U.S. patent application number 09/732159 was filed with the patent office on 2001-05-03 for multi-function chamber for a substrate processing system.
This patent application is currently assigned to Applied Komatsu Technology, Inc.. Invention is credited to Blonigan, Wendell T., Richter, Michael W., White, John M..
Application Number | 20010000747 09/732159 |
Document ID | / |
Family ID | 22170808 |
Filed Date | 2001-05-03 |
United States Patent
Application |
20010000747 |
Kind Code |
A1 |
White, John M. ; et
al. |
May 3, 2001 |
Multi-function chamber for a substrate processing system
Abstract
A load lock chamber includes a chamber body having an aperture
to allow a substrate to be transferred into or out of the chamber.
The load lock chamber is configurable in several configurations,
including a base configuration for providing a transition between
two different pressures, a heating configuration for heating the
substrate and providing a transition between two different
pressures, and a cooling configuration for cooling the substrate
and providing a transition between two different pressures. Various
features of the chamber configurations help increase the throughput
of the system by enabling rapid heating and cooling of substrates
and simultaneous evacuation and venting of the chamber, and help
compensate for thermal losses near the substrate edges, thereby
providing a more uniform temperature across the substrate.
Inventors: |
White, John M.; (Hayward,
CA) ; Blonigan, Wendell T.; (Union City, CA) ;
Richter, Michael W.; (Sunnyvale, CA) |
Correspondence
Address: |
Patent Counsel
APPLIED MATERIALS, INC.
P.O. Box 450A
Santa Clara
CA
95052
US
|
Assignee: |
Applied Komatsu Technology,
Inc.
|
Family ID: |
22170808 |
Appl. No.: |
09/732159 |
Filed: |
December 7, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09732159 |
Dec 7, 2000 |
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09502117 |
Feb 10, 2000 |
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6193507 |
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09502117 |
Feb 10, 2000 |
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09082375 |
May 20, 1998 |
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6086362 |
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Current U.S.
Class: |
432/4 ; 432/129;
432/184 |
Current CPC
Class: |
H01L 21/67173 20130101;
H01L 21/67248 20130101; H01L 21/67748 20130101; H01L 21/67109
20130101; H01L 21/67098 20130101; H01L 21/67201 20130101; H01L
21/67236 20130101 |
Class at
Publication: |
432/4 ; 432/129;
432/184 |
International
Class: |
F27B 009/02; F27B
017/00 |
Claims
What is claimed is:
1. An evacuable chamber, comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; wherein the chamber is configurable using removable
components in at least two of the following configurations: a base
configuration for providing a transition between two different
pressures, a heating configuration for heating the substrate and
providing a transition between two different pressures, and a
cooling configuration for cooling the substrate and providing a
transition between two different pressures; and wherein when
configured in the base configuration, the chamber further includes
at least one removable volume reducing element disposed therein,
when configured in the heating configuration, the chamber further
includes an upper heating assembly and a heating platen, and when
configured in the cooling configuration, the chamber further
includes an upper cooling assembly and a cooling platen.
2. The chamber of claim 1 wherein the chamber is configurable in
the base configuration, the heating configuration and the cooling
configuration.
3. The chamber of claim 1 wherein the chamber can be re-configured
from a first one of the configurations to a second one of the
configurations.
4. The chamber of claim 1, wherein when configured in the base
configuration, the chamber further includes upper and lower volume
reducing elements, wherein the substrate support mechanism is
disposed between the upper and lower volume reducing elements.
5. The chamber of claim 4 wherein the chamber is configured in the
base configuration as an input chamber to provide a transition from
atmospheric pressure to a process pressure.
6. The chamber of claim 4 wherein the chamber is configured in the
base configuration as an output load lock chamber to provide a
transition from a process pressure to atmospheric pressure.
7. The chamber of claim 1 further comprising: a substrate support
mechanism disposed within the chamber; and a lid attached to the
chamber body; wherein, when in the heating configuration, the upper
heating assembly is disposed between the lid and the substrate
support mechanism; and the heating platen is movable to lift a
substrate positioned on the support mechanism to a heating position
below the upper heating assembly, and to lower the substrate from
the heating position onto the support mechanism.
8. The chamber of claim 7 wherein the chamber is configured as an
input load lock chamber in the heating configuration to provide a
transition from atmospheric pressure to a process pressure.
9. The chamber of claim 7 wherein the chamber is configurable as an
ashing chamber.
10. The chamber of claim 9 wherein the chamber is configured as an
output load lock chamber in the ashing configuration to provide a
transition from a process pressure to atmospheric pressure.
11. The chamber of claim 1 further comprising: a substrate support
mechanism disposed within the chamber; and a lid attached to the
chamber body, wherein, when in the cooling configuration, the upper
cooling assembly is disposed between the lid and the substrate
support mechanism; and the cooling platen is movable to lift a
substrate positioned on the support mechanism to a cooling position
below the upper cooling assembly, and to lower the substrate from
the cooling position onto the support mechanism.
12. The chamber of claim 11 wherein the chamber is configured as an
output load lock chamber in the cooling configuration to provide a
transition from a process pressure to atmospheric pressure.
13. A load lock chamber, comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; a lid attached to the chamber body; a substrate support
mechanism disposed within the chamber; and at least one removable
volume reducing element disposed within the chamber.
14. The load lock chamber of claim 13 wherein at least one volume
reducing element includes a plastic material.
15. The load lock chamber of claim 13 further comprising a
removable volume reducing element positioned adjacent and below a
lid of the chamber.
16. The load lock chamber of claim 13 wherein the chamber has a
bottom interior surface and includes a removable volume reducing
element positioned adjacent and above the bottom interior
surface.
17. The load lock chamber of claim 13 further comprising removable
upper and lower volume reducing elements, wherein the substrate
support mechanism is disposed between the upper and lower volume
reducing elements.
18. The load lock chamber of claim 17 further comprising a gas
delivery tube attached to the chamber, wherein the upper volume
reducing element includes vertical channels to allow a gas to be
delivered from the delivery tube to an interior region of the
chamber via the vertical channels.
19. A load lock chamber-comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; a lid attached to the chamber body; a substrate support
mechanism disposed within the chamber; an upper heating assembly
disposed between the lid and the substrate support mechanism; and a
heating platen that is movable to lift a substrate positioned on
the support mechanism to a heating position below the upper heating
assembly, and to lower the substrate from the heating position onto
the support mechanism, wherein surface temperatures in the chamber
are controllable to compensate for thermal losses near edges of the
substrate.
20. The load lock chamber of claim 19 wherein the heating platen
includes inner and outer heating loops whose temperatures are
independently controllable.
21. The load lock chamber of claim 20 wherein, during operation,
the temperature of the outer loop is maintained at a higher
temperature than the inner loop.
22. The load lock chamber of claim 19 wherein the heating platen
includes an upper surface having a pattern of horizontal channels
therein.
23. The load lock chamber of claim 22 wherein the heating platen
includes a plurality of holes therethrough.
24. The load lock chamber of claim 22 wherein a concentration of
the channels is designed to control a contact area between a
substrate and the heating platen when the substrate is supported on
the upper surface of the platen.
25. The load lock chamber of claim 24 wherein the heating platen
has a perimeter and a center, and wherein the concentration of the
channels is greater near the center of the platen than near its
perimeter.
26. The load lock chamber of claim 19 wherein the upper heating
assembly includes a stationary plate having inner and outer heating
loops whose temperatures can be controlled independently of one
another.
27. The load lock chamber of claim 26 further comprising a gas
delivery tube attached to the chamber body, wherein the stationary
plate includes a plurality of vertical holes to allow a gas to be
delivered from the delivery tube to an interior region of the
chamber via the vertical holes.
28. The load lock chamber of claim 27 wherein the plurality of
holes includes an inner zone of holes near a center of the
stationary plate and an outer zone of holes near a perimeter of the
stationary plate.
29. The load lock chamber of claim 27 wherein the upper heating
assembly further includes a diffusion screen disposed between the
stationary plate and the substrate heating position.
30. The load lock chamber of claim 29 further comprising an inert
gas source coupled to the delivery tube.
31. The load lock chamber of claim 27 further comprising an ash gas
source coupled to the delivery tube.
32. A load lock chamber, comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; a lid attached to the chamber body; a gas delivery tube; a
substrate support mechanism disposed within the chamber; an upper
heating assembly disposed between the lid and the substrate support
mechanism; and a heating platen that is movable to lift a substrate
positioned on the support mechanism to a heating position below the
upper heating assembly, and to lower the substrate from the heating
position onto the support mechanism; wherein the upper heating
assembly includes: a stationary plate having a plurality of
vertical holes to allow a gas to be delivered from the delivery
tube to an interior region of the chamber via the vertical holes;
and
33. The load lock chamber of claim 32 wherein the stationary plate
further includes inner and outer heating loops whose temperatures
can be controlled independently of one another.
34. The load lock chamber of claim 32 wherein the plurality of
holes includes an inner zone of holes near a center of the
stationary plate and an outer zone of holes near a perimeter of the
stationary plate.
35. A load lock chamber, comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; a lid attached to the chamber body; a substrate support
mechanism disposed within the chamber; an upper cooling assembly
disposed between the lid and the substrate support mechanism; a
cooling platen that is movable to lift a substrate positioned on
the support mechanism to a cooling position below the upper cooling
assembly, and to lower the substrate from the cooling position onto
the support mechanism, wherein surface temperatures in the chamber
are controllable to compensate for thermal losses near edges of the
substrate.
36. The load lock chamber of claim 35 wherein the cooling platen
includes a plurality of cooling tubes through which a cooling fluid
can flow.
37. The load lock chamber of claim 36 wherein the cooling platen
includes a center and a perimeter, wherein a concentration of the
cooling tubes near the center of the platen is greater than a
concentration near the perimeter.
38. The load lock chamber of claim 35 wherein the cooling platen
includes an upper surface having a pattern of horizontal channels
therein.
39. The load lock chamber of claim 38 wherein the cooling platen
includes a plurality of holes therethrough.
40. The load lock chamber of claim 38 wherein a concentration of
the channels is designed to control a contact area between a
substrate and the cooling platen when the substrate is supported on
the upper surface of the platen.
41. The loadlock chamber of claim 40 wherein the cooling platen has
a perimeter and a center, and wherein the concentration of the
channels is greater near the perimeter of the cooling platen than
near the center.
42. The load lock chamber of claim 34 further comprising a gas
delivery tube attached to the chamber, wherein the upper cooling
assembly includes a stationary plate having a plurality of vertical
holes to allow a gas to be delivered from the delivery tube to an
interior region of the chamber via the vertical holes.
43. The load lock chamber of claim 42 wherein the stationary plate
has a perimeter, and wherein the plurality of holes includes an
inner zone of holes near a center of the stationary plate and an
outer zone of holes near a perimeter of the stationary plate.
44. The load lock chamber of claim 42 wherein the upper cooling
assembly further includes a diffusion screen disposed between the
stationary plate and the substrate cooling position.
45. The load lock chamber of claim 42 further comprising an inert
gas source coupled to the delivery tube.
46. The load lock chamber of claim 45 wherein the stationary plate
includes a plurality of cooling tubes through which a cooling fluid
can be provided to flow.
47. The load lock chamber of claim 46 wherein the stationary plate
has a perimeter and a center, and wherein a concentration of the
cooling tubes is greater near the center of the stationary plate
than near the perimeter.
48. A load lock chamber comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; a lid attached to the chamber body; a gas delivery tube; a
substrate support mechanism disposed within the chamber; an upper
cooling assembly disposed between the lid and the substrate support
mechanism; and a cooling platen that is movable to lift a substrate
positioned on the support mechanism to a cooling position below the
upper cooling assembly, and to lower the substrate from the cooling
position onto the support mechanism; wherein the upper cooling
assembly includes a stationary plate having a plurality of vertical
holes to allow a gas to be delivered from the delivery tube to an
interior region of the chamber via the vertical holes.
49. The load lock chamber of claim 48 wherein the stationary plate
further includes a plurality of cooling tubes through which a
cooling fluid can flow.
50. The load lock chamber of claim 48 wherein the stationary plate
has a perimeter and a center, and wherein a concentration of the
cooling tubes is greater near the center of the stationary plate
than near the perimeter.
51. The load lock chamber of claim 48 wherein the plurality of
holes includes an inner zone of holes near a center of the
stationary plate and an outer zone of holes near a perimeter of the
stationary plate.
52. A load lock chamber comprising: a chamber body having an
aperture to allow a substrate to be transferred into or out of the
chamber; and a thermally conductive platen for supporting a
substrate within the chamber, wherein the platen has multiple zones
for preferentially changing the temperature of the substrate by
conduction so as to compensate for thermal losses near edges of the
substrate.
53. The load lock chamber of claim 52 wherein the platen is a
heating platen.
54. The load lock chamber of claim 53 wherein the heating includes
inner and outer heating loops whose temperatures are independently
controllable.
55. The load lock chamber of claim 54 wherein, during operation,
the temperature of the outer loop is maintained at a higher
temperature than the inner loop.
56. The load lock chamber of claim 55 wherein the heating platen
includes an upper surface having a pattern of horizontal channels
therein, wherein a concentration of the channels is designed to
control a contact area between a substrate and the heating platen
when the substrate is supported on the upper surface of the
platen.
57. The load lock chamber of claim 56 wherein the heating platen
has a perimeter and a center, and wherein the concentration of the
channels is greater near the center of the platen than near its
perimeter.
58. The load lock of claim 52 wherein the platen is a cooling
platen.
59. The load lock chamber of claim 58 wherein the cooling platen
includes a perimeter, a center, and an upper surface having a
pattern of horizontal channels therein, and wherein a concentration
of the channels is greater near the perimeter of the cooling platen
than near the center.
60. The load lock chamber of claim 59 wherein the cooling platen
includes a plurality of cooling tubes through which a cooling fluid
can flow and wherein the cooling platen includes a center and a
perimeter, wherein a concentration of the cooling tubes near the
center of the platen is greater than a concentration near the
perimeter.
61. A method of processing a substrate in a load lock chamber, the
method comprising: supporting the substrate on a substrate support
mechanism within the chamber; changing the pressure in the chamber
from a first pressure to a second pressure; and controlling surface
temperatures in the chamber to compensate for thermal losses near
edges of the substrate.
62. The method of claim 61 comprising heating walls of the chamber
to compensate for thermal losses near the edges of the
substrate.
63. The method of claim 62 comprising heating a lid of the chamber
to compensate for thermal losses near the edges of the
substrate.
64. The method of claim 61 further comprising heating the substrate
in the load lock chamber by conduction.
65. The method of claim 64 further comprising transferring the
substrate from the support mechanism onto a heating platen.
66. The method of claim 65 wherein transferring the substrate
comprises raising the heating platen to lift the substrate off the
support mechanism.
67. The method of claim 65 wherein heating the substrate by
conduction comprises heating the platen so that an upper surface of
the platen has a temperature gradient that generally increases from
a point near a center of the platen to a point near a perimeter of
the platen.
68. The method of claim 67 wherein heating the substrate by
conduction comprises providing a contact area between the upper
surface of the platen and a first surface area of the substrate
near the perimeter of the substrate that is greater than a contact
area between the upper surface of the platen and a second surface
area of the substrate near the center of the substrate, wherein the
first and second surface areas of the substrate are the same
size.
69. The method of claim 61 further comprising heating the substrate
in the load lock chamber by radiation.
70. The method of claim 69 wherein heating the substrate by
radiation comprises: raising the substrate to a heating position
near a stationary plate; and heating the stationary plate so that
the plate has a temperature gradient that generally increases from
a point near a center of the plate to a point near a perimeter of
the plate.
71. The method of claim 70 further comprising heating the substrate
in the load lock chamber by forced convection.
72. The method of claim 71 wherein heating the substrate by forced
convection comprises providing a gas to an interior of the
chamber.
73. The method of claim 72 wherein providing the gas to the
interior of the chamber comprises forcing the gas to travel through
the stationary plate.
74. The method of claim 73 wherein providing the gas to the
interior of the chamber further comprises forcing the gas to travel
along an upper surface of the stationary plate prior to travelling
through the plate.
75. The method of claim 73 further comprising forcing the gas to
travel through a diffusion screen after travelling through the
stationary plate to control the diffusion of the gas into the
chamber interior.
76. The method of claim 75 wherein the gas is an inert gas.
77. The method of claim 75 wherein the gas is an ash gas.
78. The method of claim 61 further comprising: transferring the
substrate from the support mechanism onto a heating platen; and
moving the heating platen to a position within the chamber to
reduce a viewing angle of the substrate with respect to walls of
the chamber.
79. The method of claim 61 further comprising cooling the substrate
in the load lock chamber by conduction.
80. The method of claim 79 further comprising transferring the
substrate from the support mechanism onto a cooling platen.
81. The method of claim 80 wherein transferring the substrate
comprises raising the cooling platen to lift the substrate off the
support mechanism.
82. The method of claim 80 wherein cooling the substrate by
conduction comprises cooling the platen so that an upper surface of
the platen has a temperature gradient that generally increases from
a point near a center of the platen to a point near a perimeter of
the platen.
83. The method of claim 82 wherein cooling the substrate by
conduction comprises providing a contact area between the upper
surface of the platen and a first surface area of the substrate
near the perimeter of the substrate that is less than a contact
area between the upper surface of the platen and a second surface
area of the substrate near the center of the substrate, wherein the
first and second surface areas of the substrate are the same
size.
84. The method of claim 61 further comprising cooling the substrate
in the load lock chamber by radiation.
85. The method of claim 84 wherein cooling the substrate by
radiation comprises: raising the substrate to a cooling position
near a stationary plate; and cooling the stationary plate so that
the plate has a temperature gradient that generally increases from
points near a center of the plate to points near a perimeter of the
plate.
86. The method of claim 85 further comprising cooling the substrate
in the load lock chamber by forced convection.
87. The method of claim 86 wherein cooling the substrate by forced
convection comprises providing a gas to an interior of the
chamber.
88. The method of claim 87 wherein providing the gas to the
interior of the chamber comprises forcing the gas to travel through
the stationary plate.
89. The method of claim 88 wherein providing the gas to the
interior of the chamber further comprises forcing the gas to travel
along an upper surface of the stationary plate prior to travelling
through the plate.
90. The method of claim 88 further comprising forcing the gas to
travel through a diffusion screen after travelling through the
stationary plate to control the diffusion of the gas into the
chamber interior.
91. The method of claim 90 wherein the gas is an inert gas.
92. The method of claim 90 wherein the gas in an ash gas.
93. The method of claim 61 further comprising transferring the
substrate from the support mechanism onto a cooling platen, wherein
controlling surface temperatures includes heating walls of the
chamber to compensate for thermal looses from the edges of the
substrate.
94. The method of claim 61 further comprising transferring the
substrate from the support mechanism onto a cooling platen, wherein
controlling surface temperatures includes heating a lid of the
chamber to reduce thermal looses from edges of the substrate.
95. The method of claim 61 further comprising: transferring the
substrate from the support mechanism onto a cooling platen; and
moving the cooling platen to a position within the chamber to
reduce a viewing angle of the substrate with respect to walls of
the chamber.
Description
RELATED APPLICATIONS
1. The present application is related to co-pending U.S. patent
application Ser. No. 08/946,922, filed Oct. 8, 1997 and entitled
"Modular On-Line Processing System," as well as the following U.S.
patent applications which are being filed concurrently with this
application: (1) "Method and Apparatus for Substrate Transfer and
Processing" [attorney docket 2519/US/AKT (05542/235001)]; (2)
"Isolation Valves," [attorney docket 2157/US/AKT (05542/226001)];
(3) "An Automated Substrate Processing System," [attorney docket
2429/US/AKT (05542/245001)]; (4) "Substrate Transfer Shuttle Having
a Magnetic Drive," [attorney docket 2638/US/AKT (05542/264001)];
(5) "Substrate Transfer Shuttle," [attorney docket 2688/US/AKT
(05542/265001)]; (6) "In-Situ Substrate Transfer Shuttle,"
[attorney docket 2703/US/AKT (05542/266001)]; and (7) "Modular
Substrate Processing System," [attorney docket 2311/US/AKT
(05542/233001)].
2. The foregoing patent applications, which are assigned to the
assignee of the present application, are incorporated herein by
reference in their entirety.
BACKGROUND
3. The present invention relates generally to substrate processing
systems, and, in particular, to a multi-function chamber for a
substrate processing system.
4. Glass substrates are being used for applications such as active
matrix television and computer displays, among others. Each glass
substrate can form multiple display monitors each of which contains
more than a million thin film transistors.
5. The processing of large glass substrates often involves the
performance of multiple sequential steps, including, for example,
the performance of chemical vapor deposition (CVD) processes,
physical vapor deposition (PVD) processes, or etch processes.
Systems for processing glass substrates can include one or more
process chambers for performing those processes.
6. The glass substrates can have dimensions, for example, of 550 mm
by 650 mm. The trend is toward even larger substrate sizes, such as
650 mm by 830 mm and larger, to allow more displays to be formed on
the substrate or to allow larger displays to be produced. The
larger sizes place even greater demands on the capabilities of the
processing systems.
7. Some of the basic processing techniques for depositing thin
films on the large glass substrates are generally similar to those
used, for example, in the processing of semiconductor wafers.
Despite some of the similarities, however, a number of difficulties
have been encountered in the processing of large glass substrates
that cannot be overcome in a practical way and cost effectively by
using techniques currently employed for semiconductor wafers and
smaller glass substrates.
8. For example, efficient production line processing requires rapid
movement of the glass substrates from one work station to another,
and between vacuum environments and atmospheric environments. The
large size and shape of the glass substrates makes it difficult to
transfer them from one position in the processing system to
another. As a result, cluster tools suitable for vacuum processing
of semiconductor wafers and smaller glass substrates, such as
substrates up to 550 mm by 650 mm, are not well suited for the
similar processing of larger glass substrates, such as 650 mm by
830 mm and above. Moreover, cluster tools require a relatively
large floor space.
9. Similarly, chamber configurations designed for the processing of
relatively small semiconductor wafers are not particularly suited
for the processing of these larger glass substrates. The chambers
must include apertures of sufficient size to permit the large
substrates to enter or exit the chamber. Moreover, processing
substrates in the process chambers typically must be performed in a
vacuum or under low pressure. Movement of glass substrates between
processing chambers, thus, requires the use of valve mechanisms
which are capable of closing the especially wide apertures to
provide vacuum-tight seals and which also must minimize
contamination.
10. Furthermore, relatively few defects can cause an entire monitor
formed on the substrate to be rejected. Therefore, reducing the
occurrence of defects in the glass substrate when it is transferred
from one position to another is critical. Similarly, misalignment
of the substrate as it is transferred and positioned within the
processing system can cause the process uniformity to be
compromised to the extent that one edge of the glass substrate is
electrically non-functional once the glass has been formed into a
display. If the misalignment is severe enough, it even may cause
the substrate to strike structures and break inside the vacuum
chamber.
11. Other problems associated with the processing of large glass
substrates arise due to their unique thermal properties. For
example, the relatively low thermal conductivity of glass makes it
more difficult to heat or cool the substrate uniformly. In
particular, thermal losses near the edges of any large-area, thin
substrate tend to be greater than near the center of the substrate,
resulting in a non-uniform temperature gradient across the
substrate. The thermal properties of the glass substrate combined
with its size, therefore, makes it more difficult to obtain uniform
characteristics for the electronic components formed on different
portions of the surface of a processed substrate. Moreover, heating
or cooling the substrates quickly and uniformly is more difficult
as a consequence of its poor thermal conductivity, thereby reducing
the ability of the system to achieve a high throughput.
12. Depending on the functions or processes to be performed within
a particular process chamber, pre-processing or post-processing,
such as heating or cooling of a substrate, may be required. Such
pre-processing and post-processing functions may be performed in
chambers separate from a primary process chamber. Due to the
various functions that a particular chamber is designed to perform,
each chamber may be configured differently from other chambers.
Moreover, once a chamber is designed to perform a particular
function, such as pre-process heating of the substrate, it may not
be possible to reconfigure the chamber to perform another different
function, such as post-process cooling of the substrate. Such
designs can limit the flexibility offered by a given chamber.
SUMMARY
13. In general, according to one aspect, an evacuable chamber
includes a chamber body having an aperture to allow a substrate to
be transferred into or out of the chamber. The chamber is
configurable using removable components in at least two of the
following configurations: a base configuration for providing a
transition between two different pressures, a heating configuration
for heating the substrate and providing a transition between two
different pressures, and a cooling configuration for cooling the
substrate and providing a transition between two different
pressures.
14. When the chamber is configured in the base configuration, the
chamber includes at least one removable volume reducing element.
The removable volume reducing elements can be made, for example, of
plastic, aluminum or other vacuum-compatible material. One volume
reducing element can be positioned adjacent and below a lid of the
chamber. Another volume reducing element can be positioned adjacent
and above the bottom interior surface of the chamber.
15. When configured in the heating configuration, the chamber
includes an upper heating assembly and a heating platen. The upper
heating assembly can be disposed between a lid of the chamber and a
substrate support mechanism. The heating platen can be movable to
lift a substrate positioned on the support mechanism to a heating
position below the upper heating assembly, and to lower the
substrate from the heating position onto the support mechanism.
16. The heating platen can include inner and outer heating loops
whose temperatures are independently controllable. For example,
during operation, the temperature of the outer loop can be
maintained at a higher temperature than the inner loop. The heating
platen also can have an upper surface having a pattern of
horizontal channels designed to control a contact area between a
substrate and the heating platen when the substrate is supported on
the upper surface of the platen. For example, the concentration of
channels can be greater near the center of the platen than near its
perimeter.
17. The upper heating assembly can have a stationary plate with
inner and outer heating loops whose temperatures can be controlled
independently of one another. A gas delivery tube can be attached
to the chamber, and the stationary plate can include a series of
vertical holes to allow a gas to be delivered from the delivery
tube to an interior region of the chamber via the vertical holes.
The upper heating assembly also can have a diffusion screen
disposed between the stationary plate and the substrate heating
position.
18. Various of the foregoing features can help compensate for
thermal losses near the edges of a large glass substrate and can
provide a more uniform temperature across the substrate when the
chamber is configured in the heating configuration.
19. The heating configuration also can be used to perform ashing
processes.
20. When configured in the cooling configuration, the chamber can
include a cooling platen and may also include an upper cooling
assembly. When an upper cooling assembly is employed, it can be
disposed between a lid of the chamber and a substrate support
mechanism. The cooling platen can be movable to lift a substrate
positioned on the support mechanism to a cooling position below the
upper cooling assembly, and to lower the substrate from the cooling
position onto the support mechanism.
21. The cooling platen can include multiple cooling tubes through
which a cooling fluid can flow. In one implementation, the
concentration of cooling tubes near the center of the platen can be
greater than the concentration near the perimeter. The cooling
platen can have an upper surface with a pattern of horizontal
channels designed to control a contact area between a substrate and
the cooling platen when the substrate is supported on the upper
surface of the platen. In one implementation, the concentration of
channels near the perimeter of the cooling platen is greater than
near the center.
22. The upper cooling assembly also can have a stationary plate
with multiple cooling tubes through which a cooling fluid can be
provided to flow. In some implementations, the concentration of
cooling channels is greater near the center of the stationary plate
than near the perimeter. A gas delivery tube can be attached to the
chamber. The stationary plate includes a series of vertical holes
to allow a gas to be delivered from the delivery tube to an
interior region of the chamber via the vertical holes. The upper
cooling assembly further can include a diffusion screen disposed
between the stationary plate and the substrate cooling
position.
23. Various of the foregoing features can help compensate for, or
take into account, thermal losses near the edges of a large glass
substrate and can provide a more uniform temperature across the
substrate when the chamber is configured in the cooling
configuration.
24. Resistive elements can be provided to heat the chamber body and
the lid to maintain them within a specified temperature range and
to compensate for thermal losses near the substrate edges. The
resistive elements can be used, for example, when the chamber is
configured as a cooling chamber.
25. Water cooling can be provided to the chamber body and lid when
the chamber is configured as a heating chamber if removal of excess
heat is necessary to limit and control temperature.
26. In yet a further aspect, a load lock chamber includes a chamber
body having an aperture to allow a substrate to be transferred into
or out of the chamber; and a thermally conductive platen for
supporting a substrate within the chamber. The platen has multiple
zones for preferentially changing the temperature of the substrate
by conduction so as to compensate for thermal losses near edges of
the substrate.
27. In addition, a method of processing a substrate in a load lock
chamber includes supporting the substrate on a substrate support
mechanism within the chamber and changing the pressure in the
chamber from a first pressure to a second pressure. The method
further includes controlling various surface temperatures in the
chamber to compensate for, or take into account, thermal losses
near edges of the substrate.
28. Various implementations include one or more of the following
advantages. A single load lock chamber can be configured in
multiple configurations depending on the requirements of the
particular substrate process system. The chamber design, therefore,
facilitates changes in system design because the chamber can be
re-configured relatively easily and quickly. Furthermore, the
various configurations of the chamber allow transitions between
first and second pressures, such as atmospheric and process
pressures, to be performed quickly.
29. Various features also enable a large glass substrate to be
cooled or heated quickly, thereby increasing the throughput of the
system. Depending on the particular configuration used, various
features of the chamber design help compensate for thermal losses
near the substrate edges to provide a more uniform temperature
across substrate. Various features also can help maintain the edges
of a substrate in compression which can reduce the likelihood of
substrate breakage during heating, cooling and other processes.
30. Additionally, the disclosed techniques for distributing a gas
throughout the chamber provide improvements over prior techniques,
which were not well suited for handling large substrates.
31. Other features and advantages will be apparent from the
following detailed description, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
32. FIG. 1 is a top plan schematic view of a substrate processing
system.
33. FIG. 2 is a cross-sectional view of a load lock chamber
according to the invention.
34. FIG. 3 is a cross-sectional view of the chamber of FIG. 2
configured as a base load lock chamber.
35. FIG. 4 is a cross-sectional view of the chamber of FIG. 2
configured as a heating or ashing load lock chamber.
36. FIG. 5 is an enlarged partial view of the chamber of FIG.
4.
37. FIG. 6 is a top view of a lower heating platen according to one
implementation of the invention.
38. FIG. 7 is a top view of an upper heating assembly and chamber
according to one implementation of the invention.
39. FIG. 8 is a top view of an upper heating assembly and chamber
according to another implementation of the invention.
40. FIG. 9 is a cross-sectional view of the chamber of FIG. 2
configured as a cooling load lock chamber.
41. FIG. 10 is an enlarged partial view of the chamber of FIG.
9.
42. FIG. 11 is a top view of a lower cooling platen according to
one implementation of the invention.
43. FIG. 12 is a top view of an upper cooling assembly according to
one implementation of the invention.
DETAILED DESCRIPTION
44. As shown in FIG. 1, a glass substrate processing system may
include one or more islands 2. Each island 2 includes a first or
input load lock chamber 4, one or more process chambers 6, and a
second or output load lock chamber 8. In various implementations,
the process chamber 6 can be, for example, a chemical vapor
deposition (CVD) chamber, a physical vapor deposition (PVD)
chamber, or an etch chamber.
45. Glass substrates, which can be on the order of one square
meter, are transferred, for example, by a continuous conveyor 10,
to and from the island 2 where one or more process steps can be
performed sequentially to the substrate. An atmospheric loading
robot 12 with an end effector 14 can deliver substrates from the
conveyor 10 to the input load lock chamber 4. Similarly, an
atmospheric unloading robot 16 with an end effector 18 can deliver
substrates from the output load lock chamber 8 to the conveyor 10.
As illustrated in FIG. 1, a fresh substrate 20A is loaded into the
load lock chamber 4 by the loading end effector 14, and a processed
substrate 20B is removed from the load lock chamber 8 by the
unloading end effector 18. A substrate transfer mechanism (not
shown in FIG. 1) can transfer the substrates 20A, 20B between the
various chambers 4, 6 and 8 through apertures such as transfer or
slit valves 5, 7.
46. In general, substrate processing performed in the process
chamber 6 typically must be done under low pressure, or in a vacuum
such as approximately 10.sup.-8 Torr. Thus, the load lock chambers
4, 8 perform a transition between atmospheric pressure and the
pressure in the process chamber 6. For example, the load lock
chamber 4 can be pumped down to a low pressure, such as
approximately 10.sup.-3 Torr, prior to transferring the substrate
to the process chamber 6. Similarly, after the substrate is
transferred from the process chamber 6 to the load lock chamber 8,
the load lock chamber 8 can be brought to atmospheric pressure
prior to opening the load lock chamber and transferring the
substrate to the conveyor 10.
47. Referring to FIG. 2, an evacuable chamber 30, such as a load
lock chamber, includes a temperature controlled chamber body 32 and
a temperature controlled lid 34 attached to the chamber body. The
chamber body 32 and lid 34 can be formed, for example, of aluminum,
and can be heated by coupling resistive elements 48 to the outer
surfaces of the chamber body and lid. The temperature of the
resistive elements 48 can be controlled by a computer or other
controller 66. An aperture 36 in one of the sidewalls of the
chamber body 32 serves as a passageway for transferring a substrate
into or out of the load lock chamber 30. The aperture 36 can be
used, for example, when a substrate is transferred from the end
effector 14 prior to processing or to the end effector 18 after
processing. A separate opening (not shown) in another one of the
chamber sidewalls can be used to transfer the substrate between the
load lock chamber 30 and a process chamber, such as the process
chamber 6 (FIG. 1).
48. A substrate transfer and support mechanism 38 is disposed
within the load lock chamber 30. The transfer and support mechanism
38 is used to transfer a substrate into and out of the load lock
and can support the substrate within the chamber interior. In one
implementation, the substrate transfer mechanism is a transfer
shuttle, such as the shuttle described in the U.S. patent
application referred to above, entitled "Method and Apparatus for
Substrate Transfer and Processing." During the transition from
atmospheric pressure to vacuum or some other processing pressure,
the transfer mechanism 38 is cleaned of particles as the flow of
gas in the load lock chamber 30 is directed past the transfer
mechanism prior to leaving the chamber through a vacuum port (not
shown) in the bottom 40 of the chamber.
49. The chamber 30 also includes a gas delivery pipe or tube 42
through which a gas can be delivered to the interior of the chamber
30. Additionally, the chamber 30 includes an aperture 44 extending
through the bottom 40 of the chamber 30. As described below,
thermocouples, heating elements and/or a water line can be provided
to the interior of the chamber through the aperture 44. In some
implementations, the aperture 44 is closed or sealed.
50. As described in greater detail below, the load lock chamber 30
can be configured in at least the following configurations: a base
configuration for providing a transition between two different
pressures, a heating configuration for heating the substrate and
providing a transition between two different pressures, or a
cooling configuration for cooling the substrate and providing a
transition between two different pressures. The load lock chamber
30 also can be configured in an ashing configuration. In general,
the chamber 30 can be configured in at least two of the foregoing
configurations. Furthermore, the load lock chamber 30 can be
re-configured relatively easily from one configuration to another
configuration.
51. The chamber 30 can be configured as a base load lock chamber
30A (FIG. 3) which can be used, for example, for transitions
between first and second pressures, such as atmospheric pressure
and a processing pressure. In the base configuration, one or more
removable volume reducing elements 50A, 50B are added to the
interior of the chamber 30A. In the illustrated implementation, an
upper volume reducing element 50A is disposed adjacent and below
the lid 34 and a lower volume reducing element 50B is disposed
adjacent and above a bottom interior surface of the chamber. The
mechanism 38 which supports the substrate is positioned between the
upper and lower volume reducing elements 50A, 50B. In one
implementation, the volume reducing elements 50A, 50B can be
rectangular-shaped and can be formed, for example, of a plastic
material such as LEXAN or aluminum. In general, the volume reducing
elements 50A, 50B are designed to be as large as possible without
interfering with the operation of the transfer mechanism 38 or the
end effectors 14, 18 of the robots 12, 16 (FIG. 1) when the
substrate is transferred from one position to another. The upper
volume reducing element 50A can be attached to the chamber lid 34,
for example, with screws, bolts or pins. The lower volume reducing
element SOB can rest on the chamber floor.
52. One advantage of using the volume reducing elements 50A, 50B is
that when the chamber 30A is used as an input load lock chamber,
the pressure in the chamber can be pumped down to the processing
pressure more quickly, thereby increasing the throughput of the
system. Similarly, when the chamber 30A is used as an output load
lock chamber, the pressure in the chamber can be brought back to
atmospheric pressure more quickly. Furthermore, when the chamber
30A is used as an output load lock chamber, an inert gas such as
nitrogen or argon, is provided to the chamber interior, via the gas
delivery tube 42, to provide the transition to atmospheric
pressure. For this purpose, the upper volume reducing element 50A
can include one or more vertical channels 52 that allow the gas to
be provided to an interior region of the chamber. The upper surface
of the volume reducing element 50A also can include horizontal
channels (not shown) that allow the gas to flow from the delivery
tube 42 to the vertical channels 52.
53. In some etch systems, substrates are maintained at temperatures
of less than approximately 100.degree.C. The base configuration is
suitable, for example, as either the input or output load lock
chamber in such etch systems.
54. The chamber 30 (FIG. 2) can also be configured as a heating
load lock chamber 30B (FIGS. 4-7). In the heating configuration,
the volume reducing elements 50A, 50B are removed, and are replaced
by a removable upper heating assembly 56 and a removable lower
heating platen 54, respectively. The upper heating assembly 56,
which is described in greater detail below, can be attached to the
chamber lid 34, for example, by shoulder screws, clamps, or
bolts.
55. The lower heating platen 54 is a vertically movable temperature
controlled hot plate, which can be formed, for example, from
stainless steel. When a substrate is placed on the lower platen 54,
the lower platen conducts heat directly into the substrate. The
lower platen 54 includes an inner heating loop 58A and an outer
heating loop 58B, each of which has one or more heating elements,
such as coils. The heating elements for the inner and outer loops
58A, 58B can be coupled to the controller 66 by connections 62
through a tube 46 which extend through the aperture 44 and which is
welded to the lower platen 54. Thermocouples for measuring the
temperature of the lower platen 54 also can be connected from the
platen 54 to the controller 66 by connections 64 through the tube
46. The tube 46 can be surrounded by a bellows (not shown) to
provide a vacuum seal within the chamber when the platen 54 moves
vertically.
56. The temperature of the inner and outer heating loops 58A, 58B
can be controlled independently. The independent temperature
control allows the surface of the platen 54 near its perimeter to
be maintained at a different temperature from the surface of the
platen near its center. In one implementation, the temperature of
the outer loop 58B is maintained at a higher temperature than the
inner loop 58A. Such a temperature difference helps compensate for
the heat loss in the substrate near its edges and helps reduce the
possibility of substrate breakage due to cracks propagating through
the substrate as a result of edge defects. Rapid heating of
substrates is, therefore, facilitated.
57. The upper surface of the lower platen 54 includes a pattern of
one or more horizontal grooves or channels 60 (FIGS. 5-6). In one
implementation, two sets of channels 60 are formed across the
surface of the lower platen 54 with one set of channels formed
radially and the other set formed circularly. In the illustrated
implementation, the channels 60 have a width of about 6 mm and a
depth of about 1 mm. Other dimensions may be suitable for
particular applications. The spacing between adjacent channels, or
the concentration of the channels, is designed to control the
contact area between a substrate and the platen 54 and provides
further control of the temperature gradient across the substrate.
For example, in one implementation, fewer channels 60 per unit area
are provided near the perimeter of the platen 54 compared to the
number of channels near the center of the platen. Such a pattern
increases the contact area between the platen and a surface of the
substrate near the substrate edges compared to the contact area
between the platen and a surface of the substrate near the
substrate center. Therefore, the pattern of channels 60 also can
help compensate for thermal losses near the edges of the substrate
to provide a more uniform temperature profile across the
substrate.
58. In operation, according to one implementation, an external
robot, such as the robot 12 (FIG. 1), loads a substrate into the
heating load lock chamber 30B and places the substrate onto the
transfer mechanism 38. The lower heating platen 54 is raised and
lifts the substrate off the transfer mechanism 38. The platen 54
continues rising until the substrate is brought to a heating
position. The heating position should be as close as possible to
the position in which the thermal losses from the edges of the
substrate to the cooler walls of the chamber body 32 are minimized.
In one implementation, for example, the substrate can be lifted to
within several millimeters of the upper heating assembly 56 so that
the viewing angle of the substrate edge with respect to the chamber
walls is reduced as much as possible. As the chamber is heated,
cooling water tubes with an appropriate degree of thermal contact
to the outer walls of the chamber help maintain the temperature of
the chamber walls within a desired range and prevent the walls from
becoming too hot. The cooling tubes may be joined to a plate which
is affixed to the chamber walls. For example, in one
implementation, the temperature of the chamber walls is maintained
at approximately 100.degree.C. In addition, thermal barriers can be
provided along the outside walls of the chamber to protect workers
or others from touching the hot chamber surfaces.
59. As the lower platen 54 lifts the substrate off from the
transfer mechanism 38 and raises it to the heating position, some
of the channels 60 on the upper surface of the platen and holes
through the platen allow gas that is between the platen and the
substrate to escape. The channels 60 and holes thus help prevent
the formation of a trapped cushion of gas that could cause the
substrate to float and drift from its initial desired position on
the platen 54.
60. The upper heating assembly 56 includes a stationary plate 68,
which can be made of stainless steel and which includes an inner
heating loop 69A and an outer heating loop 69B, each of which has
one or more heating elements, such as coils. The temperature of the
loops 69A, 69B can be controlled so as to obtain a more uniform
temperature across the substrate. Thermocouples can be attached to
the plate 68 for measuring its temperature. The thermocouples and
heating elements can be coupled to the controller 66 by connections
70 and 72, respectively.
61. The stationary plate 68 further includes a series of vertical
holes 78 (FIG. 7) which are formed through the plate 68. In the
illustrated implementation, an outer zone 78A of holes 78 and an
inner zone 78B of holes are formed through the plate 68. The
heating assembly 56 also includes a diffusion screen 74 (FIG. 5)
which can comprise one or more fine mesh screens or filters with
multiple holes. The diffusion screen 74 is mounted to the
stationary plate 68, for example, by a clamp 76.
62. Once a substrate is moved to its heating position in the
chamber 30B, the upper heating assembly 56 heats the substrate
primarily by conduction and radiation. Using an upper heater
assembly which has zones of various emissivities on the surface
facing the substrate can be used to facilitate the substrate
heating rate, and thermal uniformity can be controlled. An inert
gas, such as nitrogen or argon, can be introduced from a gas source
100A via the delivery tube 42 to the back-side or upper surface 80
of the plate 68 to facilitate the heating process further. The gas
flows along the upper surface 80 of the plate 68 toward the holes
78. The gas, which is heated as it flows along the upper surface
80, then can pass through the holes 78 to the front-side or lower
surface of the plate 68. The amount of gas flow exiting from the
inner and outer zones 78A, 78B relative to one another into the
chamber can be changed by varying the size or the number of holes
78 in the stationary plate 68, as well as by varying the gas
pressure in the zones.
63. Once the gas flows to the front-side of the plate 68, the
diffusion screen 74 directs the gas onto the substrate surface
facing the heating assembly 56. The diffusion screen 74 can
restrict the flow of the gas to limit disturbances that otherwise
may be caused as the gas flows onto the substrate. The diffusion
screen 74 also can bias the heat transfer to the substrate to
improve the uniformity of the substrate temperature. For example,
the diffusion screen 74 preferentially can introduce more (or less)
gas near the outer portions of the chamber to provide a more
uniform temperature across the substrate. If a diffusion screen is
not used, the gas flows directly on to the substrate.
64. The configuration of FIGS. 4-7 can be used, for example, as an
input load lock chamber in which a substrate is heated prior to
being transferred to a process chamber. Such pre-process heating
may be required or desirable, for example, in CVD and PVD systems,
as well as other substrate processing systems. When the load lock
chamber 30B is used as an input chamber to heat the substrate prior
to its transfer to a process chamber, the amount and extent of gas
flow from the delivery tube 42 may need to be regulated or limited
to allow the chamber 30B to be pumped down to a vacuum or some
other process pressure.
65. Once the desired heating of the substrate occurs, the platen 54
is lowered, allowing the substrate to be transferred back to the
transfer mechanism 38. The substrate then can be transferred by the
transfer mechanism 38, for example, to the process chamber 6.
66. The chamber 30B also can be used as an ash load lock chamber.
In such an application, the inert gas source 100 is replaced by an
ash gas source 100B (FIG. 8). Such a configuration can be used, for
example, as an output load lock chamber where, in addition to
providing a transition to atmospheric pressure, a post-process ash
takes place. In one implementation, the chamber 30B can be used as
an ash load lock to ash a photoresist layer on a substrate that is
received from a primary process chamber, such as the chamber 6
(FIG. 1).
67. When the chamber 30B is configured as an ash load lock chamber,
the chamber is typically heated to a lower temperature than when
the chamber is used as an input heating load lock. In one exemplary
application, the controller 66 heats the chamber 30B to
approximately 150.degree.C., and an ash gas, such as oxygen
(O.sub.2) or carbon tetra fluoride (CF.sub.4), is provided to the
chamber interior via the delivery tube 42. Once the ashing process
is completed, the load lock is pumped, purged and vented to
atmospheric pressure. The substrate then can be transferred, for
example, by the robot 16 to the conveyor 10.
68. The chamber 30 (FIG. 2) also can be configured as a cooling
load lock chamber 30C (FIGS. 9-12). The cooling configuration 30C
includes a removable upper cooling assembly 86 and a removable
lower cooling platen 84. The upper cooling assembly 86, which is
described in greater detail below, can be attached to the chamber
lid 34, for example, by shoulder screws, clamps or bolts.
69. The lower cooling platen 84 is a vertically movable temperature
controlled cooling plate, which can be formed, for example, from
stainless steel or aluminum. When a substrate is placed on the
lower platen 84, the lower platen conducts heat directly from the
substrate, thereby cooling the substrate. When temperatures of the
chamber walls and arriving substrates are sufficiently low, the
lower platen may have sufficient heat loss to the chamber to allow
continuous operation without the need to be actively cooled, for
example, by running water through it. When necessary, however, the
lower platen 84 includes multiple cooling tubes 92 through which a
cooling fluid, such as water, can flow. The water can be provided
to the cooling tubes 92 through a stainless steel water line 82
which extends through the aperture 44 and which is welded to the
lower platen 84. The controller 66 can control the flow of water
through the water line 82 to the tubes 92. The water line 82 can be
surrounded by a bellows (not shown) to maintain the pressure within
the chamber when the platen 84 moves vertically as described below.
The position and concentration of the cooling tubes 92 is selected
to obtain a more uniform temperature profile across the substrate
by taking into account or compensating for thermal losses near the
edges of the substrate. Thus, for example, the concentration of
cooling tubes 92 near the center of the platen 84 can be greater
than the concentration near its perimeter. Such a configuration can
provide a more uniform temperature profile throughout the
substrate, can help reduce the likelihood of substrate breakage,
and can facilitate the rapid cooling of the substrate in the load
lock chamber 30C.
70. The upper surface of the lower platen 84 includes a pattern of
one or more horizontal grooves or channels 90 (FIGS. 10-11). In one
implementation, twosets of channels 90 are formed across the
surface of the lower platen 84 with one set of channels formed
substantially perpendicular to the other set. In the illustrated
implementation, the channels 90 have a width of about 6 mm and a
depth of about 1 mm. Other dimensions may be suitable for
particular applications. The spacing between the channels 90, or
the concentration of the channels, is designed to control the
contact area between a substrate and the platen 84 and provides
further control of the temperature gradient across the substrate.
For example, in one implementation, more channels 90 per unit area
are provided near the perimeter of the platen 84 compared to the
number of channels per unit area near the center of the platen.
Such a pattern increases the contact area between the platen 84 and
a first surface of the substrate near its center compared to the
contact area between the platen and a second surface of the
substrate near its perimeter where the first and second areas are
the same size. In general, the pattern of channels 90 on the platen
84 can be designed to take into account or compensate for thermal
losses near the edges of the substrate so as to provide a more
uniform temperature profile throughout the substrate.
71. In operation, according to one implementation, a substrate is
loaded from a process chamber, such as the chamber 6 (FIG. 1), onto
the transfer mechanism 38 in the cooling load lock chamber 30C. The
lower cooling platen 84 is raised and lifts the substrate off the
transfer mechanism 38. The platen 84 continues rising until the
substrate is brought to a cooling position. The substrate can be
lifted, for example, to within several millimeters of the upper
cooling assembly 86 so that the viewing angle of the substrate edge
with respect to the chamber walls is reduced as much as possible
when the substrate is in its cooling position.
72. The upper cooling assembly 86 includes a stationary plate 98,
which can be made of stainless steel or aluminum and which includes
multiple cooling tubes 102 through which a cooling fluid, such as
water, can flow. The configuration of the cooling tubes 102 also is
designed to provide a more uniform temperature throughout the
substrate by taking into account or compensating for thermal losses
near the edges of the substrate. In one implementation, the
concentration of the cooling channels is greater near the center of
the plate 98 than near its perimeter.
73. The stationary plate 98 further includes a series of vertical
holes 108 (FIG. 12) which are formed through the plate 98. In the
illustrated implementation, an outer zone 108A of holes 108 and an
inner zone 108B of holes 108 are formed through the plate 98. The
upper cooling assembly 86 also includes a diffusion screen 104
(FIG. 10) which can comprise one or more fine mesh screens or
filters having multiple holes. In some implementations, the
diffusion screen 104 preferentially can introduce more (or less)
gas near the center of the chamber relative to other parts of the
chamber. The diffusion screen 104 is mounted to the stationary
plate 98, for example, by a clamp 106.
74. Once a substrate is moved to its cooling position in the
chamber 30C, the upper cooling assembly 86 helps cool the substrate
primarily by forced convection and radiation processes. Zones of
various emissivities on the surface of the upper cooling assembly
facing the substrate also can be used to facilitate the cooling
process and tailor thermal uniformity. An inert gas, such as
nitrogen or argon, can be introduced from a gas source 100C via the
delivery tube 42 to the back-side or upper surface 110 of the plate
98 to facilitate the cooling process further. The gas flows along
the upper surface 110 of the plate 98 toward the holes 108. The
gas, which is cooled as it flows along the upper surface 110, then
can pass through the holes 108 to the front-side or lower surface
of the plate 98. The amount of gas flow exiting from the inner and
outer zones 108A, 108B relative to one another into the chamber can
be changed by varying the size or the number of holes 108 in the
stationary plate 98, as well as by varying the gas pressure in the
zones. Water-cooling the stationary plate may not always be
required. When it is not, the stationary plate acts to distribute
the gas flow to the back or upper side of the diffusion screen
104.
75. The diffusion screen 104 directs the gas onto the substrate
surface facing the upper cooling assembly 86. The diffusion screen
104 can restrict and distribute the flow of the gas to limit
turbulence and eddy flows that otherwise may be present as the gas
flows onto the substrate. The diffusion screen 104 also can control
the flow of gas to help bias heat transfer from the substrate. The
diffusion screen can be designed, for example, so that the flow of
the gas results in a more uniform temperature profile across the
substrate.
76. When configured as a cooling load lock chamber, the chamber
body 32 and lid 34 also can be heated using the resistive elements
48 to maintain their temperature within a specified range above the
cooling water temperature. In one implementation, the temperature
of the chamber walls is maintained at approximately 100.degree.C.
Heating the walls of the chamber body 32 during a cooling process
can provide several advantages. First, such heating can compensate
for the thermal losses near the substrate edges, thereby providing
a more uniform temperature profile across the substrate as it
cools. Furthermore, such heating can help reduce adsorption of
water vapor on the chamber walls while the chamber is open during
substrate removal. Reducing the amount of water vapor can prevent
the water vapor from combining with residual by-products from the
process chamber 6, such as chlorine gas (Cl.sub.2). Preventing the
combination of water vapor and such residual by-products is
important because the combination of such chemicals can cause
corrosion of the chamber 30C. Additionally, when the cooling load
lock is arranged adjacent a process chamber in which heating of the
walls is desirable or necessary, the hot surfaces of the chamber
body also prevent the cooling load lock from acting as a heat sink
and drawing heat from the process chamber.
77. The configuration of FIGS. 9-12 can be used, for example, as an
output load lock chamber in which a substrate is cooled and the
chamber is returned to atmospheric pressure prior to being
transferred to the conveyor 10 (FIG. 1). Such post-process cooling
may be required or desirable, for example, in CVD or PVD systems
where processing temperatures may reach 200-450.degree.C. To
accelerate the transition to atmospheric pressure, an inert gas
such as nitrogen or argon can be provided to the chamber 30C from
the delivery tube 42. The channels 90 in the upper surface of the
lower cooling platen 84 and holes through the platen allow gas to
reach the backside of the substrate which facilitates separating
the substrate from the platen. The substrate then can be
transferred to the transfer mechanism 38 and to the conveyor 10
(FIG. 1).
78. Although the control system is shown as a single controller 66,
the control system can include multiple dedicated controllers to
control such features as the movement of the lower platens 54, 84,
as well as the temperature of the lower platens, the temperature of
the upper assemblies 56, 86, the temperature of the chamber body 32
and chamber lid 34, the flow of a cooling fluid through the line
82, and the flow of gas through the gas tube 42.
79. As described above, a single load lock chamber 30 (FIG. 1) can
be configured in multiple configurations depending on the
requirements of the particular substrate process system. The
chamber design, therefore, facilitates changes in system design
because the chamber 30 can be reconfigured relatively easily and
quickly. Furthermore, the various configurations of the chamber 30
allow transitions between first and second pressures, such as
atmospheric and process pressures, to be performed quickly.
80. Various features of the load lock chamber can provide a more
uniform temperature across a substrate as it is heated or cooled.
Although it is desirable to obtain a perfectly uniform temperature
across the substrate, it is difficult, if not impossible, to
achieve such perfect uniformity in practice. Accordingly, various
features of the load lock are designed to ensure that portions of
the substrate near its edges are maintained at a temperature at
least as high as the temperatures in other portions of the
substrate. Such features result in a slight compressive force to
the edges of the substrate and help reduce the likelihood of
substrate breakage in the chamber. The various configurations also
enable a substrate to be cooled or heated quickly, thereby
increasing the throughput of the system.
81. Other implementations are within the scope of the following
claims.
* * * * *