacted cleaning gas to attack the interior of the pump).
[0042] Moreover, such functionality is provided without the need to
employ expensive, corrosion resistant, materials for any parts of
the pump, and so the cost of the vacuum pumping arrangement is not
unduly increased.
[0043] It is possible to monitor the thickness of deposit by
monitoring the temperature profile of the pump, or the motor
current profile to look for abnormalities caused by the decrease in
running clearances in the pump as the deposition residue
accumulates.
[0044] In an exemplary embodiment, the accumulation member includes
a residue thickness monitor coupled therewith and the control
module monitors at least one of the accumulation and the removal of
deposition residue from the accumulation member by interpreting
signals from the residue thickness monitor to determine the
thickness of the deposition residue on the accumulation member.
[0045] The inclusion of a residue thickness monitor provides a
relatively accurate and real-time indication of the level of
deposition residue on the accumulation member, and so facilitates
the control module in ensuring that a desired amount of deposition
residue remains on the accumulation member at the end of a
deposition-clean cycle.
[0046] Optionally the control module monitors the accumulation of
deposition residue on the accumulation member using the
stoichiometry of the reaction between the deposition residue and
cleaning gas by determining the volume of deposition process flow
which passes through the pump during the deposition step, and/or
the control module monitors the removal of deposition residue from
the accumulation member by determining the volume of cleaning
process flow which passes through the pump during the cleaning
step.
[0047] The control module may include timer module, and the control
module may monitor the accumulation of deposition residue on the
accumulation member by determining the period of time for which the
deposition process flows, and/or the control module may monitor the
removal of deposition residue from the accumulation member by
determining the period of time for which the cleaning process
flows.
[0048] The foregoing arrangements provide a ready means of at least
estimating the amount of deposition residue on the accumulation
member in a manner which requires little or no additional
modification to a pump.
[0049] Preferably the accumulation member includes a cooling
element, and the control module is configured to selectively
operate the cooling element during the deposition step to cool the
accumulation member and thereby selectively increase the rate of
accumulation of deposition residue on the accumulation member.
[0050] Such an arrangement allows the control module to increase
the level of deposition residue on the accumulation member, as
desired, e.g. in the event of a large volume of cleaning process
flow being expected during the cleaning step.
[0051] In another exemplary embodiment, the accumulation member
includes a heating element, and the control module is configured to
selectively operate the heating element during the cleaning step to
heat the accumulation member and thereby selectively increase the
rate of removal of deposition residue from the accumulation
member.
[0052] Such an arrangement allows the control module to reduce the
level of deposition residue on the accumulation member, as desired,
e.g. in the event that the level of deposition residue may begin to
adversely impact on the reliability of the pump.
[0053] The accumulation member can be a separate member attached to
the pump and/or the internal surfaces of the pumping mechanism. The
heating and cooling can be effected using a stand-alone heater and
cooling device, or using the cooling circuit of the pump by varying
the temperature of the cooling fluid circulated.
[0054] Optionally the control module monitors at least one of the
accumulation and the removal of deposition residue from the
accumulation member and controlling a characteristic of at least
one of the deposition process residue accumulation step and the
cleaning process deposition reaction step in response to said
monitoring to control the level of deposition residue remaining at
the end of a deposition-clean cycle. Leaving substantially no
deposition residue on the accumulation member at the end of the
deposition-clean cycle is advantageous since it means that no more
deposition residue accumulated than was required to preferentially
remove the aggressive constituents from the cleaning process flow,
and so unnecessary waste of the deposition process flow
constituents is avoided.
[0055] It will be apparent that it is also possible to monitor the
thickness of deposition residce accumulated on an accumulation
member in the first primary pump, namely the one configured for
normally pumping the deposition process by-products, and
selectively divert cleaning gases through the first primary pump
until the deposition process residue has been substantially removed
therefrom.
[0056] According to a further aspect there is provided a method of
controlling a vacuum pumping arrangement during a deposition step
and a subsequent cleaning step which together define a
deposition-clean cycle, the vacuum pumping arrangement including a
pump configured principally to handle cleaning process flows and
having arranged therein an accumulation member lying in fluid
communication with the internal swept volume of the pump, the
method comprising the steps of:
[0057] (a) during the deposition step selectively diverting a
deposition process flow through the internal swept volume of the
pump whereby a deposition residue accumulates on the accumulation
member;
[0058] (b) during the cleaning step allowing a cleaning process
flow to flow through the internal swept volume of the pump whereby
the cleaning process flow reacts with the deposition residue and
removes at least a portion of the deposition residue from the
accumulation member;
[0059] (c) monitoring at least one of the accumulation and the
removal of deposition residue from the accumulation member; and
[0060] (d) controlling a characteristic of at least one of the
deposition process residue accumulation step and the cleaning
process deposition reaction step in response to said monitoring to
control the level of deposition residue remaining at the end of a
deposition-clean cycle.
[0061] The method of such embodiments shares the benefits
associated with the corresponding features of the vacuum pumping
arrangement of the embodiments.
[0062] However, as described above, it is preferable that both the
first and second primary pumps associated with the first and second
common pumping lines are chosen for optimum pumping ability and
service interval lifetime for the exhaust gases pumped down said
first and second common pumping line to which they are more often
fluidly connected thereto.
[0063] In an exemplary embodiment, at least the first or second
common pumping line includes an interconnecting member fluidly
connectable to a common pumping line of at least one other vacuum
pumping arrangement.
[0064] The exemplary embodiment also preferable includes at least
two pumping arrangements, as described above, wherein at least one
of the common pumping lines is fluidly interconnected by respective
interconnecting members.
[0065] The ability to fluidly interconnect at least the first or
second common pumping lines of respective vacuum pumping
arrangements via, for example, a valve arrangement provides the
option of including a degree of primary pump and/or abatement
module redundancy within, e.g. a semiconductor fabrication
facility, to accommodate the breakdown or maintenance of a primary
pump, or an abatement module, without the need to shut down the
whole fabrication facility. In addition, the additional evacuated
volume provided by the interconnecting pipelines of each common
pumping line can provide a degree of buffering against any pressure
changes within the facility.
[0066] The vacuum pumping arrangement may further include one or
more rough down pumping lines, each having a first end arranged in
fluid communication with at least one of the first or second
primary pumps and a second end including a bleed valve, the bleed
valve being fluidly connectable to a respective process chamber to
initially evacuate the said process chamber.
[0067] Conveniently the first end of the rough down pumping line is
arranged in fluid communication with the primary pump via one
of:
[0068] a pumping line inlet of the common pumping line; and
[0069] an interstage of the primary pump.
[0070] Alternatively the vacuum pumping arrangement may further
include one or more rough down pumping lines, and wherein each
valve module has an additional outlet and the first end of the
rough down pumping line is arranged in fluid communication with a
third common pumping line comprising a third or further primary
pump and the second end of the rough down pumping line is in fluid
communication with the additional outlet of the valve module.
[0071] The inclusion of one or more rough down pumping lines having
the aforementioned features helps to minimise pressure fluctuations
within the vacuum pumping arrangement which both protects the
processes in other process chambers and minimises perturbation
(disruption) of the downstream abatement modules.
[0072] According to a further aspect there is provided a
semiconductor fabrication facility (factory) that includes a
plurality of semiconductor fabrication tools each of which
includes:
[0073] a plurality of process chambers; and
[0074] a vacuum pumping arrangement including a primary pump having
an inlet and an outlet, the inlet being fluidly connected to a
common pumping line, the common pumping line including a plurality
of pumping line inlets each of which is fluidly connected to at
least one corresponding process chamber,
[0075] the common pumping line of the vacuum pumping arrangement of
one semiconductor fabrication tool being fluidly connected to the
common pumping line of the vacuum pumping arrangement of at least
one other semiconductor fabrication tool.
[0076] Fluidly interconnecting the common pumping lines (used for
pumping similar/compatible exhaust gas species/mixtures) of
respective vacuum pumping arrangements provides a degree of primary
pump and/or abatement module redundancy within the semiconductor
fabrication facility, which permits the facility to, for example,
accommodate the servicing or breakdown of a primary pump and/or
abatement module without the need to shut down the whole
fabrication facility or a particular process tool.
[0077] According to a still further aspect there is provided a
vacuum pumping arrangement for evacuating at least first and second
vacuum process chambers, said vacuum pumping arrangement
comprising: at least first and second vacuum pumps, said first
vacuum pump inlet in fluid communication with an outlet of the
first process chamber, said second vacuum pump inlet in fluid
communication with an outlet of the second process chamber; at
least first and second valve modules, said valve modules being at
least three way valve modules comprising an inlet, a first outlet
and a second outlet, said first valve module inlet in fluid
communication with an outlet of the first vacuum pump, said second
valve arrangement inlet in fluid communication with an outlet of
the second vacuum pump; at least first and second common pumping
lines, the first common pumping line in fluid communication with
the first outlets of both of the first and second valve modules,
the second common pumping line in fluid communication with the
second outlets of both the first and second valve modules, wherein
the first and second vacuum pumps are secondary vacuum pumps and
each of the first and second common pumping lines comprises at
least respective first and second primary vacuum pump to provide
sufficient pumping capacity for each of the at least first and
second vacuum pumps when in fluid communication via the first
and/or second valve modules; and wherein at least one of the common
pumping lines is in fluid communication with an abatement
device.
[0078] The provision of the at least three way valve modules for at
least two process chambers and a plurality of common pumping lines
in fluid communication with said valve modules allows for common
process flows, namely chemically similar, or compatible, unused
process gasses (precursors) and their by-products exhausted from
different process chambers to be directed, via the valve module, to
a common pumping line (conduit). Thus, the chemically similar, or
compatible, unused process gasses (precursors) and their
by-products directed to each common pumping conduit (exhaust pipe)
can then treated in a more specific, suitable, and therefore
efficient, abatement device for said exhaust gas flow type. In
addition, the utilisation of such an apparatus also means that the
primary vacuum pumps can also be optimised for a particular process
flow.
[0079] In an exemplary embodiment, the first common pumping line is
in fluid communication with a first abatement device and the second
common pumping line is in fluid communication with a second
abatement device so that the process exhaust gases conveyed to each
of said common pumping lines can be directed to an abatement module
optimised for said exhaust gases conveyed thereto.
[0080] The at least first and second vacuum pumps are, by example,
selected from at least one of a roots booster vacuum pump and/or a
molecular vacuum pump and the at least first and second primary
vacuum pumps are selected from at least one of a claw, roots,
screw, scroll, rotary vane and liquid ring vacuum pump depending on
the composition and flow rates of exhaust gases directed to each of
the at least first and second common pumping lines.
[0081] It is possible to control the valves manually, but in
accordance with one embodiment, the vacuum pump arrangement further
includes a controller configured to control the valve modules,
vacuum pumps and abatement modules dependent on a received signal,
said signal indicating the composition of the gases exhausted from
the at least first and/or second vacuum process chambers. This
provides a more efficient solution compared to manually monitoring
the processes and switching the valve modules gases.
[0082] The Summary is provided to introduce a selection of concepts
in a simplified form that are further described in the Detail
Description. This summary is not intended to identify key features
or essential features of the claimed subject matter, nor is it
intended to be used as an aid in determining the scope of the
claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0083] There now follows a brief description of embodiments, by way
of non-limiting example, with reference being made to the following
figures in which:
[0084] FIG. 1 shows a schematic view of a vacuum pumping
arrangement according to a first embodiment;
[0085] FIG. 1b shows a schematic view of a portion of the vacuum
pumping arrangement according to a first embodiment;
[0086] FIG. 2 shows a schematic view of a vacuum pumping
arrangement according to a second embodiment;
[0087] FIG. 3 shows a schematic view of a vacuum pumping
arrangement according to a third embodiment;
[0088] FIG. 4 shows a schematic view of a known vacuum pumping
arrangement; and
[0089] FIG. 5 shows a schematic view of a further known vacuum
pumping arrangement.
[0090] FIGS. 6a and 6b show schematic views of the protective
deposition and cleaning pumping arrangement.
DESCRIPTION OF THE EMBODIMENTS
[0091] A vacuum pumping arrangement according to a first embodiment
is designated generally by reference numeral 70.
[0092] The first vacuum pump arrangement 70 includes a first
primary pump 72, selected from, for example, at least one of a
multistage claw and/or roots, screw, scroll, rotary vane and liquid
ring vacuum pump, which has a first inlet 74 and a first outlet 76.
The first inlet 74 is fluidly connected to a first common pumping
line 78 which includes four first pumping line inlets 80. In other
embodiments (not shown) the common pumping line 78 may include
fewer than or more than four pumping line inlets 80. Each first
pumping line inlet 80 is, in use, fluidly connected to a single
process chamber 22 within a group of process chambers forming part
of a first semiconductor fabrication tool 86.
[0093] The first semiconductor fabrication tool 86 is configured to
manufacture silicon chips, but could also equally be configured to
manufacture flat panel displays, solar panels or LEDs. The tools
86, illustrated in FIGS. 1, 2 and 3 are a chemical vapour
deposition tool (CVD) in which both deposition and chamber cleaning
steps are carried out.
[0094] The first vacuum pump arrangement 70 also includes a second
primary pump 88, also selected from, for example, at least one of a
multistage claw and/or roots, screw, scroll, rotary vane and liquid
ring vacuum pump, which has a second inlet 90 and a second outlet
92. The second inlet 90 is fluidly connected to a second common
pumping line 94 which in this example also includes four second
pumping line inlets 96. Each second pumping line inlet is, in use,
fluidly connected to a single process chamber 22 within the first
semiconductor fabrication tool 86.
[0095] Respective pairs 98, 100, 102, 104 of first and second
pumping line inlets 80, 96 are fluidly interconnected by a valve
module 106 which in turn is, in use, fluidly connected to a
corresponding process chamber 22.
[0096] Each valve module 106 includes a fail-safe arrangement (not
shown), such as a one way valve, a mechanical interlock or an
electronic handshake, to prevent mixing of different, possibly
incompatible, process flows downstream (i.e. in the common pumping
lines 78, 94) or upstream (i.e. in the process chamber 22) of the
valve module 106.
[0097] In the embodiment shown the valve module 106 includes a
three-way valve 108. In other embodiments, however, the valve
module 106 may include a different valve arrangement, e.g. a pair
of simple valves and a two-way pipeline branch.
[0098] The first vacuum pumping arrangement 70 also includes a
first abatement module 110 which is arranged in fluid communication
with the first primary pump 72.
[0099] The first abatement module 110 in the first embodiment is a
DC plasma device 112 which is arranged at an interstage port 114 of
the first primary pump 72. The first abatement module 110, however,
also includes a process flow cooling element, i.e. a heat
exchanger, (not shown) and particulate trap (not shown) which are
located downstream of the DC plasma device 112 to provide a degree
of protection to the vacuum pump 72. In addition, the first
abatement module 110 may include a fluid inlet (not shown) to allow
the introduction of, e.g. nitrogen or air, to urge any particles
produced by the DC plasma device 112 through the first abatement
module 110.
[0100] In other embodiments, the first abatement module 110 may
also be or include a radio frequency (RF) plasma device, a
microwave plasma device, or a flame-based device; and it may
alternatively be arranged upstream or downstream of the first
primary pump 72.
[0101] In addition, the first vacuum pumping arrangement 70
includes a second abatement module 116 which is arranged downstream
of and in fluid communication with the first abatement module 110.
The second abatement module 116 is in the form of a wet scrubber
118.
[0102] A first common scrubber line 120 which, in use, may also be
fluidly connected to a similar first common scrubber line 120 of
another vacuum pumping arrangement (not shown), fluidly connects
the wet scrubber 118 with the first abatement module 110, via the
first primary pump 72. In this manner a single wet scrubber 118 is
able to service a number of first primary pumps 72 in otherwise
separate second semiconductor fabrication tools 86.
[0103] The second abatement module 116, i.e. the wet scrubber 118,
is also arranged in fluid communication with the second primary
pump 88, in such a way that the second abatement module 116 defines
a `first` abatement module from the perspective of the second
primary pump 88.
[0104] The second abatement module 116, i.e. the wet scrubber 118,
is fluidly connected to the second primary pump 88 by a second
common scrubber line 122 which, in use, is fluidly connected to a
similar second common scrubber line 122 of another vacuum pumping
arrangement (not shown). As a result a single wet scrubber 118 is
able also to service a number of second primary pumps 88 in
otherwise separate second semiconductor fabrication tools 86 (as
well as the number of first primary pumps 72 indicated above).
[0105] As an alternative, the second abatement module 116, i.e. the
wet scrubber 118, may be fluidly connected solely to only a single
first primary pump 72 and/or to only a single second primary pump
88.
[0106] The wet scrubber 118 may additionally include an
electrostatic dust trap (not shown) to capture any dust particles
passing therethrough.
[0107] The first and second abatement modules 110, 116 are chosen
with sufficient capacity to abate (treat) the total maximum
possible simultaneous process exhaust gas/by-product gas flow from
all four process chambers 22.
[0108] Each of the first and second common pumping lines 78, 94
additionally includes first and second interconnecting members 46
each of which is, in use, fluidly connected to a corresponding
first or second common pumping line (not shown) of another vacuum
pumping arrangement. In other embodiments, one or other of the
first and second common pumping lines 78, 94 may include fewer than
or more than two such interconnecting members.
[0109] Each of the interconnecting members takes the form of a
simple valve 46, so as to allow selective disconnection of one
common pumping line 78, 94 from another corresponding common
pumping line 78, 94. Other types of interconnecting member are also
possible however.
[0110] In addition to the foregoing, the first and second pumping
line inlets 80, 96 within each respective pair 98, 100, 102, 104
are arranged in fluid communication, via the corresponding valve
module 106, with a chamber connecting line 48 (foreline).
[0111] Each chamber connecting line 48 is, in use, fluidly
connected to a respective process chamber 22.
[0112] Each chamber connecting line 48 also includes at least a
first secondary pump 50, in the form of a roots blower 58, and/or a
turbomolecular pump (not shown), which is fluidly connected
therewithin. The first secondary pump 50 is, in each instance,
located upstream of the corresponding valve module 106 and,
advantageously, is located on the same floor 60 as, and directly
mounted on, the corresponding process chamber 22 (i.e. in the clean
room). Each at least first secondary pump 50 is preferably a
two-stage roots booster vacuum pump 58 to produce a higher exhaust
pressure (because it will have a higher compression ratio between
its inlet and outlet compared to a single stage roots blower). The
use of said two stage blower 58, allows for the use of a primary
pump 72, 88 with a lower ultimate pressure rating than required
with a single stage blower. In addition, the roots blower 58
reduces pressure fluctuations in process chambers caused by
pressure changes in other process chambers connected via a common
pumping line 78, 94.
[0113] In the alternative, a primary pump 72, 88 with a higher
pumping speed may be used instead, or as well as the two-stage
roots blower 58. The higher capacity primary pump 72, 88 can
maintain or vary the pressure in the common pumping line by varying
its rotational frequency and/or with the use of an additional flow
control valve 483 located at its inlet.
[0114] The first vacuum pumping arrangement 70 also includes a
controller 482 which, in use, communicates with the corresponding
second semiconductor fabrication tool 86 and monitors the process
flow composition within various regions of the first vacuum pumping
arrangement 70.
[0115] The controller 482, advantageously includes a speed control
module which controls the speed of the first and/or second primary
pumps 72, 88 in order to help stabilise the pressure within the
corresponding first or second common pumping lines 78, 94.
[0116] The controller is also configured to control the valves 106,
the abatement modules 118, 110 and the valves 483.
[0117] The controller 482 controls which common pumping line 78, 94
the exhaust gases from the process chambers 22 are directed to via
the valves 106 dependent on the signal indicating the composition
of the exhaust gases from a particular chamber 22.
[0118] The first vacuum pumping arrangement 70 also includes a
cleaning connecting line 503 which fluidly interconnects the second
common pumping line 94 and the first primary pump 72. The cleaning
connecting line further includes valve members 501 to selectively
allow process flow to pass through the cleaning connecting line
503.
[0119] The ability to, as required, fluidly connect the second
common pumping line 94 in isolation with the first primary pump 72
permits selective cleaning of the first primary pump 72, i.e.
removal of any deposition process by-products from the first
primary pump 72. By selectively passing etch, or clean process
by-product exhaust gases (fluorinated gases) in isolation through
the first primary pump 72 it is possible to periodically clean the
internal vacuum pump mechanism.
[0120] It is also possible to selectively fluidly connect the first
common pumping line (used for pumping deposition process by-product
gases for example) 78 with the second primary pump 88 in isolation
from the second common pumping 94 line to allow small amounts of
"protective" deposits build up on the internal vacuum pump
mechanisms of the second primary pump 88 to reduce the effect of
the corrosive gases.
[0121] This protective deposition, or pump cleaning concept is
illustrated in more detail in FIGS. 6a and 6b.
[0122] In use a vacuum pumping arrangement 610 lies within a
semiconductor fabrication assembly 622, as described above, and to
this end is shown in FIG. 6a fluidly connected to a process chamber
22 of a semiconductor fabrication tool 616. The vacuum pumping
arrangement 610 also has a dedicated abatement module 136 fluidly
connected downstream thereof.
[0123] In other embodiments, the vacuum pumping arrangement 610 may
be fluidly connected to a plurality of such process chambers 22 by
the common cleaning gas pumping line 94. Indeed, still greater
benefits of various embodiments are realised when the vacuum
pumping arrangement 610 is configured principally to handle the
cleaning process flows from each of a plurality of process chambers
22.
[0124] As shown most clearly in FIG. 6b, the vacuum pumping
arrangement 610 includes a pump 88 which is configured principally
to handle cleaning process flows, e.g. cleaning gasses such as
fluorine.
[0125] The pump 88 has arranged therein an accumulation member 610
which lies in fluid communication with the internal swept volume
622 of the pump 88. The accumulation member 610 may be formed from
a metal or corrosion resistant plate such as stainless steel that
can be subjected to cooling and heating cycles. The accumulation
member may simply be the internal surfaces of the pumping mechanism
with the cooling/heating circuit being that of the vacuum pump
itself. The accumulation member may also be an additional plate or
surface provided within the inlet to the pump.
[0126] The vacuum pumping arrangement 610 also includes a control
module 482 which is operatively connected to the pump 88. In use
the control module 482 operates the pump 88 during a deposition
step and a subsequent cleaning step which, together, define a
deposition-clean cycle.
[0127] The accumulation member 610 includes a residue thickness
monitor 616 coupled therewith. One type of suitable residue
thickness monitor 616 is a crystal oscillator film thickness
monitor, although other thickness monitors are also possible.
[0128] The accumulation member 610 also includes a cooling element
(not shown) and a separate heating element (not shown). In other
embodiments, the cooling and heating elements may be combined in a
single temperature control element.
[0129] In use the control module 482, during the deposition step,
selectively diverts a deposition process flow, e.g. via a valve 501
fluidly connected to a deposition pumping line 503, through the
internal swept volume 622 of the pump 88.
[0130] During such flow a deposition residue, i.e. a reactive
component of the deposition flow, accumulates on the accumulation
member 610.
[0131] The control module 482 may, optionally, during the
deposition step selectively operate the cooling element within the
accumulation member 610 to cool the accumulation member 610. Such
cooling of the accumulation member 610 promotes the condensing of
deposition process flow onto the accumulation member 610, and so
increases the rate at which deposition residue accumulates on the
accumulation member 610.
[0132] During the subsequent cleaning step the control module 482
allows a cleaning process flow to flow through the internal swept
volume 622 of the pump 88, e.g. by operating the valve 501 to
fluidly connect the pump 88 to its associated cleaning gas pumping
line 94.
[0133] During the flow of cleaning process flow through the pump 88
any aggressively corrosive constituents of the cleaning process
flow, e.g. any remaining, un-reacted cleaning gas in the cleaning
process flow, preferentially reacts with the deposition residue and
removes it from the accumulation member 610.
[0134] The control module 482 may during this cleaning step,
optionally, selectively operate the heating element to heat the
accumulation member 610. Increasing the temperature of the
accumulation member 610 increases the rate of reaction of the
cleaning process flow with the deposition residue, and so increases
the rate at which deposition residue is removed from the
accumulation member 610.
[0135] During each of the deposition and cleaning steps the control
module 482 monitors the respective accumulation and removal of
deposition residue with respect to the accumulation member 610.
More particularly, in the embodiment shown, the control module 482
interprets signals from the residue thickness monitor 616 to
determine the thickness of deposition residue on the accumulation
member 610, and hence the overall level of deposition residue
remaining on the accumulation member 610.
[0136] In other embodiments,the control module 482 may monitor only
one of either the accumulation of deposition residue or the removal
of deposition residue from the accumulation member 610.
[0137] In still further other embodiments, (not shown) the control
module 482 may alternatively monitor the accumulation and/or
removal of deposition residue from the accumulation member 610 by:
[0138] determining the volume of deposition process flow which
passes through the pump during the deposition step, and/or
determining the volume of cleaning process flow which passes
through the pump during the cleaning step; or [0139] determining
the period of time for which the deposition process flows, and/or
determining the period of time for which the cleaning process
flows.
[0140] Returning the embodiment shown, the control module 482
additionally alters a characteristic of each of the deposition
residue accumulation step and the cleaning reaction step, i.e.
cools the accumulation member 610 during the deposition residue
accumulation step and/or heats the accumulation member 610 during
the cleaning gas reaction step, in response to the aforementioned
monitoring of the accumulation and removal of deposition residue
from the accumulation member 610, so as to leave substantially no
deposition residue on the accumulation member 610 at the end of the
deposition-clean cycle.
[0141] In other embodiments, the control module 482 may alter a
characteristic of one or other of the deposition residue
accumulation and cleaning gas reaction steps in order to leave a
portion of deposition residue on the accumulation member 610 at the
end of the deposition-clean cycle, or to remove all of the
deposition residue from the accumulation member 610 before the end
of the deposition-clean cycle.
[0142] It will be apparent that it is also possible to monitor the
thickness of deposition residue accumulated on an accumulation
member in the first primary pump 72, namely the one configured for
normally pumping the deposition process by-products, and
selectively divert cleaning gases through the first primary pump 72
until the deposition process residue has been substantially removed
therefrom.
[0143] Referring again to FIG. 1, in use, the first primary pump 72
and the first common pumping line 78 handle a deposition process
flow. The first abatement module 110, e.g. a DC plasma device 112,
produces fine dry powders from deposition gases such as silane and
TEOS during sub-atmospheric abatement, while the second abatement
module 116, e.g. a second wet scrubber 118, collects the fine dry
powders in the downstream deposition process flow.
[0144] Meanwhile, in use, the second primary pump 88 and the second
common pumping line 94 handle a process chamber cleaning process
flow with the second abatement module 116, i.e. the second wet
scrubber 118, again removing fluorine and any other water soluble
gases such as HF, SiF.sub.4, COF.sub.2 etc., in the cleaning
process flow.
[0145] A portion of the first vacuum pumping arrangement 70 is
shown in FIG. 1b. It illustrates schematically two possible options
for rough down pumping lines 480a, 480b, used to initially evacuate
the process chambers 22 prior to processing steps being carried
out.
[0146] A first rough down pumping line 480a has a first end which
is arranged, in fluid communication with the primary pump 72 via
the interstage 114. A second end of each rough down pumping line
480a includes a bleed valve 481 which, in use, is fluidly connected
to a respective process chamber 22. The bleed valve and first rough
down pumping line 480a are used to initially evacuate the process
chamber in a controlled manner protecting the common pumping lines
78, 94, and therefore other process chambers 22, and abatement
systems 110, 116, 118 from pressure fluctuations.
[0147] An alternative option (not shown) is for the first end of
the rough down pumping line 480a and bleed valve 481 to be in fluid
communication, via an additional inlet 80 of the common pumping
line 78, with the primary pump 72 (or via inlet 96, common pumping
line 94 and primary pump 88). Again the bleed valve 481 and first
rough down pumping line 480a are used to initially evacuate the
process chamber in a controlled manner protecting the common
pumping line 78, and therefore other process chambers 22, and
abatement systems 110, 116, 118 from pressure fluctuations.
[0148] An alternative second rough pumping line 480b has a first
end which is arranged in fluid communication with a third common
pumping line 480c comprising a third primary pump 720. Each valve
module 106 comprises a third outlet in fluid communication with the
second end of the second rough pumping line 480b. Thus, in use,
when it is required to initially roughly evacuate the process
chamber the gas is conveyed to the third primary pump 720 via the
valve module 106 and third common pumping line 480c.
[0149] A vacuum pump arrangement 130 according to a second
embodiment is illustrated schematically in FIG. 2.
[0150] The second vacuum pump arrangement 130 is very similar to
the first vacuum pump arrangement 70 shown in FIG. 1, and like
features share the same reference numerals.
[0151] However, one way in which the second vacuum pump arrangement
130 differs from the first vacuum pump arrangement 70 is that it
includes a first abatement module 110 in the form of a hot oxidizer
132 which is located downstream of the first primary pump 72. In
still further embodiments, the hot oxidizer 132 may be located at
the interstage 114 of the first primary pump 72.
[0152] A further difference in the second vacuum pump arrangement
130 is that it includes separate third and fourth wet scrubbers
134, 136 each of which is fluidly connected downstream of a
respective one of the first or second primary pumps 72, 88. Such an
arrangement allows for further optimisation of each wet scrubber
134, 136 according to the nature of the process flow it is intended
to handle.
[0153] More particularly the third wet scrubber 134 is arranged
downstream of the hot oxidizer 132, and so defines a `second`
abatement module from the perspective of the first primary pump
72.
[0154] The third wet scrubber 134 and the hot oxidizer 132 are
fluidly interconnected by a first common scrubber line 120 which,
in use, is fluidly connected to a similar first common scrubber
line 120 of another vacuum pumping arrangement (not shown). In this
manner the single third wet scrubber 134 is able to service a
number of first primary pumps 72 in otherwise separate second
semiconductor fabrication tools 86.
[0155] Meanwhile the fourth wet scrubber 136 is arranged
immediately downstream of the second primary pump 88, and so
defines a `first` abatement module from the perspective of the
second primary pump 88.
[0156] A second common scrubber line 122 which, in use, is fluidly
connected to a similar second common scrubber line 122 of another
vacuum pumping arrangement (not shown), fluidly connects the fourth
wet scrubber 136 with the second primary pump 88. In this manner
the single fourth wet scrubber 136 is able to service a number of
second primary pumps 88 in otherwise separate second semiconductor
fabrication tools 86. Thus the chemically similar, or compatible
gases conveyed (collated) from several vacuum pumping arrangements
in a particular common pumping line can be serviced by a single, or
plurality of optimised abatement devices. Even if a plurality of
optimised abatement device are required to service the exhaust
gases from several interconnected common pumping lines, the
redundancy provided by the various embodiments should still achieve
a reduction in the total number of abatement devices required to be
active at any point in time compared to the non-interconnected
vacuum pumping arrangements of FIGS. 4 and 5.
[0157] In addition, the second vacuum pumping arrangement 130
differs from the first vacuum pumping arrangement 70 in that only
two of the first booster pumps 50 are on the same floor 60 as, and
are mounted on, the corresponding process chamber 22. The other two
first booster pumps are located on a different floor to the
corresponding process chamber 22, and hence are spaced further from
the corresponding process chamber 22.
[0158] Otherwise, in use, the fourth vacuum pumping arrangement 130
operates in essentially the same manner as the first vacuum pumping
arrangement 70, i.e. with the first primary pump 72 and the first
common pumping line 78 handling a deposition process flow, and the
second primary pump 88 and the second common pumping line 94
handling a cleaning process flow.
[0159] FIG. 3 illustrates schematically a third vacuum pumping
arrangement for evacuating at least a first and second vacuum
process chamber 22a and 22b of a process tool 86. At least two
process steps are carried out in each chamber 22a, 22b, for example
a deposition step and a chamber clean or an etch step. The vacuum
pumping arrangement 600 comprises first and second secondary vacuum
pumps 50a and 50b respectively, selected from, for example, at
least one of a roots booster and/or turbomolecular pump. The first
secondary vacuum pump 50a comprises an inlet 501a and outlet 502a.
The first secondary pump inlet 501a is in fluid communication with
an outlet 101a of the first process chamber 22a. The second
secondary vacuum pump 50b comprises an inlet 501b and outlet 501b.
The second secondary vacuum pump inlet 501b is in fluid
communication with an outlet 101b of the second process chamber
22b. The arrangement 600 also comprises first and second three way
valve modules 106a, 106b. The first valve module 106a comprises an
inlet 107a, a first outlet 108a and a second outlet 109a, said
first valve module inlet 107a is in fluid communication with the
outlet 502a of the first secondary vacuum pump 50a. The second
valve module 106b comprises an inlet 107b, a first outlet 108b and
a second outlet 109b. The second valve inlet 107b is in fluid
communication with an outlet 501b of the second secondary vacuum
pump 50b. The arrangement further comprises first and second common
pumping lines 78, 94 respectively. The first common pumping line 78
is in fluid communication with the first outlets 108a, 108b of both
of the first and second valve modules 106a, 106b. The second common
pumping line 94 is in fluid communication with the second outlets
109a, 109b of both the first and second valve modules 106a,
106b.
[0160] The first and second common pumping lines 78, 94 comprise a
respective first and second primary vacuum pump 72, 88, selected
from, for example, at least one of a multistage claw and/or roots,
screw, scroll, rotary vane and liquid ring vacuum pump and chosen
to provide sufficient pumping capacity for evacuating the first and
second chambers 22a, 22b and backing each of the first and second
secondary vacuum pumps 50a, 50b when in fluid communication via the
first and/or second valve modules 106a, 106b. For example, if the
first and second three way valve modules 106a and 106b are fluidly
connecting both the first and second process chambers 22a, 22b via
the first and second secondary pumps 50a, 50b to the first common
pumping line 78 (because, for example a deposition step is being
carried out in both the first and second chambers 22a, 22b), then
the first primary pump 72 must be of sufficient pumping capacity to
ensure the pressure in each chamber 22a, 22b is stable.
[0161] To this end the arrangement 600 also comprises a controller
482 to control both the operational state of the first and second
three way valves (to determine which common pumping line 78, 94 the
gas exhausted from the chambers 22a, 22b is conveyed to); and the
rotational speed of the first and/or second primary pumps based on
a signal from the process tool (or equivalent device such as a
central information system) indicating the composition of the gases
being exhausted from each chamber 22a, 22b.
[0162] In addition, the first and second primary pumps 72, 88 are
chosen depending on the composition and flow rates of exhaust gases
directed to each of the at least first and second common pumping
lines 78, 94. For example if the first set of compatible gases to
be conveyed to the first common pumping line 78 are powder forming
gases, such as TEOS or silane, then the first primary pump 72 used
can be a screw pump, or multistage dry vacuum pump operating at
temperatures above 80.degree. C. to 100.degree. C. with large
amounts of nitrogen purge to prevent powder collecting the in the
mechanism. Similarly, if the second set of compatible gases to be
conveyed to the second common pumping line 94 are halogenated
gases, such as those used in cleaning or etch steps, then the
second primary pump 88, can be a multistage roots or claw dry pump
which is operated at a temperature below 80.degree. C. to
100.degree. C.
[0163] Each of the common pumping lines 78, 94 are in fluid
communication with an abatement device 1001, 1002 respectively,
both chosen to optimise the abatement of the exhaust gases conveyed
to each of the common pumping lines 78, 94 from the chamber 22a,
22b. For example, if the first set of compatible gases to be
conveyed to the first abatement device are flammable, or powder
forming gases, such as SiH.sub.4/N.sub.2O or TEOS/O.sub.3 which are
often used in the deposition steps, then DC plasma device may be
the most suitable abatement device to complete the reaction between
unreacted precursor gases; whereas if the second set of compatible
gases to be conveyed to the second common pumping line 94 are
halogenated gases such as NF.sub.3/F.sub.2 or any of the PFCs,
which are often used as chamber cleaning gases, then the second
abatement device 1001 could preferably be and RF plasma device into
which oxygen is supplied for the destruction of PFCS such as
CF.sub.4, C.sub.2F.sub.6, etc., (which would not be safe for the
deposition gases mentioned above).
[0164] The controller 482 can also be configured to control the
first and/or second abatement devices 1001, 1001 (for example
turning them off when not required to save energy)
[0165] The provision of the at least three way valve modules 106a,
106b for each process chamber 22a, 22b respectively, and a
plurality of common pumping lines 78, 94 in fluid communication
with the outlets of said valve modules 106a, 106b allows, in use,
for common process flows, namely chemically similar, or compatible,
unused process gasses (precursors) and their by-products exhausted
from different process chambers 22a, 22b to be directed, via the
valve modules 106a, 106b, to the desired common pumping line 78,
94. Thus, the chemically similar, or compatible, unused process
gasses and their by-products directed to each common pumping
conduit 78, 94 can then be treated in a more specific, suitable,
and therefore efficient, abatement device for said exhaust gas flow
type.
[0166] If more than two chemically incompatible exhaust gas species
or mixtures are exhausted from the process chambers 22a, 22b then
the valve modules 106a, 106b will be chosen to have a corresponding
number of outlets and there will need to be a corresponding number
of common pumping lines; for example if the process chambers 22a,
22b carried out three separate steps, all of which produced three
different types of incompatible gas species, then the valve modules
106a, 106b would comprise three outlets (not shown) all conveying
the specific exhaust gases to a first, second and third common
pumping lines with first, second and a third primary pumps and
first, second and, if necessary, third abatement devices
respectively.
[0167] Similarly if the process tool comprises more than two
process chambers, each additional chamber will have at least one
three way valve module 106 and at least one secondary pump 50
associated therewith to convey the exhaust gases to the first or
second (or third etc.) common pumping lines 78, 94.
[0168] As with the previous examples, it is advantageous for at
least one of the common pumping lines 78, 94 to be in fluid
communication with a corresponding common pumping line of another
process tool (not shown) to enable a level of both primary pump and
abatement device redundancy between process tools in the
semiconductor fabrication plant.
[0169] Although the subject matter has been described in language
specific to structural features and/or methodological acts, it is
to be understood that the subject matter defined in the appended
claims is not necessarily limited to the specific features or acts
described above. Rather, the specific features and acts described
above are described as example forms of implementing the
claims.
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