U.S. patent application number 14/853594 was filed with the patent office on 2016-01-07 for reaction chamber with removable liner.
The applicant listed for this patent is Ultratech, Inc.. Invention is credited to Jill S. Becker, Roger R. Coutu, Douwe Johannes Monsma.
Application Number | 20160002781 14/853594 |
Document ID | / |
Family ID | 42784570 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160002781 |
Kind Code |
A1 |
Coutu; Roger R. ; et
al. |
January 7, 2016 |
REACTION CHAMBER WITH REMOVABLE LINER
Abstract
A reaction chamber assembly for thin film deposition processes
or the like includes an outer wall assembly for enclosing an outer
volume and a removable liner installed into the outer volume
through an outer aperture for preventing precursors or reactants
from coming into contact with internal surfaces of the outer wall
assembly and forming thin film layers thereon. The removable liner
encloses a reaction chamber and includes substrate support trays or
the like for supporting substrates being coated. Thin film layers
are formed onto internal surfaces of the removable liner instead of
onto surfaces of the outer wall assembly. The removable liner may
be disposable or may comprise stainless steel, which can be removed
when contaminated, cleaned by abrasive blasting such as bead
blasting, and replaced. Two removable liners can be used to
periodically swap removable liners and clean one of the liners
while the other is in service with minimal disruption to production
coating schedules. Other removable cleanable elements such as input
and output plenums, door liners and conduits comprising stainless
steel can be periodically removed and cleaned by abrasive
blasting.
Inventors: |
Coutu; Roger R.; (Hooksett,
NH) ; Becker; Jill S.; (Cambridge, MA) ;
Monsma; Douwe Johannes; (Amsterdam, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ultratech, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
42784570 |
Appl. No.: |
14/853594 |
Filed: |
September 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12609308 |
Oct 30, 2009 |
9175388 |
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14853594 |
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61197948 |
Nov 1, 2008 |
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61208875 |
Feb 27, 2009 |
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Current U.S.
Class: |
427/255.28 |
Current CPC
Class: |
C23C 16/45582 20130101;
C23C 16/4401 20130101; C23C 16/45504 20130101; C23C 16/45525
20130101; C23C 16/4412 20130101; C23C 16/4407 20130101 |
International
Class: |
C23C 16/455 20060101
C23C016/455; C23C 16/44 20060101 C23C016/44 |
Claims
1. A method for operating a reaction chamber assembly comprising
the steps of: installing a first removable liners into an outer
chamber of the reaction chamber assembly through an outer aperture
formed through outer walls of the outer chamber for receiving the
removable liner there through; coating a plurality of batches of
one or more substrates supported inside the first removable liner
with one or more material layers being applied to the one or more
substrates during each coating batch, wherein each coating batch
also coats internal surfaces of the first removable liner with the
one or more material layers; and, replacing the first removable
liner with a second removable liner that is substantially identical
with the first removable liner when the internal surfaces of the
first removable liner become undesirably contaminated by the
material layers coated thereon.
2. The method of claim 1 wherein the reaction chamber assembly
includes an access door movable to an open position suitable for
loading and unloading the one or more substrates into and out of
the removable liner installed into the outer volume; further
comprising step of gas sealing each of the outer chamber and the
removable liner by moving the access door to the closed
position.
3. The method of claim 2 wherein the outer chamber and the
removable liner installed into the outer chamber are configured to
provide a clearance gap volume disposed between internal surfaces
of the outer chamber and external surfaces of the removable liner
installed in the outer chamber, further comprising the step of
creating a pressure gradient between the clearance gap volume and
the a reaction chamber enclosed by the removable liner installed by
delivering a purge gas into the clearance gap volume.
4. The method of claim 1 wherein each of the first and the second
removable liners is constructed from a material suitable removing
the one or more material layers formed therefrom by a cleaning
process that is performed repeatedly, further comprising the steps
of: cleaning the first removable liner of the one or more material
layers formed on while coating a plurality of batches of one or
more substrates in the second removable liner; replacing the second
removable liner with the first removable liner when internal
surfaces of the second removable liner become undesirably
contaminated by the material layers coated thereon; and, repeating
the steps of replacing the removable liner installed in the outer
volume when the internal surfaces thereof become undesirably
contaminated by the material layers coated thereon with a clean
removable liner and thereafter cleaning the contaminated removable
liner.
5. The method of claim 4 wherein the step of removing the one or
more material layers is performed by abrasive blasting.
6. The method of claim 1 further comprising the step of heating a
reaction chamber housed inside the removable liner with heating
elements disposed external to the removable liner.
7. The method of claim 1 further comprising the step of heating a
reaction chamber housed inside the removable liner with heating
elements disposed external to the outer chamber.
8. The method of claim 7 wherein surfaces of the removable liner is
configured to make mating contact with surfaces of an outer wall
assembly surrounding the outer chamber further comprising the step
of conducting thermal energy from the outer wall assembly to the
removable liner installed in the outer volume.
Description
1 CROSS REFERENCE TO RELATED U.S. PATENT APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119(e) to provisional U.S. Patent Application Ser. No.
61/197,948 (Docket No. 0082-PHOENIX) filed Nov. 1, 2008, and
provisional U.S. Patent Application Ser. No. 61/208,875 (Docket No.
0087-TAHITI) filed Feb. 27, 2009, both of which are incorporated
herein by reference in its entirety and for all purposes.
2 COPYRIGHT NOTICE
[0002] A portion of the disclosure of this patent document may
contain material that is subject to copyright protection. The
copyright owner has no objection to the facsimile reproduction by
anyone of the patent document or the patent disclosure, as it
appears in the Patent and Trademark Office patent files or records,
but otherwise reserves all copyright rights whatsoever. The
following notice shall apply to this document: Copyright 2009,
Cambridge NanoTech, Inc.
3 BACKGROUND OF THE INVENTION
[0003] 3.1 Field of the Invention
[0004] The present invention relates to a reaction chamber assembly
that includes outer walls enclosing an outer volume such as an oven
structure and a removable liner enclosing a reaction chamber
installed into the outer chamber to substantially contain reactants
inside the reaction chamber thereby preventing the outer walls from
being contaminated by reactants. The removable liner can be removed
from the outer volume when it is contaminated by reactants and
replaced. Preferably, the removable liner can be cleaned or
decontaminated and reused.
[0005] 3.2 The Related Art
[0006] Reaction chambers such as gas deposition chambers can become
contaminated with reactants and or reactant byproducts. This may
occur over prolonged use wherein reactants introduced into the
reaction chamber react with internal walls thereof and with other
elements inside the reaction chamber and build up extensive coating
layers or contaminants on the internal walls and the other
elements, rendering them unusable. Over time, contaminant build up
on the internal walls may begin to crack and peel causing substrate
coating failures. Other failures due to contaminant build up
include sensor failure, reduced wall and substrate temperatures, or
increases in thermal cycling times and concerns for human safety.
In production environments, the reaction chamber is typically
broken down and cleaned or replaced on a regular maintenance
schedule, which may be based on the number of coating cycles
performed and which may vary according to the type of reactants
being used. While such cleaning occurrences are predictable and can
be planned for, they nonetheless disrupt production cycles.
[0007] Unscheduled cleaning or maintenance events may occur when a
deposition chamber becomes accidently contaminated by a hazardous
material and needs to be decontaminated immediately for human
safety reasons. In these cases, the cleaning or decontamination is
unexpected and may be very disruptive to a production cycle.
Accordingly, there is a need in the art for a faster solution for
decontaminating a reaction chamber.
[0008] Cook et al. in U.S. Pat. Appl. Pub. No. 2005/0188923,
suggests that an ex situ cleaning approach can be used to clean a
chamber by disassembling the chamber and cleaning the chamber parts
byetching them in an acid bath or the like. However, the ex situ
method is undesirable because of the excessive time required to
disassemble, clean and reassemble the chamber. Cook et al. further
suggests an in situ cleaning method wherein an etching gas is
pumped into the chamber to etch material layers from internal
surfaces of the chamber. However the in situ cleaning method is
undesirable because the etch rate is slow, because the etching gas
is corrosive and otherwise hazardous, e.g. a hazard to human
safety, and because the etching gas may remain in the chamber and
contaminate future substrate coating cycles. Cool et al. suggest a
third approach for cleaning the chamber, which is to configure one
or more removable liners that cover the chamber wall and that the
liner may be removed and cleaned or replaced, avoiding extensive
cleaning of the other chamber hardware. However, beyond
recommending materials for the liner, Cook et al. does not disclose
a liner structure of any kind and is completely silent about how
the reactants can be contained within the one or more removable
liners covering the chamber walls in order prevent the chamber
walls from becoming contaminated.
[0009] Some reaction chambers are pumped down to a low, medium, or
high vacuum pressure (less than 760 ton to about 10 micro ton). The
pump down cycle removes air, water vapor, and other gases from the
reaction chamber before introducing reactants to ensure that only a
desired reactant is present in the chamber during a coating cycle.
Additionally, the pump down cycle establishes a chamber vacuum
pressure that enhances the desired thin film formation. A pump down
or purge cycle is again performed after each reactant has been
introduced to remove the reactant from the chamber. Pumping down
the chamber provides an added benefit in that it creates a high
pressure gradient across the reaction chamber walls and this serves
to prevent reactants from leaking through the chamber walls but may
cause contaminates to leak through the chamber walls form outside
the reaction chamber. When a liner is introduced into the reaction
chamber, as suggested by Cook et al., there is no high pressure
gradient across that liner wall since the entire chamber, including
the liner, is substantially at the same gas pressure. An effective
liner needs to contain reactants therein in order to prevent the
reactants from contaminating the chamber walls and this containment
is made more difficult without the benefit of a high pressure
gradient across the liner wall. One solution for preventing
corrosive gas from reaching electrical elements housed inside a
reaction chamber is disclosed in U.S. Pat. No. 7,015,426 by Doering
et al. entitled PURGED HEATER-SUSCEPTOR FOR AN ADUCVD REACTOR
wherein corrosive elements, e.g. conductive wires and the like,
disposed inside the gas chamber, are enclosed by a hollow sleeve
and a flow of purge gas is continuously passed through the hollow
sleeve. The purge gas flowing through the hollow sleeve surrounds
the corrosive elements thereby isolating the corrosive elements
from the process gasses inside the chamber. The purge gas is
allowed to pass from the hollow sleeve into the chamber to mix with
the process gas and to be exhausted out of the chamber with the
process gasses. While the solution proposed by Doering at al.
isolates conductive elements inside the chamber from exposure to
process gasses Doering et al. is completely silent about containing
reactants inside a removable liner by creating a pressure gradient
across the walls of the removable liner by introducing a purge gas
flow to surround the removable liner.
[0010] More generally, there is a need in the art to increase the
size of reaction chambers to handle larger substrates. There is a
further need in the art to increase coating throughput by providing
reaction chambers suited for batch coating cycles. There is a still
further need in the art, to decrease scheduled or unscheduled down
time of production oriented reaction chamber systems by providing a
reaction chamber that can be easily and quickly decontaminated.
TABLE-US-00001 4 List of Item Reference Numbers 1000 Dual Chamber
Gas Deposition System 1100 Vent 1110 Lighting Tower 1120 Upper Gas
Deposition Chamber 1130 Right Side Face 1135 Upper Input Gas Supply
1140 Frame 1145 Upper Cross Frame Platform 1150 Lower Gas
Deposition Chamber 1155 Lower Cross Frame Platform 1160 Lower Input
Gas supply 1165 Electronic Controller 1170 Lower Load Lock Door
1180 Front Face 1190 Upper Load Lock Door 1200 Single User
Interface 2000 First ALD System 2010 Floor Standing System Cabinet
2020 Cabinet Feet 2030 Cabinet Front Face 2040 Access Door 2050
Door Handle 2060 Outer Door Panel 2070 Inner Door Panel 2080 Door
Cover 2090 Door Heater 2100 Insulation Layer 2110 Aluminum Plate
2120 Resistive Heating Element 3000 Chamber Assembly 3050 Removable
Back panel 3060 Back Perimeter flange 3070 Outer Volume 3080
Movable Access Door 3090 Support Structure 3100 Door Actuators 3110
Heating Elements 3120 Thermal Insulation Layers 3125 Reaction
Chamber 3130 Right Rectangular Through Aperture 3140 Left
Rectangular Through Aperture 3150 Input Plenum 3160 Input Plenum
Flange 3170 Top Input Plenum Wall 3180 Bottom Input Plenum Wall
3190 Input Plenum Side Wall 3200 Input Plenum Side Wall 3210 Input
Plenum Chamber 3220 Input Plenum End Wall 3230 Input Port Assembly
3240 Gas Supply Module 3250 Output Plenum 3260 Output Plenum Flange
3270 Top Output Plenum Wall 3280 Bottom Output Plenum Wall 3290
Output Plenum Side Wall 3300 Output Plenum Chamber 3310 Exit Port
Assembly 3320 Exit Port Module 3330 Stop Valve 3340 Vacuum Pressure
Gauge 3350 Substrate Support Surface 3360 Back Panel Eye Bolts 3370
Cone-Shaped Passage 3380 Liner Fasteners 3390 Pin Actuator Assembly
3400 Lift Post 3410 Pneumatic Cylinder and Piston Assembly 3420
Vacuum Bellows 3430 Circular Through Hole 3440 Guide Rods 3450
Stiffening Ribs 4000 First Reaction Chamber Assembly 4010 Outer
Wall Assembly 4020 Removable Liner 4025 Front Face 4030 Input Port
Assembly 4040 Exit Port Assembly 4050 Top Outer Wall 4060 Bottom
Outer Wall 4070 Right Side Outer Wall 4080 Left Side Outer Wall
4090 Back Outer Wall 4095 Front Outer Wall 4100 Outer Aperture 4110
Outer Volume 4120 Resistive Heating Elements 4130 Top Liner Wall
4140 Bottom Liner Wall 4150 Right Side Liner Wall 4160 Left Side
Liner Wall 4170 Back Liner Wall 4180 Chamber Aperture 4190 Reaction
Chamber 4200 Rectangular Flange Portion 4205 Rectangular Recess
4210 Substrate Tray 4215 Clearance Gap Volume 4220 Bottom Substrate
Tray 4230 Tray Supports 4240 Trap 4250 Vacuum Valve 4260
Cone-Shaped Conduit 4270 Pressure Gauge 4280 Cylindrical Flange
4290 Trap Seal 4300 Attaching Screws 4310 4320 First 0-ring Seal
4330 Second 0-ring Seal 4340 4350 Gas Input Port 4360 Gas Output
Port 4370 Exit Port Assembly 4380 Tray Bottom Surface 4390 Stop
Pins 4400 Tray Top Surface 4500 Exit Port 6000 Removable Liner 6010
Liner Base Wall 6020 Liner Top Wall 6030 Chamber Aperture 6040
Liner Back Wall 6050 Right Liner Aperture 6060 Left Liner Aperture
6070 Liner Lifting Handle 6080 Tooling Ball 6090 Liner Back
Aperture 7000 Substrate 7010 7015 Input Plenum Liner 7020 Top
Plenum Liner Wall 7030 Bottom Plenum Liner Wall 7040 Rectangular
Fluid Conduit 7050 Input Plenum Liner Flange 7060 Bottom Plenum
Liner Wall Top Surface 7070 (not used) 7080 Output Plenum Liner
7090 Upper Volume 7100 Lower Volume 7110 Pin Hole (Through Hole)
7120 Lift Pin 7130 Movable Pin Plate D Pin Height Dimension 8000
Outer Wall Assembly 8010 Outer Aperture 8020 Second Outer Aperture
8030 Right Side Wall 8040 Left Side Wall 8050 Top Wall 8060 Bottom
Wall 8100 Third Reaction Chamber 8110 Removable Liner 8120
Substrate Tray 8130 Tray Supports 8140 Reaction Chamber 8150
Overhanging (Substrate) Edge 8160 Input plenum 8170 Exit Plenum
8180 Outer wall assembly 8190 Heating element 8200 Electrical
Connector 9005 Gas Fittings 9010 Input Port 9015 Outer Tube 9020
9030 Input Port Flange 9040 Screws 9050 9060 Precursor Tube 9070
Annular Flange 9080 Front Edge 10030 10040 Triangular Input Plenum
10050 Trapezoidal Exit Plenum 10060 Upper Wall Portion 10070 Lower
Wall Portion 10080 Lower Wall Portion 10090 Triangular Vertical
Wall 10100 Trapezoidal Vertical Wall 10110 Front Vertical Flow
Channel 10120 Back Vertical Flow Channel
5 SUMMARY OF THE INVENTION
[0011] The present invention provides various reaction chamber
assembly embodiments for coating large rectangular substrates in
single or batch mode by ALD, ALD and other thin film deposition
methods and each embodiment includes removable liner and other
removable elements configured and positioned to prevent reactants
or precursors from contaminating internal walls of an outer
chamber. Preferably the removable liner and other elements are
cleanable for reuse.
[0012] The reaction chamber assembly includes an outer wall
assembly for enclosing an outer volume. The outer wall assembly
preferably comprises an oven chamber with heaters disposed to heat
the outer volume. The outer wall assembly preferably forms a gas
tight outer volume and preferably comprises metal outer walls but
any material that meets the structural requirements and can be used
over the full range of operating temperatures, such as ceramics is
suitable. The preferred material for the outer walls is 6000 series
aluminum because it meets the structural and temperature
requirements of the outer wall assembly and it also provide
excellent thermal conductivity, which is desirable to conduct
thermal energy from the heaters into the outer volume. At least one
outer wall includes an outer aperture passing through to the outer
volume.
[0013] A removable liner is installed into the outer volume through
the outer aperture and the removable liner is formed to enclose a
reaction chamber. The removable liner includes liner walls
surrounding the reaction chamber and a chamber aperture passes
through one of the liner walls to the reaction chamber and the
chamber aperture is co-aligned with outer aperture so that
substrates being coated can be installed into the reaction chamber
through the outer aperture and the chamber aperture. The liner
walls in cooperation with an access door are configured to
substantially contain reactants, precursors and other gases
delivered into the reaction chamber inside the reaction chamber. In
other embodiments the outer walls may include two outer apertures
with a front outer aperture being coaligned with a chamber aperture
of the removable liner for installing substrates into the reaction
chamber through a front wall and a back outer aperture being used
to install the removable liner into the outer volume.
[0014] The liner walls are formed from a material that permit
reactants deposited thereon as thin film layers to be removed by a
cleaning process. The preferred cleaning process is a mechanical
bead blast and the preferred material is 300 series stainless
steel, however other material having a Brinell Hardness of greater
than HB 150 may be used. Alternately, the liner may be chemically
cleaned and other wall materials may be suitable. The removable
liner may be formed as a unitary structure by various forming
methods. The removable liner includes surfaces that are in mating
contact with the outer walls to provide thermally conductive
pathways from the outer walls to the liner walls to more
efficiently and quickly heat the removable liner, the reaction
chamber, substrate support surfaces and substrates. In addition, a
clearance gap volume is provided between outside surfaces of the
removable liner and inside surfaces of the outer walls and a flow
of inert gas is delivered into the clearance gap through an input
port to maintain a pressure gradient between the clearance gap and
the reaction chamber. Excessive pressure in the clearance gap
volume may also be vented by a relieve valve or the like in fluidic
communication with the clearance gap volume. Alternately, the
clearance gap volume may be in fluidic communication with a vacuum
pump for removing gases therefrom and for maintaining the clearance
gap volume at a vacuum pressure while still providing a positive
pressure gradient with respect to the reaction chamber.
[0015] One or more substrate support trays are disposed
horizontally in the reaction chamber and supported with respect to
one or more removable liner walls. When a plurality of tray are
used they are tacked one above another with an open volume provided
between the trays for source gases to flow through and one or more
substrate are supported horizontally on each tray with a surface to
be coated facing vertically up. Preferably, each tray is sized to
receive a particular rectangular size substrate thereon so that a
batch of identical substrates can be coated during each coating
cycle. The range of standard rectangular substrate sizes ranges
from GEN 1 (300.times.400 mm) through the GEN 7 substrate dimension
standards (2160.times.2460 mm) and reaction chamber assemblies
according to the present invention may be sized according to the
desired substrate size. Of course any other substrate type
including non-standard rectangular sizes and three dimensional
objects that can be fit into the reaction chamber can be coated as
required.
[0016] An access door is movably disposed with respect to the
reaction chamber assembly for providing access to the reaction
chamber through the chamber aperture and an outer aperture when the
access door is in an open position and for closing and gas sealing
the chamber aperture and outer aperture when the access door is in
a closed position. The access door includes a removable inner door
liner positioned to substantially contain reactants inside the
reaction chamber and formed from a material that permit reactants
deposited as thin film layers onto the inner door liner to be
removed by a cleaning process. Thus the inner door liner comprises
300 series stainless steel or another material with a Brinell
Hardnes of HB 150 or higher. In addition the access door may
include heating elements disposed to heat the reaction chamber
through the inner door panel.
[0017] An input plenum disposed between reactant gas sources and
the reaction chamber includes input plenum walls formed to for
enclosing an input plenum volume or conduit that include an input
port passing through one of the input plenum walls. The input
plenum is shaped to allow gas entering into the input plenum volume
to expand over the full transverse width of the reaction chamber
before the gas enters into the reaction chamber or at least before
the gas begins to flow over any substrates supported inside the
reaction chamber. In one example the input plenum is integrally
formed with the removable liner and is specifically formed with or
by a bottom liner wall and delivers input gases into a vertical
flow conduit at a front area of the reaction chamber that extend
over the entire width of the reaction chamber. In another example,
the input plenum is supported outside the reaction chamber and
delivers gas flow into the reaction chamber through an aperture
extending through an outer wall and a liner wall and the aperture
extands of the entire longitudinal length or transverse width of
the reaction or of substrates being coated in the reaction
chamber.
[0018] An exit plenum is disposed between a vacuum pump and the
reaction chamber for drawing outflow out of the reaction chamber.
The exit plenum includes walls for enclosing an exit plenum volume
or conduit and an exit port passes through one of the exit plenum
walls. The exit plenum volume is shaped to allow gas to be drawn
into the exit plenum volume substantially over the entire
longitudinal length or transverse width of the reaction and or of
the substrates being coated. The exit plenum is also formed to
reduce a volume of the gas being drawn into the exit plenum before
the gas enters into the exit port. One or mores traps are disposed
between the exit plenum and the vacuum pump to remove undesirable
materials from the outflow. In one embodiment, the exit plenum is
integrally formed with the removable liner. In another embodiment,
the exit plenum is external to the reaction chamber. In either case
the exit plenum forms and exit plenum aperture that extends over
the longitudinal length or transverse width of the reaction chamber
or a substrates being coated. Preferably both of the external input
and exit plenums comprise stainless steel with internal surfaces
roughened by bead blasting so that the input and output plenums can
be cleaned by mechanical cleaning methods.
[0019] The invention also includes a method for operating a
reaction chamber assembly. The steps include installing a first
removable liners into an outer chamber of the reaction chamber
assembly through an outer aperture, coating substrates supported
inside the first removable liner with thin film layers that also
coat internal surfaces of the first removable liner and replacing
the first removable liner with a second removable liner when the
internal surfaces of the first removable liner become undesirably
contaminated by the thin film layers. The method also includes gas
sealing each of the outer chamber and the removable liner by moving
the access door to the closed position. The method further includes
delivering a purge gas into a clearance gap volume formed between
the removable liner and the outer volume. In addition some surfaces
of the removable liner and the outer walls are in mating contact
for conducting thermal energy from the outer wall assembly to the
removable liner installed in the outer volume.
[0020] The method also includes cleaning the first removable liner
to remove the thin film layers and then replacing the second
removable liner with the first cleaned removable liner by abrasive
blasting when internal surfaces of the second removable liner
become undesirably contaminated and repeating the removing,
cleaning and replacing steps.
[0021] These and other aspects and advantages will become apparent
when the Description below is read in conjunction with the
accompanying Drawings.
6 BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The features of the present invention will best be
understood from a detailed description of the invention and a
preferred embodiment thereof selected for the purposes of
illustration and shown in the accompanying drawings in which:
[0023] FIG. 1 depicts an isometric view of a first exemplary
improved ALD system configured with a chamber housed within a
system cabinet and with a chamber door shown in a closed position
according to one aspect of the present invention.
[0024] FIG. 2 depicts an isometric view of an improved ALD system
configured with a chamber housed within a system cabinet and with a
chamber door shown in an open position according to one aspect of
the present invention.
[0025] FIG. 3 depicts an exploded isometric view of an ALD reaction
chamber configured with a removable liner according to an
embodiment of the present invention.
[0026] FIG. 4 depicts an isometric view of an assembled ALD
reaction chamber configured with a removable liner according to an
embodiment of the present invention.
[0027] FIG. 5 depicts a side section view taken through an
exemplary improved ALD reaction chamber configured with a removable
liner and five substrate trays according to an embodiment of the
present invention.
[0028] FIG. 6 depicts a rear section view taken through an
exemplary improved ALD reaction chamber configured with a removable
liner and a purge gas input port for delivering purge gas to a
small clearance gap formed between the removable liner and an outer
wall assembly of an exemplary improved ALD reaction chamber
according to an embodiment of the present invention.
[0029] FIG. 7 depicts a top section view taken through a removable
liner depicting a reaction chamber input aperture proximate to the
apex of a triangular plenum and a larger reaction chamber exit
aperture proximate to the narrow end of a trapezoidal plenum
according to an embodiment of the present invention.
[0030] FIG. 8 depicts a side section taken through an improved ALD
reaction chamber input port assembly according to an embodiment of
the present invention.
[0031] FIG. 9 depicts an isometric view of a substrate tray
suitable for supporting substrates inside a removable liner
installed into an improved ALD reaction chamber according to an
embodiment of the present invention.
[0032] FIG. 10 depicts a side section view of an improved ALD
reaction chamber showing the gas flow path from input port to exit
port through an exemplary embodiment of the improved ALD reaction
chamber according to the present invention.
[0033] FIG. 11 depicts an isometric view showing a dual chamber gas
deposition system without external skins according to an embodiment
of the present invention.
[0034] FIG. 12 depicts a front isometric front view of a gas
deposition chamber assembly according to an embodiment of the
invention:
[0035] FIG. 13 depicts a back isometric back view of a gas
deposition chamber assembly according to an embodiment of the
invention:
[0036] FIG. 14 depicts an isometric view of showing section A-A
taken through a gas deposition chamber assembly according to an
embodiment of the invention.
[0037] FIG. 15 depicts an isometric view of a welded chamber liner
assembly according to an embodiment of the present invention.
[0038] FIG. 16 depicts schematic representation of an exploded
section view showing a substrate supported on the chamber liner
assembly and a pair of plenum liners according to an embodiment of
the present invention
[0039] FIG. 17 depicts an isometric view of a second exemplary
outer wall assembly according to the present invention.
[0040] FIG. 18 depicts a front view of a third exemplary embodiment
of a reaction chamber assembly configured with a removable liner
and six substrate support trays according to the present
invention.
[0041] FIG. 19 depicts an exploded front view of a portion of the
third exemplary embodiment of a reaction chamber assembly according
to the present invention.
7 DESCRIPTION OF THE PREFERRED EMBODIMENTS
ALD System First Embodiment
[0042] Referring to FIGS. 1 and 2, an exemplary first embodiment of
an atomic layer deposition system (ALD) (2000) configured according
to the present invention is constructed with a floor standing
system cabinet (2010) supported on four feet (2020) having a front
face (2030) that includes an access door assembly (2040). The
access door assembly (2040) includes a door handle (2050) mounted
on an outer door panel (2060). Both the outer door panel (2060) and
the door handle are thermally insulated to protect an operator when
handling the door handle (2050). The access door assembly (2040) is
shown in a closed or operating position in FIG. 1 and in an open or
loading/unloading position in FIG. 2. The access door assembly
(2040) provides access through the system cabinet (2010) to a gas
deposition or reaction chamber (4000) described below. The gas
deposition chamber (4000) is housed inside the system cabinet
(2010) behind the access door assembly (2040). In the first example
ALD system shown in FIGS. 1 and 2, the gas deposition chamber
(4000) is configured to coat solid substrates using ALD coating
cycles and the access door assembly (2040) provides the only access
to the gas deposition chamber (4000). Accordingly, substrates to be
coated are loaded into the gas deposition chamber (4000) and
removed from the gas deposition chamber (4000) through the access
door assembly (2040). As will be recognized, the present invention
is not limited to ALD coating cycles but can be used in various
reaction chamber environments wherein reactants may contaminate the
chamber walls. An advantage of the first exemplary embodiment is
that is has a small floor space footprint. The small floor space
footprint is due in part to the position of input and output
plenums used to deliver and remove reactant gases from the reaction
chamber. In particular, as will be described below, the input and
output plenums are incorporated within the reaction chamber volume
and therefore do not increase the floor space footprint of the ALS
system (2000).
Reaction Chamber
[0043] Referring now to FIGS. 3-6 a first example gas deposition
chamber or reaction chamber assembly (4000) according to the first
embodiment of the present invention includes an outer wall assembly
(4010), a removable liner (4020), an input port assembly (4030) for
delivering gas reactants into the reaction chamber through an input
plenum and an exit port assembly (4040) for removing gases from the
reaction chamber through an output plenum. As shown in the section
views of FIGS. 5 and 6, the outer wall assembly (4010) comprises a
rectangular shell structure formed by opposing and substantially
parallel top and bottom rectangular outer walls (4050) and (4060),
opposing and substantially parallel rectangular side outer walls
(4070) and (4080) and opposing and substantially parallel
rectangular front and back outer walls (4090) and (4095). The
rectangular shell structure of the outer wall assembly (4010)
encloses an outer volume (4110) which has a front-to-back
longitudinal length and a side-to-side transverse width in a
horizontal plane and a vertical height. The longitudinal length is
shown in the side view of FIG. 5 and the transverse width is shown
in the back cutaway view of FIG. 6 with the vertical height shown
in both figures. An outer aperture (4100), shown in FIG. 3, passes
through the front outer wall (4095) to the outer volume (4110). In
the present example, the outer volume has a rectangular
cross-section in the horizontal and vertical planes and the outer
aperture (4100) is rectangular in the vertical plane with a
transverse width and a vertical height dimension substantially
matched to the transverse width and vertical height dimensions of
the outer volume (4110). More generally, the outer walls may have
various shapes and sizes to enclose an outer volume of a desired
shape and size without deviating from the present invention.
Moreover, the outer aperture (4100) may be formed with various
shapes and sizes and extend through any one of the side, top or
bottom outer walls to provide access to the outer volume as
required by the application. In particular, various outer wall
configurations can be used to enclose an outer volume with various
polygon or circular shaped cross-sections, including a cylindrical
or pipe chamber, without deviating from the present invention.
[0044] Generally, the outer wall assembly (4010) comprises an oven
structure that includes or may include resistive heating elements,
or the like, (4120) disposed on or in grooves formed in external
surfaces of all or some of the outer walls (4050-4095).
Alternately, according to an advantage of the present invention,
the heating elements (4120) may be disposed on or in grooves formed
on internal surfaces of some or all of the outer walls because the
removable liner described below prevents the internal surfaces of
the outer walls and any heating elements disposed thereon from
being contaminated by reactants. Otherwise, the heating elements
(4120) can be disposed inside some or all of the outer walls
(4050-4095) such as by being sandwiched between opposing outer wall
portions. The heating elements (4120) heat the chamber assembly
(4000) to a deposition or reaction temperature and maintain the
chamber assembly at the desired temperature over prolonged periods
of use. In addition, solid substrates that are being coated in the
reaction chamber are also heated to the reaction temperature and
the solid substrates maybe heated before being inserted into the
reaction chamber or it may be required to delay any coating steps
until the solid substrates are heated to the reaction temperature.
Accordingly, the chamber assembly (4000) includes temperature
sensors and one or more controllers for controlling the operation
of the heating elements to achieve and maintain desired operating
temperatures. Alternately, other heating means including heating
elements disposed external to the outer wall assembly (4010) are
usable without deviating from the present invention. In still
further embodiments, the chamber assembly (4000) may not require
heating elements or may instead include cooling elements to achieve
desired reaction temperatures.
[0045] When heating elements are disposed outside the outer volume
(4110) it is desirable to direct thermal energy into the outer
volume (4110). Accordingly, the outer walls (4050-4095) preferably
comprise a material having a high thermal conductivity in order to
provide a conductive path between the heating elements (4120) and
the outer volume (4110). In addition, it is desirable that the
outer wall material meet its structural and thermal property
characteristics over the range of operating temperatures that the
chamber assembly (4000) is expected to be subjected to, e.g.
85-500.degree. C.
[0046] Ideally, the outer wall assembly (4110) comprises a
substantially gas tight structure when the access door (2040) is in
a closed position. In particular, the outer volume (4110) may be
pumped to vacuum pressures ranging down to about 10 microtorr to
remove contaminants, reactants, and reactant byproducts from the
chamber assembly and to maintain the outer volume at a desired
vacuum pressure during coating cycles. Accordingly, it is desirable
to join the outer walls (40504095) with welded seams to prevent gas
leaks and to configure any ports and fittings associated with the
ports that pass through the outer walls (4050-4095) with gas tight
gaskets and the like as are generally used in vacuum chambers.
[0047] In the present example, the preferred material for
constructing the outer walls (4050-4095) is aluminum and
particularly 6061 aluminum, which has good weldability, an
acceptable thermal conductivity of approximately 167 W/m-K or 1160
BTU-in/hr-ft2-.degree. F., and a melting temperature of
approximately 600.degree. C. or 1150 F. Alternately, any weldable
aluminum, other weldable metals or ceramic materials can be used
without deviating form the present invention. Preferably, the outer
walls (4050-4095) comprise sheet or plate stock, folded, formed,
machined, welded and fastened together as required to enclose the
outer volume (4110) with gas tight seams and to provide the desired
structural and thermal performance characteristics. Moreover, one
or more of the outer walls (4050-4095) may be made thicker than
required to perform structurally in order to provide a heat sink
suitable for maintaining the outer wall assembly (4010) at a
desired operating temperature and allow quick reheating e.g. after
the access door has been opened and new substrates have been added
for coating. In the preferred embodiment, a layer of thermal
insulation is disposed over the external surfaces of the outer
walls (4050-4095) to reduce thermal radiation to the air
surrounding the outer wall assembly (4010).
Removable Liner
[0048] Referring to FIGS. 3-6, the reaction chamber (4000) further
comprises a removable liner (4020). The removable liner (4020)
comprises a shell structure sized to fit into the outer wall
assembly (4010) when installed through the outer aperture (4100).
The liner (4020) is configured to line the inside surfaces of the
outer walls and specifically the top and bottom outer walls (4050,
4060), the side outer walls (4070, 4080) and the back outer wall
(4090). In the example first embodiment of the present invention
the removable liner (4020) comprises opposing and substantially
parallel top and bottom rectangular liner walls (4130, 4140),
opposing and substantially parallel side rectangular liner walls
(4150, 4160) and a rectangular back liner wall (4170), shown in
FIG. 5. The removable liner (4020) encloses a reaction chamber or
inner volume (4190), which has a front-toback longitudinal length
and a side-to-side transverse width in a horizontal plane and a
vertical height. The removable liner further includes a chamber
aperture (4180) passing through one of the liner walls to provide
access to the reaction chamber (4190). In the present example the
reaction chamber (4190) has a rectangular cross-section in the
horizontal and vertical planes and the chamber aperture (4180) is
substantially rectangular in the vertical plane with a transverse
width and vertical height dimension substantially matched to the
transverse width and vertical height dimensions of the reaction
chamber (4190). As best viewed in FIGS. 3 and 4, the chamber
aperture (4180) faces front in the reaction chamber assembly and is
substantially centered in the outer aperture (4100) such that the
outer aperture (4100) receives the removable liner (4020) into the
outer volume (4110) and the chamber aperture (4180) receives
substrates to be coated into the reaction chamber (4190) formed by
the removable liner.
[0049] The removable liner (4020) also includes a rectangular
flange (4200) surrounding the chamber aperture (4180) and the
flange substantially forms the removable liner (4020) front wall.
The flange stiffens the removable liner (4020) to prevent buckling
and distortion of the liner and of the chamber aperture (4180). The
flange (4200) contacts the front outer wall (4095) when the
removable liner is installed into the outer wall assembly (4010).
The front outer wall face (4095) includes a rectangular recess
(4205) surrounding the outer aperture (4100) for receiving the
rectangular flange (4200) therein. In the installed position, an
inside surface of the flange (4200) is in mating contact with the
rectangular recess (4205) and an outside surface of the flange
(4200) is flush with the outside surface of the front outer wall
(4095).
[0050] In its operating position, the removable liner (4020) makes
mating contact with several surfaces of the outer wall assembly
(4010). Ideally, the removable liner (4020) is sized to exactly
mate with all or most internal surfaces of the outer rectangular
volume (4110) such that an uninterrupted thermal conduction path
extends from the heating elements (4120) to surfaces of the
removable liner (4020) and to substrate trays (described below)
supported by the removable liner (4020). However, exact mating over
all surfaces is not practical so the removable liner (4020) and or
outer wall assembly may be configured with contacting surface
features e.g. bumps, ridges, interlocking guides, etc., not shown
in the first example embodiment, with sufficient mating contact
area provided between the outer walls and the removable liner to
readily conduct thermal energy from heating elements to all
surfaces of the removable liner. In addition, a thermal conduction
pathway is provided at the interface between the rectangular flange
portion (4200) and the front face (4025). In areas where there is
no mating contact between the outer walls and the removable liner,
a clearance gap volume, e.g. the clearance gap volume (4215) shown
in FIG. 6, extends between external surfaces of the liner walls
(4130-4170) and internal surfaces of the outer walls (4050-4090).
The clearance gap volume (4215) is continuously purged with an
inert gas to prevent reactants from reacting with the outside wall
assembly (4010).
[0051] The removable liner (4020) and the outer wall assembly
(4010) may be mechanically interlocked such as by sliding
interlocking features e.g. by a rod or bar guided in a slot or by a
dovetail bar guided in a mating dovetail slot or the like. With one
half of the interlocking feature on the removable liner (4020) and
the other half on the outer wall assembly (4010), the interlocking
features serve to align and guide the removable liner (4020) into
and out of its desired operating position and may increase thermal
conduction by increasing the area of mating contact between the
liner and outer walls. In a preferred embodiment, the removable
liner (4020) is mechanically held in place by its engagement or
mating contact with the outer wall assembly (4010). Accordingly,
the removable liner (4020) is held in place without fasteners. This
provides an advantage that a contaminated liner can be removed and
replaced with a clean liner quickly and without tools. This further
eliminates the problem of dealing with reactant build up on
fasteners, which may render the fasteners unusable. Alternately,
fasteners can be used to fasten the flange portion (4200) to the
front outer wall (4095).
[0052] In a preferred embodiment, the removable liner (4020)
comprises a material that can be cleaned to remove reactant
contaminants from its surfaces and be reused in the reaction
chamber assembly; however, disposable liners also can be used and
are within the scope of the present invention. In addition, it is
desirable that the liner material meet its structural and thermal
property characteristics over the range of operating temperatures
that the chamber assembly (4000) is expected to be subjected to,
(85-500.degree. C.). Additionally the liner material should have
good resistance to breakdown and or other detrimental reactions
with reactants that the chamber assembly (4000) is expected to be
subjected to. In addition, since the liner is periodically removed
and replaced, it is desirable to keep the liner weight low.
[0053] It is desirable to clean liners removed from the reaction
chamber assembly to remove contaminants therefrom. Solid film
layers deposited onto the removable liner by reactants or
precursors are removed primarily by abrasive blasting, e.g. sand,
shot or bead blasting and the liner material should be able to
withstand repeated abrasive blasting. Moreover, internal surfaces
of the removable liner are abrasive blasted during fabrication to
roughen surfaces that may become coated with thin film build up
because the thin film build up has better adhesion to the roughen
surfaces and is therefore less susceptible to peeling or cracking
Otherwise, the solid film layers can be removed by chemical methods
such by an acid etching or using solvents or the like. In other
cases, the liner may become contaminated by an undesirable reactant
or reaction byproduct and need to be replaced immediately for
safety reasons. In this case is beneficial to have a clean liner on
hand and to clean the contaminated liner for reuse as required.
[0054] According to the present invention the removable liner
comprises thin single layer sheet metal walls comprising stainless
steel ranging in thickness from 0.5-2.0 mm thick (0.02-0.80 inch).
The stainless steel is readily cleanable by a bead blast using
180-grit glass or ceramic beads after a highpressure hot deionizer
water wash. In particular, the stainless steel has a Brinnell
Hardness of approximately HB 200, which is high enough to be
subjected to repeated bead blasting. Otherwise, the stainless steel
liner is readily cleanable by a hydrofluoric acid in a liquid bath
or vapor chamber. Additionally the stainless steel liner meets the
thermal and structural requirements.
[0055] Preferably, the removable liner (4020) is formed as a
unitary element such as by cold forming or deep drawing the liner
from a preformed blank. Otherwise the liner is formable by various
know sheet metal forming methods. Ideally, the removable liner
forms a gas tight reaction chamber (4190) with gas tight, e.g.
welded seams and gas sealed fitting interface apertures that
prevent reaction gases from reaching the outer wall assembly
(4010). However, in practical embodiments, some leakage through the
removable liner (4020) into the clearance gap volume (4215) between
the removable liner (4120) and the outer wall assembly (4010) is
expected. Accordingly, a pressure gradient may be established
between the clearance gap volume (4215) and the reaction chamber
(4190) by purging the clearance gap volume (4215) with an inert gas
provided at a gas pressure that is higher than the gas pressure
inside the reaction chamber, e.g. an inert gas at atmospheric
pressure or greater.
Pressurized Clearance Gap
[0056] Referring now to FIG. 6, the clearance gap volume (4215) is
purged with inert gas through a gas input port (4350). The port
(4350) installs through the side outer wall (4080) and is in
fluidic communication with a gas supply container to deliver an
inert purge gas into the clearance gap volume (4215) surrounding
the removable liner (4020). Preferably, the purge gas is nitrogen.
Purge gas is substantially constantly delivered into the clearance
gap volume (4215) preferably at atmospheric pressure or greater. A
gas output port (4360) passing through the side outer wall (4070)
is in fluidic communication with clearance gap volume (4215). The
output port (4360) includes a pressure relief valve, not shown, set
to relieve excess pressure in clearance gap volume (4215) if the
pressure therein exceeds a preset pressure limit. The preferred
pressure in the clearance gap volume (4215) exceeds the pressure in
the reaction chamber to prevent gas in the reaction chamber (4190)
from leaking into the clearance gap volume (4215). The continuous
flow of inert gas flowing into the clearance gap volume (4215)
through the port (4350) fills the clearance gap volume (4215) and
then leaks into the reaction chamber through any leaks in the
removable liner (4020). The inert gas leaked into the reaction
chamber is exhausted out of the reaction chamber through the exit
port described below. The gas pressure in the clearance gap volume
(4215) is maintained at about 1-5 pounds per square inch above
atmospheric pressure. Any higher gas pressures will cause the
relief valve to open to reduce the pressure inside the clearance
gap volume (4215) and exhaust gas out of the clearance gap volume
(4215) through the port (4360). In other embodiments, one or both
of the ports (4350) and (4360) may be in fluidic communication with
the reaction chamber exit port assembly (4040) or another conduit
in fluidic communication with the system vacuum pump, described
below, to evacuate the clearance gap volume (4215) and maintain the
gas pressure in the clearance gap volume (4215) at less than
atmospheric pressure but still at a higher pressure than is
maintained inside the reaction chamber (4190).
Access Door
[0057] Referring to FIG. 5, the access door assembly (2040) is
shown in side view in the closed position. The access door assembly
(2040) includes the outer door panel (2060), the door handle
(2050), an inner door panel (2070), a door cover (2080), a door
heating element (2090), disposed between the inner door panel
(2070) and a thermal insulation layer (2100) disposed between the
door heating element (2090) and the door cover (2080). The inner
door panel (2070) has rectangular dimensions that exceed the
rectangular dimension of the front outer wall (4095). In the
present embodiment, the entire access door assembly (2040) is
supported on one or more vertically disposed rails or rods, not
shown, to move the door assembly vertically upward, or downward, to
an open position to allow access to the reaction chamber (4190)
through the chamber aperture (4180). In the closed position, shown
in FIG. 5, the inner door panel seals both the outer aperture
(4100) with a first outer rectangular o-ring seal (4320) and the
chamber aperture (4180) with a second inner rectangular oring seal
(4330). Each of the o-ring seals (4320) and (4330) has an closed
rectangular form that fits into a matching rectangular groove
formed on the inner door panel (2070) facing the reaction chamber.
The o-ring seals may have a circular or square cross-section and
may comprise a material suitable for the sealing application, e.g.
a metal o-ring suitable for the range of temperature and pressure
of the reaction chamber.
[0058] The heating assembly (2090) includes a rectangular aluminum
plate (2110) approximately matching the rectangular dimensions of
the inner door panel (2070) and mounted in mating contact
therewith. A resistive heating element (2120) is mounted in mating
contact with the rectangular aluminum plate (2110) opposed to the
inner door panel (2070) such that thermal energy generated by the
heating element (2120) is conducted through the rectangular
aluminum plate (2110) and through the stainless steel inner door
panel (2070) to radiate into the reaction chamber (4190). The
insulation layer (2100) is rectangular and approximately matches
the dimensions of the aluminum plate (2110) and is mounted in
contact with the heating assembly (2090) opposed to the inner door
panel (2070). The door cover (2080) is attached to the aluminum
plate (2110) and holds the insulation layer (2100) in place.
[0059] According to a further aspect of the present invention, the
stainless steel inner door panel (2070) is removable from the
access door assembly (2040) for periodic cleaning and replacement.
In particular, the inner door panel (2070) is removed when the
removable liner (4020) is removed for cleaning and both the
removable liner (4020) and the inner door panel (2070) are cleaned.
Alternately, either of the inner door panel or removable liner may
be disposed of and replaced with new elements. The cleanable inner
door panel (2070) is fabricated from stainless steel so that it can
be cleaned using bead blasting or a chemical method as described
above in relation to cleaning the removable liner. Preferably, the
inner door panel (2070) is attached without fasteners or at least
without fasteners that are exposed to the reaction chamber (4190).
The inner door panel (2070) may be clamped or held in place by
interlocking features located between the inner door panel (2070)
and the aluminum plate (2110). Preferably the surface of the inner
door panel that faces the reaction chamber is bead blasted during
fabrication to roughen the surface for improving adhesion by
coating layers formed thereon.
10 Substrate Support
[0060] Referring now to FIGS. 5-9 the reaction chamber (4190) of
the first example embodiment is configured to support a plurality
of substrate trays (4210), shown in FIG. 9, on tray supports
(4230), shown in FIG. 7. The tray supports (4230) are attached to
and extend out from opposing side walls (4150, 4160) of the
removable liner (4020) to receive the substrate trays thereon. The
substrate trays (4210) may be gravity supported on the tray
supports (4230) or may be otherwise fastened or clamped to the side
walls (4150, 4160) or supported from the top or bottom liner walls
(4130, 4140). Preferably, each substrate tray (4210) is fabricated
from ALPASE K100-S which is an aluminum plate material specifically
designed for vacuum applications and which possesses desirable
characteristics for gas deposition environments such as dimensional
stability, excellent machinability, weldability, low stress
content, and equiaxial grain structure. Preferably, the tray
supports (4230) and substrate trays (4210) provide a thermally
conductive path extending from the removable liner (4020) to solid
substrates supported on the substrate trays (4210) to reduce the
time required to heat substrates to a desired reaction temperature.
Aluminum is particularly desirable for the substrate trays (4210)
because of its high thermal conductivity (e.g. 812
BTU-in/hr-ft2-.degree. F.) to quickly and uniformly conduct thermal
energy to substrates supported thereon, thereby raising the
substrate temperature to a desired deposition temperature more
quickly than other substrate tray materials. The substrate trays
(4210) are not cleanable by the bead blasting or chemical cleaning
processes described above and therefore are usually disposed of and
replaced with new trays when they become unusable due to material
contamination built up by many deposition cycles. Alternately, the
substrate trays (4210) can be fabricated from stainless steel so
that the trays can becleaned and reused or other cleaning methods
more suitable for aluminum trays may be used to clean the aluminum
trays.
[0061] Solid substrates in the form of thin rectangular glass
sheets are loaded one on each substrate tray (4210) for ALD, ALE or
other gas deposition coating. The substrates are only coated on
exposed surfaces so the substrate bottom surface is not coated. As
shown in FIG. 5 the reaction chamber includes five substrate
support trays in the reaction chamber (4190). In the present
example embodiment, the longitudinal length and transverse width of
the substrate trays (4210) support a GEN 1 rectangular glass plate
disposed horizontally thereon. In particular, the GEN 1 substrate
has length and width dimensions of 400.times.300 mm and the example
rectangular reaction chamber (4190) has length and width dimensions
of 465 mm (18.3 in.) and 416 mm (16.4 in.). Of course larger
reaction chambers with similar characteristics can be constructed
to receive larger rectangular glass plates thereon, (e.g. GEN 2-7,
or larger) without deviating from the present invention. In
addition, the substrate trays (4210) can be removed and other solid
substrate types such as batches of circular wafers held in coating
cassettes and various other solid substrates standing alone or
supported on various substrate holding elements can be loaded into
the reaction chamber (4190).
[0062] Referring to FIG. 9, a substrate tray (4210) is shown with
its bottom surface (4380) facing upward. Each substrate tray may
include a plurality of stop pins (4390) or similar alignment aids
that extend vertically up from a top surface (4400) or from a side
surface of the substrate trays. The stop pins (4390) serve as a
guide for aligning edges of substrates supported on the support
tray.
[0063] In the present example embodiment shown in FIGS. 6 and 7,
the reaction chamber (4190) has a vertical height of 106 mm (4.17
in.) and is configured to support five substrate trays (4210)
disposed horizontally and substantially evenly spaced apart
vertically. According to one aspect of the invention, each of the
five substrate trays (4210) is removable from the reaction chamber
(4190) through the chamber aperture (4180) when the access door
(2040) is open. Thus, the reaction chamber (4190) is operable using
any combination of from one to five substrate trays (4210);
however, as will be described in detail below, it is preferable to
keep a bottom tray (4220) or a suitable substitute for a bottom
tray in place for most gas deposition applications.
Input Port Assembly
[0064] Referring to FIG. 5, the input port assembly (4030) passes
through each of the bottom outer wall (4060) and the bottom liner
wall (4140) to deliver reactants or precursors into the reaction
chamber (4190). Other gases such as an inert purge gas may also be
delivered into the reaction chamber (4190) through the input port
assembly (4030) as required. In a preferred embodiment, the chamber
assembly (4000) utilizes a single input port (4030) that is in
fluidic communication with an input manifold fluidly connected with
a plurality of gas containers and configured to precisely deliver
desired volumes of reactants or precursors and other gases into the
reaction chamber (4190) according to predefined coating cycle
formulas. Generally, the reaction chamber assembly is configured to
deliver a flow of source material comprising one or more gases,
vapors, aerosols or the like into the reaction chamber through the
input port assembly (4030). In addition, the input manifold is
configured to deliver a continuous flow of an inert purge gas, e.g.
nitrogen, to flush out the reaction chamber (4190) and the input
port assembly (4030) as may be required. In other embodiments, a
plurality of input ports can be used with each input port being in
communication with different gas supply containers. In other
embodiments, input ports can pass through other walls of the
reaction chamber (4190) without deviating from the present
invention.
[0065] FIG. 8 depicts a section view taken through the input port
assembly (4030) and the interface of the input port assembly (4030)
with the bottom outer wall (4060) and the bottom liner wall (4140).
Gasses are delivered into the reaction chamber (4190) through an
input port (9010), which passes through the bottom liner wall
(4140). A gas fitting (9005) suitable for attaching to an input
manifold, not shown, and receiving input gasses therefrom is
supported on an outer tube (9015). The outer tube (9015) extends
from the gas fitting (9005) and passes substantially through the
bottom outer wall (4060). An input port flange (9030) is attached
to the bottom outer wall (4060) by screws (9040) and includes a
through aperture for receiving the outer tube (9015) there through.
A precursor tube (9060) installs into the outer tube (9015) from
inside the reaction chamber (4190). In particular, the precursor
tube (9060) installs through the input port (9010) and extends from
inside the reaction chamber (4190) to fit snugly into the inside
diameter of the outer tube (9015). The precursor tube (9060)
engages with the outer tube (9015) to a length that extends beyond
the bottom outer wall (4060). The precursor tube (9060) has an
outside diameter that closely matches the inside diameter of the
outer tube (9015) to reduce leakage therebetween. The precursor
tube (9060) is withdrawn from the outer tube (9015) in order to
remove the removable liner (4020) from the outer wall assembly
(4010) and preferably the precursor tube is removable from the
outer tube by hand, without using tools.
Exit Port Assembly
[0066] Referring to FIG. 5, the exit port assembly (4040) is
disposed between and in fluidic communication with the reaction
chamber volume (4190) and a vacuum pump, not shown. The exit port
assembly (4040) includes a trap (4240), a vacuum valve (4250), a
cone shaped conduit (4260), disposed between the trap (4240) and
the vacuum valve (4250), and a pressure gage (4270) disposed to
measure pressure in the cone shaped conduit (4260).
[0067] Referring to FIGS. 3, 5, 6, and 7, the cone shaped conduit
(4260) includes a cylindrical flange (4280) attached to the bottom
outer wall (4060) with attaching screws (4300). The cylindrical
flange (4280) supports the entire exit port assembly (4040). An
exit port (4500) passes through the bottom liner wall (4140) and
fluidly connects with the cone shaped conduit (4260) through a trap
seal, (4290). The trap seal (4290) comprises an annular o-ring,
e.g. a stainless steel o-ring, positioned between the cylindrical
flange (4280) and the bottom liner wall (4140) surrounding the exit
port (4500). The trap seal (4290) is attached to the bottom outer
wall (4060) and a top surface of the trap seal is positioned to
receive the bottom liner wall (4140) thereon when the removable
liner is installed into the outer volume.
[0068] The trap seal (4290) functions as a gas seal between the
removable liner (4020) and the cylindrical flange (4280) to gas
seal the interface between the exit port assembly (4370) and the
bottom outer wall (4060). The removable liner and trap seal are
drawn tightly together in reaction to a pressure drop in the cone
shaped conduit generated by the vacuum pump. However even in the
event that the trap seal (4290) leaks, the surrounding volume is
purged with inert gas at a higher pressure than the gas pressure in
side the reaction chamber and cone shaped conduit so that any
leakage is substantially inert gas leaking into the reaction
chamber so that reactants are prevented form leaking out. One of
the removable liner, cylindrical flange, bottom outer wall or trap
seal may include feature provided thereon to engage the exit port
with the trap seal when the removable liner is installed.
[0069] The trap comprises a cylindrical trap (4240) or appropriate
filter disposed in the fluid path of gasses drawn out of the
reaction chamber (4190) by the vacuum pump. The trap serves to
trap, react with, filter or otherwise prevent undesirable materials
from exiting from or damaging the gas deposition system, or its
components, such as the vacuum pump, valves or piping. The trap
(4310) is configured for periodic replacement as required.
Gas Flow Dynamics
[0070] Referring now to FIGS. 7 and 10 the removable liner (4020)
is shown in top section view in FIG. 7, which is substantially a
top view of the bottom liner wall (4110). As shown, the input port
(9010) comprises a small aperture, e.g. 12 mm (0.47 inch),
substantially centered with respect to a transverse width W of the
bottom liner wall (4110) and positioned approximately one third of
the longitudinal length L away from a front edge (9080) of the
bottom liner wall (4110). The input port (9010) is positioned near
an apex of a triangular input plenum (10040). As will be further
described below, the bottom liner wall (4110) cooperates with a
bottom substrate tray (4220) to substantially enclose a triangular
input plenum volume and the input plenum volume is open to a front
region of the reaction chamber over its full transverse width W. In
preferred embodiments, the input plenum is shaped in a manner
allows gas entering the reaction chamber to continuously expand in
volume as it flows from the input port (9010) to the reaction
chamber. Moreover, the shape of the input plenum volume preferably
allows reactant gases to expand to fill the full transverse width W
of the reaction chamber before the reactant gases reach surfaces of
the substrates to be coated. The increase in gas volume in the
input plenum further serves to reduce the gas flow velocity and
vapor pressure prior to the gas reaching the reaction chamber.
[0071] The exit port (4500) comprises a large aperture, e.g. 200 mm
(7.87 inches), substantially centered with respect to the
transverse width W and positioned approximately two thirds of the
longitudinal length L away from the front edge (9080). The exit
port (4500) is positioned proximate to a narrow width of a
trapezoidal exit plenum (10050). As will be further described
below, the bottom liner wall (4110) cooperates with a bottom
substrate tray (4220) to substantially enclose a trapezoidal input
plenum volume and the input plenum volume is open to a back region
of the reaction chamber over its full transverse width W. In
preferred embodiments, the exit plenum is shaped in a manner allows
gas to be draw from the reaction chamber substantially over its
full transverse width W and to continuously decrease in volume as
it flows from the reaction chamber to the exit port (4500).
Moreover, the decrease in gas volume shape of the input plenum
volume preferably allows reactant gases to expand to fill the full
transverse width W of the reaction chamber before the reactant
gases reach surfaces of the substrates to be coated The decrease in
gas volume in the exit plenum further serves to increase the gas
flow velocity and vapor pressure prior to the gas exiting the
reaction chamber and this increase in flow velocity reduces the
time required to purge the reaction.
[0072] The bottom liner wall (4140) includes an upper horizontal
wall portion (10060), shown black in FIG. 7 and two lower
horizontal wall portions (10070) and (10080). All three horizontal
wall portions (10060-10080) are substantially parallel and
horizontal. The upper horizontal wall portion (10060) is separated
from each of the lower horizontal wall portions (10070) and (10080)
by approximately 20 mm (0.78 inch).
[0073] The upper horizontal wall portion (10060) forms a floor
surface of the removable liner (4020) and may be used to support
the bottom substrate tray (4220) thereon. A triangular lower
horizontal wall portion (10070) comprises a bottom surface of the
triangular plenum (10040) and includes the input port (9010)
passing therethrough. A trapezoidal horizontal wall portion (10080)
comprises a bottom wall of the trapezoidal plenum (10050) and
includes the exit port (4500) passing therethrough. The triangular
plenum (10040) is bounded by a continuous triangular vertical wall
(10090) that extends between the upper horizontal wall portion
(10060) and the lower horizontal wall portion (10070). The
trapezoidal plenum (10050) is bounded by a continuous trapezoidal
vertical wall (10100) that extends between the upper horizontal
wall portion (10060) and the lower horizontal wall portion
(10080).
[0074] Referring now to FIG. 10 a side section view of the chamber
(4000) schematically depicts gas flow through the chamber when a
plurality of horizontal substrate support trays (4210) are
installed therein. The bottom substrate tray (4220) is supported
parallel with and substantially in contact with the upper
horizontal wall portion (10060) to partially cover each of the
triangular plenum (10040) and the trapezoidal plenum (10050). As
gasses enter the chamber through the input port (9010) they expand
to fill the triangular plenum (10040). However, the location of the
bottom support tray (4220) acts as a baffle or vane that prevents
upward flow of the gasses out of the triangular plenum (10040)
except at the base or widest part of the triangular plenum (10040)
proximate to a front edge of the reaction chamber (4190). In
particular, the bottom substrate tray (4220) and each of the other
substrate trays is positioned with it's front edge approximately
disposed along the dashed line A shown in FIG. 7, which is
approximately 30 mm (1.18 inch) from the front edge (9080).
[0075] Forward of the dashed line A, gasses flowing into the
triangular plenum (10040) begin to expand vertically upward to
substantially fill a front vertical gas flow channel (10110). The
front vertical gas flow channel (10110) extends vertically upward
from the triangular lower horizontal wall (10070) proximate to the
base or widest part of the triangular plenum to the top liner wall
(4130) and extends horizontally substantially across the entire
transverse width of the reaction chamber (4190).
[0076] The front vertical gas flow channel (10110) is in fluidic
communication with the reaction chamber (4190) above the bottom
substrate tray (4220) which extends over the longitudinal length L
and transverse width W and has a vertical height that encloses the
five horizontally disposed substrate support trays (4210) spaced
vertically apart with sufficient space in between trays to allow a
sufficient volume of reactant gas to flow over each substrate tray.
In particular, the gas expands to flow from the front vertical flow
channel (10110) into the open volume between the substrate trays
(4210 and 4220) where the gas flows over and around any substrates
that are supported on the substrate trays. Moreover, the gas flow
between the substrate trays is substantially uniformly distributed
over the chamber transverse width W and is substantially laminar to
ensure uniform distribution of reactant over the exposed surfaces
of the substrates as the gas flows from front to back in the
reaction chamber (4190).
[0077] The location of a back edge of the bottom support tray
(4220) acts as a baffle that prevents downward flow of the gasses
into the trapezoidal plenum (10050) except at the widest part of
the trapezoidal plenum (10050) proximate to the back liner wall
(4170). In particular, the bottom substrate tray (4220) and each of
the other substrate trays is positioned with back edges thereof
approximately disposed along the dashed line B shown in FIG. 7,
which is approximately 30 mm (1.18 inch) from the inside surface of
the back liner wall (4170).
[0078] Forward of the dashed line B, gasses are flowing over the
five substrate trays and are blocked from flowing directly into the
trapezoidal plenum (10050) by the bottom substrate tray (4220).
Rearward of the dashed line B gasses passing over the substrate
trays enter into and substantially fill a rear vertical gas flow
channel (10120). The rear vertical gas flow channel (10120) extends
vertically from the trapezoidal lower horizontal wall (10080)
proximate to the base or widest part of the trapezoidal plenum
(10050) to the top liner wall (4130) and extends horizontally
substantially across the entire transverse width W of the reaction
chamber (4190).
[0079] The rear vertical gas flow channel (10120) is in fluidic
communication with the open volume between the substrate support
trays (4210) and (4220) where reaction gases flow over and around
any substrates that are supported on the substrate trays. In
particular, reaction gases entering from the triangular plenum
(10040) expand or are drawn in response to operation of the vacuum
pump through the exit port to flow from the open volume between the
substrate support trays (4210) and (4220) into the rear vertical
gas flow channel (10120) and then to the base of the trapezoidal
plenum (10050).
[0080] In the case where the vacuum valve (4250) is closed and or
the vacuum pump, not shown, is not drawing gas out from the
chamber, the gas dynamics within the chamber volume are
substantially governed by expansion of the input gasses to fill the
volume. In the case where the vacuum valve (4250) is opened and gas
is being drawn out from the chamber by the vacuum pump, a low gas
pressure area is established in the trapezoidal plenum (10050) at
the narrowest part of the trapezoidal plenum (10050) surrounding
the exit port (4500) and the low pressure surrounding the exit port
draws gas from the widest part of the trapezoidal plenum (10050)
and from the rear vertical gas flow channel (10120) substantially
uniformly across the entire transverse width W. In either case, the
baffling provided by the bottom support tray (4220) prevents gas
entering the triangular plenum (10040) from vertical upward flow
until it reaches the widest part of the triangular plenum (10040)
and also prevents gas from vertical downward flow into the
trapezoidal plenum (10050) except at its widest part of the
trapezoidal plenum. In either case, reactant gases as substantially
uniformly distributed over the entire transverse width W in the
open volume between the substrate support trays (4210) and (4220)
where reaction gases flow over and around any substrates that are
supported on the substrate trays.
[0081] As will be recognized by those skilled in the art, the
volume of the front and rear flow channels (10110) and (10120) can
be varied by changing the positions of front and back edges of the
substrate support trays (4010) and (4020) and especially the bottom
support tray (4020). In other variations of the five substrate tray
configuration described above, the chamber can be configured with
just one bottom substrate support tray (4020) to provide the
desired plenum baffling. Alternately, one or more plenum baffles
can be installed or integrally formed in the bottom liner wall
(4140) instead of the using the bottom support tray (4020) as a
baffle. In other configurations, the chamber can be configured with
any number of substrate trays and or with other substrate holder
suitable for non-rectangular substrates such as circular wafers and
any other object(s) that can be fit into the reaction chamber
through the access door.
ALD System Second Embodiment
[0082] A second exemplary embodiment of the present invention
comprises a dual chamber gas deposition system (1000) shown in
isometric view with the external skins removed in FIG. 11. The
system (1000) includes a front face (1180) which is used for
loading substrates into each of two gas deposition chambers (1120)
and (1150). In a preferred embodiment, the front face (1180)
interfaces with a clean room wall and the substrates are loaded and
unloaded from inside the clean room through the clean room wall.
For that reason, the removable liners installed into and removable
from each of the gas deposition chambers of the second exemplary
embodiment are installed and removed through a back face, opposed
to the front face (1180).
[0083] A right side face (1130) includes a single user interface
device (1200) which can be used to enter commands for operating
both of the gas deposition chamber assemblies (1120) and (1150). In
alternate embodiments, each gas deposition chamber assembly may
include a separate user interface device (1200). In further
alternate embodiments the control systems of both gas deposition
chamber assemblies can be networked to a remote device that
includes a remote user interface, not shown.
[0084] The system (/000) comprises a frame (1140) constructed to
support an upper ALD or ALE reaction chamber assembly (1120)
supported by an upper cross frame platform (1145) and a lower ALD
or ALE reaction chamber assembly (1150) supported by a lower cross
frame platform (1155). Each of the chamber assemblies (1120) and
(1150) is constructed to receive a single large area rectangular
substrate therein and to support the substrate in a substantially
horizontal plane. In the present example, each reaction chamber
assembly (1120) and (1150) is configured to coat a single GEN 4.5
glass substrate, which has rectangular dimensions of 920 mm wide by
730 mm long. The chamber assemblies (1120) and (1150) are
configured with a front opening or load port having a width
dimension that is larger than 920 mm for receiving the desired
substrate wide dimension through the front port. Each substrate
comprises a top face, to be coated, and an opposing bottom face
that is not coated. The substrates have an approximate thickness of
0.5 mm, and are therefore fragile and difficult to handle. The
glass substrates are used to manufacture rectangular LCD screens
and the like. Each chamber assembly includes a horizontal substrate
support surface for receiving a bottom face of a substrate thereon
with an opposing top face of the substrate top face facing upward.
Generally one GEN 4.5 substrate is loaded into a chamber assembly
at a time for coating; however, a plurality of smaller glass
substrates can be loaded into each of the chamber assemblies (1120)
or (1150) and coated simultaneously.
[0085] The frame (1140) supports a plurality of subsystems
associated with each of the two chamber assemblies (1120) and
(1150). In particular, the system (1000) includes all of the
subsystems required to operate each of the two chamber assemblies
(1120) and (1150) independently and simultaneously. Accordingly,
the upper gas deposition chamber assembly (1120) includes an upper
input gas supply system (1135) and the lower chamber assembly
(1150) includes a lower gas input supply system (1160). Each of the
input gas supply systems (1135) and (1160) include reservoirs of
reactant or precursor gases or solid or liquid reactants or
precursors that can be carried by a vapor or aerosol, for
delivering various precursors used in ALD and ALE coating cycles
into the reaction chamber assemblies. In addition, the input gas
supply systems (1135) and (1160) may include inert gases usable to
purge various areas of the reaction chamber assemblies and other
reactants that can be delivered into a reaction chamber as may be
required for reacting with solid substrates contained within the
reaction chamber assemblies. In addition, each of the input gas
supply systems (1135) and (1160) includes one or more manifolds,
mass flow controllers, sensors, filters, vaporizers, bubblers,
atomizes or the like as may be required to prepare and delivering a
volume of gas or vaporized reactant and or a purge gas into the
corresponding input plenum. Additionally, each gas supply system
may include a heater and temperature sensors for delivering gases
at desired temperatures.
[0086] Each gas deposition chamber assembly (1120) and (1150)
includes a front facing load port with a load lock door (1190) and
(1170) disposed to move vertically downward, or upward as may be
required, to provide access to the respective chamber through its
front facing load port and to move vertically upward, or downward,
to close the load port and substantially gas seal the gas
deposition chamber during substrate coating cycles. Each gas
deposition chamber assembly (1120) and (1150) includes an
electronic controller (1165), only one shown, for controlling
operations of the respective chamber, for logging data, and for
processing operator input commands. In addition, both of the
electronic controllers (1165) are preferably connected to a
computer network in order to communicate with and exchange data and
or operating commands with external devices as may be required.
Generally, each electronic controller (1165) includes a
programmable microprocessor, one or more digital memory devices, a
network interface, a user interface, a power distribution module
and interfaces to each electrical subsystem used to operate the
chamber assembly. Each gas deposition chamber assembly (1120) and
(1150) further includes a vacuum pump and associated vacuum
hardware, detailed below, for removing contaminates, reaction gases
or vapors, reaction byproducts and the like from the respective
chamber and for otherwise processing and directing gas outflow from
the chamber. In addition, each gas deposition chamber assembly
(1120) and (1150) includes elements for heating and insulating the
outer walls of the chamber and or monitoring conditions such as gas
pressure, various temperatures, load lock door position, whether a
substrate is loaded, safety and other conditions. In addition, the
preferred dual chamber gas deposition system (1000) includes a vent
(1100) located in the center of a top face for venting gas outflow
from both chambers to a safe venting area and a lighting tower
(1110) extending upward from the top face and including several
different colored lighting elements that are used to display an
operating status of the dual chambers (1120, 1150).
Reaction Chamber
[0087] Referring now to FIGS. 12-17 a preferred gas deposition
chamber assembly (3000) according to a second embodiment of the
present invention is shown in various views with like elements
having the same reference number. The chamber (3000) is shown in
front isometric view in FIG. 12, in rear isometric view in FIG. 13
and in section view with the section A-A being shown in FIG. 14. As
best viewed in FIGS. 14 and 17, the chamber assembly (3000)
comprises an outer wall assembly (8000) surrounding an outer volume
(3070), a removable liner (6000), shown in isometric view in FIG.
14, for installing into the outer volume (3070) through a second
outer aperture, (8020), passing through a back wall of the outer
wall assembly (8000). The chamber assembly further includes an
input plenum (3150) and input port assembly (3230) for delivering
gas reactants, precursors and inert gases, generally source
material into the reaction chamber through a right side wall (8030)
and an exit or output plenum (3250) and exit port assembly (3310)
for removing an outflow of gases from the reaction chamber through
a left side wall (8040).
[0088] The outer wall assembly (8000) generally encloses an oven
structure and the removable liner (6000) generally encloses a
reaction chamber (3125) and provides a substrate support surface
(3350) horizontally disposed therein. The removable liner (6000) as
well as plenum liners (7015) and (7080) cooperate to substantially
prevent reactants from reacting with inside surfaces of the outer
wall assembly (8000). Each of the removable liner (6000), plenum
liners (7015) and (7080), input and output plenums (3150) and
(3250), plus a removable inner panel on the access door, detailed
above, are removable from the chamber assembly (3000) when they
become contaminated by reactants or reactant byproducts to be
replaced and each may be cleanable for reuse or disposable after
one use. Moreover, each maybe fabricated with bead blasted internal
surfaces to prevent flaking or cracking of the build up of thin
film layers that may form thereon between cleaning cycles.
[0089] The outer wall assembly (8000) comprises a plurality of
outer walls formed by opposing top and bottom rectangular outer
walls (8050) and (8060) attached to opposing left and right
rectangular outer walls (8040) and (8030) for enclosing an outer
volume (3070). As best viewed in FIG. 13, a back outer wall
comprises a removable back panel (3050) which includes a back
perimeter flange (3060) for attaching and gas sealing the back
panel (3050) to a back face of each of the top, bottom, left and
right outer walls. The back wall includes the second outer aperture
(8020) for receiving the removable liner (6000) there through. The
second outer aperture (8020) passes through the back outer wall or
the second outer aperture (8020) may be formed by back inside edges
of each of the top bottom and side outer walls. The second outer
aperture (8020) provides back access to the outer volume (3070) for
installing the removable liner (6000), shown in isometric view in
FIG. 15, therein. The back panel may also attach to the removable
liner (6000) before or after installing the removable liner (6000).
The back panel (3050) also includes at least one rectangular o-ring
disposed between the back panel and the back face of each of the
top, bottom, left and right outer walls surrounding the second
outer aperture (8020) to gas seal the outer volume (3070). In
addition, if the removable liner includes a back aperture (6090), a
second rectangular o-ring seal may be included between the back
panel and liner back wall (6040) surrounding the back aperture
(6090) to gas seal the reaction chamber. Accordingly, the back
panel (3050) may also include eye bolts (3360), or the like,
attached thereto, suitable for attaching to a lifting device in
order to support the back panel and attached removable liner (6000)
from above during installation and removal. An outer aperture
(8010), passes through a front wall of the outer wall assembly
(8000) to provide access to the outer volume (3070). Substrates to
be coated are inserted into the removable liner (6000) through the
outer aperture (8010). The removable liner (6000) includes a
chamber aperture (6030) that substantially co-aligns with the front
outer aperture (8010) when the removable liner is installed in the
outer volume (3070).
[0090] The outer wall assembly (8000) encloses the outer volume
(3070) with top and bottom (8050) and 35 (80600) and left and right
(8040) and (8030) walls. In the present example, the outer volume
(3070) has rectangular cross-sections in a horizontal and a
vertical plane. The rectangular outer aperture (8010) passes
through a front wall of the outer wall assembly (8000) or is formed
by front inside edges of the top, bottom and side walls of the
outer wall assembly (8000). The outer aperture (8010) provides
front access into the reaction chamber (3125) for inserting and
removing substrates into the reaction chamber (3125) through the
chamber aperture (6030). The second outer aperture (8020) passes
through a back wall of the outer wall assembly or is formed by back
inside edges of the top, bottom and side walls of the outer wall
assembly and is provided to receive the removable liner (6000) into
the outer volume there through. The second outer aperture (8020) is
gas sealed by the back panel (3050). This embodiment is
particularly preferred when chamber assembly front face (1180)
interfaces with a clean room wall or the like and substrates
installed into the reaction chamber are installed into the reaction
chamber through the open access door, described below, from the
clean room. In this case it would not be acceptable to install or
remove the removable liner (6000) through the front face (1180)
because access to the front face is from inside the clean room.
Instead, the second embodiment provides access for installing the
removable liner through the second outer aperture (8020). However,
in some configurations the removable liner can be installed and
removed from either or the front outer aperture (8010) or the back
or second outer aperture (8020) as may be required.
[0091] A movable access door (3080) is movably supported with
respect to a support structure (3090) which is fixedly attached to
the bottom outer wall (8060). A door actuator (3100) is disposed
between the support structure (3090) and the access door (3080) to
guide and transport the movable access door along a vertical axis.
In a down position, the access door exposes the outer aperture
(8010) to provide access the outer volume (3070) and further
exposes the chamber aperture (6030) that passes through a front
face of the reaction chamber (3125) enclosed by the removable liner
(6000). In an up position, the access door (3080) closes and gas
seals both the outer aperture (8010) and the chamber aperture
(6030) during coating cycles. As described above in the first
embodiment, an outer rectangular o-ring, not shown in the second
embodiment, is engaged with a rectangular groove formed in the
inner door panel facing the reaction chamber to gas seal the outer
volume (3070). The outer rectangular o-ring is disposed between the
inner door panel and a front face of each of the top, bottom, left
and right outer walls of the outer wall assembly (8000). Similarly,
an inner rectangular o-ring not shown in the second embodiment, is
engaged with a rectangular groove formed in the inner door panel
facing the reaction chamber to gas seal the outer volume (3070) and
disposed between the inner door panel and a front face of the
removable liner to gas seal the reaction chamber.
[0092] Generally, the outer wall assembly (8000) comprises an oven
structure that includes or may include resistive heating elements,
or the like, (3110) disposed on or in grooves formed in external
surfaces of all or some of the outer walls. Alternately, according
to an advantage of the present invention, the heating elements
(3110) may be disposed on or in grooves formed on internal surfaces
of some or all of the outer walls because the removable liner
prevents the internal surfaces of the outer walls and any heating
elements disposed thereon from being contaminated by reactants.
Otherwise, the heating elements (3110) can be disposed inside some
or all of the outer walls such as by being sandwiched between
opposing outer wall portions. The heating elements (3110) heat the
outer wall assembly (8000) to a desired temperature and maintain
the outer wall assembly at the desired temperature over prolonged
periods of use. In addition, solid substrates that are being coated
in the reaction chamber are heated to a desired reaction
temperature after they have been installed into the reaction
chamber, e.g. ranging from 85 to about 500.degree. C., and or the
solid substrates may be preheated before being inserted into the
reaction chamber to reduce substrate heating times. Additionally,
separately controllable heating elements may be disposed proximate
to or assembled to substrate support trays to more directly and
quickly heat substrates to a desired reaction temperature.
Accordingly, the chamber assembly (3000) includes temperature
sensors and one or more controllers for controlling the operation
of the heating elements to achieve and maintain desired operating
temperatures. Alternately, other heating means including heating
elements disposed external to the outer wall assembly (8000) are
usable without deviating from the present invention. In still
further embodiments, the chamber assembly (3000) may not require
heating elements or may instead include cooling elements to achieve
desired reaction temperatures without deviating from the present
invention.
[0093] When heating elements are disposed outside the outer volume
(3070) it is desirable to direct thermal energy into the outer
volume (3070). Accordingly, the outer walls (8030, 8040, 8050 and
8060) preferably comprise a material having a high thermal
conductivity in order to provide a conductive path between the
heating elements (3110) and the outer volume (3070). In addition,
it is desirable that the outer wall material meet its structural
and thermal property characteristics over the range of operating
temperatures that the chamber assembly (3000) is expected to be
subjected to.
[0094] Ideally, the outer wall assembly (8000) including the back
panel (3050) and access door (3080) comprises a substantially gas
tight structure when the access door (3080) in a closed position.
In particular, the outer volume (3070) may be pumped to low medium
or high vacuum pressures ranging from less than 760 to 10 microtorr
to remove contaminants, reactants, and reactant byproducts from the
chamber assembly. Accordingly, it is desirable to join the outer
walls (8030, 8040, 8050, and 8060) with welded seams to prevent gas
leaks and to configure any ports and fittings associated with the
ports that pass through the outer walls with gas tight gaskets and
the like as are generally used in vacuum or gas tight chambers.
[0095] In the present example, the preferred material for
constructing the outer walls (8030, 8040, 8050, 8060)) is aluminum
and particularly 6061 aluminum, which has good weldability, an
acceptable thermal conductivity of approximately 167 W/m-K or 1160
BTU-in/hr-ft2-.degree. F., and a melting temperature of
approximately 600.degree. C. or 1150 F. Alternately, any weldable
aluminum and other weldable metals can be used without deviating
from the present invention. Preferably, the outer walls (8030,
8040, 8050, 8060)) comprise sheet or plate stock, folded, formed,
machined, welded and fastened together as required to enclose the
outer volume (3070) with gas tight seams and to provide the desired
structural and thermal performance characteristics. Moreover, one
or more of the outer walls (8030, 8040, 8050, 8060) may be made
thicker than required to perform structurally in order to provide a
heat sink suitable for maintaining the outer wall assembly (8000)
at a desired operating temperature and allow quick reheating e.g.
after the access door has been opened and new substrates have been
added for coating. In the preferred embodiment, a layer of thermal
insulation is disposed over the external surfaces of the outer
walls (8030, 8040, 8050, and 8060) and back panel (3050) as well as
in the access door (3080) to reduce thermal radiation to the air
surrounding the outer wall assembly.
Input and Output Plenums
[0096] Referring now to FIGS. 12, 14 and 17, the right outer wall
(8030) extends along a Y-axis and is formed with a right
rectangular through aperture (3130) passing there through to the
outer volume (3070). The Y-axis dimension and position of the right
rectangular through aperture (3130) substantially corresponds with
the Y-axis position and dimension of a substrate positioned inside
the reaction chamber for coating. An input plenum (3150) is
attached to the right outer wall (8030) by an input plenum flange
(3160). The input plenum flange (3160) forms a gas tight seal with
the right outer wall (8030). The bolt pattern and sealing elements
of the input plenum flange (3160) and the right outer wall (8030)
are modular to allow a user to reconfigure the chamber assembly
(3000) with various input plenum configurations or to bolt other
elements to the right side outer wall (8030) as may be required,
including an output plenum to reverse the flow direction of the
chamber assembly.
[0097] In the preferred embodiment the input plenum (3150)
comprises opposing substantially triangular shaped top and bottom
input plenum walls (3170) and (3180) attached to opposing
substantially trapezoid shaped input plenum side walls (3190) and
(3200). The top and bottom input plenum walls (3170) and (3180) and
the side input plenum walls (3190) and (3200) combine to enclose a
substantially triangular shaped input plenum chamber (3210). A
short input plenum end wall (3220) attaches to each of the top and
bottom input plenum walls (3170) and (3180) and the side input
plenum walls (3190) and (3200) to truncate an apex of the
triangular shaped input plenum chamber (3210). A gas input port
(3230) passes through the input plenum end wall (3220) and a gas
supply module (3240) delivers gases through the input port (3230)
into the input plenum chamber (3210) near the truncated triangular
apex. As best viewed in the isometric views of FIGS. 12 and 13, the
width or Y-axis dimension of the triangular shaped input plenum
chamber (3210) expands linearly from it apex to a base dimension of
the triangular volume enclosed thereby. Accordingly, the volume of
the input plenum expands from a small volume near the input port
(3230) to a larger volume at the plenum flange (3160) and the
height or Z-axis dimension of the triangular shaped input plenum
chamber (3210) also expands linearly from the input port (3230) to
the plenum flange (3160). Accordingly, gases delivered through the
input port (3230) expand to substantially fill the volume of the
triangular shaped input plenum chamber (3210) and this causes gas
flowing through the input plenum chamber (3210) to expand to
substantially fill the right rectangular through aperture (3130)
while also reducing the gas pressure and velocity in proportion to
distance from the input port (3230). Accordingly, the shape of the
input plenum chamber (3210) helps to substantially distribute input
gas flow over the entire wide of the fill the right rectangular
through aperture (3130) which has a width matched to a longitudinal
length or Y-axis dimension of a substrate being coated. The
triangular shaped input plenum chamber (3210) also helps to prevent
turbulent gas flow and eddy currents from being generated inside
the input plenum chamber (3210) and contributes to producing a less
turbulent gas flow through the right rectangular through aperture
(3130) and, as will be described in detail below, over the top
surface of a substrate being coated.
[0098] The left outer wall (8040) extends along the Y-axis opposed
to the right outer wall (8030) and is formed with a left
rectangular through aperture (3140) passing through the left outer
wall (8040) to the outer volume (3070). The Y-axis dimension and
position of the left rectangular through aperture (3140) are
matched with the Y-axis position and dimension of the right
rectangular through aperture (3130) and to a substrate positioned
inside the reaction chamber for coating. Accordingly, gas enters
the outer volume (3070) through the right rectangular aperture
(3130), flows over the top surface of a substrate supported inside
the hollow rectangular chamber (3070) for coating and exits the
hollow rectangular chamber (3070) through the left rectangular
aperture (3140). An output plenum (3250) is attached to the left
outer wall (8040) by an output plenum flange (3260). The output
plenum flange (3260) forms a gas seal with the left outer wall
(8040). The bolt pattern and sealing elements of the output plenum
flange (3260) and the left outer wall (8040) are modular and
matched to the bolt pattern of the input plenum (3150) and right
side wall (8030) to allow a user to reconfigure the chamber
assembly (3000) with various output plenum configurations, as may
be required, or to bolt other elements to the left side outer wall
(8040) as may be required, including an input plenum as required to
reverse the flow direction of the chamber assembly.
[0099] In the preferred embodiment the output plenum (3250)
comprises opposing substantially triangular shaped top and bottom
output plenum walls (3270) and (3280), attached to opposing
substantially rectangular output plenum side walls (3290), only one
is shown. The triangular shaped top and bottom output plenum walls
(3270) and (3280) and the opposing rectangular output plenum side
walls (3290), only one shown, combine to enclose a substantially
triangular shaped output plenum chamber (3300). A short end wall,
not shown, attaches to each of the top and bottom walls (3270) and
(3280) and the opposing rectangular side walls (3290), the other
not shown, to truncate an apex of the triangular shaped output
plenum chamber (3300). A base of the triangular shaped output
plenum chamber is open to the left rectangular aperture (3140). An
exit port (3310) passes through the bottom output plenum wall
(3280) and an exit port module (3320) attached to the exit port
(3310) is in fluidic communication with a vacuum pump, not shown.
Alternately, the exit port (3310) can be formed in the top output
plenum wall (3270).
[0100] The exit port module (3320) includes a cone shaped passage
(3370) terminated by a stop valve (3330) for closing the exit port
(3310). A vacuum pressure gauge (3340) is disposed in the cone
shaped passage (3370) for sensing gas pressure in the exit port
module (3320). The vacuum pump, not shown, is operated to draw gas
through the exit port module (3320) to evacuate the chamber
assembly (3000) by pumping gas out of the chamber assembly (3000).
As best viewed in the section view of FIG. 14, the volume of the
triangular shaped output plenum chamber (3300) is smaller at the
exit port (3310) than it is at its base at the output plenum flange
(3260) and the triangular shape of the output plenum chamber (3300)
draws gas exiting from the reaction chamber substantially uniformly
across the entire left rectangular aperture (3140) to draw gas even
across the entire y-Axis dimension of a substrate supported in the
reaction chamber. The narrowing volume of the triangular shaped
output plenum also causes the velocity of gas flowing there through
to increase as it approaches the exit port (3310). The increase in
gas velocity proximate to the exit port decreases the cycle time
required to purge or evacuate the reaction chamber.
[0101] Each of the input and output plenums (3150) and (3250)
include structural stiffening ribs (3450) disposed and welded on
the top and bottom plenum walls (3170, 3180, 3270, 3280) to prevent
the top and bottom plenum walls from buckling under the substantial
pressure gradient between a lower pressure inside each plenum and
atmospheric external pressure. In addition, each of the input and
output plenums (3150) and (3250) is easily removable and
replaceable should the plenums become contaminated by reactants or
reactant byproducts flowing there through. Preferably, the input
and output plenum walls are fabricated from metals, e.g. stainless
steel, that are cleanable by mechanical or chemical cleaning
processes such as those described above. Moreover internal surfaces
of the plenums may be roughened (e.g. by shot or bead blasting)
prior to use to improve reactant coating adhesion to the plenum
internal surfaces and thereby prevent cracking or flaking of
reactant layers between cleaning or replacement cycles.
[0102] Accordingly, each of the input and output plenums (3150) and
(3250) can be removed for cleaning or swapped with an auxiliary set
of clean plenums to avoid production down time. In addition,
external surfaces of each of the input and output plenums (3150)
and (3250) may be thermally insulated to prevent thermal losses
through the plenum walls and the external surfaces may be heated by
electrical heating coils disposed thereon to preheat or post heat
reactants and reactant 30 byproducts flowing there through. In
addition, each plenum may include various sensors for sensing
temperature, pressure, gas type, and other conditions inside or
proximate to the plenums. In addition, each plenum may include
internal baffles, not shown, e.g. disposed on or between internal
surfaces of the top and bottom plenum walls (3170, 3180, 3270, and
3280) to more efficiently direct gas flow along desired flow paths
inside the plenum.
Gas Flow
[0103] Referring now to the section AA shown in FIG. 14, gas
entering the triangular input plenum chamber (3210) through the
input port (3230) expands in the input plenum and flows through the
right rectangular aperture (3130) with a substantially uniform gas
distribution over its Y and Z Axis dimensions. The gas then flows
through the reaction chamber (3125) enclosed by the removable liner
(6000) and over the top surface of a substrate positioned inside
the removable liner (6000) with a substantially uniform gas
distribution over the Y axis dimension of the substrate. Thereafter
the gas flows through the left rectangular aperture (3140) and into
the triangular output plenum chamber (3300) where it is compressed
in volume as it flows toward the exit port (3310). The joints or
seams of the outer walls (8030, 8040, 8050, and 8060) are welded
and any flanges, ports or other apertures passing through the outer
walls are configured with seals and bolt patterns that are suitable
for providing gas tight seals to prevent gas leakage into or out of
the plenums or the outer volume. In some applications, the outer
walls, the input and output plenums, the movable access door
(3080), the back panel (3050) and any ports that pass through any
of these elements are constructed for substantially leak proof
operation in high vacuum and preferably the outer volume can be
pumped down to vacuum pressures of about 10 microton. In addition,
the gas supply module (3240) includes a controllable stop valve for
closing the input port (3230) and the exit port stop valve (3330)
is controllable for closing the exit port (3310) as required by
various gas deposition cycles. Accordingly, the outer volume can be
isolated and maintained at a vacuum pressure for an extended period
as may be required. In addition, the gas supply module and the
vacuum pump can be operated continuously to pass a constant gas
flow through the outer volume, such as to purge all passages with
an inert purge gas such as nitrogen. Otherwise the gas supply
module may operate non-continuously to deliver a precise volume of
a desired gas, such as a precursor gas, into the reaction
chamber.
Removable Liner
[0104] Referring now to FIGS. 13, 14, 15 and 17, a removable liner
assembly (6000) is shown in isometric view in FIG. 15. The liner
assembly (6000) installs into the chamber assembly (3000) through
the second outer aperture (8020) formed through the back outside
wall when the back panel (3050) is removed. The back panel (3050)
and the liner assembly (6000) may be assembled together using the
fasteners (3380) and installed into the outer wall assembly as a
unit. The liner assembly (6000) includes a bottom liner wall
(6010), the top surface of which comprises a substrate support
surface (3350) for supporting a substrate being coated. The liner
assembly (6000) encloses the reaction chamber (3125) which supports
the substrate being coated therein. The liner assembly
substantially prevents reactants from contaminating internal
surfaces of the outer walls (8030, 8040, 8050, and 8060) thereby
preventing reactant layers from forming on inside surfaces of the
outer wall assembly (8000). In other embodiments, the liner
assembly (6000) may be configured to be installed and removed
through the front outer aperture (8010).
[0105] The liner assembly includes a liner base wall (6010) and an
opposing liner top wall (6020). The top surface of the liner base
wall (6010) functions as the substrate support surface (3350) shown
in FIG. 14. A liner front wall forms a rectangular aperture that
serves as the chamber aperture (6030). The chamber aperture (6030)
substantially co-aligns with the outer aperture (8010) passing
through the front face of the outer wall assembly. A liner back
wall (6040) attaches to the back panel (3050) with fasteners (3380)
and includes a rectangular back aperture (6090) in order to provide
back access to the reaction chamber (3125). An inside surface of
the back panel (3050) opposed to the rectangular back aperture
(6090) may comprise stainless steel in order to be cleanable by the
mechanical or chemical cleaning methods described above.
Alternately, the liner back wall (6040) may comprise a solid wall
to protect the back panel (3050) from reactant contamination. The
back panel (3050) is attached to the outer wall assembly by the
back perimeter flange (3060). The liner assembly (6000) includes
opposing side walls that each includes a side rectangular through
aperture (6050) and (6060) and these side rectangular through
apertures align with the left and chamber right rectangular
apertures (3140) and (3130) passing through left and right outer
walls (8040) and (8030) when the liner assembly (6000) is installed
inside the chamber assembly (3000). All of the liner assembly walls
comprise stainless steel, which is cleanable by mechanical
abrasion. The liner assembly (6000) can be swapped with a clean
auxiliary liner assembly when it is contaminated to allow
production to continue while the contaminated liner is cleaned.
Alternately, the liner assembly (6000) may be disposable after it
has been contaminated. Internal surfaces of the removable liner may
be roughened by bead blasting or the like to improve adhesion of
thin film layers built up thereon and this prevents cracking or
peeling of the built up layers. However, depending on the
application, the substrate support surface is not roughened.
[0106] Because the liner assembly weighs about 120 pounds, lifting
handles (6070) are provided on the liner top wall (6020) to allow
the liner assembly to be supported from an over head crane or a
lifting tool by straps or hooks. Similarly the back panel eye bolts
(3360) can be supported by a lifting device while the liner
assembly is guided into the outer wall assembly. Four rolling
tooling balls (6080), or the like, are mounted on the liner base
wall (6010). The rolling tooling balls (6080) contact with and roll
along the bottom outer wall (8060) as the liner assembly is guided
into the chamber assembly (3000) through the second outer aperture
(8020). The height or Z-axis dimension of the tooling balls (6080)
establishes the Z-axis position of the substrate support surface
(3350) to align the substrate support surface with the left and
right rectangular apertures (3140) and (3130) and to position the
top surface of a substrate being coated at a desired Z-axis height
with respect to gas flow in the chamber. The liner assembly back
wall (6040) is formed to make mating contact with back end surface
of the outer walls (8030, 8040, 8050, 8060) when the removable
liner is installed to provide a thermally conductive path between
the heated outer wall and the liner assembly (6000). Alternately or
additionally, other surfaces of the liner assembly (6000) may be
configured to make mating contact with the outer walls to provide
additional thermally conductive paths between the removable liner
and the outer walls.
Plenum Liners Substrate Position, Purge Gas and Lift Pins
[0107] Referring now to FIG. 16, an exploded section view of the
right side of chamber assembly (3000) shows the top and bottom
input plenum walls (3170) and (3180) and the input plenum flange
(3160), the top and bottom outer walls (8050) and (8060), the
electrical heaters (3110), thermal insulation layers (3120), the
right outer wall (8030) and the right rectangular aperture (3130)
passing there through. The bottom and top removable liner walls
(6010) and (6020) are shown coaligned with the right rectangular
aperture (3130) such that gas enters the reaction chamber from the
input plenum and flows over a substrate (7000) supported on the
bottom liner wall (6010) substrate support surface (3350). The left
side of the chamber assembly (3000) is substantially identically
formed.
[0108] As is further shown in FIGS. 14 and 16, an input plenum
liner (7015) comprises a rectangular tube shaped element formed by
opposing top and bottom plenum liner walls (7020) and (7030) each
connected to opposing back and front plenum liner walls, not shown,
configured to enclose a rectangular fluid conduit (7040). The
plenum liner conduit (7040) is in fluidic communication with the
input plenum and with the right liner aperture (6050). The input
plenum liner installs through the right rectangular aperture (3130)
from inside the outer wall assembly. A right end of the plenum
liner interfaces with internal surfaces of the input plenum (3170)
and both elements are formed to provide a smooth interface that
prevents eddy current formation as gas flow over the interface. A
flange (7050) formed on the left side of the plenum liner (7030)
butts up against the removable liner right side wall and the plenum
liner conduit (7040) is aligned with the right liner aperture
(6050) to deliver eddy free gas flow into the reaction chamber. The
flange (7050) is formed on four sides of the input plenum liner for
surrounding the entire right liner aperture (6050) and gas seals
the interface between the flange (7050) and the removable liner
(6000). The opposite end of the input plenum liner (7015)
interfaces with the input plenum (3150) and forms a gas seal
therewith such that gas flows flowing out of the input chamber
passes through the rectangular fluid conduit (7040) to the reaction
chamber. Accordingly, the input plenum liner prevents reaction
gases from contaminating the chamber right outer wall (8030) and
from entering the outer volume (3070) except into the reaction
chamber (3125). A top surface (7060) of the bottom plenum liner
wall (7030) is disposed substantially coplanar with of a top
surface of the substrate (7000). Gas exiting from the input plenum
flows through the input plenum liner and over the top surface of
the substrate (7000). By positioning the input plenum liner top
surface (7060) coplanar with the stop surface of the substrate
(7000) eddy current formation at the leading edge of the substrate
(7000) is avoided. An output plenum liner (7080), shown in FIG. 14,
is substantially identical to the input plenum liner described
above and installs through the left rectangular aperture (3140).
Both plenum liners are made of a cleanable material such as
stainless steel and internal surfaces of the plenum liner conduits
may be bead blasted to roughen the surfaces.
[0109] As best viewed in FIG. 16 open area of the outer volume
(3070) are outside reaction chamber enclosed by the removable liner
(6000). In particular, an upper volume (7090) and a lower volume
(7100) extend between the removable liner (6000) and the top and
bottom outer walls (8050) and (8060). The volumes (7090) and (7100)
may also be fluidly connected with each other at the front and rear
of the outer volume (3070). In addition, the lower volume (7100) is
used to house a movable pin assembly, described below, and the
lower volume (7100) is in fluidic communication with the inside of
the liner assembly (6000) through pin holes (7110) that pass
through the bottom liner wall (6010). To further prevent reactants
from contaminating internal surfaces exposed to the upper and lower
volume (7090) and (7100) the outer volume (3070) is substantially
continuously purged with nitrogen or an inert gas. The purge gas is
pumped into the outer volume (3070) or separately into the upper
and lower volumes (7090) and (7100) at a low positive pressure
(e.g. less than about 5 pounds per square inch) such that a
pressure gradient is created by the purge gas causing the outer
volume to have a higher gas pressure than the reaction chamber. The
pressure gradient further helps to prevent reactants from leaking
into the outer volume through the removable liner, plenum liners,
or plenums.
Movable Pin Assembly
[0110] Referring now to FIGS. 14 and 16 a plurality of lift pins
(7120) are movably supported by a movable pin plate (7130) disposed
in the lower volume (7100) between the bottom outer wall (8060) and
the bottom liner wall (6010). The pin plate (7130) is a rectangular
plate and the plurality of lift pins (7120) are arranged in rows
and columns with each lift pin fixedly attached to the pin plate
(7130) and with the top of each lift pin extending to an equal
height above the movable pin plate such that the top of each lift
pin (7120) forms one point of a substrate support surface. The
bottom liner wall (6010) includes a plurality of through holes
(7110) passing there through with one through hole (7110)
corresponding with each of the plurality of lift pins (7120). When
the movable pin plate (7130) is raised to a lift position, the
plurality of lift pins (7120) extend through the plurality of
corresponding through holes (7110) to either lift the substrate
(7000) away from the substrate support surface (7110) or to
position the pin tops at a height (D) above the substrate support
surface (3350) for receiving a substrate (7000) on the pin tops. In
particular, the height (D) corresponds to a height that allows
robotic substrate handler lifting arms to be inserted into the
reaction chamber between the pin tops and the substrate support
surface (3350) to load a substrate (7000) onto the pin tops or to
unload a substrate from the pin tops. When the movable pin plate
(7130) is lowered, the pin tops are lowered below the substrate
support surface (3350) such that a substrate supported on the pin
tops is placed in contact with the substrate support surface
(3350). Preferably, the lift pins (7120) remain engaged with the
through holes (7110) when the pins are lower to limit the flow of
purge gas through the holes (7110), however the pins can be lowered
to a position below the bottom liner wall (6010) as shown in FIG.
16.
[0111] Referring now to FIG. 14, a pin actuator assembly (3390) is
disposed outside the chamber assembly attached to an external
surface of the bottom outer wall (8060). A lift post (3400) extends
between a pneumatic cylinder and piston assembly (3410) and the
movable pin plate (7130) by passing through a circular hole (3430)
through the bottom outer wall (8060). A vacuum bellows (3420)
extends from the pneumatic cylinder and piston assembly (3410) to
the bottom outer wall and gas seals the circular through hole
(3430). The pin actuator assembly (3390) further includes a pair of
guide rods (3440) for guiding movement of the pneumatic cylinder
and piston assembly (3410) and the lift post (3400). The system
controller coordinates actuation of the pin actuator assembly to
raise and lower the movable pin plate when the access door is open
for the loading and unloading of substrates.
[0112] Referring to FIGS. 14 and 16, according to the present
invention, a rectangular glass substrate to be coated is installed
into the reaction chamber (3070) by lowering the movable access
door (3080) and raising the movable pin plate (7130). The substrate
(7000) is then inserted into the chamber by a robotic substrate
handler or another insertion device and set down resting on the
tops of the plurality of lift pins (7120). One dimension of the
substrate (7000) is substantially centered between the input and
output plenums (3150) and (3250) and the other dimension of the
substrate is centered with respect to the left and right
rectangular apertures (3140) and (3130). The movable pin plate
(7130) is then lowered to set the substrate (7000) onto the
substrate support surface (7110) and the access door (3080) is
closed. The reaction chamber is then heated to raise the substrate
to the gas deposition temperature and the vacuum pump is started to
remove air and other contaminants from the reaction chamber which
may be pumped to a low medium or high vacuum pressure. The reaction
chamber also may be purged with an inert gas during the initial
pump down to remove contaminants such as water vapor. When the
chamber is at the desired pressure and the substrate at the desired
temperature, a gas deposition recipe can begin. Generally, the
recipe begins by closing the stop valve (3330) and introducing a
reactant gas or vapor into the reaction chamber through the input
port (3230). Alternately, the reactant can be introduced with the
stop valve (3330) open and the vacuum pump operating. After the
first reactant has reacted with the substrate, the reaction chamber
is purged by running the vacuum pump and flushing the reaction
chamber with a purge gas. The cycle is then repeated for a second
reactant gas or vapor and the two reactant cycles may be repeated
many thousands of times in order to build up a desired coating
thickness. When substrate coating is complete, the stop valve
(3330) is closed and the chamber is purged to atmosphere through
the input port or another port. The movable access door (3080) is
opened and the movable pin plate (7130) is raised to lift the
coated substrate from the substrate support surface. The robotic
substrate handler then removes the coated substrate form the
chamber and installs an uncoated substrate into the chamber for the
next coating cycle.
ALD System Third Embodiment
[0113] Referring now to FIGS. 14 and 18-19, a third embodiment of a
chamber assembly (8100) according to the present invention is
configured substantially like the reaction chamber (3000) described
above except that the X-axis dimension of the chamber assembly
(8100) is more than doubled and a removable liner (8110) is
configured with six substrate trays (8120) instead on one substrate
support surface. The substrate trays (8120) are supported in two
stacks of three trays each with side by side substrate trays being
substantially coplanar. Substrate trays (8120) are supported at
each end thereof by a plurality of tray supports (8130) fixedly
attached to the removable liner (8110). Each substrate tray (8120)
supports a single substrate (7000) in a substantially horizontal
orientation with a surface to be coated facing up.
[0114] The removable liner (8110) houses a reaction chamber (8140)
suitable for batch coating six rectangular substrates (7000)
supported on horizontal substrate trays (8120). The substrate trays
are sized to allow the substrates (7000) to overhang the substrate
trays (8120) at each end so that opposing edges of the substrates
(8150) can be used to pick up the substrates (7000) when a
substrate manipulating arm, or the like, is used to pick up and
lower substrates using the overhanging edges (8150). Otherwise, the
chamber assembly (8100) includes an input plenum (8160) an exit
plenum (8170) and an outer wall assembly (8180) all substantially
configured like the corresponding elements of the chamber assembly
(3000) described above except that the chamber assembly (8100) does
not include plenum liners as described above.
[0115] Accordingly, reactant gas enters the reaction chamber
assembly (8100) from the input plenum (8160), flows through the
reaction chamber (8140) and over all six substrates before exiting
from the reaction chamber (8140) through the exit plenum (8170).
Preferably, the chamber assembly (8100) is configured to coat six
GEN 4.5 glass substrates, each having rectangular dimensions of 920
mm wide by 730 mm long in a single coating run or batch. More
specifically, the GEN 4.5 glass substrates are supported with the
920 mm dimension disposed along the reaction chamber Xaxis.
[0116] Each substrate tray (8120) includes a resistive heating
element (8190) disposed in grooves along its bottom surface, or
otherwise disposed proximate to the substrate tray (8120) for
individually heating each substrate tray (8120) and the substrate
(7000) supported thereby. Preferably, each substrate tray (8120)
comprises ALPASE K100-S which is an aluminum plate material
specifically designed for vacuum applications and provides a
relatively high thermal conductivity (e.g. 812
BTU-in/hr-ft2.degree. F.) to quickly and uniformly conduct thermal
energy form the heating elements (8190) to the substrates (7000).
Alternately, the substrate trays (8120) can be fabricated from
stainless steel so that the trays can be cleaned by mechanical
abrasion and reused.
[0117] The chamber assembly (8100) also includes an electrical
connector (8200) associated with each of the substrate trays (8120)
and disposed inside the reaction chamber (8140) along a back wall
thereof. The electrical connectors (8200) provide power to the
resistive heating element (8190) associated with each substrate
tray (8120) and may be configured such that the resistive heating
element connects to the electrical connector (8200) when each
substrate tray (8120) is mounted in its operating position.
[0118] It will also be recognized by those skilled in the art that,
while the invention has been described above in terms of preferred
embodiments, it is not limited thereto. Various features and
aspects of the above described invention may be used individually
or jointly. Further, although the invention has been described in
the context of its implementation in a particular environment, and
for particular applications, those skilled in the art will
recognize that its usefulness is not limited thereto and that the
present invention can be beneficially utilized in any number of
environments and implementations where it is desirable to coat
objects with thin layers of material. Accordingly, the claims set
forth below should be construed in view of the full breadth and
spirit of the invention as disclosed herein.
* * * * *