U.S. patent application number 11/176747 was filed with the patent office on 2007-01-11 for load lock chamber with substrate temperature regulation.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Akihiro Hosokawa, Makoto Inagawa.
Application Number | 20070006936 11/176747 |
Document ID | / |
Family ID | 37617224 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070006936 |
Kind Code |
A1 |
Hosokawa; Akihiro ; et
al. |
January 11, 2007 |
Load lock chamber with substrate temperature regulation
Abstract
A load lock chamber and method for regulating the temperature of
substrates positioned within a chamber are provided. In one
embodiment, the load lock chamber is configured to remove gases
heated during venting of the load lock chamber. In another
embodiment, the load lock chamber is configured to provide a cross
flow of vent gases. In yet another embodiment, the load lock
chamber includes a resistive heating element configured to
uniformly head substrates positioned within the load lock
chamber.
Inventors: |
Hosokawa; Akihiro;
(Cupertino, CA) ; Inagawa; Makoto; (Palo Alto,
CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
37617224 |
Appl. No.: |
11/176747 |
Filed: |
July 7, 2005 |
Current U.S.
Class: |
141/8 |
Current CPC
Class: |
H01L 21/67201
20130101 |
Class at
Publication: |
141/008 |
International
Class: |
B65B 31/00 20060101
B65B031/00 |
Claims
1. A load lock chamber comprising: a chamber body having a first
side adapted for coupling to a vacuum chamber and a second side
adapted for coupling to a factory interface; N vertically stacked
substrate transfer chambers formed in the chamber body, where N is
an integer greater than two; N-1 interior walls, each interior wall
separating and environmentally isolating adjacent substrate
transfer chambers; a substrate support disposed in each of the
substrate transfer chambers; a plate disposed above the substrate
support in at least one of the substrate transfer chambers; and a
resistive heater coupled to the plate.
2. The load lock chamber of claim 1, wherein the resistive heater
is configured to provide greater heat flux proximate an edge of the
plate relative to a center of the plate.
3. The load lock chamber of claim 1, wherein each of the substrate
transfer chambers further comprises: a cooling plate.
4. The load lock chamber of claim 3, wherein the cooling plate
further comprises: a plurality of passages adapted to flow a heat
transfer fluid therethrough.
5. The load lock chamber of claim 3, wherein the substrate supports
further comprises: a plurality of substrate support pins, at least
one of the substrate support pins disposed through the cooling
plate.
6. The load lock chamber of claim 5 further comprising: an actuator
coupled to the cooling plate and adapted to control the elevation
of the cooling plate relative to a distal end of the substrate
support pins.
7. The load lock chamber of claim 1, wherein the substrate transfer
chamber has an internal volume of less than or equal to about 1000
cubic liters.
8. The load lock chamber of claim 1, wherein each of the substrate
transfer chambers are adapted to accommodate a substrate having a
plan area of at least 2.7 square meters.
9. The load lock chamber of claim 1, wherein at least a first
chamber of the substrate transfer chambers further comprises: at
least one inlet port and at least one outlet port adapted to
regulate pressure within the first chamber, wherein at least one
inlet port is disposed on a sidewall of the first chamber opposite
the outlet port.
10. The load lock chamber of claim 1, wherein at least a first
chamber of the substrate transfer chambers further comprises: a
plurality of inlet ports; at least two control valves coupled to
the inlet ports and adapted to independently regulate flow from at
least two of the inlet ports into the first chamber.
11. The load lock chamber of claim 1, wherein at least a first
chamber of the substrate transfer chambers further comprises: a
plurality of inlet ports; at least two heaters configured to
independently regulate temperatures of flows from at least two of
the inlet ports into the first chamber.
12. A load lock chamber comprising: a chamber body having a first
substrate transfer port and a second substrate transfer port
disposed therein; a substrate transfer chamber formed in the
chamber body; a plurality of vent ports disposed through at least
one sidewall of the chamber body and fluidly coupled to the
substrate transfer chamber; and at least one pump port disposed in
at least one sidewall of the chamber body and fluidly coupled to
the substrate transfer chamber.
13. The load lock chamber of claim 12, wherein the pump port is
disposed on a sidewall opposite at least one of the vent ports.
14. The load lock chamber of claim 12, at least one pump port
further comprises: a plurality of vent ports.
15. A method for regulating temperature of a substrate in a load
lock chamber, comprising: transferring a substrate from a vacuum
environment into a load lock chamber; sealing the load lock chamber
from the vacuum environment; flowing a vent gas into the load lock
chamber to increase pressure therein; removing a portion of the
vent gas from the load lock chamber; and opening a substrate access
port between the load lock chamber and an environment having a
pressure greater than the vacuum environment.
16. The method of claim 15 further comprising: flowing vent gas
between an inlet port and an outlet port while increasing the
pressure within the load lock chamber.
17. The method of claim 15 further comprising: flowing vent gas
between an inlet port and an outlet port while maintaining
substantially constant pressure within the load lock chamber.
18. The method of claim 17 further comprising: flowing vent gas
between an inlet port and an outlet port while increasing the
pressure within the load lock chamber for a first period of time;
and flowing vent gas between the inlet port and the outlet port
while maintaining substantially constant pressure within the load
lock chamber for a second period of time.
19. The method of claim 15 further comprising: flowing vent gas
into the load lock chamber from a first inlet port; and flowing
vent gas into the load lock chamber from a second inlet port.
20. The method of claim 19 further comprising: controlling a flow
rate of vent gas through the first inlet port independently from a
flow rate of vent gas through the second inlet port.
21. The method of claim 19 further comprising: controlling a
temperature of the vent gas flowing through the first inlet port
independently from a temperature of the vent gas flowing through
the second inlet port.
22. The method of claim 15, wherein the load lock chamber further
comprises an upper transfer chamber, a middle transfer chamber and
a lower transfer chamber, and wherein the method further comprises:
transferring all substrates to be processed from the ambient
environment to the vacuum environment through the upper transfer
chamber; and transferring substrates from the vacuum environment to
the ambient environment through the lower transfer chamber.
23. The method of claim 22 further comprising: heating substrates
passing through the upper transfer chamber by applying power to a
resistive heater disposed in the upper transfer chamber.
24. The method of claim 22 further comprising: transferring
substrates from the vacuum environment to the ambient environment
only through the lower transfer chamber and the middle transfer
chamber.
25. A method for regulating temperature of a substrate in a load
lock chamber, comprising: providing a substrate in the load lock
chamber sealed between a vacuum environment and an ambient
environment; flowing a gas into contact with the substrate disposed
in the sealed chamber; and removing a portion of the gas from the
sealed load lock chamber.
26. The method of claim 25, wherein the steps of flowing and
removing the gas further comprises: flowing the gas from at least
one inlet port across the substrate and out an exhaust port in a
direction substantially parallel to a plane of the substrate.
27. The method of claim 25, wherein the step of flowing the gas
into the load lock chamber further comprises: controlling a flow
rate of gas through a first inlet port independently from a flow
rate of gas through a second inlet port.
28. The method of claim 25, wherein the step of flowing the gas
into the load lock chamber further comprises: controlling a
temperature of the gas flowing through a first inlet port
independently from a temperature of a gas flowing through a second
inlet port.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is related to U.S. patent application Ser.
No. 10/832,795, entitled "LOAD LOCK CHAMBER FOR LARGE AREA
SUBSTRATE PROCESSING SYSTEM", filed Apr. 26, 2004, which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the invention generally relate to a load lock
chamber having substrate temperature regulation and methods of
operation of the same.
[0004] 2. Description of the Related Art
[0005] Thin film transistors (TFT) formed by flat panel technology
are commonly used for active matrix displays such as computer and
television monitors, cell phone displays, personal digital
assistants (PDAs), and an increasing number of other devices.
Generally, flat panels comprise two glass plates having a layer of
liquid crystal materials sandwiched therebetween. At least one of
the glass plates includes one conductive film disposed thereon that
is coupled to a power source. Power, supplied to the conductive
film from the power source, changes the orientation of the crystal
material, creating a pattern display.
[0006] With the marketplace's acceptance of flat panel technology,
the demand for larger displays, increased production and lower
manufacturing costs have driven equipment manufacturers to develop
new systems that accommodate larger size glass substrates for flat
panel display fabricators. Current glass processing equipment is
generally configured to accommodate substrates slightly greater
than about one square meter. Processing equipment configured to
accommodate larger substrate sizes is envisioned in the immediate
future.
[0007] Equipment to fabricate such large substrates represents a
substantial investment to flat panel display fabricators.
Conventional systems require large and expensive hardware. In order
to offset this investment, high substrate throughput is very
desirable.
[0008] Heating and/or cooling of the substrate within the load lock
chamber is important to achieving high system throughput. Moreover,
as cleanrooms generally operate at humidity levels greater than 50
percent to minimize static electricity, hot substrates entering the
load lock chamber must be cooled carefully to avoid promoting
condensation thereon. Condensation is undesirable as moisture often
contaminates subsequent processing steps. As future processing
systems are envisioned to process even larger size substrates, the
need for improved load lock chambers capable of rapid transfer of
large area substrates is of great concern.
[0009] Thus, there is a need for an improved load lock chamber.
SUMMARY OF THE INVENTION
[0010] A load lock chamber and method for regulating the
temperature of substrates positioned therein are provided. In one
embodiment, a load lock chamber is configured to remove gases
heated during venting of the load lock chamber. In another
embodiment, a load lock chamber is configured to provide a flow of
vent gases across the surface of a substrate. In yet another
embodiment, a load lock chamber includes a resistive heating
element configured to uniformly heat substrates positioned within
the load lock chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of
the invention are attained and can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to the embodiments thereof which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0012] FIG. 1 is a sectional view of one embodiment of load lock
chamber;
[0013] FIGS. 2A-B are side sectional views of alternative
embodiments of a load lock chamber of the present invention;
[0014] FIG. 3 is a top sectional view of the load lock chamber of
FIG. 1;
[0015] FIGS. 4A-B are perspective views of two embodiments of a
temperature regulating plate;
[0016] FIG. 5 is another embodiment of a temperature regulating
plate;
[0017] FIG. 6 is one embodiment of a method for regulating
temperature of a substrate;
[0018] FIG. 7 is another embodiment of a method for regulating
temperature of a substrate;
[0019] FIG. 8 is a top plan view of one embodiment of a processing
system for processing large area substrates;
[0020] FIG. 9 is a side sectional view of one embodiment of a
multiple chamber load lock chamber;
[0021] FIG. 10 is a side sectional view of the load lock chamber of
FIG. 9 taken along section line 10-10;
[0022] FIGS. 11A-B are partial sectional views of a substrate
support of the load lock chamber of FIG. 9;
[0023] FIG. 12 is a sectional view of one embodiment of an
alignment mechanism; and
[0024] FIGS. 13-14 are sectional views of another embodiment of an
alignment mechanism.
[0025] To facilitate understanding, identical reference numerals
have been used, wherever possible, to designate identical elements
that are common to the figures. It is contemplated that elements of
one embodiment may be advantageously utilized in other embodiments
without further recitation.
DETAILED DESCRIPTION
[0026] A load lock chamber configured to regulate the temperature
of substrates positioned therein is provided. The embodiments
described herein promote rapid transfer between ambient and vacuum
environments while minimizing particulate generation and the threat
of condensation.
[0027] FIG. 1 depicts one embodiment of a load lock chamber 100 of
the present invention. The load lock chamber 100 includes a body
102 fabricated from a rigid material such as stainless steel,
aluminum or other suitable material. The body 102 may be fabricated
from a single piece of material, or an assembly of components
fabricated into a leak-free structure. The body 102 includes a top
104, a bottom 106, and sidewalls 108, 110, 112, and 114. The fourth
sidewall 114, which is positioned opposite the first sidewall 112,
is illustrated in FIG. 3.
[0028] At least one substrate access port 116 is disclosed in each
of the sidewalls 112 and 114 to allow entry and egress of
substrates from an internal volume 120 of the chamber body 102. The
substrate access ports 116 are selectively sealed by slit valves,
which are well known in the art. One slit valve that may be adapted
to benefit from the invention is described in U.S. patent
application Ser. No. 10/867,100, entitled CURVED SLIT VALVE DOOR,
filed Jun. 14, 2004 by Tanase, et al., and is incorporated by
reference in its entirety.
[0029] A substrate support structure 118 is disposed in the
internal volume 120 defined by the body 102. The substrate support
structure 118 generally is configured to support one or more
substrates 122 being transferred between an ambient and a vacuum
environment separated by the load lock chamber 100. Although the
substrate support structure 118 depicted in FIG. 1 is illustrated
supporting a single substrate 122, it is contemplated that other
substrate support structures may also benefit from the
invention.
[0030] For example, as depicted in FIG. 2A, a load lock chamber 210
includes a substrate support structure 218 in the form of a
cassette 220. The cassette 220 includes a plurality of substrate
support slots 224, each configured to retain a single substrate 122
therein. The cassette 220 is typically coupled to a lift mechanism
222 that selectively positions one of the substrates disposed in a
predetermined slot 224 of the cassette 220 in alignment with the
substrate access ports 216 formed in a body 212 of the load lock
chamber 210. One load lock chamber having a cassette disclosed
therein which may be adapted to benefit from the invention is
described in U.S. Pat. No. 5,607,009, issued Mar. 4, 1997 to Turner
et al., and is incorporated by reference in its entirety. In a
second example depicted in FIG. 2B, a load lock chamber 230
includes a substrate support structure 238 having multiple
substrate support plates 232. Each substrate support plate 232 is
configured to support a single substrate 122 thereon. Such
substrate support plates may be configured with an optional lift
mechanism 222 to align a selected substrate 122 with a substrate
access port 216. Alternatively, the substrate support structure 238
may be fixed within the chamber 230, requiring a robot making the
wafer exchange to provide the vertical motion necessary to lift the
substrate off the support plate 232. One load lock chamber which
may be adapted to benefit from the invention having similar
substrate support structure is described in U.S. patent Ser. No.
09/957,784, entitled DOUBLE DUAL SLOT LOAD LOCK FOR PROCESS
EQUIPMENT, filed Sep. 21, 2001 by Kurita et al., and is
incorporated by reference in its entirety. It is contemplated that
load lock chambers of other configurations may also benefit from
the invention.
[0031] Returning to the embodiment depicted in FIG. 1, the
substrate support structure 118 includes a plate 124 and a
plurality of pins 126. The pins 126 are coupled to the bottom 106
of the body 102, and extend through holes 132 formed in the body in
the plate 124. The plate 124 is typically fabricated from aluminum
or other suitable material.
[0032] A lift mechanism 138 is provided to control the elevation of
the plate 124 within the internal volume 120 of the load lock
chamber 100. In a lower position, the distal end of the pins 126
extend beyond an upper surface 136 of the plate 124, thereby
supporting the substrate 122 in a spaced-apart relation relative to
the plate 124. The lift mechanism 138 may selectively raise the
plate 124 to an upper position such that the distal end of the pins
126 are recessed below the upper surface 136 of the plate 124,
thereby causing the substrate 122 to be supported on the upper
surface of the plate 124.
[0033] In one embodiment, the lift mechanism 138 generally includes
an actuator 140 coupled to the plate 124 by a bar 142. The actuator
140 may be a pneumatic cylinder, a ball screw or other actuator
suitable for controlling the elevation of the substrate support
structure 118. The bar 142 generally extends from the plate 124
through an aperture 176 formed in the sidewall of the body 102. A
portion of the bar 142 disclosed outside the body 102 is enclosed
by a housing 144.
[0034] In one embodiment, a portion of the actuator 140 extends
through the housing 144 and is coupled to the bar. A bellows or
other suitable seal is engaged between the housing 144 and at least
one of the actuator 140 or the bar 142 to prevent leakage through
the aperture 176 and to maintain the leak-tight integrity of the
load lock chamber 100.
[0035] In one embodiment, the substrate support structure 118 may
be configured as a temperature regulating plate 124. The
temperature regulating plate 124 is adapted, to control the
temperature of the substrate 122 positioned thereon or proximate
thereto. For example, the plate 124 may include a plurality of
passages 130 coupled to a fluid source 128. The fluid source 128
provides a heat transfer fluid that is circulated through the
passages 130 to heat (or cool) the substrate 122. To maximize heat
transfer between the plate 124 and the substrate 122, the plate 124
may be elevated to support the substrate 122 directly thereon
(i.e., with the pins 126 retracted below upper surface 136 of the
plate 124).
[0036] The upper surface 136 of the plate 124 may include one or
more slots 134. The slots 134 are configured to provide channels
that provide clearance for an end effector of a robot (not shown)
that is positioned under the substrate 122 during substrate handoff
with the substrate support structure 118.
[0037] The load lock chamber 100 may additionally include a
temperature regulating plate 166 coupled to the top 104 of the body
102. In one embodiment, the temperature regulating plate includes a
resistive heater (heater 402 is shown in FIG. 4A) coupled to a
power source 168. Exemplary embodiments of the temperature
regulating plate 166 are described further below with reference to
FIGS. 4A-B and 5.
[0038] A pressure control system 150 is coupled to the load lock
chamber 100 to control the pressure within the internal volume 120
of the body 102. The pressure control system 150 generally includes
a gas source 152 and an exhaust system 154. The gas source 152 is
coupled to at least one inlet port 160 formed through the chamber
body 102. The gas source 152 provides a vent gas utilized to raise
and/or regulate pressure within the internal volume 120 of the
chamber body 102. For example, the gas source 152 may flow vent gas
into the internal volume 120 to facilitate transfer of the
substrate 122 from a vacuum environment to an ambient environment.
In one embodiment, the vent gas comprises at least one of nitrogen,
helium, air or other suitable gas.
[0039] An inlet control valve 156 is disposed between the gas
source 152 and the inlet port 160 to selectively control the flow
of vent gases into the internal volume 120 of the body 102. The
inlet control valve 156 is capable of providing a substantially
leak-tight seal under vacuum conditions. In one embodiment, the gas
source 152 is configured to control the attributes of the vent gas,
such as the flow rate, temperature and/or humidity of the vent
gas.
[0040] The exhaust system 154 is generally coupled to at least one
exhaust port 162 formed through the chamber body 102. The exhaust
system 154 is configured to remove gases from the internal volume
120 of the load lock chamber 100. The exhaust system 154 may
include one or more vacuum pumps (not shown) and may be ultimately
coupled to the facilities exhaust system (also not shown). For
example, the exhaust system 154 may pump out gas from the internal
volume 120 to facilitate transfer of the substrate 122 from an
ambient environment to a vacuum environment.
[0041] An exhaust control valve 158 is disposed between the exhaust
system 154 and the exhaust port 162 to selectively control the flow
of gases exiting the internal volume 120 of the body 102. The
exhaust control valve 158 is typically similar to the inlet control
valve 156 and is capable of providing a substantially leak-tight
seal under vacuum conditions.
[0042] In the embodiment depicted in FIG. 1, the exhaust port 162
and inlet port 160 are shown formed through opposing sidewalls 110,
108. Thus, when venting the internal volume 120, and/or during
cooling of the substrate 122, a flow of vent gases (as represented
by flow arrows 180) may be established across the surface of the
substrate 122. The flow 180 is generally parallel to the plane of
the substrate 122 and flows from one side to an opposite side of
the substrate. The flow 180 generally increases the heat transfer
rate between the substrate 122 and vent gases, advantageously
increasing the cooling rate of the substrate. Moreover, by removing
the vent gases during venting of the chamber, the vent gases heated
by the substrate may be removed from the internal volume 120 of the
load lock chamber 100 and replaced with cooler vent gases, thereby
increasing the cooling rate of the substrate by substantially
maintaining the temperature differential between the vent gas and
substrate.
[0043] FIG. 3 is a schematic plan view of the load lock chamber 100
illustrating the flow 180 across the substrate 122. As stated in
above with reference to FIG. 1, at least one exhaust port 162 and
at least one inlet port 160 may be formed through opposing
sidewalls 110, 108 of the chamber body 102. It is contemplated that
a plurality of inlet ports 160 and/or a plurality of exhaust ports
162 may be utilized to tailor the profile of the flow 180 utilized
to cool the substrate 122. For example as illustrated in FIG. 3,
flow from each of the inlet ports 160 may be independently
controlled by a dedicated flow inlet control valve 156. Optionally,
and as shown in FIG. 3, the flow exiting the chamber body 102
through each of the exhaust ports 160 may be independently
controlled by a dedicated exhaust control valve 158. By controlling
the open/close state, and/or orifice of each of the valves 156,
158, the velocity of the flow 180 across different portions of the
substrate 122 may be tailored to control the cooling rate of
different portions of the substrate 122. The control of the
substrate's cooling rate profile allows processors to compensate
for the tendency of the substrate to cool more rapidly at the edges
of the substrate, thereby facilitating uniform cooling the
substrate. It is contemplated that a control valve may be coupled
to more than one port. It is also contemplated that the inlet ports
160 may be distributed on more than one of the sidewalls of the
body 102. It is also contemplated that the exhaust ports 162 may be
distributed on more than one of the sidewalls of the body 102. It
is also contemplated that some of the inlet and/or vent ports 160.
162 may be opened and/or closed over different periods of time to
selectively change profile the flow 180, to initially vent the
internal volume 120 of the chamber rapidly prior to creating a
cross flow, and/or to remove heated vent gases during any stage of
the transfer cycle through the load lock chamber 100.
[0044] In the embodiment depicted in FIG. 3, the gas source 156 is
configured to individually control the temperature of the gases
provided to the different inlet ports 160. For example, the gas
source 156 may include a plurality of resistive heaters 350 (or
other suitable temperature control device) for controlling the
temperature of the vent gas traveling through each gas line 352
respectively routed to an inlet port 160. Alternatively, the
heaters 350 may be interfaced with the gas lines 352 externally
from the gas source 156. The heaters 350 allow the individual
streams of vent gases entering the chamber body 102 through the
inlet ports 160 to be set to different temperatures, thereby
allowing greater flexibility in controlling the cooling rate
profile of the substrate 122.
[0045] FIGS. 4A-B are perspective and top views of two embodiments
of the temperature regulating plate 166. The temperature regulating
plate 166 is generally fabricated from a thermally conductive or
other suitable material, such as aluminum, and has a resistive
heating element coupled thereto. One example of a resistive heating
element 402 is depicted in FIG. 4A while another embodiment of a
resistive heating element 442 is depicted in FIG. 4B.
[0046] The temperature regulating plate 166 is typically shaped to
cover the plan area of the substrate. In the embodiments depicted
in FIGS. 4A-B, the temperature regulating plate 166 is rectangular,
having short sides 410 and long sides 412.
[0047] A plurality of holes 420 are formed through the temperature
regulating plate 166 to allow fasteners 422 to pass therethrough.
The fasteners 422 are utilized to couple the temperature regulating
plate 166 to the top 104 of the load lock chamber 100. A stand-off
418 is disposed on each of the fasteners 422 to maintain a
predefined spacing between the temperature regulating plate 166 and
the top 104 of the load lock chamber 100. Optionally, the holes 420
around the perimeter of the temperature regulating plate 166 may be
slotted to allow the temperature regulating plate 166 to expand and
contract while maintaining a planar profile. The planar profile of
the temperature regulating plate 166 beneficially maintains the
spacing between the temperature regulating plate 166 and the
substrate 122, thereby maintaining a predictable heating rate.
[0048] The resistive heating element 402 is generally disposed in a
pattern on the plate 166. Terminals 404 are provided to couple to
the power source 168. The resistive heating element 402 may be
patterned to provide greater heat flux at predefined portions of
the plate 166.
[0049] In the embodiment depicted in FIG. 4B, the resistive heating
element 442 is configured to have a greater surface coverage (and,
thus provide greater heat flux) along the sides 412 of the
resistive heating element 402 relative to the center of the
resistive heating element 402. This allows greater heat capacity
proximate the edges of the substrate 112, which typically are
difficult to maintain at a temperature proximate the center of the
substrate.
[0050] FIG. 5 is a plan view of another embodiment of a temperature
regulating plate 556. The plate 556 is generally similar to the
plate 166 described above, except wherein the plate 556 includes
zone heating control. For example, a plurality of resistive heating
elements (two elements 502, 504 are illustratively shown, although
any number of heating elements are contemplated) are disposed on
the plate 556. Each heating element 502, 504 is independently
controlled by the power source 168 so that the heating profile of
the plate 556, and thus the temperature profile of the substrate
122, may be controlled. In the embodiment depicted in FIG. 5, the
heating element 502 is located proximate the edges of the plate
556, while the heating element 504 is arranged primarily in an
interior portion of the plate 556, thereby allowing the temperature
of the substrate to be regulated independently between the
substrate's edges and center region. The independent control
between the zones, for example the substrate's edge and center
regions, compensates for differences in the heating/cooling rates
in those areas, allowing the substrate to be heated more
uniformly.
[0051] FIG. 6 is a flow diagram of one embodiment of a method 600
for regulating the temperature of a substrate. The method 600
begins at step 602 by transferring a substrate 122 into the load
lock chamber 100 from a vacuum environment, for example, from a
transfer chamber of a cluster tool. At step 604, the substrate is
isolated from the vacuum environment by sealing the substrate
access port 116 with a slit valve door. At step 606, the inlet
valve 156 is opened to vent the internal volume 120 of the load
lock chamber 100. At step 608, the outlet valve 158 is opened to
establish a flow of vent gases between the inlet port 160 and the
exhaust port 162 across the surface of the substrate 122. The cross
flow of vent gases across the substrate enhances the heat transfer
efficiency between the vent gas and substrate, thereby cooling the
substrate more rapidly. The rate and distribution of the vent gas
flow across the substrate may be tailored to provide a desired
temperature transfer profile as discussed above with reference to
FIG. 3 by controlling which valves 156, 158 are open, and by
controlling the temperature of the individual flows of vent gas
entering the internal volume 120 of the load lock chamber 100
through the inlet ports 160. Optionally, at step 610, the cross
flow is maintained after the pressure within the internal volume
120 of a load lock chamber 100 reaches a predefined value. At step
612, the substrate 122 is removed from the load lock chamber 100
into an ambient environment through the other substrate access port
116.
[0052] FIG. 7 is a flow diagram of another embodiment of a method
700 for regulating temperature of a substrate. The method 700
begins at step 702 by transferring a substrate 122 into the load
lock chamber 100 from a vacuum environment. At step 704, the
substrate is isolated from the vacuum environment by sealing the
substrate access port 116 with a slit valve door. At step 706, the
inlet valve 156 is opened to vent the internal volume 120 of the
load lock chamber 100. At step 708, the outlet valve 158 is opened
to remove vent gases heated by the substrate 122 from the internal
volume 120 through the exhaust port 162. Step 708 may occur
periodically, before and/or after the pressure within the internal
volume 120 of a load lock chamber 100 reaches a predefined value.
By removing the heated vent gas and maintaining a "fresh" supply of
cool vent gas, the temperature differential between the substrate
and vent gases is substantially maximized. At step 710, the
substrate 122 is removed from the load lock chamber 100 into an
ambient environment through the other substrate access port
116.
[0053] FIG. 8 is a top plan view of one embodiment of a process
system 850 suitable for processing large area substrates (e.g.,
substrates having a plan area greater than about 2.7 square meter).
The process system 850 typically includes a transfer chamber 808
coupled to a factory interface 812 by a load lock chamber 800
having a plurality of single substrate transfer chambers. The
transfer chamber 808 has at least one dual blade vacuum robot 834
disposed therein that is adapted to transfer substrates between a
plurality of circumscribing process chambers 832 and the load lock
chamber 800. In one embodiment, one of the process chambers 832 is
a pre-heat chamber that thermally conditions substrates prior to
processing to enhance throughput of the system 850. Typically, the
transfer chamber 808 is maintained at a vacuum condition to
eliminate the necessity of adjusting the pressures between the
transfer chamber 808 and the individual process chambers 832 after
each substrate transfer.
[0054] The factory interface 812 generally includes a plurality of
substrate storage cassettes 838 and a dual blade atmospheric robot
836. The cassettes 838 are generally removably disposed in a
plurality of bays 840 formed on one side of the factory interface
812. The atmospheric robot 836 is adapted to transfer substrates
806 between the cassettes 838 and the load lock chamber 800.
Typically, the factory interface 812 is maintained at or slightly
above atmospheric pressure.
[0055] FIG. 9 is a sectional view of one embodiment of the
multi-chamber load lock 800 of FIG. 8. The load lock chamber 800
has a chamber body 912 that includes a plurality of
vertically-stacked, environmentally-isolated substrate transfer
chambers that are separated by vacuum-tight, horizontal interior
walls 914. Although three single substrate transfer chambers 920,
922, 924 are shown in the embodiment depicted in FIG. 9, it is
contemplated that the chamber body 912 of load lock chamber 800 may
include two or more vertically-stacked substrate transfer chambers.
For example, the load lock chamber 800 may include N substrate
transfer chambers separated by N-1 horizontal interior walls 914,
where N is an integer greater than one.
[0056] The substrate transfer chambers 920, 922, 924 are each
configured to accommodate a single large area substrate 810 so that
the volume of each chamber may be minimized to enhance fast pumping
and vent cycles. In the embodiment depicted in FIG. 9, each
substrate transfer chamber 920, 922, 924 has an internal volume of
equal to or less than about 8000 liters to accommodate substrates
having a plan surface area of about 9.7 square meters. For
comparison, a dual slot dual substrate transfer chamber of a
conventional design described in U.S. patent application Ser. No.
09/957,784 has an internal volume of about 1600 liters. It is
contemplated that a substrate transfer chamber of the present
invention having a greater width and/or length and equal height may
be configured to accommodate even larger substrates.
[0057] The chamber body 912 includes first sidewall 902, a second
sidewall 904, a third sidewall 906, a bottom 908 and a top 910. A
fourth sidewall 1002 is shown opposite the third sidewall 906 in
FIG. 10. The body 912 is fabricated from a rigid material suitable
for use under vacuum conditions. In one embodiment, the chamber
body 912 is fabricated from a single block (e.g., one piece) of
aluminum. Alternatively, the chamber body 912 may be fabricated
from modular sections, each modular section generally comprising a
portion of one of the substrate transfer chambers 920, 922, 924,
and assembled in a fashion suitable to maintain vacuum integrity,
such as continuous welds shown by dashed lines 918.
[0058] In the embodiment depicted in FIG. 9, the interior walls 914
and the remaining portions of the chamber body 912 other than the
second sidewall 906 are fabricated from a single contiguous mass of
material. The second sidewall 906 is sealably coupled to the other
portions of the chamber body 912 to facilitate machining of the
substrate transfer chambers 920, 922, 924 and to allow access to
the interior portions of the chamber body 912 during fabrication
and assembly.
[0059] Alternatively, the horizontal walls 914 of the chamber body
912 may be vacuum sealed to sidewalls of the chamber body 912,
thereby isolating the substrate transfer chambers 920, 922, 924.
For example, the horizontal walls 914 may be continuously welded to
the chamber body 912 to allow greater access to the entire interior
of the chamber body 912 during early assembly stages of the load
lock chamber 800.
[0060] Each of the substrate transfer chambers 920, 922, 924
defined in the chamber body 912 includes two substrate access
ports. The ports are configured to facilitate the entry and egress
of large area substrates 810 from the load lock chamber 800. In the
embodiment depicted in FIG. 9, the first substrate transfer chamber
920 bounded at the bottom 908 of the chamber body 912 includes a
first substrate access port 930 and a second substrate access port
932 having a width greater than 2000 mm. The first substrate access
port 930 is formed through the first sidewall 902 of the chamber
body 912 and couples the first substrate transfer chamber 920 to
the central transfer chamber 808 of the processing system 850. The
second substrate access port 932 is formed through the second wall
904 of the chamber body 912 and couples the first substrate
transfer chamber 920 to the factory interface 812. In the
embodiment depicted in FIG. 9, the substrate access ports 930, 932
are disposed on opposite sides of the chamber body 912, however,
the ports 930, 932 may alternatively be positioned on adjacent
walls of the body 912.
[0061] Each of the substrate access ports 930, 932 is selectively
sealed by a respective slit valve 926, 928 adapted to selectively
isolate the first substrate transfer chamber 920 from the
environments of the transfer chamber 808 and the factory interface
812. The slit valves 926, 928 are moved between an open and closed
position by an actuator 942 (one actuator 942 shown in phantom in
FIG. 9 is normally positioned outside the chamber body 912). In the
embodiment depicted in FIG. 9, each of the slit valves 926, 928 is
pivotally coupled to the chamber body 912 along a first edge and
rotated between the open and closed position by the actuator
942.
[0062] The first slit valve 926 seals the first substrate access
port 930 from the interior side of the first sidewall 902 and is
thereby positioned within the first substrate transfer chamber 920
such that a vacuum (e.g., pressure) differential between the first
substrate transfer chamber 920 and the vacuum environment of the
central transfer chamber 808 assists in loading and sealing the
slit valve 926 against the first sidewall 902, thereby enhancing
the vacuum seal. Correspondingly, the second slit valve 928 is
disposed on the exterior of the second sidewall 904 and is thereby
positioned such that the pressure differential between the ambient
environment of the factory interface 812 and the vacuum environment
of the first substrate transfer chamber 920 assists in sealing the
second substrate access port 932. Examples of slit valves that may
be adapted to benefit from the invention are described in U.S. Pat.
No. 5,579,718, issued Dec. 10, 1996 to Freerks and U.S. Pat. No.
6,045,620, issued Apr. 11, 2000 to Tepman et al., both of which are
hereby incorporated by reference in their entireties.
[0063] The second substrate transfer chamber 922 is similarly
configured with access ports 934, 936 and slit valves 926, 928. The
third substrate transfer chamber 924 is similarly configured with
access ports 938, 940 and slit valves 926, 928.
[0064] The substrate 810 is supported above the bottom 908 of the
first substrate transfer chamber 920 and the interior walls 914
bounding the bottom of the second and third substrate transfer
chambers 922, 924 by a plurality of substrate supports 944. The
substrate supports 944 are configured and spaced to support the
substrate 810 at an elevation above the bottom 908 (or walls 914)
to avoid contact of the substrate with the chamber body 912. The
substrate supports 944 are configured to minimize scratching and
contamination of the substrate. In the embodiment depicted in FIG.
9, the substrate supports 944 are stainless pins having a rounded
upper end 946. Other suitable substrate supports are described in
U.S. Pat. No. 6,528,767, filed Mar. 11, 2003; U.S. patent
application Ser. No. 09/982,406, filed Oct. 17, 2001; and U.S.
patent application Ser. No. 10/376,857, filed Feb. 27, 2003, all of
which are incorporated by reference in their entireties.
[0065] FIG. 10 is a sectional view of the load lock chamber 800
taken along section line 10-10 of FIG. 9. The sidewalls of each of
the substrate transfer chambers 920, 922, 924 include at least one
port disposed therethrough to facilitate controlling the pressure
within the internal volume of each chamber. In the embodiment
depicted in FIG. 10, the chamber body 912 includes an inlet port
1004 formed through the fourth sidewall 1002 and an outlet port
1006 formed through the third sidewall 906 of the chamber body 912
for venting and pumping down of the first substrate transfer
chamber 920. Valves 1010, 1012 are respectively coupled to the
inlet port 1004 and outlet port 1006 to selectively prevent flow
therethrough. The outlet port 1006 is coupled to a vacuum pump 1008
that is utilized to selectively lower the pressure within the
internal volume of the first substrate transfer chamber 920 to a
level that substantially matches the pressure of the transfer
chamber 808. The flow through inlet and outlet ports 1004, 1006 may
be controlled to enhance cooling of substrates as described with
reference to FIGS. 1-7.
[0066] Referring additionally to FIG. 9, when the pressures between
the transfer chamber 808 and the first substrate transfer chamber
920 of the load lock chamber 800 are substantially equal, the slit
valve 926 may be opened to allow processed substrates to be
transferred to the load lock chamber 800 and substrates to be
processed transferred to the transfer chamber 808 by the vacuum
robot 834 through the first substrate access port 930. After
placing the substrate returning from the transfer chamber 808 in
the first substrate transfer chamber 920 of the load lock chamber
800, the slit valve 926 is closed and the valve 1010 is opened
thereby allowing venting gas, for example N2 and/or He, into the
first substrate transfer chamber 920 of the load lock chamber 800
through the inlet port and raising the pressure within the internal
volume 8.10. Typically, the venting gas entering the internal
volume 810 through the inlet port 1004 is filtered to minimize
potential particulate contamination of the substrate. Once the
pressure within the first substrate transfer chamber 920 is
substantially equal to that of the factory interface 812, the slit
valve 924 opens, thus allowing the atmospheric robot 836 to
transfer substrates between the first substrate transfer chamber
920 and the substrate storage cassettes 838 coupled to the factory
interface 812 through the second substrate access port 932.
[0067] The other substrate transfer chambers 922, 924 are similarly
configured. Although each of the substrate transfer chambers 920,
922, 924 are shown with individual pumps 1008, one or more of the
substrate transfer chambers 920, 922, 924 may share a single vacuum
pump equipped with appropriate flow controls to facilitate
selective pumping between chambers.
[0068] As the substrate transfer chambers 920, 924, 926 are
configured with less than or equal to about 1000 liters of volume,
the load lock chamber 800 may transfer about 840 substrates per
hour at a reduced pumping rate as compared to a conventional dual
substrate dual slot load lock chamber 900, as described in FIG. 9
above, which has a substrate transfer rate of about 830 substrates
per hour. Increasing the pumping rate of the load lock chamber 900
to boost the throughput would result in condensation forming within
the chamber. The reduced pumping rate of the present invention is
between about 160-180 seconds per pump/vent cycles as compared to
about 130 seconds per cycle of the load lock chamber described in
the conventional design described in U.S. patent application Ser.
No. 09/957,784. The substantially longer cycle reduces air velocity
within the chamber, thereby reducing the probability of particular
contamination of the substrate, while eliminating the condensation.
Moreover, greater substrate throughput is achieved using pumps 1008
having lower capacity, which contributes to reducing the system
costs.
[0069] Furthermore, due to the stacked configuration of the
substrate transfer chambers, greater substrate throughput is
realized without increasing the footprint of the load lock chamber
more than would be necessary to transfer a single substrate. A
minimized footprint is highly desirable in reducing the overall
cost of the FAB. Additionally, the overall height of the load lock
having three substrate transfer chambers 920, 922, 924 is less than
conventional dual chambered system, further providing greater
throughput in a smaller, less expensive package.
[0070] The stacked configuration also allows for predefined
substrate transfer chambers to be dedicated for heating or cooling.
For example, a greater number of substrate transfer chambers may be
configured to heat the substrates entering the transfer chamber
than cool processed substrates (and vice versa). For example the
substrate transfer chambers 920, 922 may be configured to heat
substrates (e.g., have a heating plate), while the substrate
transfer chamber 924 may be configured to cool the substrate. In
another example, the substrate transfer chambers 920, 922 may be
configured to cool substrates, while the substrate transfer chamber
924 may be configured to heat the substrate.
[0071] In yet other embodiment, substrate transfers through the
substrate transfer chambers (such as the chambers 920, 922, 924)
may be dedicated for only heating (or cooling). In this
configuration, the chambers 920, 922, 924 undergo less thermal
cycling than if one or more of the chambers were utilized for
heating and cooling, thereby reducing the amount of chamber
expansion and contraction which may result in particle generation
and/or particle release from chamber components.
[0072] The bottom 908 of the first substrate transfer chamber 920
and the interior walls 914 bounding the bottom of the second and
third substrate transfer chambers 922, 924 may also include one or
more grooves 1016 formed therein. As depicted in FIGS. 11A-B, the
grooves 1016 are configured to provide clearance between the
substrate 810 disposed on the substrate supports 944 and a robot
blade 1102.
[0073] The blade 1102 (one finger of which is shown in FIGS. 11A-B)
is moved into the groove 1016. Once in a predefined position within
the first substrate transfer chamber 920, the blade 1102 is
elevated to lift the substrate 810 from the supports 944. The blade
1102 carrying the substrate 810 is then retracted from the first
substrate transfer chamber 920. The substrate 810 is placed on the
substrate supports 944 in the reverse manner.
[0074] FIG. 12 is a partial sectional view of the chamber body 912
showing one embodiment of an alignment mechanism 1200 that may be
utilized to urge the substrate 810 into a predefined position in
the first substrate transfer chamber 920. A second alignment
mechanism (not shown) is disposed in the opposite corner of the
first substrate transfer chamber 920 to work in concert with the
mechanism 1200 shown. Optionally, one alignment mechanism 1200 may
be disposed in each corner of the first substrate transfer chamber
920. The other substrate transfer chambers 922, 926 are similarly
equipped to align the substrates.
[0075] For example, the alignment apparatus 1200 may correct
positional inaccuracies between a deposited position of the
substrate 810 as placed by the atmospheric robot 836 on the
substrate supports 944 and a predefined (i.e., designed) position
of the substrate 810 relative the substrate supports 944. Having
the position of the substrate 810 aligned by the alignment
apparatus 1200 within the load lock chamber 800 independent from
conventional correction methods that utilize the atmospheric robot
836 to adjust the substrate placement allows greater flexibility
and lower system costs. For example, the support plate 860 with
alignment apparatus 1200 provides greater compatibility between the
load lock chamber 800 and user supplied factory interfaces 812
since the load lock chamber 800 is more tolerant to substrate
position on the substrate supports 944, thereby reducing the need
for robots of great precision and/or corrective robot motion
algorithms generated by the factory interface provider. Moreover,
as the positional accuracy designed criteria for the atmospheric
robot 836 is diminished, less costly robots may be utilized.
[0076] In the embodiment of FIG. 12, the alignment mechanism
includes two rollers 1202, 1204 coupled to a first end 1206 of a
lever 1208. The lever 1208 extending through a slot 1218 formed
through the sidewall 1002 pivots about a pin 1210. An actuator 1212
is coupled to the lever 1208 such that the rollers 1202, 1204 may
be urged against adjacent edges 1214, 1216 of the substrate 810.
The actuator 1212, such as a pneumatic cylinder, is generally
positioned on the exterior of the chamber body 912. A housing 1220
is sealably disposed over the slot 1218 and includes bellows or
other suitable seals 1122 to facilitate coupling of the actuator
1212 to the lever 1208 without vacuum leakage. The alignment
mechanism 1200 and the opposing alignment mechanism (not shown)
work in concert to position the substrate in a predefined position
within the first substrate transfer chamber 920. Other substrate
alignment mechanisms that may be utilized are described in U.S.
patent application Ser. No. 10/094,156, filed Mar. 15, 2002; and
U.S. patent application Ser. No. 10/084,762, filed Feb. 22, 2002,
all of which are incorporated by reference in their entireties.
[0077] FIGS. 13-14 are sectional views of another embodiment of an
alignment mechanism 1300. The alignment mechanism 1300 is
configured to operate similar to the alignment mechanism 1200
described above. Although only one alignment mechanism 1300 is
shown in FIG. 13, the alignment mechanism 1300 operates in concert
with another alignment mechanism (not shown) disposed in the
opposite corner of the chamber body 920. Optionally, each corner of
the chamber body 900 may includes an alignment mechanism.
[0078] The alignment mechanism 1300 generally includes an interior
lever 1302 coupled to an actuator 1308 by a shaft 1304 disposed
through the chamber body 920. In the embodiment depicted in FIGS.
13-14, the actuator 1308 is coupled to the shaft 1304 by an
exterior lever 1306. The exterior lever 1306 is coupled to a post
1420 of the shaft 1304 that extended into a recess 1402 defined in
the exterior wall of the chamber body 920. The actuator 1308 may be
a motor, linear actuator or other device suitable for imparting
rotary motion to the shaft 1304. The interior lever 1302 rotates
with the shaft 1304, thereby moving a pair of rollers 1202, 1204
extending from the lever 1302 to urge a substrate 810 (shown in
phantom) into a predefined position.
[0079] The shaft 1304 passes through a horizontal wall 1312
defining the bottom of the recess 1310. The shaft 1304 is disposed
through a hollow housing 1314 that is secured to the chamber body
920 by a plurality of fasteners 1316. A pair of bushings 1406, 1412
are disposed in a bore 1408 of the housing 1314 to facilitate
rotation of the shaft 1304 within the housing 1314. A seal 1404 is
disposed between a flange 1410 of the housing 1314 to maintain the
vacuum integrity of the chamber body 920.
[0080] A plurality of seals 1414 are disposed between the shaft
1304 and housing 1314 to prevent vacuum loss. In the embodiment
depicted in FIG. 14, the seals 1414 comprise three cup seals having
an open end facing the exterior lever 1306. The seals 1414 are
retained within the bore 1408 by a washer 1416 and retaining ring
1418.
[0081] Thus, a load lock chamber having substrate temperature
control is provided. The configuration of ports providing and
removing vent gases from the chamber enhance substrate cooling.
Additionally, the temperature regulating plate with resistive
heater facilitates good control of substrate heating while
minimizing particulate generation. In one embodiment, the
vertically stacked single substrate transfer chambers contributes
to reduced size and greater throughput as compared to conventional
state of the art, dual slot dual substrate designs. Moreover, the
increased throughput has been realized at reduced pumping and
venting rates, which corresponds to reduced probability of
substrate contamination due to particulates and condensation.
[0082] While the foregoing is directed to the preferred embodiment
of the invention, other and further embodiments of the invention
may be without departing from the basic scope thereof. The scope of
the n is determined by the claims which follow.
* * * * *