U.S. patent application number 11/416871 was filed with the patent office on 2006-09-07 for systems for depositing material onto workpieces in reaction chambers and methods for removing byproducts from reaction chambers.
This patent application is currently assigned to Micron Technology, Inc.. Invention is credited to Cem Basceri, Kevin L. Beaman, Lyle D. Breiner, Trung T. Doan, David J. Kubista, Er-Xuan Ping, Ronald A. Weimer, Lingyi A. Zheng.
Application Number | 20060196538 11/416871 |
Document ID | / |
Family ID | 34520982 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196538 |
Kind Code |
A1 |
Kubista; David J. ; et
al. |
September 7, 2006 |
Systems for depositing material onto workpieces in reaction
chambers and methods for removing byproducts from reaction
chambers
Abstract
Systems for depositing material onto workpieces in reaction
chambers and methods for removing byproducts from reaction chambers
are disclosed herein. In one embodiment, the system includes a gas
phase reaction chamber, a first exhaust line coupled to the
reaction chamber, first and second traps each in fluid
communication with the first exhaust line, and a vacuum pump
coupled to the first exhaust line to remove gases from the reaction
chamber. The first and second traps are operable independently to
individually and/or jointly collect byproducts from the reaction
chamber. It is emphasized that this Abstract is provided to comply
with the rules requiring an abstract. It is submitted with the
understanding that it will not be used to interpret or limit the
scope or meaning of the claims.
Inventors: |
Kubista; David J.; (Nampa,
ID) ; Doan; Trung T.; (Vallejo, CA) ; Breiner;
Lyle D.; (Meridian, ID) ; Weimer; Ronald A.;
(Boise, ID) ; Beaman; Kevin L.; (Boise, ID)
; Ping; Er-Xuan; (Meridian, ID) ; Zheng; Lingyi
A.; (Manassas, VA) ; Basceri; Cem; (Reston,
VA) |
Correspondence
Address: |
PERKINS COIE LLP;PATENT-SEA
PO BOX 1247
SEATTLE
WA
98111-1247
US
|
Assignee: |
Micron Technology, Inc.
8000 South Federal Way
Boise
ID
83716-9632
|
Family ID: |
34520982 |
Appl. No.: |
11/416871 |
Filed: |
May 2, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10687458 |
Oct 15, 2003 |
|
|
|
11416871 |
May 2, 2006 |
|
|
|
Current U.S.
Class: |
137/14 ; 118/715;
427/248.1 |
Current CPC
Class: |
C23C 16/45544 20130101;
Y10T 137/0396 20150401; C23C 16/4412 20130101 |
Class at
Publication: |
137/014 ;
118/715; 427/248.1 |
International
Class: |
F17D 1/16 20060101
F17D001/16; C23C 16/00 20060101 C23C016/00 |
Claims
1-23. (canceled)
24. A method for removing byproducts from a reaction chamber
through a first mainline, the first mainline being coupled to the
reaction chamber and having first and second branchlines downstream
from the reaction chamber, the method comprising: exhausting
byproducts from the reaction chamber through the first mainline;
collecting byproducts in a first trap in the first branchline of
the first mainline; and collecting byproducts in a second trap in
the second branchline of the first mainline.
25. The method of claim 24, further comprising dynamically
controlling the flow of byproducts into the second branchline to
maintain a pressure differential in the first mainline within a
desired range.
26. The method of claim 24, further comprising dynamically
controlling the flow of byproducts into the second branchline to
maintain a generally consistent throughput in the first
mainline.
27. The method of claim 24, further comprising: monitoring the
difference between the pressure in the first mainline upstream from
the first trap and the pressure in the first mainline downstream
from the first trap; and regulating a throttling valve in the
second branchline in response to the monitored pressure
differential in the first mainline to flow byproducts into the
second branchline to maintain the pressure differential in the
first mainline within a desired range.
28. The method of claim 24, further comprising: closing a first
valve in the first branchline upstream from the first trap and a
second valve in the first branchline downstream from the first
trap; and servicing and/or replacing the first trap while
collecting byproducts in the second trap.
29. The method of claim 24 wherein the first mainline further
comprises a third branchline and a fourth branchline each
downstream from the first and second branchlines, and wherein the
method further comprises: drawing byproducts from the reaction
chamber through the first mainline with a first vacuum pump coupled
to the third branchline of the first mainline; and drawing
byproducts from the reaction chamber through the first mainline
with a second vacuum pump coupled to the fourth branchline of the
first mainline.
30. A method for removing byproducts from a reaction chamber
through a first mainline, the first mainline having first and
second branchlines downstream from the reaction chamber, the method
comprising: exhausting byproducts from the reaction chamber through
the first mainline; and dynamically controlling the flow of
byproducts into the second branchline of the first mainline to
maintain a pressure differential in the first mainline within a
desired range.
31. The method of claim 30, further comprising: collecting
byproducts in a first trap in the first branchline of the first
mainline; and collecting byproducts in a second trap in the second
branchline of the first mainline.
32. The method of claim 30, further comprising: monitoring the
difference between the pressure in the first mainline upstream from
a first trap and the pressure in the first mainline downstream from
the first trap, the first trap being disposed in the first
branchline; wherein dynamically controlling the flow of byproducts
comprises regulating a throttling valve in the second branchline in
response to the monitored pressure differential in the first
mainline to maintain the pressure differential in the first
mainline within the desired range.
33. The method of claim 30 wherein the first mainline further
comprises a third branchline and a fourth branchline each
downstream from the first and second branchlines, and wherein the
method further comprises: drawing byproducts from the reaction
chamber through the first mainline with a first vacuum pump coupled
to the third branchline of the first mainline; and drawing
byproducts from the reaction chamber through the first mainline
with a second vacuum pump coupled to the fourth branchline of the
first mainline.
34. A method for removing byproducts from a reaction chamber, the
method comprising: exhausting byproducts from the reaction chamber
through a first mainline; collecting byproducts in a first trap in
a first branchline of the first mainline; monitoring the difference
between the pressure in the first mainline upstream from the first
trap and the pressure in the first mainline downstream from the
first trap; and regulating a throttling valve in a second
branchline of the first mainline in response to the monitored
pressure differential in the first mainline to flow byproducts into
the second branchline to maintain the pressure differential in the
first mainline within a desired range.
35. The method of claim 34, further comprising collecting
byproducts in a second trap in the second branchline.
36. The method of claim 34 wherein the throttling valve comprises a
first valve, and wherein the method further comprises: closing a
second valve in the first branchline upstream from the first trap
and a third valve in the first branchline downstream from the first
trap after regulating the first valve; collecting byproducts in a
second trap in the second branchline; and servicing and/or
replacing the first trap while collecting byproducts in the second
trap.
37. The method of claim 34 wherein the first mainline further
comprises a third branchline and a fourth branchline each
downstream from the first and second branchlines, and wherein the
method further comprises: drawing byproducts from the reaction
chamber through the first mainline with a first vacuum pump coupled
to the third branchline of the first mainline; and drawing
byproducts from the reaction chamber through the first mainline
with a second vacuum pump coupled to the fourth branchline of the
first mainline.
38. A method for removing byproducts from a reaction chamber, the
method comprising: removing byproducts from the reaction chamber
through a first mainline; collecting byproducts in a first trap in
a first branchline of the first mainline; closing a first valve in
the first branchline upstream from the first trap and a second
valve in the first branchline downstream from the first trap;
servicing and/or replacing the first trap; and collecting
byproducts in a second trap in a second branchline of the first
mainline while the first and second valves are closed.
39. The method of claim 38 wherein the first mainline further
comprises a third branchline and a fourth branchline each
downstream from the first and second branchlines, and wherein the
method further comprises: drawing byproducts from the reaction
chamber through the first mainline with a first vacuum pump coupled
to the third branchline of the first mainline; and drawing
byproducts from the reaction chamber through the first mainline
with a second vacuum pump coupled to the fourth branchline of the
first mainline.
40. A method for removing byproducts from a reaction chamber, the
method comprising: drawing byproducts from the reaction chamber
through a first mainline with a first vacuum pump coupled to a
first branchline of the first mainline; and drawing byproducts from
the reaction chamber through the first mainline with a second
vacuum pump coupled to a second branchline of the first
mainline.
41. The method of claim 40, further comprising collecting
byproducts in a trap in the first mainline.
42. The method of claim 40 wherein the first mainline further
comprises a third branchline and a fourth branchline each upstream
from the first and second branchlines, and wherein the method
further comprises: collecting byproducts in a first trap in the
third branchline of the first mainline; and collecting byproducts
in a second trap in the fourth branchline of the first
mainline.
43. The method of claim 40, further comprising dynamically
controlling a throttling valve in the second branchline to maintain
a generally consistent throughput in the first mainline.
44. The method of claim 40, further comprising dynamically
controlling a throttling valve in the second branchline to maintain
a generally consistent vacuum conductance in the first
mainline.
45. The method of claim 40, further comprising: monitoring a
pressure in the first mainline; and regulating a throttling valve
in the second branchline in response to the monitored pressure to
maintain a generally consistent pressure in the first mainline.
Description
TECHNICAL FIELD
[0001] The present invention is related to systems for depositing
material onto workpieces in reaction chambers and methods for
removing byproducts from reaction chambers.
BACKGROUND
[0002] Thin film deposition techniques are widely used in the
manufacturing of microfeatures to form a coating on a workpiece
that closely conforms to the surface topography. The size of the
individual components in the workpiece is constantly decreasing,
and the number of layers in the workpiece is increasing. As a
result, both the density of components and the aspect ratios of
depressions (i.e., the ratio of the depth to the size of the
opening) are increasing. Thin film deposition techniques
accordingly strive to produce highly uniform conformal layers that
cover the sidewalls, bottoms, and corners in deep depressions that
have very small openings.
[0003] One widely used thin film deposition technique is Chemical
Vapor Deposition (CVD). In a CVD system, one or more precursors
that are capable of reacting to form a solid thin film are mixed
while in a gaseous or vaporous state, and then the precursor
mixture is presented to the surface of the workpiece. The surface
of the workpiece catalyzes the reaction between the precursors to
form a solid thin film at the workpiece surface. A common way to
catalyze the reaction at the surface of the workpiece is to heat
the workpiece to a temperature that causes the reaction.
[0004] Although CVD techniques are useful in many applications,
they also have several drawbacks. For example, if the precursors
are not highly reactive, then a high workpiece temperature is
needed to achieve a reasonable deposition rate. Such high
temperatures are not typically desirable because heating the
workpiece can be detrimental to the structures and other materials
already formed on the workpiece. Implanted or doped materials, for
example, can migrate within the silicon substrate at higher
temperatures. On the other hand, if more reactive precursors are
used so that the workpiece temperature can be lower, then reactions
may occur prematurely in the gas phase before reaching the
substrate. This is undesirable because the film quality and
uniformity may suffer, and also because it limits the types of
precursors that can be used.
[0005] Atomic Layer Deposition (ALD) is another thin film
deposition technique. FIGS. 1A and 1B schematically illustrate the
basic operation of ALD processes. Referring to FIG. 1A, a layer of
gas molecules A coats the surface of a workpiece W. The layer of A
molecules is formed by exposing the workpiece W to a precursor gas
containing A molecules and then purging the chamber with a purge
gas to remove excess A molecules. This process can form a monolayer
of A molecules on the surface of the workpiece W because the A
molecules at the surface are held in place during the purge cycle
by physical adsorption forces at moderate temperatures or
chemisorption forces at higher temperatures. Referring to FIG. 1B,
the layer of A molecules is then exposed to another precursor gas
containing B molecules. The A molecules react with the B molecules
to form an extremely thin layer of solid material on the workpiece
W. The chamber is then purged again with a purge gas to remove
excess B molecules.
[0006] FIG. 2 illustrates the stages of one cycle for forming a
thin solid layer using ALD techniques. A typical cycle includes (a)
exposing the workpiece to the first precursor A, (b) purging excess
A molecules, (c) exposing the workpiece to the second precursor B,
and then (d) purging excess B molecules. In actual processing,
several cycles are repeated to build a thin film on a workpiece
having the desired thickness. For example, each cycle may form a
layer having a thickness of approximately 0.5-1.0 .ANG., and thus
several cycles are required to form a solid layer having a
thickness of approximately 60 .ANG..
[0007] FIG. 3 schematically illustrates a single-wafer ALD reactor
10 having a reaction chamber 20 coupled to a gas supply 30 and a
vacuum 40. The reactor 10 also includes a heater 50 that supports
the workpiece W and a gas dispenser 60 in the reaction chamber 20.
The gas dispenser 60 includes a plenum 62 operably coupled to the
gas supply 30 and a distributor plate 70 having a plurality of
holes 72. In operation, the heater 50 heats the workpiece W to a
desired temperature, and the gas supply 30 selectively injects the
first precursor A, the purge gas, and the second precursor B, as
shown above in FIG. 2. The vacuum 40 maintains a negative pressure
in the reaction chamber 20 to draw the gases from the gas dispenser
60 across the workpiece W and then through an outlet of the
reaction chamber 20. A trap 80 captures and collects the byproducts
from the reaction chamber 20 to prevent fouling of the vacuum
40.
[0008] One drawback of ALD processing is that it has a relatively
low throughput compared to CVD techniques. For example, each
A-purge-B-purge cycle can take several seconds. This results in a
total process time of several minutes to form a single thin layer
of only 60 .ANG.. In contrast to ALD processing, CVD techniques
require only about one minute to form a 60 .ANG. thick layer. The
low throughput limits the utility of the ALD technology in its
current state because ALD may create a bottleneck in the overall
manufacturing process.
[0009] Another drawback of both ALD and CVD processing is the
downtime required to service or replace the trap. As the trap
collects byproducts from the reaction chamber, the byproducts
restrict the flow from the reaction chamber 20 to the vacuum 40,
and consequently, the pressure in the chamber increases. The
increased pressure in the reaction chamber impairs effective
removal of the byproducts from the reaction chamber. Accordingly,
the trap is cleaned or replaced periodically to avoid significant
increases in the pressure in the reaction chamber. Servicing the
trap requires that the reactor be shut down, which results in a
reduction in throughput. One approach to reduce the downtime of the
reactor includes increasing the size of the trap. Although this
approach reduces the downtime, a significant need still exists to
eliminate the downtime required to service the trap and to maintain
a consistent pressure in the reaction chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1A and 1B are schematic cross-sectional views of
stages in ALD processing in accordance with the prior art.
[0011] FIG. 2 is a graph illustrating a cycle for forming a layer
using ALD techniques in accordance with the prior art.
[0012] FIG. 3 is a schematic representation of a system including a
reactor for depositing material onto a microfeature workpiece in
accordance with the prior art.
[0013] FIG. 4 is a schematic representation of a system for
depositing material onto a microfeature workpiece in accordance
with one embodiment of the invention.
[0014] FIG. 5 is a schematic representation of a portion of a
system for depositing material onto a workpiece in accordance with
another embodiment of the invention.
[0015] FIG. 6 is a schematic representation of a portion of a
system for depositing material onto a workpiece in accordance with
another embodiment of the invention.
DETAILED DESCRIPTION
A. Overview
[0016] The following disclosure describes several embodiments of
systems for depositing material onto workpieces in reaction
chambers and methods for removing byproducts from reaction
chambers. Many specific details of the invention are described
below with reference to single-wafer reactors for depositing
material onto microfeature workpieces, but several embodiments can
be used in batch systems for processing a plurality of workpieces
simultaneously. Moreover, several embodiments can be used for
depositing material onto workpieces other than microfeature
workpieces. The term "microfeature workpiece" is used throughout to
include substrates upon which and/or in which microelectronic
devices, micromechanical devices, data storage elements, read/write
components, and other features are fabricated. For example,
microfeature workpieces can be semiconductor wafers such as silicon
or gallium arsenide wafers, glass substrates, insulative
substrates, and many other types of materials. Furthermore, the
term "gas" is used throughout to include any form of matter that
has no fixed shape and will conform in volume to the space
available, which specifically includes vapors (i.e., a gas having a
temperature less than the critical temperature so that it may be
liquefied or solidified by compression at a constant temperature).
Several embodiments in accordance with the invention are set forth
in FIGS. 4-6 and the following text to provide a thorough
understanding of particular embodiments of the invention. A person
skilled in the art will understand, however, that the invention may
have additional embodiments, or that the invention may be practiced
without several of the details of the embodiments shown in FIGS.
4-6.
[0017] One aspect of the invention is directed to systems for
depositing material onto workpieces in reaction chambers. In one
embodiment, a system includes a gas phase reaction chamber, a first
exhaust line coupled to the reaction chamber, first and second
traps each in fluid communication with the first exhaust line, and
a vacuum pump coupled to the first exhaust line to remove gases
from the reaction chamber. The first and second traps are operable
independently to individually and/or jointly collect byproducts
from the reaction chamber. In one aspect of this embodiment, the
first exhaust line includes a first branchline and a second
branchline each downstream from the reaction chamber. The first
trap can be disposed in the first branchline and the second trap
can be disposed in the second branchline. The first and second
branchlines can be configured in a parallel arrangement. In another
aspect of this embodiment, the system further includes a throttling
valve in the second branchline, a pressure monitor, and a
controller operably coupled to the throttling valve and the
pressure monitor. The pressure monitor can determine the difference
between the pressure in the first exhaust line upstream from the
first trap and the pressure in the first exhaust line downstream
from the first trap. The controller can operate the throttling
valve to control the flow of byproducts into the second branchline
to maintain the pressure differential in the first exhaust line
within a desired range.
[0018] In another embodiment, a system includes a gas phase
reaction chamber, a first exhaust line coupled to the reaction
chamber, a trap in the first exhaust line to collect byproducts
from the reaction chamber, and first and second vacuum pumps. The
first and second vacuum pumps are each in fluid communication with
the first exhaust line and positioned downstream from the trap. The
first and second vacuum pumps are operable independently to
individually and/or jointly exhaust byproducts from the reaction
chamber. In one aspect of this embodiment, the first exhaust line
includes a first branchline and a second branchline each downstream
from the reaction chamber. The first vacuum pump can be coupled to
the first branchline and the second vacuum pump can be coupled to
the second branchline. The system can also include a throttling
valve in the second branchline to control the pressure in the first
exhaust line.
[0019] Another aspect of the invention is directed to methods for
removing byproducts from a reaction chamber through a first
mainline. The first mainline has first and second branchlines
downstream from the reaction chamber. In one embodiment, the method
includes exhausting byproducts from the reaction chamber through
the first mainline and dynamically controlling the flow of
byproducts into the second branchline of the first mainline to
maintain a pressure differential in the first mainline within a
desired range. In one aspect of this embodiment, the method further
includes collecting byproducts in a first trap in the first
branchline of the first mainline and collecting byproducts in a
second trap in the second branchline of the first mainline. In
another aspect of this embodiment, the method further includes
monitoring the difference between the pressure in the first
mainline upstream from the first trap and the pressure in the first
mainline downstream from the first trap. In response to the
monitored pressure differential, a throttling valve in the second
branchline can be regulated to maintain the pressure differential
within the desired range.
B. Deposition Systems
[0020] FIG. 4 is a schematic representation of a system 100 for
depositing material onto a microfeature workpiece W in accordance
with one embodiment of the invention. In this embodiment, the
system 100 includes a reactor 110 having a reaction chamber 120
coupled to a gas supply 130 and a vacuum pump 140. The reactor 110
also includes a gas distributor 160 coupled to the reaction chamber
120 and the gas supply 130 to dispense gas(es) into the reaction
chamber 120 and onto the workpiece W. Byproducts including excess
and/or unreacted gas molecules are removed from the reaction
chamber 120 by the vacuum pump 140 and injecting a purge gas into
the chamber 120.
[0021] The gas supply 130 includes a plurality of gas sources 132
(identified individually as 132a-c) and a plurality of gas lines
136 coupled to the gas sources 132. The gas sources 132 can include
a first gas source 132a for providing a first gas, a second gas
source 132b for providing a second gas, and a third gas source 132c
for providing a third gas. The first and second gases can be first
and second precursors, respectively. The third gas can be a purge
gas. The first and second precursors are the gas and/or vapor phase
constituents that react to form the thin, solid layer on the
workpiece W. The purge gas can be a suitable type of gas that is
compatible with the reaction chamber 120 and the workpiece W. In
other embodiments, the gas supply 130 can include a different
number of gas sources 132 for applications that require additional
precursors or purge gases. In additional embodiments, the gas
sources 132 can include one or more etchants for deposition onto a
microfeature workpiece during etching.
[0022] The system 100 of the illustrated embodiment further
includes a valve assembly 133 coupled to the gas lines 136 and a
controller 134 operably coupled to the valve assembly 133. The
controller 134 generates signals to operate the valve assembly 133
to control the flow of gases into the reaction chamber 120 for ALD
and CVD applications. For example, the controller 134 can be
programmed to operate the valve assembly 133 to pulse the gases
individually through the gas distributor 160 in ALD applications or
to mix selected precursors in the gas distributor 160 in CVD
applications. More specifically, in one embodiment of an ALD
process, the controller 134 directs the valve assembly 133 to
dispense a pulse of the first gas (e.g., the first precursor) into
the reaction chamber 120. Next, the controller 134 directs the
valve assembly 133 to dispense a pulse of the third gas (e.g., the
purge gas) to purge excess molecules of the first gas from the
reaction chamber 120. The controller 134 then directs the valve
assembly 133 to dispense a pulse of the second gas (e.g., the
second precursor), followed by a pulse of the third gas. In one
embodiment of a pulsed CVD process, the controller 134 directs the
valve assembly 133 to dispense a pulse of the first and second
gases (e.g., the first and second precursors) into the reaction
chamber 120. Next, the controller 134 directs the valve assembly
133 to dispense a pulse of the third gas (e.g., the purge gas) into
the reaction chamber 120. In other embodiments, the controller 134
can dispense the gases in other sequences.
[0023] In the illustrated embodiment, the reactor 110 also includes
a workpiece support 150 to hold the workpiece W in the reaction
chamber 120. In one aspect of this embodiment, the workpiece
support 150 can be heated to bring the workpiece W to a desired
temperature for catalyzing the reaction between the first gas and
the second gas at the surface of the workpiece W. For example, the
workpiece support 150 can be a plate with a heating element. The
workpiece support 150, however, may not be heated in other
applications.
[0024] The system 100 further includes an exhaust mainline 170
coupled to the vacuum pump 140 and the reaction chamber 120 to
remove byproducts, including excess and/or unreacted gas molecules,
from the reaction chamber 120. The mainline 170 includes an
upstream portion 170a, a downstream portion 170b, a first
branchline 172a, and a second branchline 172b. The branchlines
172a-b can be configured in a parallel arrangement and coupled to
the upstream and downstream portions 170a-b. Accordingly, discrete
byproducts flow through either the first branchline 172a or the
second branchline 172b. In this embodiment, the system 100 further
includes a first trap 180a disposed in the first branchline 172a
and a second trap 180b disposed in the second branchline 172b. The
traps 180a-b capture and collect byproducts in the branchlines
172a-b to prevent damage to the vacuum pump 140. In other
embodiments, the system can include a different number of
branchlines and/or traps.
[0025] In one aspect of this embodiment, the system 100 further
includes a throttling valve 190 in the second branchline 172b, a
valve controller 194 operably coupled to the throttling valve 190,
and a pressure monitor 198 operably coupled to the valve controller
194. The throttling valve 190 and the valve controller 194 regulate
the flow of byproducts into the second branchline 172b, and the
pressure monitor 198 determines the pressure difference between the
upstream and downstream portions 170a-b of the mainline 170. The
throttling valve 190, the valve controller 194, and the pressure
monitor 198 can operate together to maintain the pressure in the
upstream portion 170a of the mainline 170 within a desired range.
For example, the pressure differential across the first trap 180a
increases as the first trap 180a collects byproducts because the
byproducts in the first trap 180a obstruct the flow from the
reaction chamber 120 to the vacuum pump 140. The pressure monitor
198 detects this increase in the pressure differential across the
first trap 180a and sends a signal to the valve controller 194. In
response to the signal, the valve controller 194 at least partially
opens the throttling valve 190 to allow some of the flow of
byproducts to pass through the second branchline 172b. The
throttling valve 190 is opened sufficiently to reduce the pressure
differential in the upstream and downstream portions 170a-b of the
mainline 170 to within the desired range. In additional
embodiments, the system 100 can include a throttling valve in the
first branchline 172a that is coupled to the valve controller
194.
[0026] One feature of this embodiment of the system 100 is that it
maintains the pressure differential between the upstream and
downstream portions 170a-b of the mainline 170 as the traps 180a-b
collect byproducts. Accordingly, the pressure in the upstream
portion 170a and the reaction chamber 120 can remain generally
consistent. An advantage of this feature is that a consistent
pressure in the reaction chamber 120 helps create a consistent flow
through the reaction chamber 120. More specifically, a consistent
pressure facilitates the consistent, effective removal of
byproducts, including excess and/or unreacted gas molecules, from
the reaction chamber 120. In contrast, the pressure in many prior
art reaction chambers increases as the trap collects byproducts
that obstruct the exhaust line. This increase in pressure (i.e.,
decrease in negative pressure) in the prior art reaction chambers
impairs consistent, effective removal of the byproducts from the
reaction chambers, and consequently, the byproducts may react with
incoming gases.
[0027] In another aspect of the illustrated embodiment, the system
100 can include a plurality of valves 192 (identified individually
as 192a-c) to selectively isolate the first and/or second traps
180a-b for service or replacement. The first branchline 172a, for
example, can include a first valve 192a (shown in hidden lines)
upstream from the first trap 180a and a second valve 192b (shown in
hidden lines) downstream from the first trap 180a. The first and
second valves 192a-b can be closed to allow the first trap 180a to
be serviced or replaced without interrupting the deposition process
of the system 100. For example, when the first and second valves
192a-b are closed, the throttle valve 190 can be opened enough to
exhaust the byproducts solely through the second branchline 172b of
the mainline 170. The first trap 180a can then be replaced with a
new trap without shutting down the system 100. Similarly, the
second branchline 172b can include a third valve 192c (shown in
hidden lines) downstream from the second trap 180b. The throttling
valve 190 and the third valve 192c can be closed to allow the
second trap 180b to be serviced or replaced without interrupting
the deposition process of the system 100. In other embodiments, the
system 100 may not include the valves 192.
[0028] One feature of the illustrated embodiment is that the system
100 does not need to be shut down to replace and/or service the
traps 180. Each trap 180 can be isolated for service or
replacement, and while one trap 180 is serviced, the other trap 180
can collect byproducts. An advantage of this feature is that the
throughput of the system 100 is increased because the downtime
resulting from servicing the traps 180 is reduced or
eliminated.
C. Other Systems to Remove Byproducts
[0029] FIG. 5 is a schematic representation of a portion of a
system 200 for depositing material onto a workpiece in accordance
with another embodiment of the invention. The system 200 can be
generally similar to the system 100 described above with reference
to FIG. 4. For example, the system 200 includes a reaction chamber
120, a mainline 270 coupled to the reaction chamber 120, and a trap
180 in the mainline 270 to capture and collect the byproducts from
the reaction chamber 120. The mainline 270 includes a first
branchline 272a and a second branchline 272b each downstream from
the trap 180. The system 200 further includes a first vacuum pump
140a coupled to the first branchline 272a and a second vacuum pump
140b coupled to the second branchline 272b.
[0030] In one aspect of this embodiment, the system 200 includes a
throttling valve 190 in the second branchline 272b, a valve
controller 194 operably coupled to the throttling valve 190, and a
pressure monitor 298 operably coupled to the valve controller 194
to determine the pressure in the mainline 270 downstream from the
trap 180. The throttling valve 190, the valve controller 194, and
the pressure monitor 298 can operate together to maintain a
consistent pressure in the mainline 270 and/or maintain a
consistent mass flow rate and/or fluid velocity of byproducts
through the mainline 270. For example, in one embodiment, if the
first vacuum pump 140a is fouled because the trap 180 fails to
capture all the byproducts in the mainline 270, the pressure in the
mainline 270 will increase and the throughput of byproducts through
the mainline 270 will decrease. The pressure monitor 298 detects
the pressure increase and sends a signal to the valve controller
194. In response to the signal, the valve controller 194 opens the
throttling valve 190 sufficiently to allow the second vacuum pump
140b to reduce the pressure in the mainline 270 to a desired range
and to increase the throughput of byproducts in the mainline 270 to
a consistent level. In other embodiments, the pressure monitor 298
can monitor the pressure differential in the mainline 270 upstream
and downstream of the trap 180 (shown in broken line). In this
embodiment, if the trap 180 is fouled, the pressure upstream from
the trap 180 will increase. The valve controller 194 can
accordingly open the valve 190 to reduce the pressure downstream
from the trap 180 and thus increase the flow rate across the trap
180. The system 200 can include a different number of branchlines
and vacuum pumps than shown in FIG. 5, or the system 200 can
include a throttling valve in the first branchline 272a in still
another embodiment.
[0031] In one aspect of this embodiment, the first branchline 272a
can include a valve 192 (shown in hidden lines) to control the flow
through the first branchline 272a. The valve 192 allows the first
vacuum pump 140a to be serviced or replaced without interrupting
the deposition process of the system 200. For example, when the
valve 192 is closed to service or replace the first vacuum pump
140a, the second vacuum pump 140b can continue to remove byproducts
from the reaction chamber 120.
[0032] One feature of the embodiment illustrated in FIG. 5 is that
the system 200 does not need to be shut down to replace and/or
service one of the vacuum pumps 140 because the valves 190 and 192
can isolate the vacuum pump 140. An advantage of this feature is
that the throughput of the system 200 is increased because the
downtime for servicing the vacuum pumps 140 is reduced or
eliminated. Another feature of this embodiment is that a consistent
pressure can be maintained in the mainline 270, and consequently,
byproducts can be removed from the reaction chamber 120 at a
consistent rate. An advantage of this feature is that removing
byproducts from the reaction chamber 120 at a consistent rate
results in a more consistent deposition process and reduces the
likelihood that byproducts may recirculate in the reaction chamber
120 and react with incoming gases.
[0033] FIG. 6 is a schematic representation of a portion of a
system 300 for depositing material onto a workpiece in accordance
with another embodiment of the invention. The system 300 can be
generally similar to the systems 100 and 200 described above with
reference to FIGS. 4 and 5. For example, the system 300 includes a
reaction chamber 120, a mainline 370 coupled to the reaction
chamber 120, a plurality of traps 180 (identified individually as
180a-b) in the mainline 370, and a plurality of vacuum pumps 140
(identified individually as 140a-b) coupled to the mainline 370.
The mainline 370 includes first and second branchlines 372a-b
configured in a parallel arrangement and third and fourth
branchlines 372c-d configured in a parallel arrangement downstream
from the first and second branchlines 372a-b. In the illustrated
embodiment, a first trap 180a is disposed in the first branchline
372a, a second trap 180b is disposed in the second branchline 372b,
a first vacuum pump 140a is coupled to the third branchline 372c,
and a second vacuum pump 140b is coupled to the fourth branchline
372d.
[0034] The system 300 of the illustrated embodiment can further
include a first throttling valve 190a in the second branchline
372b, a second throttling valve 190b in the fourth branchline 372d,
a valve controller 194 operably coupled to the throttling valves
190a-b, and a pressure monitor 198 coupled to the valve controller
194. The pressure monitor 198 monitors the pressure difference
between an upstream portion 370a of the mainline 370 and a
downstream portion 370b of the mainline 370. As described above
with reference to FIG. 4, the valve controller 194 can regulate the
first throttling valve 190a to create a desired pressure
differential in the upstream and downstream portions 370a-b of the
mainline 370. Moreover, as described above with reference to FIG.
5, the valve controller 194 can regulate the second throttling
valve 190b to create a consistent pressure in the mainline 370 if
the first vacuum pump 140a is fouled. The system 300 can further
include a plurality of valves 192 (identified individually as
192a-d) to isolate the traps 180a-b and/or vacuum pumps 140a-b so
that the traps 180a-b and vacuum pumps 140a-b can be serviced or
replaced without interrupting the deposition process in the system
300, as described above with reference to FIGS. 4 and 5. In other
embodiments, the system can include additional traps, vacuums,
and/or branchlines.
[0035] From the foregoing, it will be appreciated that specific
embodiments of the invention have been described herein for
purposes of illustration but that various modifications may be made
without deviating from the spirit and scope of the invention.
Accordingly, the invention is not limited, except as by the
appended claims.
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