U.S. patent application number 14/398119 was filed with the patent office on 2015-03-26 for method and apparatus for warming up a vacuum pump arrangement.
The applicant listed for this patent is Edwards Limited. Invention is credited to Jack Raymond Tattersall.
Application Number | 20150086387 14/398119 |
Document ID | / |
Family ID | 46330713 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150086387 |
Kind Code |
A1 |
Tattersall; Jack Raymond |
March 26, 2015 |
METHOD AND APPARATUS FOR WARMING UP A VACUUM PUMP ARRANGEMENT
Abstract
A method for warming up a vacuum pump arrangement having a
booster pump and a backing pump downstream of the booster pump for
evacuating a process chamber includes setting the booster pump at a
first speed higher than an idle speed of the booster pump when the
same is in an idle mode; and controlling a backing pressure at an
outlet of the booster pump within a range from 0.1 mbar to 10 mbar
at least for a period of time from when the vacuum pump arrangement
is activated from the idle mode to when the booster pump reaches a
temperature equal to or exceeding a first predetermined threshold
value. Such method is implemented in system where a controlled is
configured to carry out the above-motioned actions.
Inventors: |
Tattersall; Jack Raymond;
(Victoria, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Edwards Limited |
Crawley, West Sussex |
|
GB |
|
|
Family ID: |
46330713 |
Appl. No.: |
14/398119 |
Filed: |
April 24, 2013 |
PCT Filed: |
April 24, 2013 |
PCT NO: |
PCT/GB2013/051033 |
371 Date: |
October 30, 2014 |
Current U.S.
Class: |
417/53 ; 417/2;
417/216 |
Current CPC
Class: |
F04B 2201/0801 20130101;
F04C 28/06 20130101; F04B 49/20 20130101; F04C 2220/30 20130101;
F04D 27/0261 20130101; F04B 49/02 20130101; F04D 19/046 20130101;
F04C 2270/701 20130101; F05D 2260/85 20130101; F04D 27/0292
20130101; F04C 23/005 20130101; F04B 23/04 20130101; F04C 25/02
20130101 |
Class at
Publication: |
417/53 ; 417/2;
417/216 |
International
Class: |
F04B 49/02 20060101
F04B049/02; F04B 23/04 20060101 F04B023/04; F04B 49/20 20060101
F04B049/20 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2012 |
GB |
1207721.0 |
Claims
1. A method for warming up a vacuum pump arrangement having a
booster pump and a backing pump downstream of the booster pump for
evacuating a process chamber, comprising: setting the booster pump
at a first speed higher than an idle speed of the booster pump when
the booster pump is in an idle mode; and controlling a backing
pressure at an outlet of the booster pump within a range from 0.1
millibar to 10 millibar at least for a period of time from when the
vacuum pump arrangement is activated from the idle mode to when the
booster pump reaches a temperature equal to or exceeding a first
predetermined threshold temperature value.
2. The method of claim 1, wherein the controlling a backing
pressure comprising adjusting a speed of the backing pump, wherein
an inlet of the backing pump is connected to the outlet of the
booster pump.
3. The method of claim 2, wherein the backing pump is set at a
second speed when the vacuum pump arrangement is activated from the
idle mode.
4. The method of claim 3, wherein the second speed of the backing
pump is decreased to a predetermined level in order for the backing
pressure of the booster pump to fall within the range from 0.1
millibar to 10 millibar.
5. The method of claim 4, wherein the second speed is decreased to
the predetermined level incrementally over a number of time
intervals.
6. The method of claim 1, wherein the controlling the backing
pressure comprising injecting a purge gas at the outlet of the
booster pump.
7. The method of claim 6, wherein a flow rate of the purge gas is
controlled in a manner that the backing pressure of the booster
pump is adjusted into the range from 0.1 millibar to 10
millibar.
8. The method of claim 1, wherein the vacuum pump arrangement is
set to be ready for evacuating the process chamber in a normal
operation mode when the temperature of the booster pump is equal to
or exceeds the first predetermined threshold value and a
temperature of the backing pump is equal to or exceeds a second
predetermined threshold value.
9. An apparatus comprising: a process chamber; a booster pump
having an inlet fluidly connected to an outlet of the process
chamber; a backing pump having an inlet fluidly connected to an
outlet of the booster pump for, together with the booster pump,
evacuating the process chamber; and a controller electrically
coupled with the booster pump and the backing pump, the controller
being configured to control a backing pressure at the outlet of the
booster pump within a range from 0.1 millibar to 10 millibar at
least for a period of time from when the booster pump and the
backing pump are activated from an idle mode to when the booster
pump reaches a temperature equal to or exceeding a first
predetermined threshold value.
10. The apparatus of claim 9, wherein the controller is configured
to control the backing pressure of the booster by adjusting a speed
of the backing pump.
11. The apparatus of claim 10, wherein the controller is configured
to set the backing pump at a predetermined speed when the vacuum
pump arrangement is activated from the idle mode.
12. The apparatus of claim 11, wherein the controller is configured
to reduce the predetermined speed of the backing pump to a
predetermined level in order for the backing pressure of the
booster pump to fall within into the range from 0.1 millibar to 10
millibar.
13. The apparatus of claim 12, wherein the controller is configured
to reduce the predetermined speed to the predetermined level
incrementally over a number of time intervals.
14. The apparatus of claim 9, further comprising a source of purge
gas fluidly connected at the outlet of the booster pump.
15. The apparatus of claim 14, wherein the controller is configured
to control a flow rate of a purge gas being injected at the outlet
of the booster pump, thereby controlling the backing pressure of
the booster pump within the range from 0.1 millibar to 10
millibar.
16. The apparatus of claim 9, wherein the booster pump and the
backing pump are set to be ready for evacuating the process chamber
in a normal operation mode when the temperature of the booster pump
is equal to or exceeds the first predetermined threshold value and
a temperature of the backing pump is equal to or exceeds a second
predetermined threshold value.
Description
[0001] This application is a national stage entry under 35 U.S.C.
.sctn.371 of International Application No. PCT/GB2013/051033, filed
Apr. 24, 2013, which claims the benefit of G.B. Application
1207721.0, filed May 2, 2012. The entire contents of International
Application No. PCT/GB2013/051033 and G.B. Application 1207721.0
are incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates to a method and/or apparatus for
warming up a vacuum pump arrangement after it was put into an idle
mode.
BACKGROUND
[0003] A system used in manufacturing semiconductor devices
typically includes, among other things, a process tool, a vacuum
pump arrangement having a booster pump and a backing pump, and an
abatement device. The process tool typically includes a process
chamber, in which a semiconductor wafer is processed into a
predetermined structure. The vacuum pump arrangement is connected
to the process tool for evacuating the process chamber to create a
vacuum environment in the process chamber in order for various
semiconductor processing techniques to take place. The gas
evacuated from the process chamber by the vacuum pump arrangement
might be directed to the abatement device, which destroys or
decomposes the harmful or toxic components of the gas before it is
released to the environment.
[0004] It is desired to manage and reduce the utilities, such as
electric power, fuel, and water, consumed by the vacuum pumps and
abatement device during the semiconductor manufacturing processes.
The power consumed by the vacuum pumps and abatement device
represents a significant portion of the total power consumed by the
entire system in manufacturing semiconductor wafers. Many efforts
have been made in the semiconductor industry to improve the
efficiency of utility consumption of the vacuum pumps in order to
reduce the manufacturing costs of semiconductor wafers. In addition
to cost savings, new environmental regulations would often put
pressure on semiconductor manufacturers to improve the energy
efficiency of their manufacturing processes.
[0005] One conventional method for improving the efficiency is to
put the vacuum pump arrangement and the abatement device in an idle
mode, when the process tool does not require that the vacuum pump
arrangement and the abatement device operate in their normal
capacities. The term "idle mode" here is used interchangeably with
other terms, such as sleep mode, green mode, hibernation,
reduced/low power mode, active utility control mode, that are often
customarily used in various industries. For example, when
semiconductor wafers are being transferred into or out of the
process chamber, the vacuum pump arrangement and abatement device
might be put in the idle mode, in which they consume fewer
resources than they do in a normal operation mode. When the process
tool requires the vacuum pump arrangement and abatement device to
operate in their normal capacities, they can be brought back to
their normal operation mode from the idle mode.
[0006] One drawback of the conventional method is that it usually
takes a long time to bring the vacuum pump arrangement and the
abatement device back to the normal operation mode from the idle
mode. When the vacuum pump arrangement is in the idle mode, it
cools down to a low temperature. Before the vacuum pump arrangement
can operate in normal conditions, it needs be warmed up to a
certain temperature, which can take a long time. The longer the
warming-up takes, the longer the process tool is sitting idle,
waiting for the vacuum pump arrangement to be ready. This
translates into lost productivity, and decreased throughput.
[0007] Thus, what is needed is a method for quickly warming up the
vacuum pump arrangement from the idle mode, thereby shortening the
time required for bringing a processing system from the idle mode
to the normal operation mode.
SUMMARY
[0008] This invention relates to a method and/or apparatus for
warming up a vacuum pump arrangement after it was put into an idle
mode. In some embodiments of the invention, a method for warming up
a vacuum pump arrangement having a booster pump and a backing pump
downstream of the booster pump for evacuating a process chamber
includes steps of: setting the booster pump at a first speed higher
than an idle speed of the booster pump when the same is in an idle
mode; and controlling a backing pressure at an outlet of the
booster pump within a range from 0.1 mbar to 10 mbar, wherein
suitable backing pressure will need to be selected depending on the
size of the booster pump, at least for a period of time from when
the vacuum pump arrangement is activated from the idle mode to when
the booster pump reaches a temperature equal to or exceeding a
first predetermined threshold value.
[0009] In some embodiments of the invention, an apparatus includes:
a process chamber; a booster pump having an inlet fluidly connected
to an outlet of the process chamber; a backing pump having an inlet
fluidly connected to an outlet of the booster pump for, together
with the booster pump, evacuating the process chamber; and a
controller electrically coupled with the booster pump and the
backing pump, the controller being configured to control a backing
pressure at the outlet of the booster pump within a range from 0.1
mbar to 10 mbar at least for a period of time from when the booster
pump and the backing pump are activated from an idle mode to when
the booster pump reaches a temperature equal to or exceeding a
first predetermined threshold value.
[0010] The construction and method of operation of the invention,
however, together with additional objectives and advantages thereof
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
[0011] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 illustrates a schematic view of a system where a
process chamber, a booster pump, and a backing pump, among other
things, are connected in series in accordance with some embodiments
of the invention.
[0013] FIGS. 2A and 2B illustrate flow charts showing various
processes for warming up a vacuum pump arrangement in accordance
with some embodiments of the invention.
[0014] FIG. 3 illustrates a flow chart showing a process for
warming up a vacuum pump arrangement in accordance with some
embodiments of the invention.
[0015] FIG. 4 is a graph showing that the disclosed method and/or
apparatus shortens the time required to warm up a vacuum pump
arrangement.
DETAILED DESCRIPTION
[0016] The disclosure is directed to a method and/or apparatus for
warming up a vacuum pump arrangement after it was put in an idle
mode. The vacuum pump arrangement in its simplified configuration
has a booster pump and a backing pump downstream thereof. An inlet
of the booster pump is connected to an outlet of a process chamber,
which can be part of a semiconductor process tool, or any other
equipment that requires an internal vacuum environment in order to
properly function. An outlet of the booster pump is connected to an
inlet of the backing pump, of which an outlet is typically in fluid
connection with an abatement device, or in some cases directly with
an atmospheric environment. As the vacuum pump arrangement is
warming up, the speed of the booster pump is raised to and
maintained at a level higher than an idle speed of the booster pump
when it was in the idle mode. The backing pressure of the booster
pump, that is the pressure at the outlet of the booster pump, is
also raised to and maintained at a relatively high level, compared
to the backing pressure, in either the normal operation mode, or in
some cases the idle mode, employed by conventional methods. As a
result, the power required to compress the gas through the booster
pump during the warm-up period would be increased, and therefore
causing the temperature of the booster pump to increase more
quickly. Because the booster pump typically takes a longer time to
fully warm up than the backing pump, the method and/or apparatus of
the disclosure is able to shorten the time required for warming up
the entire vacuum pump arrangement from the idle mode. This in turn
increases the throughput of the process tool.
[0017] FIG. 1 illustrates a schematic view of a system 10 where a
process chamber 12 and a vacuum pump arrangement 20, among other
things, are connected in series in accordance with some embodiments
of the invention. The vacuum pump arrangement 20 draws gases out of
the process chamber 12 and creates a vacuum environment in it to
carry out certain processes, such as depositions, etching, ion
implantation, epitaxy, etc. The gases can be introduced into the
process chamber 12 from one or more gas sources, such as the ones
designated by 14a and 14b in this figure. The gas sources 14a and
14b can be connected to the process chamber 12 via control valves
16a and 16b, respectively. The timing of introducing various gases
into the process chamber 12 can be controlled by selectively
turning on or off the control valves 16a and 16b. The flow rates of
the gases introduced from the gas sources 14a and 14b into the
process chamber 12 can be controlled by adjusting the fluid
conductance of the control valves 16a and 16b.
[0018] The vacuum pump arrangement 20 includes a booster pump 22
and a backing pump 24 connected in series. The inlet of the booster
pump 22 is connected to the outlet of the process chamber 12. The
outlet of the booster pump 22 is connected to the inlet of the
backing pump 24. The outlet of the backing pump 24 might be
connected to an abatement device (not shown in the figure) where
the exhaust gases emitted from the backing pump 24 are treated in
order to reduce the harmful impact the exhaust gases might have on
the environment. Sensors (not shown in the figure) can be
implemented in the vacuum pump arrangement to collect data of
various measurements, such as the temperatures, power consumptions,
pump speeds, etc., of the booster pump 22 and the backing pump 24.
Sensors can also be implemented to measure the gas pressures at the
inlets and/or outlets of the booster pump 22 and/or the backing
pump 24. A controller 30 is configured to control various
parameters of the booster pump 22 and the backing pump 24 in
response to the data collected by the sensors. For example, the
controller 30 might put the booster pump 22 and the backing pump 24
in a low utility consumption state, e.g., the idle mode, upon
receiving a signal indicating that no immediate process is expected
to be performed in the process chamber 12. Such signal might be
provided by the process chamber 12, or the process tool
incorporating the process chamber 12, directly to the controller
30. Alternatively, such signal might be provided by a central
control unit of a semiconductor manufacturing facility to the
controller 30.
[0019] Upon receiving a wake-up signal, the controller 30 effects
an increase of electric power supply to the vacuum pump arrangement
20, and raises the speeds of the booster and backing pumps 22 and
24 to higher levels from their respective idle speeds. The
controller 30 controls, raises, and maintains the backing pressure
at the outlet of the booster pump 22 within a range from 0.1 mbar
to 10 mbar at least for a period of time when the vacuum pump
arrangement 20 is activated from the idle mode to when the booster
pump 22 reaches a temperature equal to or exceeding a predetermined
threshold value, which is required in order for the booster pump to
operate in normal conditions. The pressure range disclosed herein
is higher than the backing pressure of the booster pump 22 in
typical, conventional warm-up processes.
[0020] Mathematically, the compression power (W) of the booster
pump 22 equals to its swept volume (V) times the pressure
differential (dP) there across. Given that the swept volume of the
booster pump 22 is constant, raising the pressure differential by
raising backing pressure would require higher power to compress the
gas through the booster pump 22, and therefore generating more heat
as a result. This would cause the temperature of the booster pump
22 to reach the predetermined threshold value suitable for normal
pump operation much quickly from the temperature when the booster
pump 22 is in the idle mode.
[0021] In some embodiments of the invention, the backing pressure
of the booster pump 22 can be controlled by adjusting the speed of
the backing pump 24. The slower the speed of the backing pump 24,
the higher the backing pressure of the booster pump 22. An
exemplary process for controlling the backing pressure of the
booster pump 22 is illustrated in FIG. 2A. The process starts at
step 200. At step 202, it is determined whether the vacuum pump
arrangement 20 has received a signal to wake up from the idle mode.
If it is determined that the vacuum pump arrangement 20 has not
received such signal, the vacuum pump arrangement 20 will remain in
the idle mode. If it is determined that the vacuum pump arrangement
20 has received such signal, the process will proceed to step 204
where the speed of the booster pump 22 is set at a first speed
higher than its idle speed. At step 206, the speed of the backing
pump 24 is set at a second speed high than its idle speed. It is
noted that although steps 204 and 206 are illustrated as two
separate actions in FIG. 2A, the speeds of the booster and backing
pumps 22 and 24 might be set simultaneously in some embodiments of
the invention.
[0022] At step 208, it is determined whether the backing pressure
of the booster pump 22 is within the predetermined range from 0.1
bar to 10 mbar. If the backing pressure is not within the
predetermined range, the process proceeds to step 210 where the
speed of the backing pump 24 is decreased in order for the backing
pressure of the booster pump 22 to fall within the predetermined
range quickly. In some embodiments of the invention, the speed of
the backing pump 24 is decreased once, and the process waits for
the backing pressure of the booster pump 22 to move within the
predetermined range. In some other embodiments of the invention,
the speed of the backing pump 24 is decreased incrementally over a
number of time intervals until the backing pressure of the booster
pump 22 moves within the predetermined range. In yet some other
embodiments of the invention, the second speed of the backing pump
24 can be set low enough at step 206 for the backing pressure of
the booster pump 22 to rise up quickly, such that step 210 can be
eliminated all together. All theses embodiments are within the
scope of the invention.
[0023] If the backing pressure of the booster pump 22 is determined
to be within the predetermined range, the process proceeds to step
212. At step 212, it is determined whether the temperatures of the
booster and backing pumps 22 and 24 are equal to or exceed their
respective threshold temperatures. If they do, the vacuum pump
arrangement 20 will be set to be ready for evacuating the process
chamber 12 in a normal operation mode. Until then, the vacuum pump
arrangement 20 will remain in the warm-up process, waiting for the
temperatures to rise to proper levels. It is noted that the values
of the predetermined threshold temperatures of the booster and
backing pumps 22 and 24 may or may not be the same. Thereafter, the
process ends at step 214.
[0024] In some embodiments of the invention, the backing pressure
of the booster pump 22 can be controlled by adjusting the pump
speed and comparing the temperature of the booster pump 22 to a
threshold temperature, without directly measuring the backing
pressure. FIG. 2B illustrates a flow chart showing an exemplary
process for controlling the backing pressure of the booster pump
22, without directly measuring it. The process in FIG. 2B is
similar to that in FIG. 2A, with differences in that the backing
pressure of the booster pump 22 is not measured. At step 248, the
temperature of the booster pump 22 is measured and compared to the
threshold temperature of the booster pump. If the measured
temperature is lower than the threshold temperature, the speed of
the backing pump 24 is increased at step 250. The steps 248 and 250
are repeated periodically until the measured temperature of the
booster pump 22 is equal to or exceeds the threshold temperature.
Thereafter, the process proceeds to step 252 where it is determined
whether the temperature of the backing pump 24 is equal to or
exceeds the threshold temperature of the backing pump 24. If it
does, the vacuum pump arrangement 20 will be set as ready for
evacuating the process chamber 12 in a normal operation mode. Until
then, the vacuum pump arrangement 20 will remain in the warm-up
process, waiting for the temperatures to rise to proper levels.
Thereafter, the process ends at step 254.
[0025] In some other embodiments of the invention, the backing
pressure of the booster pump 22 can be raised by injecting a purge
gas at the outlet of the booster pump 22 or a location in the
conduit between the booster pump 22 and the backing pump 24. As
shown in FIG. 1, a source of purge gas 32 and a control valve 34
might be optionally provided. The control valve 34 might be placed
between the source 32 and the conduit between the booster pump 22
and the backing pump 24. The controller 30 is configured to adjust
the conductance of the control valve 34, thereby controlling the
flow rate of the purge gas from the source 32 to the outlet or its
downstream proximity of the booster pump 22. This in turns alters
the backing pressure at the outlet of the booster pump 22. It is
advantageous to select gases that are stable and do not react with
the process gas flowing through the vacuum pump arrangement 20 as
the purge gas. Examples of the purge gas include nitrogen, helium,
and other inert gases.
[0026] FIG. 3 illustrates a process for warming up the vacuum pump
arrangement 20 from the idle mode in accordance with some
embodiments of the invention. The process illustrated in FIG. 3 is
similar to that in FIG. 2, expect that in the latter the backing
pressure of the booster pump 22 is controlled and maintained by
adjusting the speed of the backing pump 24, whereas in the former
the backing pressure of the booster pump 22 is controlled and
maintained by injecting the purge gas at the outlet of the booster
pump 22, as described by step 300. At step 302, it is determined
whether the backing pressure of the booster pump 22 is within the
predetermined range. If it is not, the controller 30 might increase
the conductance of the control valve 34 to increase the flow rate
of the purge gas, until the backing pressure of the booster pump 22
moves within the predetermined range. Like the process in FIG. 2,
at step 300, the flow rate of the purge gas can be adjusted
incrementally over a number of time intervals or abruptly to a
predetermined level at once. If it is determined that the backing
pressure of the booster pump 22 is within the predetermined range,
the process will proceed to step 304.
[0027] At step 304, it is determined whether the temperature of the
booster pump 22 is equal to or exceeds a predetermined threshold
temperature. If it does not, the process will wait until it does
and then proceed to step 306 where the flow of the purge gas is cut
off. At step 308, it is determined whether the temperature of the
backing pump 24 is equal to or exceeds a predetermined threshold
temperature. If it does not, the process will wait unit it does and
then end the process at step 310. Like the process in FIG. 2, here,
the threshold temperatures of the booster and backing pumps may or
may not be the same.
[0028] FIG. 4 is a graph showing that the disclosed method and/or
apparatus shortens the time required to warm up a vacuum pump
arrangement after it was put into an idle mode. The left side of
the figure illustrates a time line for warming up a vacuum pump
arrangement according to conventional methods or apparatus. The
right side of the figure illustrates a time line for warming up the
vacuum pump arrangement according to the method or apparatus of the
disclosure. The comparison between the time lines shows that the
disclosed method or apparatus is able to warm up the booster and
backing pumps to their desired temperatures much more quickly than
the conventional methods or apparatus, due to the increased backing
pressure of the booster pump in the warm-up process. The shortened
warm-up period means that the process tool can be put into
operation much more quickly after the vacuum pump arrangement was
instructed to wake up from the idle mode. This in turn translates
into higher throughput for the process tool.
[0029] Although the invention is illustrated and described herein
as embodied in one or more specific examples, it is nevertheless
not intended to be limited to the details shown, since various
modifications and structural changes may be made therein without
departing from the spirit of the invention and within the scope and
range of equivalents of the claims. Accordingly, it is appropriate
that the appended claims be construed broadly and in a manner
consistent with the scope of the invention, as set forth in the
following claims.
[0030] Various embodiments of the invention have been described.
These and other embodiments are within the scope of the following
claims.
* * * * *