U.S. patent application number 12/475131 was filed with the patent office on 2009-12-31 for methods and apparatus for a chemical vapor deposition reactor.
This patent application is currently assigned to ALTA DEVICES, INC.. Invention is credited to Melissa Archer, Harry Atwater, Roger Hamamjy, Gang He, Andreas Hegedus, Gregg Higashi, Stewart Sonnenfeldt, Khurshed Sorabji.
Application Number | 20090325367 12/475131 |
Document ID | / |
Family ID | 41434666 |
Filed Date | 2009-12-31 |
United States Patent
Application |
20090325367 |
Kind Code |
A1 |
He; Gang ; et al. |
December 31, 2009 |
METHODS AND APPARATUS FOR A CHEMICAL VAPOR DEPOSITION REACTOR
Abstract
Embodiments of the invention generally relate to a chemical
vapor deposition system and related method of use. In one
embodiment, the system includes a reactor lid assembly having a
body, a track assembly having a body and a guide path located along
the body, and a heating assembly operable to heat the substrate as
the substrate moves along the guide path. The body of the lid
assembly and the body of the track assembly are coupled together to
form a gap that is configured to receive a substrate. In another
embodiment, a method of forming layers on a substrate using the
chemical vapor deposition system includes introducing the substrate
into a guide path, depositing a first layer on the substrate and
depositing a second layer on the substrate, while the substrate
moves along the guide path; and preventing mixing of gases between
the first deposition step and the second deposition step.
Inventors: |
He; Gang; (Cupertino,
CA) ; Higashi; Gregg; (San Jose, CA) ;
Sorabji; Khurshed; (San jose, CA) ; Hamamjy;
Roger; (San Jose, CA) ; Hegedus; Andreas;
(Burlingame, CA) ; Archer; Melissa; (Mountain
View, CA) ; Atwater; Harry; (South Pasadena, CA)
; Sonnenfeldt; Stewart; (Burlingame, CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, L.L.P.
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
ALTA DEVICES, INC.
Santa Clara
CA
|
Family ID: |
41434666 |
Appl. No.: |
12/475131 |
Filed: |
May 29, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61057788 |
May 30, 2008 |
|
|
|
61104284 |
Oct 10, 2008 |
|
|
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61122591 |
Dec 15, 2008 |
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Current U.S.
Class: |
438/507 ;
118/719; 118/725; 118/729; 257/E21.09; 427/248.1 |
Current CPC
Class: |
B65G 2207/06 20130101;
C30B 25/10 20130101; C30B 25/14 20130101; C30B 29/40 20130101; C30B
29/42 20130101; H01L 21/67109 20130101; C30B 25/025 20130101; C23C
16/4583 20130101; C30B 25/12 20130101; C23C 16/54 20130101; C23C
16/45519 20130101; H01L 21/67784 20130101; C30B 25/18 20130101;
C30B 25/08 20130101 |
Class at
Publication: |
438/507 ;
118/725; 118/719; 118/729; 427/248.1; 257/E21.09 |
International
Class: |
H01L 21/20 20060101
H01L021/20; C23C 16/00 20060101 C23C016/00; C23C 16/46 20060101
C23C016/46 |
Claims
1. A chemical vapor deposition reactor, comprising: a lid assembly
having a body; a track assembly having a body and a guide path
located along the longitudinal axis of the body, wherein the body
of the lid assembly and the body of the track assembly are coupled
together to form a gap therebetween that is configured to receive a
substrate; and a heating assembly containing a plurality of heating
lamps disposed along the track assembly and operable to heat the
substrate as the substrate moves along the guide path.
2. The reactor of claim 1, further comprising a track assembly
support, wherein the track assembly is disposed in the track
assembly support.
3. The reactor of claim 1, wherein the body of the track assembly
contains a gas cavity within and extending along the longitudinal
axis of the body, and a plurality of ports extending from the gas
cavity to an upper surface of the guide path and configured to
supply a gas cushion along the guide path.
4. The reactor of claim 3, wherein the body of the track assembly
comprises quartz.
5. The reactor of claim 1, wherein the body of the lid assembly
includes a plurality of ports configured to provide fluid
communication to the guide path.
6. The reactor of claim 1, wherein the heating assembly is operable
to maintain a temperature differential across the substrate,
wherein the temperature differential is less than 10 degrees
Celsius.
7. The reactor of claim 1, wherein the chemical vapor deposition
reactor is an atmospheric pressure chemical vapor deposition
reactor.
8. A chemical vapor deposition system, comprising: a entrance
isolator operable to prevent contaminants from entering the system
at an entrance of the system; an exit isolator operable to prevent
contaminants from entering the system at an exit of the system; a
intermediate isolator disposed between the entrance and exit
isolators; a first deposition zone disposed adjacent the entrance
isolator; and a second deposition zone disposed adjacent the exit
isolator, wherein the intermediate isolator is disposed between the
deposition zones and is operable to prevent mixing of gases between
the first deposition zone and the second deposition zone.
9. The system of claim 8, wherein a gas is injected into the
entrance isolator at a first flow rate to prevent back diffusion of
gases from the first deposition zone.
10. The system of claim 8, wherein a gas is injected into the
intermediate isolator at a first flow rate to prevent back mixing
of gases between the first deposition zone and the second
deposition zone.
11. The system of claim 8, wherein a gas is injected into the exit
isolator at a first flow rate to prevent contaminants from entering
the system at the exit of the system.
12. The system of claim 8, further comprising an exhaust disposed
adjacent each isolator and operable to exhaust gases injected by
the isolators.
13. The system of claim 8, further comprising an exhaust disposed
adjacent each deposition zone and operable to exhaust gases
injected into the deposition zones.
14. A chemical vapor deposition system, comprising: a housing; a
track surrounded by the housing, wherein the track contains a guide
path adapted to guide a substrate through the chemical vapor
deposition system; and a substrate carrier for moving the substrate
along the guide path, wherein the track is operable to levitate the
substrate carrier along the guide path.
15. The system of claim 14, wherein the track comprises a plurality
of openings operable to supply a gas cushion to the guide path.
16. The system of claim 15, wherein the gas cushion is applied to a
bottom surface of the substrate carrier to lift the substrate
carrier from a floor of the track.
17. The system of claim 14, wherein the track comprises a conduit
disposed along the guide path and operable to substantially center
the substrate carrier along the guide path of the track.
18. The system of claim 17, wherein a gas cushion is supplied
through the conduit to a bottom surface of the substrate carrier to
substantially lift the substrate carrier from a floor of the
track.
19. The system of claim 14, wherein the track is tilted to allow
the substrate to move from a first end of the guide path to a
second end of the guide path.
20. The system of claim 14, further comprising a heating assembly
containing a plurality of heating lamps disposed along the track
and operable to heat the substrate as the substrate moves along the
guide path.
21. A method for forming a multi-layered material during a chemical
vapor deposition process, comprising: forming a gallium arsenide
buffer layer on a gallium arsenide substrate; forming an aluminum
arsenide sacrificial layer on the gallium arsenide buffer layer;
forming an aluminum gallium arsenide passivation layer on the
aluminum arsenide sacrificial layer; and forming a gallium arsenide
active layer on the aluminum gallium arsenide passivation
layer.
22. The method of claim 21, further comprising forming a
phosphorous gallium arsenide layer on the gallium arsenide active
layer.
23. The method of claim 21, further comprising removing the
aluminum arsenide sacrificial layer to separate the gallium
arsenide active layer from the substrate.
24. The method of claim 23, wherein the aluminum arsenide
sacrificial layer is exposed to an etching solution while the
gallium arsenide active layer is separated from the substrate
during an epitaxial lift off process.
25. The method of claim 23, further comprising forming additional
multi-layered materials on the substrate during a subsequent
chemical vapor deposition process.
26. A method for forming multiple epitaxial layers on a substrate
using a chemical vapor deposition system, comprising: introducing
the substrate into a channel at an entrance of the system, while
preventing contaminants from entering the system at the entrance;
depositing a first epitaxial layer on the substrate, while the
substrate moves along the channel of the system; depositing a
second epitaxial layer on the substrate, while the substrate moves
along the channel of the system; preventing mixing of gases between
the first deposition step and the second deposition step; and
retrieving the substrate from the channel at an exit of the system,
while preventing contaminants from entering the system at the
exit.
27. The method of claim 26, further comprising heating the
substrate prior to depositing the first epitaxial layer.
28. The method of claim 26, further comprising maintaining the
temperature of the substrate as the first and second epitaxial
layers are deposited on the substrate.
29. The method of claim 26, further comprising cooling the
substrate after depositing the second epitaxial layer.
30. The method of claim 26, wherein the substrate substantially
floats along the channel of the system.
31. The method of claim 26, further comprising heating the
substrate to a temperature within a range from about 300 degree
Celsius to about 800 degrees Celsius during the depositing of the
epitaxial layers.
32. The method of claim 26, wherein a center temperature to an edge
temperature of the substrate is within 10 degrees Celsius of each
other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional
Application Ser. No. 61/057,788, filed May 30, 2008; U.S.
Provisional Application Ser. No. 61/104,284, filed Oct. 10, 2008;
and U.S. Provisional Application Ser. No. 61/122,591, filed
December 15, 2008, the disclosures of which are hereby incorporated
by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the invention generally relate to methods and
apparatuses for vapor deposition, and more particularly, to
chemical vapor deposition processes and chambers.
[0004] 2. Description of the Related Art
[0005] Chemical vapor deposition ("CVD") is the deposition of a
thin film on a substrate, such as a wafer, by the reaction of vapor
phase chemicals. Chemical vapor deposition reactors are used to
deposit thin films of various compositions on the substrate. CVD is
highly utilized in many activities, such as during the fabrication
of devices for semiconductor, solar, display, and other electronic
applications.
[0006] There are numerous types of CVD reactors for very different
applications. For example, CVD reactors include atmospheric
pressure reactors, low pressure reactors, low temperature reactors,
high temperature reactors, and plasma enhanced reactors. These
distinct designs address a variety of challenges that are
encountered during a CVD process, such as depletion effects,
contamination issues, and reactor maintenance.
[0007] Notwithstanding the many different reactor designs, there is
a continuous need for new and improved CVD reactor designs.
SUMMARY OF THE INVENTION
[0008] Embodiments of the invention generally relate to a
levitating substrate carrier or support. In one embodiment, a
substrate carrier for supporting and carrying at least one
substrate or wafer passing through a reactor is provided which
includes a substrate carrier body containing an upper surface and a
lower surface, and at least one indentation pocket disposed within
the lower surface. In another embodiment, the substrate carrier
includes a substrate carrier body containing an upper surface and a
lower surface, and at least two indentation pockets disposed within
the lower surface. In another embodiment, the substrate carrier
includes a substrate carrier body containing an upper surface and a
lower surface, an indentation area within the upper surface, and at
least two indentation pockets disposed within the lower surface. In
another embodiment, the substrate carrier includes a substrate
carrier body containing an upper surface and a lower surface, an
indentation area within the upper surface, and at least two
indentation pockets disposed within the lower surface, wherein each
indentation pocket has a rectangular geometry and four side walls
which extend perpendicular or substantially perpendicular to the
lower surface. In another embodiment, the substrate carrier
includes a substrate carrier body containing an upper surface and a
lower surface, and at least two indentation pockets disposed within
the lower surface, wherein each indentation pocket has a
rectangular geometry and four side walls which extend perpendicular
or substantially perpendicular to the lower surface.
[0009] In another embodiment, a substrate carrier for supporting
and carrying at least one substrate passing through a reactor is
provided which includes a substrate carrier body containing an
upper surface and a lower surface, and at least one indentation
pocket disposed within the lower surface. The substrate carrier
body may have a rectangular geometry, a square geometry, or another
type of geometry. In one example, the substrate carrier body has
two short sides and two long sides, wherein one of the two short
sides is the front of the substrate carrier body and the other
short side is the rear of the substrate carrier body. The substrate
carrier body may contain or be made from graphite.
[0010] In some examples, the upper surface contains at least one
indentation area disposed therein. The indentation area within the
upper surface is configured to hold a substrate thereon. In other
examples, the upper surface may have at least two, three, four,
eight, twelve, or more of the indentation areas. In another
example, the upper surface has no indentation areas.
[0011] In another embodiment, the lower surface may have at least
two of the indentation pockets, which are configured to accept a
gas cushion. In some examples, the lower surface has one, three, or
more of the indentation pockets. The indentation pocket may have a
rectangular geometry, a square geometry, or another type of
geometry. Each of the indentation pockets usually has two short
sides and two long sides. In one example, the short sides and the
long sides are straight. The short sides and the long sides are
perpendicular relative to the lower surface. In another example, at
least one of the two short sides is tapered at a first angle, at
least one of the two long sides is tapered at a second angle, and
the first angle may be greater than or less than the second angle.
In another example, at least one of the two short sides is straight
and at least one of the two long sides is tapered. In another
example, at least one of the two short sides is tapered and at
least one of the two long sides is straight. In one embodiment, the
indentation pocket has a rectangular geometry and the indentation
pocket is configured to accept a gas cushion. The indentation
pocket may have tapered side walls which taper away from the upper
surface.
[0012] In another embodiment, a method for levitating substrates
disposed on an upper surface of a substrate carrier during a vapor
deposition process is provided which includes exposing a lower
surface of a substrate carrier to a gas stream, forming a gas
cushion under the substrate carrier, levitating the substrate
carrier within a processing chamber, and moving the substrate
carrier along a path within the processing chamber. In many
examples, the movement of the substrate carrier and/or the velocity
of the substrate carrier along the path may be controlled by
adjusting the flow rate of the gas stream. The gas cushion may be
formed within at least one indentation pocket disposed within the
lower surface. In some examples, the lower surface has at least two
indentation pockets. The indentation pockets are configured to
accept the gas cushion. An upper surface of the substrate carrier
comprises at least one indentation area for supporting a substrate.
The indentation pocket may have tapered side walls which taper away
from the upper surface of the substrate carrier.
[0013] In another embodiment, a method for levitating substrates
disposed on a substrate carrier during a vapor deposition process
is provided which includes exposing a lower surface of a substrate
carrier to a gas stream, wherein at least one wafer is disposed on
an upper surface of the substrate carrier and the lower surface
contains at least one indentation pocket, forming a gas cushion
under the substrate carrier, levitating the substrate carrier
within a processing chamber, and moving the substrate carrier along
a path within the processing chamber.
[0014] In another embodiment, a method for levitating substrates
disposed on a substrate carrier during a vapor deposition process
is provided which includes exposing a lower surface of a substrate
carrier to a gas stream, wherein the lower surface contains at
least one indentation pocket, forming a gas cushion under the
substrate carrier, levitating the substrate carrier within a
processing chamber, and moving the substrate carrier along a path
within the processing chamber.
[0015] In another embodiment, a method for levitating substrates
disposed on a substrate carrier during a vapor deposition process
is provided which includes exposing a lower surface of a substrate
carrier to a gas stream, wherein the lower surface contains at
least two indentation pockets, forming a gas cushion under the
substrate carrier, levitating the substrate carrier within a
processing chamber, and moving the substrate carrier along a path
within the processing chamber.
[0016] Embodiments of the invention generally relate to a chemical
vapor deposition reactor system and related methods of use. In one
embodiment, a chemical vapor deposition system is provided which
includes a lid assembly, such as a top plate, having a plurality of
raised portions located along the longitudinal axis of the top
plate. The system includes a track having a guide path, such as a
channel, located along the longitudinal axis of the track, wherein
the channel is adapted to receive the plurality of raised portions
of the top plate, thereby forming a gap between the plurality of
raised portions and a floor of the track, wherein the gap is
configured to receive a substrate. The system includes a heating
assembly, such as a heating element, operable to heat the substrate
as the substrate moves along the channel of the track. In one
embodiment, the track is operable to float the substrate along the
channel of the track.
[0017] In one embodiment, system includes a trough that supports
the track. The gap may have a thickness between 0.5 and 5
millimeter or between 0.5 and 1 millimeter. The top plate is formed
from molybdenum or quartz, the track is formed from quartz or
silica. The top plate is operable to direct a gas to the gap and
may further include a plurality of ports located along the
longitudinal axis of the top plate and disposed between the
plurality of raised portions, thereby defining paths between the
plurality of raised portions. One or more of the plurality of ports
is adapted to communicate and/or exhaust a gas to the gap between
plurality of raised portions of the top plate and the floor of the
track.
[0018] Examples of the heating element include a heating lamp
coupled to or with the track, a plurality of heating lamps disposed
along the track, a heating lamp bank operable to move along the
track as the substrate moves along the channel of the track,
resistive heaters coupled to or with the track, an inductive
heating source coupled to or with the substrate and/or the track.
The heating element is operable to maintain a temperature
differential across the substrate, wherein the temperature
differential is less than 10 degrees Celsius. In one embodiment,
the chemical vapor deposition system is an atmospheric pressure
chemical vapor deposition system.
[0019] In one embodiment, a chemical vapor deposition system is
provided which includes an entrance isolator operable to prevent
contaminants from entering the system at an entrance of the system;
an exit isolator operable to prevent contaminants from entering the
system at an exit of the system; and an intermediate isolator
disposed between the entrance and exit isolators. The system may
further include a first deposition zone disposed adjacent the
entrance isolator and a second deposition zone disposed adjacent
the exit isolator. The intermediate isolator is disposed between
the deposition zones and is operable to prevent mixing of gases
between the first deposition zone and the second deposition
zone.
[0020] In one embodiment, the entrance isolator is further operable
to prevent back diffusion of gases injected into the first
deposition zone, the intermediate isolator is further operable to
prevent back diffusion of gases injected into the second deposition
zone, and the exit isolator is further operable to prevent back
diffusion of gases injected into the second deposition zone. An
isolation zone formed by at least one of the isolators has a length
between 1 to 2 meters. A gas, such as nitrogen, is injected into
the entrance isolator at a first flow rate, such as about 30 liters
per minute, to prevent back diffusion of gases from the first
deposition zone. A gas, such as arsine, is injected into the
intermediate isolator at a first flow rate, such as about 3 liters
per minute, to prevent back mixing of gases between the first
deposition zone and the second deposition zone. A gas, such as
nitrogen, is injected into the exit isolator at a first flow rate,
such as about 30 liters per minute, to prevent contaminants from
entering the system at the exit of the system. In one embodiment,
an exhaust is disposed adjacent each isolator and operable to
exhaust gases injected by the isolators. An exhaust may be disposed
adjacent each deposition zone and operable to exhaust gases
injected into the deposition zones.
[0021] In one embodiment, a chemical vapor deposition system is
provided which includes a housing, a track surrounded by the
housing, wherein the track defines a guide path, such as a channel,
adapted to guide the substrate through the chemical vapor
deposition system. The system includes a carrier for moving the
substrate along the channel of the track, wherein the track is
operable to levitate the carrier along the channel of the track.
The housing is formed from molybdenum, quartz, or stainless steel,
the track is formed from quartz, molybdenum, fused silica, ceramic,
and the carrier is formed from graphite.
[0022] In one embodiment, the track comprises a plurality of
openings and/or a conduit disposed along the floor of the track
each operable to supply a cushion of gas to the channel and the
bottom surface of the carrier to lift or levitate the carrier and
substantially center the carrier along the channel of the track.
The conduit may have a v-shape and the carrier may have a notch
(e.g. v-shape) disposed along its bottom surface. A gas is applied
to the notch of the carrier to substantially lift the carrier from
the floor of the track and to substantially center the carrier
along the channel of the track. The track may be tilted, such as at
an angle less than about ten, twenty, or between one and five
degrees, to allow the substrate to move and float from a first end
of the channel to a second end of the channel. The track and/or
housing may include multiple segments.
[0023] In one embodiment, the system may include a conveyor
operable to automatically introduce substrates into the channel, a
retriever operable to automatically retrieve substrates from the
channel, and/or a heating element operable to heat the substrate.
The heating element is coupled to or with the housing, the
substrate, and/or the track. The carrier is operable to carry
strips of the substrate along the channel of the track.
[0024] In one embodiment, a track assembly for moving a substrate
through a chemical vapor deposition system is provided which
includes a top section having a floor, side supports, such as a
pair of rails, disposed adjacent the floor, thereby defining a
guide path, such as a channel, to guide the substrate along the
floor. A bottom section is coupled to or with the top section to
form one or more chambers therebetween. The top section may include
a recessed bottom surface and the bottom section may include a
recessed top surface to form the chamber. In one embodiment the top
section and/or the bottom section is formed from molybdenum,
quartz, silica, alumina, or ceramic.
[0025] In one embodiment, the top section has a plurality of
openings disposed through the floor to provide fluid communication
between the chamber and the channel. A cushion of gas, such as
nitrogen, is supplied from the chamber to the channel to
substantially lift and carry the substrate from and along the floor
of the top section. The floor may be tilted, such as at an angle
less than about ten, twenty, or between one and five degrees, to
allow the substrate to move and float from a first end of the
channel to a second end of the channel.
[0026] In one embodiment, the top section has a plurality of
openings disposed through the pair of rails adjacent the floor. A
gas is supplied through the plurality of openings to substantially
center the substrate moving along the channel of the top section.
The floor may also include a tapered profile and/or a conduit
through which a gas is supplied each operable to substantially
center the substrate moving along the channel of the top section.
The conduit may have a v-shape and/or the substrate may have a
notch (e.g. v-shaped) for receiving a gas cushion disposed along a
bottom surface of the substrate operable to substantially center
the substrate moving along the channel of the top section.
[0027] In one embodiment, the track assembly may include a conveyor
operable to automatically introduce substrates into the channel
and/or a retriever operable to automatically retrieve substrates
from the channel. An injection line may be coupled to or with the
bottom section to supply a gas to the chamber through the floor to
substantially float the substrate along the floor of the top
section. The top section may further include recessed portions
adjacent the rails operable to receive reactor lid assembly, such
as a top plate. The track assembly may include a trough in which
the top section and bottom section are seated. The trough is formed
from quartz, molybdenum, or stainless steel.
[0028] In one embodiment, a method for forming a multi-layered
material during a chemical vapor deposition process is provided
which includes forming a gallium arsenide buffer layer on a gallium
arsenide substrate; forming an aluminum arsenide sacrificial layer
on the buffer layer; and forming an aluminum gallium arsenide
passivation layer on the sacrificial layer. The method may further
include forming a gallium arsenide active layer (e.g. at about 1000
nanometers thick) on the passivation layer. The method may further
include forming a phosphorous gallium arsenide layer on the active
layer. The method may further include removing the sacrificial
layer to separate the active layer from the substrate. The aluminum
arsenide sacrificial layer may be exposed to an etching solution
while the gallium arsenide active layer is separated from the
substrate during an epitaxial lift off process. The method may
further include forming additional multi-layered materials on the
substrate during a subsequent chemical vapor deposition process.
The buffer layer may be about 300 nanometers in thickness, the
passivation layer may be about 30 nanometers in thickness, and/or
the sacrificial layer may be about 5 nanometers in thickness.
[0029] In one embodiment, a method for forming multiple epitaxial
layers on a substrate using a chemical vapor deposition system is
provided which includes introducing the substrate into a guide
path, such as a channel, at an entrance of the system, while
preventing contaminants from entering the system at the entrance;
depositing a first epitaxial layer on the substrate, while the
substrate moves along the channel of the system; depositing a
second epitaxial layer on the substrate, while the substrate moves
along the channel of the system; preventing mixing of gases between
the first deposition step and the second deposition step; and
retrieving the substrate from the channel at an exit of the system,
while preventing contaminants from entering the system at the exit.
The method may further include heating the substrate prior to
depositing the first epitaxial layer; maintaining the temperature
of the substrate as the first and second epitaxial layers are
deposited on the substrate; and/or cooling the substrate after
depositing the second epitaxial layer. The substrate may
substantially float along the channel of the system. The first
epitaxial layer may include aluminum arsenide and/or the second
epitaxial layer may include gallium arsenide. In one embodiment,
the substrate substantially floats along the channel of the system.
The method may further include depositing a phosphorous gallium
arsenide layer on the substrate and/or heating the substrate to a
temperature within a range from about 300 degree Celsius to about
800 degrees Celsius during the depositing of the epitaxial layers.
A center temperature to an edge temperature of the substrate may be
within 10 degrees Celsius of each other.
[0030] In one embodiment, a chemical vapor deposition reactor is
provided which includes a lid assembly having a body, and a track
assembly having a body and a guide path located along the
longitudinal axis of the body. The body of the lid assembly and the
body of the track assembly are coupled together to form a gap
therebetween that is configured to receive a substrate. The reactor
may further include a heating assembly containing a plurality of
heating lamps disposed along the track assembly and operable to
heat the substrate as the substrate moves along the guide path. The
reactor may further include a track assembly support, wherein the
track assembly is disposed in the track assembly support. The body
of the track assembly may contain a gas cavity within and extending
along the longitudinal axis of the body and a plurality of ports
extending from the gas cavity to an upper surface of the guide path
and configured to supply a gas cushion along the guide path. The
body of the track assembly may comprise quartz. The body of the lid
assembly may include a plurality of ports configured to provide
fluid communication to the guide path. The heating assembly may be
operable to maintain a temperature differential across the
substrate, wherein the temperature differential is less than 10
degrees Celsius. In one embodiment, the chemical vapor deposition
reactor is an atmospheric pressure chemical vapor deposition
reactor.
[0031] In one embodiment, a chemical vapor deposition system is
provided which includes a entrance isolator operable to prevent
contaminants from entering the system at an entrance of the system;
an exit isolator operable to prevent contaminants from entering the
system at an exit of the system; and a intermediate isolator
disposed between the entrance and exit isolators. The system may
further include a first deposition zone disposed adjacent the
entrance isolator and a second deposition zone disposed adjacent
the exit isolator. The intermediate isolator is disposed between
the deposition zones and is operable to prevent mixing of gases
between the first deposition zone and the second deposition zone. A
gas is injected into the entrance isolator at a first flow rate to
prevent back diffusion of gases from the first deposition zone, a
gas is injected into the intermediate isolator at a first flow rate
to prevent back mixing of gases between the first deposition zone
and the second deposition zone, and/or a gas is injected into the
exit isolator at a first flow rate to prevent contaminants from
entering the system at the exit of the system. An exhaust may be
disposed adjacent each isolator and operable to exhaust gases
injected by the isolators and/or disposed adjacent each deposition
zone and operable to exhaust gases injected into the deposition
zones.
[0032] In one embodiment, a chemical vapor deposition system is
provided which includes a housing, a track surrounded by the
housing, wherein the track contains a guide path adapted to guide a
substrate through the chemical vapor deposition system, and a
substrate carrier for moving the substrate along the guide path,
wherein the track is operable to levitate the substrate carrier
along the guide path. The track may include a plurality of openings
operable to supply a gas cushion to the guide path. The gas cushion
is applied to a bottom surface of the substrate carrier to lift the
substrate carrier from a floor of the track. The track may include
a conduit disposed along the guide path and operable to
substantially center the substrate carrier along the guide path of
the track. A gas cushion may be supplied through the conduit to a
bottom surface of the substrate carrier to substantially lift the
substrate carrier from a floor of the track. The track may be
tilted to allow the substrate to move from a first end of the guide
path to a second end of the guide path. The system may include a
heating assembly containing a plurality of heating lamps disposed
along the track and operable to heat the substrate as the substrate
moves along the guide path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] So that the manner in which the above recited features of
the invention can be understood in detail, a more particular
description of the invention, briefly summarized above, may be had
by reference to embodiments, some of which are illustrated in the
appended drawings. It is to be noted, however, that the appended
drawings illustrate only typical embodiments of this invention and
are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0034] FIG. 1A depicts a chemical vapor deposition reactor
according to one embodiment of the invention;
[0035] FIG. 1B depicts a perspective view of a reactor lid assembly
according to one embodiment of the invention;
[0036] FIG. 2 depicts a side perspective view of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0037] FIG. 3 depicts a reactor lid assembly of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0038] FIG. 4 depicts a top view of a reactor lid assembly of the
chemical vapor deposition reactor according to another embodiment
described herein;
[0039] FIG. 5 depicts a wafer carrier track of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0040] FIG. 6 depicts a front view of the wafer carrier track of
the chemical vapor deposition reactor according to one embodiment
described herein;
[0041] FIG. 7 depicts a side view of the wafer carrier track of the
chemical vapor deposition reactor according to one embodiment
described herein;
[0042] FIG. 8 depicts a perspective view of the wafer carrier track
of the chemical vapor deposition reactor according to one
embodiment described herein;
[0043] FIG. 9 depicts the reactor lid assembly and the wafer
carrier track of the chemical vapor deposition reactor according to
one embodiment described herein;
[0044] FIG. 10A depicts a chemical vapor deposition reactor
according to one embodiment described herein;
[0045] FIGS. 10B-10C depict a levitating wafer carrier according to
another embodiment described herein;
[0046] FIGS. 10D-10F depict other levitating wafer carriers
according to another embodiment described herein;
[0047] FIG. 11 depicts a first layout of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0048] FIG. 12 depicts a second layout of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0049] FIG. 13 depicts a third layout of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0050] FIG. 14 depicts a fourth layout of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0051] FIG. 15 depicts a fifth layout of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0052] FIG. 16 depicts a sixth layout of the chemical vapor
deposition reactor according to one embodiment described
herein;
[0053] FIG. 17 depicts a seventh layout of the chemical vapor
deposition reactor according to one embodiment described herein;
and
[0054] FIG. 18 depicts flow path configurations of the chemical
vapor deposition reactor according to one embodiment described
herein.
DETAILED DESCRIPTION
[0055] Embodiments of the invention generally relate to an
apparatus and a method of chemical vapor deposition ("CVD"). As set
forth herein, embodiments of the invention is described as they
relate to an atmospheric pressure CVD reactor and metal-organic
precursor gases. It is to be noted, however, that aspects of the
invention are not limited to use with an atmospheric pressure CVD
reactor or metal-organic precursor gases, but are applicable to
other types of reactor systems and precursor gases. To better
understand the novelty of the apparatus of the invention and the
methods of use thereof, reference is hereafter made to the
accompanying drawings.
[0056] According to one embodiment of the invention, an atmospheric
pressure CVD reactor is provided. The CVD reactor may be used to
provide multiple epitaxial layers on a substrate, such as a wafer,
such as a gallium arsenide wafer. These epitaxial layers may
include aluminum gallium arsenide, gallium arsenide, and
phosphorous gallium arsenide. These epitaxial layers may be grown
on the gallium arsenide wafer for later removal so that the wafer
may be reused to generate additional materials. In one embodiment,
the CVD reactor may be used to provide solar cells. These solar
cells may further include single junction, heterojunction, or other
configurations. In one embodiment, the CVD reactor may be
configured to develop a 2.5 watt wafer on a 10 centimeter by 10
centimeter wafer. In one embodiment, the CVD reactor may provide a
throughput range of about 1 wafer per minute to about 10 wafers per
minute.
[0057] FIG. 1A shows a CVD reactor 10, according to one embodiment
of the invention. The reactor 10 includes a reactor lid assembly
20, a wafer carrier track 30, a wafer carrier track support 40, and
a heating lamp assembly 50. The reactor lid assembly 20 may be
formed from molybdenum, molybdenum alloys, stainless steel, and
quartz. The reactor lid assembly 20 is disposed on the wafer
carrier track 30. The wafer carrier track 30 may be formed from
quartz, molybdenum, silica (such as fused silica), alumina, or
other ceramic materials. The wafer carrier track 30 may be seated
in a wafer carrier track support 40. The wafer carrier track
support 40 may be formed from quartz or a metal, such as
molybdenum, molybdenum alloys, steel, stainless steel, nickel,
chromium, iron, or alloys thereof. Finally, a heating lamp assembly
50 (further discussed below with respect to FIG. 10) is disposed
below the wafer carrier track support 40. The overall CVD reactor
length may be in a range of about 18 feet to about 25 feet, but may
extend beyond this range for different applications.
[0058] FIGS. 1B, 2, 3, and 4 provide various views of embodiments
of the reactor lid assembly 20. Referring to FIGS. 1B and 2, the
reactor lid assembly 20 may include a plate, such as a body 28
having an upper surface 29 and a lower surface 27, having flange
members 25 extending from the lower surface 27, and/or having one
or more raised portions 26 centrally located between the flange
members 25. In one embodiment, the body 28 may define a rectangular
shape. The raised portions 26 may extend from the lower surface 27
of the plate 28 at different lengths along the reactor lid assembly
20. The raised portions 26 are disposed between the flange members
25 so that clearances are formed between the raised portions 26 and
each flange member 25. These clearances may be used to help couple
the reactor lid assembly 20 to the wafer carrier track 30 (further
described below). Both the flange members 25 and/or the raised
portions 26 may extend substantially the longitudinal length of the
reactor lid assembly 20. The reactor lid assembly 20 may be formed
as a single solid structural component, or it may be constructed
from several segments coupled together. Each raised portion 26 may
vary in length, height, width, and number, thereby defining "zones"
which may be utilized for different applications in a CVD process.
The reactor lid assembly 20 may also include multiple patterns of
raised portions 26 along its length, such as to develop numerous
layouts or stages in a CVD process. In one embodiment, the flange
members 25 and/or the raised portions 26 may define a circular
shape, a square shape, a rectangular shape, or combinations
thereof. In one embodiment, the flange members 25 and/or the raised
portions 26 may include solid structures. In one embodiment, the
flange members 25 and/or the raised portions 26 may be removable
from the body 28 of the reactor lid assembly 20. In one embodiment,
the raised portions 26 include openings disposed through the raised
portions, thereby defining housings in which one or more gas
manifold assemblies (further described below) may be located to
communicate gases with the reactor 10. The body 28 may include
corresponding openings through which the gas manifold assemblies
may be placed into the raised portions 26. In one embodiment, the
reactor lid assembly 20 may include the body 28 with one or more
openings disposed through the body from the upper surface 29 to the
lower surface 27.
[0059] FIG. 3 also shows the reactor lid assembly 20 according to
one embodiment. As stated above, the reactor lid assembly 20 as
shown in FIG. 3 may represent an entire structure or a single
segment of a larger constructed structure. Also shown, are one or
more openings, such as a plurality of inlet and outlet ports 21
disposed through the upper surface 29 of the body 28 and centrally
located along the longitudinal axis of the reactor lid assembly 20.
The ports 21 may vary in size, shape, number, and location along
the upper surface 29 of the body 28. In one embodiment, the ports
21 may define a circular shape, a square shape, a rectangular
shape, or combinations thereof. The ports 21 may extend through the
body 28 from the upper surface 29 to the lower surface 27. The
ports 21 may be used as injection, deposition, and/or exhaust ports
for communicating a gas into and/or out of the CVD reactor. In one
embodiment, each port 21 is disposed between two adjacent raised
portions 26 (as show in FIG. 2), thereby defining "paths" through
which injection, deposition, and/or exhaustion of a gas may take
place. In one example, a gas may be injected into a port 21 so that
the gas first travels along the sides of the adjacent raised
portions 26 and then travels along the bottom surfaces of the
raised portions 26 and into the flow path of a wafer. As shown in
FIG. 3, the flange members 25 are enclosed at the ends of the body
28 to encapsulate any fluids that are communicated to the "zones"
and "paths" created by the ports 21 and the raised portions 26 of
the reactor lid assembly 20.
[0060] FIG. 4 shows a top view of the reactor lid assembly 20,
according to one embodiment, having one or more openings, such as
deposition ports 23, exhaust ports 22, and injection ports 24 (also
shown in FIG. 1B) disposed through the body 28. The openings may be
disposed through the body 28 from the upper surface 29 to the lower
surface 27. These ports may be fitted with removable isolator,
showerhead, exhaust, or other gas manifold assemblies, which may
extend beyond the lower surface 27 of the body 28, to facilitate
distribution of a gas, into and/or out of the CVD reactor, and
specifically to uniformly apply the gas to a wafer passing beneath
the assemblies. In one embodiment, the ports 22, 23, 24 may define
a circular shape, a square shape, a rectangular shape, or
combinations thereof. In one embodiment, the showerhead assemblies
may include injection hole diameters in the range of about 0.1
millimeters to about 5 millimeters and may include injection hole
spacing in the range of about 1 millimeter to about 30 millimeters.
These dimensions may extend beyond these ranges for different
applications. The gas manifold assemblies and the reactor lid
assembly 20 may be configured to provide a high reactant
utilization, meaning that the gases utilized in the reactor are
nearly 100 percent consumed by the reactions during the CVD
process.
[0061] The exhaust ports 22 and the injection ports 24 may be used
to develop "isolation curtains" to help prevent contamination and
to help prevent back diffusion of the gases introduced into the CVD
reactor 10 between the various zones created in the reactor. These
"isolation curtains" may be introduced at the front end (entrance)
and the back end (exit) of the CVD reactor 10, as well as between
the various zones created within the CVD reactor 10. In one
example, nitrogen or argon may be injected into an injection port
24 to purge contaminants, such as oxygen, out of a particular zone,
which are then exhausted out of an adjacent exhaust port 22. By
utilizing the "isolation curtains" with the "paths" and "zones"
created by the reactor lid assembly 20, the CVD reactor 10 limits
the gas isolation to a two dimension configuration that protects
between zones and isolates the reactor from outside contaminants,
such as air.
[0062] FIGS. 2, 5, 6, 7, and 8 provide various views of embodiments
of the wafer carrier track 30. The wafer carrier track 30 may
provide a levitation-type system so that a wafer may float across a
cushion of a gas, such as nitrogen or argon, supplied from the gas
holes 33 of the wafer carrier track 30. Referring back to FIG. 2,
the wafer carrier track 30 generally defines a rectangular body
having an upper portion 31 and a lower portion 32. The upper
portion 31 includes side surfaces 35 extending from the top surface
of the wafer carrier track 30 and disposed along the longitudinal
length of the wafer carrier track 30, thereby defining a "guide
path" along which a wafer travels through the CVD reactor. The
width of the guide path (e.g. the distance between the inner sides
of the side surfaces 35) may be in a range of about 110 millimeters
to about 130 millimeters, the height of the guide path may be in a
range of about 30 millimeters to about 50 millimeters, and the
length of the guide path may be in a range of about 970 millimeters
to about 1030 millimeters, however, these dimensions may extend
beyond these ranges for different applications. The upper portion
31 may include a recessed bottom surface, and the bottom section
may include a recessed top surface, such that when joined together,
a gas cavity 36 is formed therebetween. The gas cavity 36 may be
used to circulate and distribute gas that is injected into the gas
cavity 36 to the guide path of the wafer carrier track 30 to
generate the cushion of gas. The number, size, shape, and location
of the gas cavity 36 along the wafer carrier track 30 may vary.
Both the side surfaces 35 and the gas cavity 36 may extent
substantially the longitudinal length of the wafer carrier track
30. The wafer carrier track 30 may be formed as a single solid
structural component, or it may be constructed from several
segments coupled together. In one embodiment, the wafer carrier
track 30 may be tilted at an angle, such that the entrance is
elevated above the exit, so that the wafers may float down the
track with the aid of gravity. As discussed above, the side
surfaces 35 of the wafer carrier track 30 may be received into the
gaps formed between the raised portions 26 and the flange members
25 of the reactor lid assembly 20 to enclose the "guide path" along
the wafer carrier track 30 and to further define the "zones" formed
with the raised portions 26 along the wafer carrier track 30.
[0063] FIG. 5 shows an embodiment of the wafer carrier track 30. As
shown, wafer carrier track 30 includes a plurality of gas holes 33
along the guide path of the wafer carrier track 30 and between the
side surfaces 35. The gas holes 33 may be uniformly disposed along
the guide path of the wafer carrier track 30 in multiple rows. The
diameter of the gas holes 33 may include a range of about 0.2
millimeters to about 0.10 millimeters and the pitch of the gas
holes 33 may include a range of about 10 millimeters to about 30
millimeters, but these dimensions may extend beyond these ranges
for different applications. The number, size, shape, and location
of the gas holes 33 along the wafer carrier track 30 may vary. In
an alternative embodiment, the gas holes 33 may include rows of
rectangular slits or slots disposed along the guide path of the
wafer carrier track 30.
[0064] Gas holes 33 are in communication with the gas cavity 36
disposed beneath the guide path of the wafer carrier track 30. Gas
that is supplied to the gas cavity 36 is uniformly released through
the gas holes 33 to develop a cushion of gas along the wafer
carrier track 30. A wafer positioned on the guide path of the wafer
carrier track 30 may be levitated by the gas supplied from
underneath and easily transported along the guide path of the wafer
carrier track 30. The gap between a levitated wafer and the guide
path of the wafer carrier track 30 may be greater than about 0.05
millimeters, but may vary depending on different applications. This
levitation-type system reduces any drag effects produced by
continuous direct contact with the guide path of the wafer carrier
track 30. In addition, gas ports 34 may be provided along the sides
of the side surfaces 35 adjacent the guide path of the wafer
carrier track 30. These gas ports 34 may be used as an exhaust for
the gas that is supplied through the ports 30. Alternatively, these
gas ports 34 may be used to inject gas laterally into the center of
the wafer carrier track 30 to help stabilize and center a wafer
that is floating along the guide path of the wafer carrier track
30. In an alternative embodiment, the guide path of the wafer
carrier track 30 may include a tapered profile to help stabilize
and center a wafer that is floating along the guide path of the
wafer carrier track 30.
[0065] FIG. 6 shows a front view embodiment of the wafer carrier
track 30. As shown, the wafer carrier track 30 includes the upper
portion 31 and the lower portion 32. The upper portion 31 includes
side surfaces 35 that define the "guide path" along the length of
the wafer carrier track 30. The upper portion 31 may further
include side surfaces 35 that define recessed portions 39 between
the sides of the side surfaces 35. These recessed portions 39 may
be adapted to receive the flange members 25 of the reactor lid
assembly 20 (shown in FIG. 2) to couple the reactor lid assembly 20
and the wafer carrier track 30 together and enclose the guide path
along the wafer carrier track 30. Also show in FIG. 5 are gas holes
33 extending from the guide path of the wafer carrier track 30 to
the gas cavity 36. The lower portion 32 may act as a support for
the upper portion 31 and may include a recessed bottom surface. An
injection line 38 may be connected to the lower portion 32 so that
gas may be injected through the line 38 and into the gas cavity
36.
[0066] FIG. 7 shows a side view of the wafer carrier track 30
having a single injection line 38 into a gas cavity 36 along the
entire wafer carrier track 30 length. Alternatively, the wafer
carrier track 30 may include multiple gas cavities 36 and multiple
injection lines 38 along its length. Alternatively still, the wafer
carrier track 30 may include multiple segments, each segment having
a single gas cavity and a single injection line 38. Alternatively
still, the wafer carrier track 30 may include combinations of the
above described gas cavity 36 and injection line 38
configurations.
[0067] FIG. 8 shows a cross sectional perspective view embodiment
of the wafer carrier track 30 having the upper portion 31 and the
lower portion 32. The upper portion 31 having side surfaces 35, gas
holes 33, and the gas cavity 36 disposed on the lower portion 32.
In this embodiment, the side surfaces 35 and the lower portion 32
are hollow, which may substantially reduce the weight of the wafer
carrier track 30 and may enhance the thermal control of the wafer
carrier track 30 relative to the wafers traveling along the wafer
carrier track 30.
[0068] FIG. 9 shows the reactor lid assembly 20 coupled to or with
the wafer carrier track 30. O-rings may be used to seal the reactor
lid assembly 20 and wafer carrier track 30 interfaces. As shown,
the entrance into the CVD reactor 10 may be sized to receive
varying sizes of wafers. In one embodiment, a gap 60, formed
between the raised portions 26 of the reactor lid assembly 20 and
the guide path of the wafer carrier track 30, in which the wafer is
received, is dimensioned to help prevent contaminants from entering
the CVD reactor 10 at either end, dimensioned to help prevent back
diffusion of gases between zones, and dimensioned to help ensure
that the gases supplied to the wafer during the CVD process are
uniformly distributed across the thickness of the gap and across
the wafer. In one embodiment, the gap 60 may be formed between the
lower surface 27 of the body 28 and the guide path of the wafer
carrier track 30, In one embodiment, the gap 60 may be formed
between the lower surface of the gas manifold assemblies and the
guide path of the wafer carrier track 30, In one embodiment, the
gap 60 may be in the range of about 0.5 millimeters to about 5
millimeters in thickness and may vary along the length of the
reactor lid assembly 20 and wafer carrier track 30. In one
embodiment, the wafer may have a length in the range of about 50
millimeters to about 150 millimeters, a width in the range of about
50 millimeters to about 150 millimeters, and a thickness in the
range of about 0.5 millimeters to about 5 millimeters. In one
embodiment, the wafer may include a base layer having individual
strips of layers disposed on the base layer. The individual strips
are treated in the CVD process. These individual strips may include
about a 10 centimeter length by about a 1 centimeter width
(although other sizes may be utilized as well), and may be formed
in this manner to facilitate removal of the treated strips from the
wafer and to reduce the stresses induced upon the treated strips
during the CVD process. The CVD reactor 10 may be adapted to
receive wafers having dimensions that extend beyond the above
recited ranges for different applications.
[0069] The CVD reactor 10 may be adapted to provide an automatic
and continuous feed and exit of wafers into and out of the reactor,
such as with a conveyor-type system. A wafer may be fed into the
CVD reactor 10 at one end of the reactor, by a conveyor for
example, communicated through a CVD process, and removed at the
opposite end of the reactor, by a retriever for example, using a
manual and/or automated system. The CVD reactor 10 may be adapted
to produce wafers in the range of one wafer about every 10 minutes
to one wafer about every 10 seconds, and may extend beyond this
range for different applications. In one embodiment, the CVD
reactor 10 may be adapted to produce 6-10 treated wafers per
minute.
[0070] FIG. 10A shows an alternative embodiment of a CVD reactor
100. The CVD reactor 100 includes a reactor body 120, a wafer
carrier track 130, a wafer carrier 140, and a heating lamp assembly
150. The reactor body 120 may define a rectangular body and may be
formed from molybdenum, quartz, stainless steel, or other similar
material. The reactor body 120 may enclose the wafer carrier track
130 and extend substantially the length of the wafer carrier track
130. The wafer carrier track 130 may also define a rectangular body
and may be formed from quartz or other low thermal conductive
material to assist with temperature distribution during the CVD
process. The wafer carrier track 130 may be configured to provide a
levitation-type system that supplies a cushion of gas to
communicate a wafer along the wafer carrier track 130. As shown, a
conduit, such as a gas cavity 137 having a v-shaped roof 135 is
centrally located along the longitudinal axis of the guide path of
the wafer carrier track 130. Gas is supplied through gas cavity 137
and is injected through gas holes in the roof 135 to supply the
cushion of gas that floats a wafer having a corresponding v-shaped
notch (not shown) on its bottom surface along the wafer carrier
track 130. In one embodiment, the reactor body 120 and the wafer
carrier track 130 each are a single structural component. In an
alternative embodiment, the reactor body 120 includes multiple
segments coupled together to form a complete structural component.
In an alternative embodiment, the wafer carrier track 130 includes
multiple segments coupled together to form a complete structural
component.
[0071] Also shown in FIG. 10A is a wafer carrier 140 adapted to
carry a single wafer (not shown) or strips 160 of a wafer along the
wafer carrier track 130. The wafer carrier 140 may be formed from
graphite or other similar material. In one embodiment, the wafer
carrier 140 may have a v-shaped notch 136 along its bottom surface
to correspond with the v-shaped roof 135 of the wafer carrier track
130. The v-shaped notch 136 disposed over the v-shaped roof 135
helps guide the wafer carrier 140 along the wafer carrier track
130. The wafer carrier 140 may be used to carry the wafer strips
160 through the CVD process to help reduce the thermal stresses
imparted on the wafer during the process. Gas holes in the roof 135
of the gas cavity 137 may direct a cushion of gas along the bottom
of the wafer carrier 140, which utilizes the corresponding v-shaped
feature to help stabilize and center the wafer carrier 140, and
thus the strips 160 of wafer, during the CVD process. As stated
above, a wafer may be provided in strips 160 to facilitate removal
of the treated strips from the wafer carrier 140 and to reduce the
stresses induced upon the strips during the CVD process.
[0072] In another embodiment, FIGS. 10B-10F depict a wafer carrier
70 which may be used to carry a wafer through a variety of
processing chambers including the CVD reactors as described herein,
as well as other processing chambers used for deposition or
etching. The wafer carrier 70 has short sides 71, long sides 73, an
upper surface 72, and a lower surface 74. The wafer carrier 70 is
illustrated with a rectangular geometry, but may also have a square
geometry, a circular geometry, or other geometries. The wafer
carrier 70 may contain or be formed from graphite or other
materials. The wafer carrier 70 usually travels through the CVD
reactor with the short sides 71 facing forward while the long sides
73 face towards the sides of the CVD reactor.
[0073] FIG. 10B illustrates a top view of the wafer carrier 70
containing 3 indentations 75 on the upper surface 72. Wafers may be
positioned within the indentations 75 while being transferred
through the CVD reactor during a process. Although illustrated with
3 indentations 75, the upper surface 72 may have more or less
indentations, including no indentations. For example, the upper
surface 72 of the wafer carrier 70 may contain 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 12, or more indentations for containing wafers. In
some example, one or multiple wafers may be disposed directly on
the upper surface 72 which does not have an indentation.
[0074] FIG. 10C illustrates a bottom view of the wafer carrier 70
containing the indentation 78 on the lower surface 74, as described
in one embodiment herein. The indentation 78 may be used to help
levitate the wafer carrier 70 upon the introduction of a gas
cushion under the wafer carrier 70. A gas flow may be directed at
the indentation 78, which accumulates gas to form the gas cushion.
The lower surface 74 of the wafer carrier 70 may have no
indentations, or may have one indentation 78 (FIG. 10C), two
indentations 78 (FIGS. 10D-10F), three indentations 78 (not shown)
or more. The indentation 78 may have straight or tapered sides. In
one example, the indentation 78 has tapered sides such that the
sides 76 are steeper or more abrupt than the sides 77 which have
more of a gradual change of angle. The sides 77 within the
indentation 78 may be tapered to compensate for a thermal gradient
across the wafer carrier 70. In another example, the indentation 78
has straight sides and tapered sides such that the sides 76 are
straight and the sides 77 have a taper or the sides 77 are straight
and the sides 76 have a taper. Alternatively, the indentation 78
may have all straight sides such that the sides 76 and 77 are
straight.
[0075] In another embodiment, FIGS. 10D-10F illustrate bottom views
of the wafer carrier 70 containing two indentations 78 on the lower
surface 74. The two indentations 78 help levitate the wafer carrier
70 upon the introduction of a gas cushion under the wafer carrier
70. A gas flow may be directed at the indentations 78, which
accumulates gas to form the gas cushion. The indentations 78 may
have straight or tapered sides. In one example, as illustrated in
FIG. 10E, the indentations 78 have all straight sides such that the
sides 76 and 77 are straight, e.g., perpendicular to the plane of
the lower surface 74. In another example, as illustrated in FIG.
10F, the indentations 78 have all tapered sides such that the sides
76 are steeper or more abrupt than the sides 77 which have more of
a gradual change of angle. The sides 77 within the indentations 78
may be tapered to compensate for a thermal gradient across the
wafer carrier 70. Alternatively, the indentations 78 may have a
combination of straight sides and tapered sides such that the sides
76 are straight and the sides 77 have a taper or the sides 77 are
straight and the sides 76 have a taper.
[0076] The wafer carrier 70 contains a heat flux which extends from
the lower surface 74 to the upper surface 72 and to any wafers
disposed thereon. The heat flux may be controlled by both the
internal pressure and length of the processing system. The profile
of wafer carrier 70 may be tapered to compensate the heat loses
from other sources. During a process, heat is lost through the
edges of the wafer carrier 70, such as the short sides 71 and the
long sides 73. However, the heat lost may be compensated by
allowing more heat flux into the edges of the wafer carrier 70 by
reducing the gap of the guide path in the levitation.
[0077] FIG. 10A also depicts the reactor body 120 disposed on the
heating lamp assembly 150. The heating lamp assembly 150 may be
configured to control the temperature profile within the CVD
reactor by increasing and decreasing the temperature of the reactor
body 120, the wafer carrier track 130, and specifically the wafer,
along the length of the CVD reactor. The heating lamp assembly 150
may include a plurality of heating lamps disposed along the
longitudinal length of the wafer carrier track 130. In one
embodiment, the heating lamp assembly 150 includes individually
controlled heating lamps disposed along the length of the wafer
carrier track 130. In an alternative embodiment, the heating lamp
assembly 150 includes a bank of heating lamps that are movable and
follow a wafer as it travels along the wafer carrier track 130. The
embodiments of the heating lamp assembly 150 may also be used as
the heating lamp assembly 50, described above with respect to FIG.
1.
[0078] In an alternative embodiment, other types of heating
assemblies (not shown) may be utilized to heat the reactor body 120
instead of the heating lamp assembly 150. In one embodiment, a
heating assembly may include resistive heating elements, such as
resistive heaters, which may be individually controlled along the
length of the wafer carrier track 130. In one example, a resistive
heating element may be bonded to or painted onto the reactor body
120, the wafer carrier track 130, or the wafer carrier 140. In
alternative embodiment, another type of heating assembly that may
be utilized to heat the reactor body 120 is an inductive heating
element, such as with a radio frequency power source (not shown).
The inductive heating element may be coupled to or with the reactor
body 120, the wafer carrier track 130, and/or the wafer carrier
140. Embodiments of the various types of heating assemblies
(including heating lamp assemblies 50 and 150) described herein may
be utilized independently or in combination with the CVD
reactor.
[0079] In one embodiment, the heating lamp assembly 150 may be
configured to heat a wafer in the CVD reactor to a temperature
within a range from about 300 degree Celsius to about 800 degrees
Celsius. In one embodiment, the heating lamp assembly 150 may be
configured to raise the temperature of the wafer to an appropriate
process temperature prior to introduction into a deposition zone of
the CVD reactor. In one embodiment, the heating lamp assembly 150
may be configured with the CVD reactor to bring the wafer to a
temperature within a range from about 300 degree Celsius to about
800 degrees prior to introduction into a deposition zone of the CVD
reactor. In one embodiment, the wafer may be heated to within a
process temperature range prior to entering one or more deposition
zones of the CVD reactor to facilitate the deposition processes,
and the temperature of the wafer may be maintained within the
process temperature range as the wafer passes through the one or
more deposition zones. The wafer may be heated to and maintained
within the process temperature range as it moves along the wafer
carrier track. A center temperature to an edge temperature of the
wafer may be within 10 degrees Celsius of each other.
[0080] FIGS. 11-17 illustrate various configurations of CVD
processes that can be utilized with the CVD reactor as described
herein. FIG. 11 illustrates a first configuration 200, having an
entrance isolator assembly 220, a first isolator assembly 230, a
second isolator assembly 240, a third isolator assembly 250, and an
exit isolator assembly 260. A plurality of deposition zones 290 may
be located along the wafer carrier track of the CVD reactor and may
be surrounded by the isolator assemblies. Between each of these
isolator assemblies, one or more exhausts 225 may be provided to
remove any gases that are supplied to the wafer at each isolator
assembly or deposition zone. As shown, a precursor gas may be
injected at the entrance isolator assembly 220, which follows a two
dimensional flow path, e.g. down to the wafer and then along the
length of the wafer carrier track, indicated by flow path 210 for
example. The gas is then exhausted up through exhaust 225, which
may be provided on each side of the isolator assembly 220. The gas
may be directed at the entrance isolator assembly 220 and then
along the length of the wafer carrier track, indicated by flow path
215 for example, to prevent contaminants from entering the entrance
of the CVD reactor. Gas injected at the intermediate isolator
assemblies, such as isolator assembly 230, or at the deposition
zones 290, may travel upstream from the flow of the wafer,
indicated by flow path 219 for example. This back diffusion of gas
may be received through the adjacent exhaust to prevent
contaminants or mixing of gases between zones along the wafer
carrier track of the CVD reactor. In addition, the flow rate of the
gases injected through the isolator assemblies, e.g. along flow
path 210, in the direction of the wafer flow may also be adapted to
further prevent back diffusion from entering the isolation zone.
The laminar flow along flow path 210 may be flowed at different
flow rates to meet any back diffusion of gas, for example at
junction 217 below exhaust 225, to prevent the back diffusion of
gas from isolator assembly 230 from entering the isolation zone
developed by isolator assembly 220. In one embodiment, the wafer
may be heated to within a process temperature range as it travels
along the wafer carrier track prior to entering the deposition
zones 290. The temperature of the wafer may be maintained within
the process temperature range as it travels along the wafer carrier
track through the deposition zones 290. The wafer may be cooled to
within a specific temperature range upon exiting the deposition
zones 290 as it travels along the remainder of the wafer carrier
track.
[0081] The lengths of the isolation zones and the deposition zones
may be varied to reduce the effects of back diffusion of gases. In
one embodiment, the lengths of the isolation zones created may
range from about 1 meter to about 2 meters in length but may extend
beyond this range for different applications.
[0082] The flow rates of the gases injected from the isolator
assemblies may also be varied to reduce the effects of back
diffusion of gases. In one embodiment, the entrance isolator
assembly 220 and the exit isolator assembly 260 may supply a
precursor gas at about 30 liters per minute, while the first 230,
second 240, and third 250 isolator assemblies may supply a
precursor gas at about 3 liters per minute. In one embodiment, the
precursor gas supplied at the entrance isolator assembly 220 and
the exit isolator assembly 260 may include nitrogen. In one
embodiment, the precursor gas supplied at the first 230, second
240, and third 250 isolator assemblies may include arsine. In one
embodiment, two isolator assemblies may supply a total of about 6
liters per minute of nitrogen. In one embodiment, three isolator
assemblies may supply a total of about 9 liters per minute of
arsine.
[0083] The gap, e.g. the thickness between the guide path of the
wafer carrier track and the raised portion of the reactor lid
assembly, alternatively, the thickness of the space through which
wafer travels into and out of the CVD reactor, of the isolation
zones may also be varied to reduce the effects of back diffusion of
gases. In one embodiment, the isolator gap may be in a range of
about 0.1 millimeters to about 5 millimeters.
[0084] FIG. 18 illustrates several flow path configurations 900
which may be provided by the CVD reactor. The flow path
configurations 900 may be used for injecting a gas through one or
more isolator assemblies, injecting a gas into a deposition zone,
and/or exhausting a gas from isolation and/or deposition zones.
Dual flow path configuration 910 shows a gas directed in the same
direction as the flow path of the wafer, as well as in the opposite
direction of the flow path of the wafer. In addition, a larger
volume of flow may be directed through the dual flow path
configuration 910 due to the wider flow area 911. This wider flow
area 911 may be adapted for use with the other embodiments
described herein. Single flow path configuration 920 shows a gas
directed in a single direction, which may be in the same or
opposite direction of the flow path of the wafer. In addition, a
low volume of flow may be directed through the single flow path
configuration 920 due to the narrow flow area 921. This narrower
flow area 921 may be adapted for use with the other embodiments
described herein. Exhaust flow path configuration 930 shows that
gas may be exhausted from adjacent zones through a wider flow area
931, such as adjacent isolation zones, adjacent deposition zones,
or an isolation zone adjacent to a deposition zone.
[0085] In one embodiment, first exhaust/injector flow path
configuration 940 shows a dual flow path configuration 941 having a
narrow flow area 943 disposed between an exhaust flow path 944 and
a single injection flow path 945. Also shown is a narrower gap 942
portion along which the wafer may travel through the CVD reactor.
As described above, the gap 942 may vary along the wafer carrier
track of the CVD reactor, thereby allowing a gas to be directly and
uniformly injected onto the surface of the wafer. This narrower gap
942 portion may be used to provide full consumption or near full
consumption of the gas injected onto the wafer during a reaction in
a deposition zone. In addition, the gap 942 may be used to
facilitate thermal control during the isolation and/or deposition
process. A gas injected in the narrower gap 942 portion may
maintain a higher temperature as it is injected onto the wafer.
[0086] In one embodiment, a second exhaust/injector flow path
configuration 950 provides a first exhaust flow path 954 having a
wide flow area, a first dual flow path configuration 951 having a
narrow gap portion 952 and flow area 953, a first single injection
flow path 955 having a wide flow area, a plurality of single
injection flow paths 956 having narrow flow areas a wide gap
portion, a second exhaust flow path 957 having a wide flow area, a
second dual flow path configuration 958 having a narrow gap portion
959 and flow area, and a second single injection flow path 960
having a wide flow area and gap portion.
[0087] In one embodiment, the gas injected through the isolator
assemblies may be directed in the same direction as the flow path
of the wafer. In an alternative embodiment, the gas injected
through the isolator assemblies may be directed in the opposite
direction as the flow path of the wafer. In an alternative
embodiment, the gas injected through the isolator assemblies may be
directed in both the same and opposite direction as the flow path
of the wafer. In an alternative embodiment, the isolator assemblies
may direct gas in different directions depending on their location
in the CVD reactor.
[0088] In one embodiment, the gas injected into the deposition
zones may be directed in the same direction as the flow path of the
wafer. In an alternative embodiment, the gas injected into the
deposition zones may be directed in the opposite direction as the
flow path of the wafer. In an alternative embodiment, the gas
injected into the deposition zones may be directed in both the same
and opposite direction as the flow path of the wafer. In an
alternative embodiment, gas may be directed in different directions
depending on the location of the deposition zone in the CVD
reactor.
[0089] FIG. 12 illustrates a second configuration 300. The wafer(s)
310 is introduced into the entrance of the CVD reactor and travels
along the wafer carrier track of the reactor. The reactor lid
assembly 320 provides several gas isolation curtains 350 located at
the entrance and the exit of the CVD reactor, as well as between
deposition zones 340, 380, 390 to prevent contamination and mixing
of the gases between deposition and isolation zones. The gas
isolation curtains and deposition zones may be provided by one or
more gas manifold assemblies of the reactor lid assembly 320. These
deposition zones include an aluminum arsenide deposition zone 340,
a gallium arsenide deposition zone 380, and a phosphorous gallium
arsenide deposition zone 390, thereby forming a multiple layer
epitaxial deposition process and structure. As the wafer(s) 310
travels along the bottom portion 330 of the reactor, which may
generally include the wafer carrier track and the heating lamp
assembly, the wafer 310 may be subjected to temperature ramps 360
at the entrance and exit of the reactor to incrementally increase
and decrease the temperature of the wafer, prior to entering and
upon exiting the deposition zones 340, 380, 390, to reduce thermal
stress imparted on the wafer 310. The wafer 310 may be heated to
within a process temperature range prior to entering the deposition
zones 340, 380, 390 to facilitate the deposition processes. As the
wafer 310 travels through the deposition zones 340, 380, 390 the
temperature of the wafer may be maintained within a thermal region
370 to assist with the deposition processes. The wafer(s) 310 may
be provided on a conveyorized system to continuously feed and
receive wafers into and out of the CVD reactor.
[0090] FIG. 13 illustrates a third configuration 400. The CVD
reactor may be configured to supply nitrogen 410 to the reactor to
float the wafer(s) along the wafer carrier track of the reactor at
the entrance and the exit. A hydrogen/arsine mixture 420 may also
be used to float the wafer along the wafer carrier track of the CVD
reactor between the exit and entrance. The stages of the third
configuration 400 may be provided by one or more gas manifold
assemblies of the reactor lid assembly. The stages along the wafer
carrier track may include an entrance nitrogen isolation zone 415,
a preheat exhaust zone 425, a hydrogen/arsine mixture preheat
isolation zone 430, a gallium arsenide deposition zone 435, a
gallium arsenide exhaust 440, an aluminum gallium arsenide
deposition zone 445, a gallium arsenide N-layer deposition zone
450, a gallium arsenide P-layer deposition zone 455, a phosphorous
hydrogen arsine isolation zone 460, a first phosphorous aluminum
gallium arsenide deposition zone 465, a phosphorous aluminum
gallium arsenide exhaust zone 470, a second phosphorous aluminum
gallium arsenide deposition zone 475, a hydrogen/arsine mixture
cool down isolation zone 480, a cool down exhaust zone 485, and an
exit nitrogen isolation zone 490. As the wafer travels along the
bottom portion of the reactor, which may generally include the
wafer carrier track and the heating lamp assembly, the wafer may be
subjected to one or more temperature ramps 411 at the entrance and
exit of the reactor to incrementally increase and decrease the
temperature of the wafer, prior to entering and upon exiting the
deposition zones 435, 445, 450, 455, 465, 475 to reduce thermal
stress imparted on the wafer. The wafer may be heated to within a
process temperature range prior to entering the deposition zones
435, 445, 450, 455, 465, 475 to facilitate the deposition
processes. As the wafer travels through the deposition zones 435,
445, 450, 455, 465, 475 the temperature of the wafer may be
maintained within a thermal region 412 to assist with the
deposition processes. As shown, the temperature of the wafer
traveling through the third configuration 400 may be increased as
it passes the entrance isolation zone 415, may be maintained as is
travels through the zones 430, 435, 440, 445, 450, 455, 460, 465,
470, 475, and may be decreased as it nears the hydrogen/arsine
mixture cool down isolation zone 480 and travels along the
remainder of the wafer carrier track.
[0091] FIG. 14 illustrates a fourth configuration 500. The CVD
reactor may be configured to supply nitrogen 510 to the reactor to
float the wafer(s) along the wafer carrier track of the reactor at
the entrance and the exit. A hydrogen/arsine mixture 520 may also
be used to float the wafer along the wafer carrier track of the CVD
reactor between the exit and entrance. The stages of the fourth
configuration 500 may be provided by one or more gas manifold
assemblies of the reactor lid assembly. The stages along the wafer
carrier track may include an entrance nitrogen isolation zone 515,
a preheat exhaust zone 525, a hydrogen/arsine mixture preheat
isolation zone 530, an exhaust zone 535, a deposition zone 540, an
exhaust zone 545, a hydrogen/arsine mixture cool down isolation
zone 550, a cool down exhaust zone 555, and an exit nitrogen
isolation zone 545. In one embodiment, the deposition zone 540 may
include an oscillating showerhead assembly. As the wafer travels
along the bottom portion of the reactor, which may generally
include the wafer carrier track and the heating lamp assembly, the
wafer may be subjected to one or more temperature ramps 511, 513 at
the entrance and exit of the reactor to incrementally increase and
decrease the temperature of the wafer, prior to entering and upon
exiting the deposition zone 540 to reduce thermal stress imparted
on the wafer. The wafer may be heated to within a process
temperature range prior to entering the deposition zone 540 to
facilitate the deposition process. In one embodiment, the wafer may
be heated and/or cooled to within a first temperature range as it
travels through the temperature ramps 511. In one embodiment, the
wafer may be heated and/or cooled to within a second temperature
range as it travels through the temperature ramps 513. The first
temperature range may be greater than, less than, and/or equal to
the second temperature range. As the wafer travels through the
deposition zone 540 the temperature of the wafer may be maintained
within a thermal region 512 to assist with the deposition
processes. As shown, the temperature of the wafer traveling through
the fourth configuration 500 may be increased as it passes the
entrance isolation zone 515, may be maintained as is travels
through the deposition zone 540, and may be decreased as it nears
the hydrogen/arsine mixture cool down isolation zone 550 and
travels along the remainder of the wafer carrier track.
[0092] FIG. 15 illustrates a fifth configuration 600. The CVD
reactor may be configured to supply nitrogen 610 to the reactor to
float the wafer(s) along the wafer carrier track of the reactor at
the entrance and the exit. A hydrogen/arsine mixture 620 may also
be used to float the wafer along the wafer carrier track of the CVD
reactor between the exit and entrance. The stages of the fifth
configuration 600 may be provided by one or more gas manifold
assemblies of the reactor lid assembly. The stages along the wafer
carrier track may include an entrance nitrogen isolation zone 615,
a preheat exhaust with flow balance restrictor zone 625, an active
hydrogen/arsine mixture isolation zone 630, a gallium arsenide
deposition zone 635, an aluminum gallium arsenide deposition zone
640, a gallium arsenide N-layer deposition zone 645, a gallium
arsenide P-layer deposition zone 650, a phosphorous aluminum
gallium arsenide deposition zone 655, a cool down exhaust zone 660,
and an exit nitrogen isolation zone 665. As the wafer travels along
the bottom portion of the reactor, which may generally include the
wafer carrier track and the heating lamp assembly, the wafer may be
subjected to one or more temperature ramps 611 at the entrance and
exit of the reactor to incrementally increase and decrease the
temperature of the wafer, prior to entering and upon exiting the
deposition zones 635, 640, 645, 650, 655 to reduce thermal stress
imparted on the wafer. The wafer may be heated to within a process
temperature range prior to entering the deposition zones 635, 640,
645, 650, 655 to facilitate the deposition processes. As the wafer
travels through the deposition zones 635, 640, 645, 650, 655 the
temperature of the wafer may be maintained within a thermal region
612 to assist with the deposition processes. As shown, the
temperature of the wafer traveling through the fifth configuration
600 may be increased as is passes the entrance isolation zone 615
and approaches the active hydrogen/arsine mixture isolation zone
630, may be maintained as it travels through the deposition zones
635, 640, 645, 650, 655, and may be decreased as it nears the cool
down exhaust zone 660 and travels along the remainder of the wafer
carrier track.
[0093] FIG. 16 illustrates a sixth configuration 700. The CVD
reactor may be configured to supply nitrogen 710 to the reactor to
float the wafer(s) along the wafer carrier track of the reactor at
the entrance and the exit. A hydrogen/arsine mixture 720 may also
be used to float the wafer along the wafer carrier track of the CVD
reactor between the exit and entrance. The stages of the sixth
configuration 700 may be provided by one or more gas manifold
assemblies of the reactor lid assembly. The stages along the wafer
carrier track may include an entrance nitrogen isolation zone 715,
a preheat exhaust with flow balance restrictor zone 725, a gallium
arsenide deposition zone 730, an aluminum gallium arsenide
deposition zone 735, a gallium arsenide N-layer deposition zone
740, a gallium arsenide P-layer deposition zone 745, a phosphorous
aluminum gallium arsenide deposition zone 750, a cool down exhaust
with flow balance restrictor zone 755, and an exit nitrogen
isolation zone 760. As the wafer travels along the bottom portion
of the reactor, which may generally include the wafer carrier track
and the heating lamp assembly, the wafer may be subjected to one or
more temperature ramps 711 at the entrance and exit of the reactor
to incrementally increase and decrease the temperature of the
wafer, prior to entering and upon exiting the deposition zones 730,
735, 740, 745, 750 to reduce thermal stress imparted on the wafer.
The wafer may be heated to within a process temperature range prior
to entering the deposition zones 730, 735, 740, 745, 750 to
facilitate the deposition processes. As the wafer travels through
the deposition zones 730, 735, 740, 745, 750 the temperature of the
wafer may be maintained within a thermal region 712 to assist with
the deposition processes. As shown, the temperature of the wafer
traveling through the sixth configuration 700 may be increased as
is passes the entrance isolation zone 715 and approaches the
gallium arsenide deposition zone 730, may be maintained as it
travels through the deposition zones 730, 735, 740, 745, 750, and
may be decreased as it nears the cool down exhaust zone 755 and
travels along the remainder of the wafer carrier track.
[0094] FIG. 17 illustrates a seventh configuration 800. The CVD
reactor may be configured to supply nitrogen 810 to the reactor to
float the wafer(s) along the wafer carrier track of the reactor at
the entrance and the exit. A hydrogen/arsine mixture 820 may also
be used to float the wafer along the wafer carrier track of the CVD
reactor between the exit and entrance. The stages of the seventh
configuration 800 may be provided by one or more gas manifold
assemblies of the reactor lid assembly. The stages along the wafer
carrier track may include an entrance nitrogen isolation zone 815,
a preheat exhaust zone 825, a deposition zone 830, a cool down
exhaust zone 835, and an exit nitrogen isolation zone 840. In one
embodiment, the deposition zone 830 may include an oscillating
showerhead assembly. As the wafer travels along the bottom portion
of the reactor, which may generally include the wafer carrier track
and the heating lamp assembly, the wafer may be subjected to one or
more temperature ramps 811, 813 at the entrance and exit of the
reactor to incrementally increase and decrease the temperature of
the wafer, prior to entering and upon exiting the deposition zone
830 to reduce thermal stress imparted on the wafer. The wafer may
be heated to within a process temperature range prior to entering
the deposition zone 830 to facilitate the deposition process. In
one embodiment, the wafer may be heated and/or cooled to within a
first temperature range as it travels through the temperature ramps
811. In one embodiment, the wafer may be heated and/or cooled to
within a second temperature range as it travels through the
temperature ramps 813. The first temperature range may be greater
than, less than, and/or equal to the second temperature range. As
the wafer travels through the deposition zone 830 the temperature
of the wafer may be maintained within a thermal region 812 to
assist with the deposition processes. As shown, the temperature of
the wafer traveling through the seventh configuration 800 may be
increased as it passes the entrance isolation zone 815 and
approaches the deposition zone 830, may be maintained as it travels
through the deposition zone 830, and may be decreased as it nears
the cool down exhaust zone 840 and travels along the remainder of
the wafer carrier track.
[0095] In one embodiment, the CVD reactor may be configured to
demonstrate high quality gallium arsenide and aluminum gallium
arsenide double heterostructure deposition at 1 um/min deposition
rate; demonstrate high quality aluminum arsenide epitaxial lateral
overgrowth sacrificial layer; and define a wafer carrier track
capable of providing 6-10 wafers per minute throughput.
[0096] In one embodiment, the CVD reactor may be configured to
provide a deposition rate of one 10 centimeter by 10 centimeter
wafer per minute. In one embodiment the CVD reactor may be
configured to provide a 300 nanometer gallium arsenide buffer
layer. In one embodiment the CVD reactor may be configured to
provide a 30 nanometer aluminum gallium arsenide passivation layer.
In one embodiment the CVD reactor may be configured to provide a
1000 nanometer gallium arsenide active layer. In one embodiment the
CVD reactor may be configured to provide a 30 nanometer aluminum
gallium arsenide passivation layer. In one embodiment the CVD
reactor may be configured to provide a dislocation density of less
than 1E4 per centimeter squared; a photoluminescence efficiency of
99%; and a photoluminescence lifetime of 250 nanoseconds.
[0097] In one embodiment the CVD reactor may be configured to
provide an epitaxial lateral overgrowth layer having a 5 nm
deposition +-0.5 nm; a etch selectivity greater than 1E6; zero
pinholes; and an aluminum arsenide etch rate greater than 0.2 mm
per hour.
[0098] In one embodiment the CVD reactor may be configured to
provide a center to edge temperature non-uniformity of no greater
than 10.degree. C. for temperatures above 300.degree. C.; a V-III
ratio of no more than 5; and a maximum temperature of 800.degree.
C.
[0099] In one embodiment the CVD reactor may be configured to
provide a deposition layers having a 300 nm gallium arsenide buffer
layer; a 5 nm aluminum arsenide sacrificial layer; a 10 nm aluminum
gallium arsenide window layer; a 700 nm gallium arsenide 2E17 Si
active layer; a 300 nm aluminum gallium arsenide 1E19 C P+ layer;
and a 300 nm gallium arsenide 1E19 C P+ layer.
[0100] In one embodiment the CVD reactor may be configured to
provide a deposition layers having a 300 nm gallium arsenide buffer
layer; a 5 nm aluminum arsenide sacrificial layer; a 10 nm gallium
indium phosphide window layer; a 700 nm gallium arsenide 2E17 Si
active layer; a 100 nm gallium arsenide C P layer; a 300 nm gallium
indium phosphide P window layer; a 20 nm gallium indium phosphide
1E20 P+ tunnel junction layer; a 20 nm gallium indium phosphide
1E20 N+ tunnel junction layer; a 30 nm aluminum gallium arsenide
window; a 400 nm gallium indium phosphide N active layer; a 100 nm
gallium indium phosphide P active layer; a 30 nm aluminum gallium
arsenide P window; and a 300 nm gallium arsenide P+ contact
layer.
[0101] Embodiments of the invention generally relate to a
levitating substrate carrier or support. In one embodiment, a
substrate carrier for supporting and carrying at least one
substrate or wafer passing through a reactor is provided which
includes a substrate carrier body containing an upper surface and a
lower surface, and at least one indentation pocket disposed within
the lower surface. In another embodiment, the substrate carrier
includes a substrate carrier body containing an upper surface and a
lower surface, and at least two indentation pockets disposed within
the lower surface. In another embodiment, the substrate carrier
includes a substrate carrier body containing an upper surface and a
lower surface, an indentation area within the upper surface, and at
least two indentation pockets disposed within the lower surface. In
another embodiment, the substrate carrier includes a substrate
carrier body containing an upper surface and a lower surface, an
indentation area within the upper surface, and at least two
indentation pockets disposed within the lower surface, wherein each
indentation pocket has a rectangular geometry and four side walls
which extend perpendicular or substantially perpendicular to the
lower surface. In another embodiment, the substrate carrier
includes a substrate carrier body containing an upper surface and a
lower surface, and at least two indentation pockets disposed within
the lower surface, wherein each indentation pocket has a
rectangular geometry and four side walls which extend perpendicular
or substantially perpendicular to the lower surface.
[0102] In another embodiment, a substrate carrier for supporting
and carrying at least one substrate passing through a reactor is
provided which includes a substrate carrier body containing an
upper surface and a lower surface, and at least one indentation
pocket disposed within the lower surface. The substrate carrier
body may have a rectangular geometry, a square geometry, or another
type of geometry. In one example, the substrate carrier body has
two short sides and two long sides, wherein one of the two short
sides is the front of the substrate carrier body and the other
short side is the rear of the substrate carrier body. The substrate
carrier body may contain or be made from graphite.
[0103] In some examples, the upper surface contains at least one
indentation area disposed therein. The indentation area within the
upper surface is configured to hold a substrate thereon. In other
examples, the upper surface may have at least two, three, four,
eight, twelve, or more of the indentation areas. In another
example, the upper surface has no indentation areas.
[0104] In another embodiment, the lower surface may have at least
two of the indentation pockets, which are configured to accept a
gas cushion. In some examples, the lower surface has one, three, or
more of the indentation pockets. The indentation pocket may have a
rectangular geometry, a square geometry, or another type of
geometry. Each of the indentation pockets usually has two short
sides and two long sides. In one example, the short sides and the
long sides are straight. The short sides and the long sides are
perpendicular relative to the lower surface. In another example, at
least one of the two short sides is tapered at a first angle, at
least one of the two long sides is tapered at a second angle, and
the first angle may be greater than or less than the second angle.
In another example, at least one of the two short sides is straight
and at least one of the two long sides is tapered. In another
example, at least one of the two short sides is tapered and at
least one of the two long sides is straight. In one embodiment, the
indentation pocket has a rectangular geometry and the indentation
pocket is configured to accept a gas cushion. The indentation
pocket may have tapered side walls which taper away from the upper
surface.
[0105] In another embodiment, a method for levitating substrates
disposed on an upper surface of a substrate carrier during a vapor
deposition process is provided which includes exposing a lower
surface of a substrate carrier to a gas stream, forming a gas
cushion under the substrate carrier, levitating the substrate
carrier within a processing chamber, and moving the substrate
carrier along a path within the processing chamber. In many
examples, the movement of the substrate carrier and/or the velocity
of the substrate carrier along the path may be controlled by
adjusting the flow rate of the gas stream. The air cushion may be
formed within at least one indentation pocket disposed within the
lower surface. In some examples, the lower surface has at least two
indentation pockets. The indentation pockets are configured to
accept the gas cushion. An upper surface of the substrate carrier
comprises at least one indentation area for supporting a substrate.
The indentation pocket may have tapered side walls which taper away
from the upper surface of the substrate carrier.
[0106] In another embodiment, a method for levitating substrates
disposed on a substrate carrier during a vapor deposition process
is provided which includes exposing a lower surface of a substrate
carrier to a gas stream, wherein at least one wafer is disposed on
an upper surface of the substrate carrier and the lower surface
contains at least one indentation pocket, forming a gas cushion
under the substrate carrier, levitating the substrate carrier
within a processing chamber, and moving the substrate carrier along
a path within the processing chamber.
[0107] In another embodiment, a method for levitating substrates
disposed on a substrate carrier during a vapor deposition process
is provided which includes exposing a lower surface of a substrate
carrier to a gas stream, wherein the lower surface contains at
least one indentation pocket, forming a gas cushion under the
substrate carrier, levitating the substrate carrier within a
processing chamber, and moving the substrate carrier along a path
within the processing chamber.
[0108] In another embodiment, a method for levitating substrates
disposed on a substrate carrier during a vapor deposition process
is provided which includes exposing a lower surface of a substrate
carrier to a gas stream, wherein the lower surface contains at
least two indentation pockets, forming a gas cushion under the
substrate carrier, levitating the substrate carrier within a
processing chamber, and moving the substrate carrier along a path
within the processing chamber.
[0109] Embodiments of the invention generally relate to a chemical
vapor deposition reactor system and related methods of use. In one
embodiment, a chemical vapor deposition system is provided which
includes a lid assembly, such as a top plate, having a plurality of
raised portions located along the longitudinal axis of the top
plate. The system includes a track having a guide path, such as a
channel, located along the longitudinal axis of the track, wherein
the channel is adapted to receive the plurality of raised portions
of the top plate, thereby forming a gap between the plurality of
raised portions and a floor of the track, wherein the gap is
configured to receive a substrate. The system includes a heating
assembly, such as a heating element, operable to heat the substrate
as the substrate moves along the channel of the track. In one
embodiment, the track is operable to float the substrate along the
channel of the track.
[0110] In one embodiment, system includes a trough that supports
the track. The gap may have a thickness between 0.5 and 5
millimeter or between 0.5 and 1 millimeter. The top plate is formed
from molybdenum or quartz, the track is formed from quartz or
silica. The top plate is operable to direct a gas to the gap and
may further include a plurality of ports located along the
longitudinal axis of the top plate and disposed between the
plurality of raised portions, thereby defining paths between the
plurality of raised portions. One or more of the plurality of ports
is adapted to communicate and/or exhaust a gas to the gap between
plurality of raised portions of the top plate and the floor of the
track.
[0111] Examples of the heating element include a heating lamp
coupled to or with the track, a plurality of heating lamps disposed
along the track, a heating lamp bank operable to move along the
track as the substrate moves along the channel of the track,
resistive heaters coupled to or with the track, an inductive
heating source coupled to or with the substrate and/or the track.
The heating element is operable to maintain a temperature
differential across the substrate, wherein the temperature
differential is less than 10 degrees Celsius. In one embodiment,
the chemical vapor deposition system is an atmospheric pressure
chemical vapor deposition system.
[0112] In one embodiment, a chemical vapor deposition system is
provided which includes an entrance isolator operable to prevent
contaminants from entering the system at an entrance of the system;
an exit isolator operable to prevent contaminants from entering the
system at an exit of the system; and an intermediate isolator
disposed between the entrance and exit isolators. The system may
further include a first deposition zone disposed adjacent the
entrance isolator and a second deposition zone disposed adjacent
the exit isolator. The intermediate isolator is disposed between
the deposition zones and is operable to prevent mixing of gases
between the first deposition zone and the second deposition
zone.
[0113] In one embodiment, the entrance isolator is further operable
to prevent back diffusion of gases injected into the first
deposition zone, the intermediate isolator is further operable to
prevent back diffusion of gases injected into the second deposition
zone, and the exit isolator is further operable to prevent back
diffusion of gases injected into the second deposition zone. An
isolation zone formed by at least one of the isolators has a length
between 1 to 2 meters. A gas, such as nitrogen, is injected into
the entrance isolator at a first flow rate, such as about 30 liters
per minute, to prevent back diffusion of gases from the first
deposition zone. A gas, such as arsine, is injected into the
intermediate isolator at a first flow rate, such as about 3 liters
per minute, to prevent back mixing of gases between the first
deposition zone and the second deposition zone. A gas, such as
nitrogen, is injected into the exit isolator at a first flow rate,
such as about 30 liters per minute, to prevent contaminants from
entering the system at the exit of the system. In one embodiment,
an exhaust is disposed adjacent each isolator and operable to
exhaust gases injected by the isolators. An exhaust may be disposed
adjacent each deposition zone and operable to exhaust gases
injected into the deposition zones.
[0114] In one embodiment, a chemical vapor deposition system is
provided which includes a housing, a track surrounded by the
housing, wherein the track defines a guide path, such as a channel,
adapted to guide the substrate through the chemical vapor
deposition system. The system includes a carrier for moving the
substrate along the channel of the track, wherein the track is
operable to levitate the carrier along the channel of the track.
The housing is formed from molybdenum, quartz, or stainless steel,
the track is formed from quartz, molybdenum, fused silica, ceramic,
and the carrier is formed from graphite.
[0115] In one embodiment, the track comprises a plurality of
openings and/or a conduit disposed along the floor of the track
each operable to supply a cushion of gas to the channel and the
bottom surface of the carrier to lift or levitate the carrier and
substantially center the carrier along the channel of the track.
The conduit may have a v-shape and the carrier may have a notch
(e.g. v-shape) disposed along its bottom surface. A gas is applied
to the notch of the carrier to substantially lift the carrier from
the floor of the track and to substantially center the carrier
along the channel of the track. The track may be tilted, such as at
an angle less than about ten, twenty, or between one and five
degrees, to allow the substrate to move and float from a first end
of the channel to a second end of the channel. The track and/or
housing may include multiple segments.
[0116] In one embodiment, the system may include a conveyor
operable to automatically introduce substrates into the channel, a
retriever operable to automatically retrieve substrates from the
channel, and/or a heating element operable to heat the substrate.
The heating element is coupled to or with the housing, the
substrate, and/or the track. The carrier is operable to carry
strips of the substrate along the channel of the track.
[0117] In one embodiment, a track assembly for moving a substrate
through a chemical vapor deposition system is provided which
includes a top section having a floor, side supports, such as a
pair of rails, disposed adjacent the floor, thereby defining a
guide path, such as a channel, to guide the substrate along the
floor. A bottom section is coupled to or with the top section to
form one or more chambers therebetween. The top section may include
a recessed bottom surface and the bottom section may include a
recessed top surface to form the chamber. In one embodiment the top
section and/or the bottom section is formed from molybdenum,
quartz, silica, alumina, or ceramic.
[0118] In one embodiment, the top section has a plurality of
openings disposed through the floor to provide fluid communication
between the chamber and the channel. A cushion of gas, such as
nitrogen, is supplied from the chamber to the channel to
substantially lift and carry the substrate from and along the floor
of the top section. The floor may be tilted, such as at an angle
less than about ten, twenty, or between one and five degrees, to
allow the substrate to move and float from a first end of the
channel to a second end of the channel.
[0119] In one embodiment, the top section has a plurality of
openings disposed through the pair of rails adjacent the floor. A
gas is supplied through the plurality of openings to substantially
center the substrate moving along the channel of the top section.
The floor may also include a tapered profile and/or a conduit
through which a gas is supplied each operable to substantially
center the substrate moving along the channel of the top section.
The conduit may have a v-shape and/or the substrate may have a
notch (e.g. v-shaped) for receiving a gas cushion disposed along a
bottom surface of the substrate operable to substantially center
the substrate moving along the channel of the top section.
[0120] In one embodiment, the track assembly may include a conveyor
operable to automatically introduce substrates into the channel
and/or a retriever operable to automatically retrieve substrates
from the channel. An injection line may be coupled to or with the
bottom section to supply a gas to the chamber through the floor to
substantially float the substrate along the floor of the top
section. The top section may further include recessed portions
adjacent the rails operable to receive reactor lid assembly, such
as a top plate. The track assembly may include a trough in which
the top section and bottom section are seated. The trough is formed
from quartz, molybdenum, or stainless steel.
[0121] In one embodiment, a method for forming a multi-layered
material during a chemical vapor deposition process is provided
which includes forming a gallium arsenide buffer layer on a gallium
arsenide substrate; forming an aluminum arsenide sacrificial layer
on the buffer layer; and forming an aluminum gallium arsenide
passivation layer on the sacrificial layer. The method may further
include forming a gallium arsenide active layer (e.g. at about 1000
nanometers thick) on the passivation layer. The method may further
include forming a phosphorous gallium arsenide layer on the active
layer. The method may further include removing the sacrificial
layer to separate the active layer from the substrate. The aluminum
arsenide sacrificial layer may be exposed to an etching solution
while the gallium arsenide active layer is separated from the
substrate during an epitaxial lift off process. The method may
further include forming additional multi-layered materials on the
substrate during a subsequent chemical vapor deposition process.
The buffer layer may be about 300 nanometers in thickness, the
passivation layer may be about 30 nanometers in thickness, and/or
the sacrificial layer may be about 5 nanometers in thickness.
[0122] In one embodiment, a method of forming multiple epitaxial
layers on a substrate using a chemical vapor deposition system is
provided which includes introducing the substrate into a guide
path, such as a channel, at an entrance of the system, while
preventing contaminants from entering the system at the entrance;
depositing a first epitaxial layer on the substrate, while the
substrate moves along the channel of the system; depositing a
second epitaxial layer on the substrate, while the substrate move
along the channel of the system; preventing mixing of gases between
the first deposition step and the second deposition step; and
retrieving the substrate from the channel at an exit of the system,
while preventing contaminants from entering the system at the exit.
The method may further include heating the substrate prior to
depositing the first epitaxial layer; maintaining the temperature
of the substrate as the first and second epitaxial layers are
deposited on the substrate; and/or cooling the substrate after
depositing the second epitaxial layer. The substrate may
substantially float along the channel of the system. The first
epitaxial layer may include aluminum arsenide and/or the second
epitaxial layer may include gallium arsenide. The method may
further include depositing a phosphorous gallium arsenide layer on
the substrate and/or heating the substrate to a temperature within
a range from about 300 degree Celsius to about 800 degrees Celsius
during the depositing of the epitaxial layers. A center temperature
to an edge temperature of the substrate may be within 10 degrees
Celsius of each other.
[0123] In one embodiment, a chemical vapor deposition reactor is
provided which includes a lid assembly having a body, and a track
assembly having a body and a guide path located along the
longitudinal axis of the body. The body of the lid assembly and the
body of the track assembly are coupled together to form a gap
therebetween that is configured to receive a substrate. The reactor
may further include a heating assembly containing a plurality of
heating lamps disposed along the track assembly and operable to
heat the substrate as the substrate moves along the guide path. The
reactor may further include a track assembly support, wherein the
track assembly is disposed in the track assembly support. The body
of the track assembly may contain a gas cavity within and extending
along the longitudinal axis of the body and a plurality of ports
extending from the gas cavity to an upper surface of the guide path
and configured to supply a gas cushion along the guide path. The
body of the track assembly may comprise quartz. The body of the lid
assembly may include a plurality of ports configured to provide
fluid communication to the guide path. The heating assembly may be
operable to maintain a temperature differential across the
substrate, wherein the temperature differential is less than 10
degrees Celsius. In one embodiment, the chemical vapor deposition
reactor is an atmospheric pressure chemical vapor deposition
reactor.
[0124] In one embodiment, a chemical vapor deposition system is
provided which includes a entrance isolator operable to prevent
contaminants from entering the system at an entrance of the system;
an exit isolator operable to prevent contaminants from entering the
system at an exit of the system; and a intermediate isolator
disposed between the entrance and exit isolators. The system may
further include a first deposition zone disposed adjacent the
entrance isolator and a second deposition zone disposed adjacent
the exit isolator. The intermediate isolator is disposed between
the deposition zones and is operable to prevent mixing of gases
between the first deposition zone and the second deposition zone. A
gas is injected into the entrance isolator at a first flow rate to
prevent back diffusion of gases from the first deposition zone, a
gas is injected into the intermediate isolator at a first flow rate
to prevent back mixing of gases between the first deposition zone
and the second deposition zone, and/or a gas is injected into the
exit isolator at a first flow rate to prevent contaminants from
entering the system at the exit of the system. An exhaust may be
disposed adjacent each isolator and operable to exhaust gases
injected by the isolators and/or disposed adjacent each deposition
zone and operable to exhaust gases injected into the deposition
zones.
[0125] In one embodiment, a chemical vapor deposition system is
provided which includes a housing, a track surrounded by the
housing, wherein the track contains a guide path adapted to guide a
substrate through the chemical vapor deposition system, and a
substrate carrier for moving the substrate along the guide path,
wherein the track is operable to levitate the substrate carrier
along the guide path. The track may include a plurality of openings
operable to supply a gas cushion to the guide path. The gas cushion
is applied to a bottom surface of the substrate carrier to lift the
substrate carrier from a floor of the track. The track may include
a conduit disposed along the guide path and operable to
substantially center the substrate carrier along the guide path of
the track. A gas cushion may be supplied through the conduit to a
bottom surface of the substrate carrier to substantially lift the
substrate carrier from a floor of the track. The track may be
tilted to allow the substrate to move from a first end of the guide
path to a second end of the guide path. The system may include a
heating assembly containing a plurality of heating lamps disposed
along the track and operable to heat the substrate as the substrate
moves along the guide path.
[0126] While the foregoing is directed to embodiments of the
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
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