U.S. patent application number 13/674421 was filed with the patent office on 2013-03-21 for method and apparatus for cleaning a substrate surface.
This patent application is currently assigned to Applied Materials, Inc.. The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to David K. Carlson, Roison L. Doherty, Errol Antonio C. SANCHEZ, Johanes S. Swenberg.
Application Number | 20130068390 13/674421 |
Document ID | / |
Family ID | 40281712 |
Filed Date | 2013-03-21 |
United States Patent
Application |
20130068390 |
Kind Code |
A1 |
SANCHEZ; Errol Antonio C. ;
et al. |
March 21, 2013 |
METHOD AND APPARATUS FOR CLEANING A SUBSTRATE SURFACE
Abstract
Embodiments described herein provide apparatus and methods for
processing a substrate. One embodiment comprises a cleaning
chamber. The cleaning chamber comprises one or more walls that form
a low energy processing region, a plasma generating source to
deliver electromagnetic energy to the low energy processing region,
a first gas source to deliver a silicon containing gas or a
germanium containing gas to the low energy processing region, a
second gas source to deliver a oxidizing gas to the low energy
processing region, an etching gas source to deliver a etching gas
to the low energy processing region, and a substrate support having
a substrate supporting surface, a biasing electrode, and a
substrate support heat exchanging device to control the temperature
of the substrate supporting surface.
Inventors: |
SANCHEZ; Errol Antonio C.;
(Tracy, CA) ; Swenberg; Johanes S.; (Los Gatos,
CA) ; Carlson; David K.; (San Jose, CA) ;
Doherty; Roison L.; (San Francisco, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc.; |
Santa Clara |
CA |
US |
|
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
40281712 |
Appl. No.: |
13/674421 |
Filed: |
November 12, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13175446 |
Jul 1, 2011 |
8309440 |
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13674421 |
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|
12146177 |
Jun 25, 2008 |
8008166 |
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13175446 |
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60952230 |
Jul 26, 2007 |
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Current U.S.
Class: |
156/345.27 |
Current CPC
Class: |
H01L 21/0262 20130101;
Y10S 438/976 20130101; C30B 29/06 20130101; H01L 21/31662 20130101;
H01L 21/67017 20130101; H01L 21/67069 20130101; C30B 25/08
20130101; H01L 21/02661 20130101; H01L 21/02532 20130101; H01L
21/67028 20130101; H01L 21/02238 20130101; H01L 21/02255 20130101;
H01L 21/02046 20130101 |
Class at
Publication: |
156/345.27 |
International
Class: |
H01L 21/67 20060101
H01L021/67 |
Claims
1. An apparatus for processing a substrate, comprising: a cleaning
chamber, comprising: one or more walls that form a low energy
processing region; a plasma generating source to deliver
electromagnetic energy to the low energy processing region; a first
gas source to deliver a silicon containing gas or a germanium
containing gas to the low energy processing region; a second gas
source to deliver a oxidizing gas to the low energy processing
region; an etching gas source to deliver a etching gas to the low
energy processing region; and a substrate support having a
substrate supporting surface, a biasing electrode, and a substrate
support heat exchanging device to control the temperature of the
substrate supporting surface.
2. The apparatus of claim 1, wherein the low energy processing
region is utilized to contain a plasma having ion energies of less
than 10 eV.
3. The apparatus of claim 2, further comprising: an epitaxial layer
deposition chamber comprising: one or more walls that form a
processing region; and a silicon gas source to deliver a silicon
containing gas to the processing region.
4. The apparatus of claim 3, further comprising: a transfer chamber
having one or more walls that enclose a transfer region and a robot
to transfer substrates between a first position within cleaning
chamber and a first position with the epitaxial layer deposition
chamber.
5. The apparatus of claim 2, further comprising: a shield
positioned between the substrate supporting surface and a lid of
the cleaning chamber.
6. The apparatus of claim 5, wherein the shield has a plurality of
holes formed therein and the shield is formed from a material
selected from a group consisting of silicon, yttrium, yttrium
oxide, germanium, boron, phosphorus, and silicon germanium.
7. The apparatus of claim 2, wherein the temperature of the
substrate supporting surface is controlled to a temperature less
than about 700.degree. C., and the temperature of the at least one
of the one or more walls is controlled to a temperature between
about 20.degree. C. and about 30.degree. C. using a heat exchanging
device.
8. The apparatus of claim 2, wherein the etching gas delivered from
the second gas source comprises nitrogen trifluoride (NF.sub.3) or
chlorine ion (Cl.sup.-).
9. The apparatus of claim 2, wherein the etching gas delivered from
the second gas source comprises helium, hydrogen, or neon.
10. The apparatus of claim 2, further comprising a UV light source
that is positioned to deliver one or more wavelengths of UV light
to a substrate disposed on the substrate support surface.
11. The apparatus of claim 2, wherein the plasma generating source
is adapted to deliver a plurality of pulses of RF energy to the
processing region.
12. An apparatus for processing a substrate, comprising: a cleaning
chamber, comprising: one or more walls that form a low energy
processing region; a plasma generating source to deliver
electromagnetic energy to the low energy processing region; a first
gas source to deliver a silicon containing gas or a germanium
containing gas to the low energy processing region; a second gas
source to deliver a oxidizing gas to the low energy processing
region; an etching gas source to deliver a etching gas to the low
energy processing region; and a substrate support having a
substrate supporting surface, a biasing electrode, and a substrate
support heat exchanging device to control the temperature of the
substrate supporting surface; and an epitaxial layer deposition
chamber comprising: one or more walls that form a processing
region; and a silicon gas source to deliver a silicon containing
gas to the processing region.
13. The apparatus of claim 12, wherein the low energy processing
region is utilized to contain a plasma having ion energies of less
than 10 eV.
14. The apparatus of claim 13, further comprising: a transfer
chamber having one or more walls that enclose a transfer region and
a robot to transfer substrates between a first position within
cleaning chamber and a first position with the epitaxial layer
deposition chamber.
15. The apparatus of claim 13, further comprising: a shield
positioned between the substrate supporting surface and a lid of
the cleaning chamber.
16. The apparatus of claim 15, wherein the shield has a plurality
of holes formed therein and the shield is formed from a material
selected from a group consisting of silicon, yttrium, yttrium
oxide, germanium, boron, phosphorus, and silicon germanium.
17. An apparatus for processing a substrate, comprising: a cleaning
chamber, comprising: one or more walls that form a low energy
processing region; a plasma generating source to deliver
electromagnetic energy to the low energy processing region; a first
gas source to deliver a silicon containing gas or a germanium
containing gas to the low energy processing region; a second gas
source to deliver a oxidizing gas to the low energy processing
region; an etching gas source to deliver a etching gas to the low
energy processing region; and a substrate support having a
substrate supporting surface, a biasing electrode, and a substrate
support heat exchanging device to control the temperature of the
substrate supporting surface; an epitaxial layer deposition chamber
comprising: one or more walls that form a processing region; and a
silicon gas source to deliver a silicon containing gas to the
processing region; and a transfer chamber having one or more walls
that enclose a transfer region and a robot to transfer substrates
between a first position within cleaning chamber and a first
position with the epitaxial layer deposition chamber.
18. The apparatus of claim 17, wherein the low energy processing
region is utilized to contain a plasma having ion energies of less
than 10 eV.
19. The apparatus of claim 18, further comprising: a shield
positioned between the substrate supporting surface and a lid of
the cleaning chamber.
20. The apparatus of claim 19, wherein the shield has a plurality
of holes formed therein and the shield is formed from a material
selected from a group consisting of silicon, yttrium, yttrium
oxide, germanium, boron, phosphorus, and silicon germanium.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/175,446 [Attorney Docket No. 12588USC1],
filed Jul. 1, 2011, which is a continuation of U.S. patent
application Ser. No. 12/146,177 [Attorney Docket No. 12588], filed
Jun. 25, 2008, which claims the benefit of the U.S. Provisional
Patent Application Ser. No. 60/952,230 [Attorney Docket No.
12588L], filed Jul. 26, 2007, all of which are herein incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to
method and apparatus for processing a semiconductor substrate. More
particularly, embodiments of the present invention relate to method
and apparatus for cleaning a surface of a silicon substrate.
[0004] 2. Description of the Related Art
[0005] Integrated circuits are formed in and on silicon and other
semiconductor substrates. In the case of single crystal silicon,
substrates are made by growing an ingot from a bath of molten
silicon, and then sawing the solidified ingot into multiple wafers.
An epitaxial silicon layer may then be formed on the
monocrystalline silicon wafer to form a defect free silicon layer
that may be doped or undoped. Semiconductor devices, such as
transistors, are manufactured from the epitaxial silicon layer. The
electrical properties of the formed epitaxial silicon layer will
generally be better than the properties of the monocrystalline
silicon substrate.
[0006] Surfaces of the monocrystalline silicon and the epitaxial
silicon layer are susceptible to contamination when exposed to
typical ambient conditions. Therefore, a substrate needs to be
cleaned to remove impurities and particles found on silicon wafer
surface prior to performing various semiconductor processes, such
as the formation of an epitaxial layer.
[0007] Conventionally, semiconductor substrates are cleaned using
wet cleaning processes or conventional plasma cleaning process.
However, wet cleaning processes have "queue time" issues, which can
cause wafer to wafer variation in wafer lots due to varying idle
times for different wafers in a lot. Conventional remote or in-situ
plasma cleaning processes can be very challenging due to the
contamination of the chamber and substrates processed in the
chamber due to the creation of unwanted species that are formed in
the gas phase or during the cleaning process. These unwanted
species either limit the cleaning action of the desired species or
introduce other complications to the cleaning process.
[0008] Therefore, there is a need for method and apparatus for
cleaning a substrate surface, especially for cleaning a substrate
surface prior to performing an epitaxial deposition process.
SUMMARY OF THE INVENTION
[0009] Embodiments described herein provide apparatus and methods
for processing a semiconductor substrate. One embodiment comprises
a cleaning chamber. The cleaning chamber comprises one or more
walls that form a low energy processing region, a plasma generating
source to deliver electromagnetic energy to the low energy
processing region, a first gas source to deliver a silicon
containing gas or a germanium containing gas to the low energy
processing region, a second gas source to deliver a oxidizing gas
to the low energy processing region, an etching gas source to
deliver a etching gas to the low energy processing region, and a
substrate support having a substrate supporting surface, a biasing
electrode, and a substrate support heat exchanging device to
control the temperature of the substrate supporting surface.
[0010] In another embodiment, an apparatus for processing a
substrate is provided. The apparatus includes a cleaning chamber,
comprising one or more walls that form a low energy processing
region, a plasma generating source to deliver electromagnetic
energy to the low energy processing region, a first gas source to
deliver a silicon containing gas or a germanium containing gas to
the low energy processing region, a second gas source to deliver a
oxidizing gas to the low energy processing region, an etching gas
source to deliver a etching gas to the low energy processing
region, and a substrate support having a substrate supporting
surface, a biasing electrode, and a substrate support heat
exchanging device to control the temperature of the substrate
supporting surface. The apparatus also includes an epitaxial layer
deposition chamber comprising one or more walls that form a
processing region, and a silicon gas source to deliver a silicon
containing gas to the processing region.
[0011] In another embodiment, an apparatus for processing a
substrate is provided. The apparatus includes a cleaning chamber,
comprising one or more walls that form a low energy processing
region, a plasma generating source to deliver electromagnetic
energy to the low energy processing region, a first gas source to
deliver a silicon containing gas or a germanium containing gas to
the low energy processing region, a second gas source to deliver a
oxidizing gas to the low energy processing region, an etching gas
source to deliver a etching gas to the low energy processing
region, and a substrate support having a substrate supporting
surface, a biasing electrode, and a substrate support heat
exchanging device to control the temperature of the substrate
supporting surface. The apparatus also includes an epitaxial layer
deposition chamber comprising one or more walls that form a
processing region, and a silicon gas source to deliver a silicon
containing gas to the processing region, and a transfer chamber
having one or more walls that enclose a transfer region and a robot
to transfer substrates between a first position within cleaning
chamber and a first position with the epitaxial layer deposition
chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features of
the present 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.
[0013] FIG. 1 schematically illustrates a sectional side view of a
cleaning chamber in accordance with one embodiment of the present
invention.
[0014] FIG. 2A schematically illustrates a sectional side view of a
cleaning chamber in accordance with another embodiment of the
present invention.
[0015] FIG. 2B schematically illustrates a sectional side view of a
cleaning chamber in accordance with one embodiment of the present
invention.
[0016] FIG. 3 illustrates a flow chart of a method for cleaning a
semiconductor substrate in accordance with one embodiment of the
present invention.
[0017] FIG. 4 schematically illustrates a partial sectional side
view of a cleaning chamber.
[0018] FIG. 5 schematically illustrates a plan view of a cluster
tool in accordance with one embodiment of the present
invention.
[0019] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0020] The present invention generally provides apparatus and
method for forming a clean and damage free surface on a
semiconductor substrate (or wafer). One embodiment of the present
invention provides a system that contains a cleaning chamber that
is adapted to expose a surface of substrate to a plasma cleaning
process prior to forming an epitaxial layer thereon. In one
embodiment, a method is employed to reduce the contamination of a
substrate processed in the cleaning chamber by depositing a
gettering material on the inner surfaces of the cleaning chamber
prior to performing a cleaning process on a substrate. The
gettering material will tend to trap contaminants found in the
cleaning chamber, thus insuring that the processed substrate is
clean, and future substrates processed in the chamber will have the
same desirable cleaning results. In one embodiment, oxidation and
etching steps are repeatedly performed on a substrate in the
cleaning chamber to expose or create a clean surface on a substrate
that can then have an epitaxial film placed thereon. In one
embodiment, a low energy plasma is used during the etching step.
The low energy of the plasma may be achieved by lowering the
substrate RF bias power, adjusting bias potential applied across
the substrate, pulsing the RF power used to generate a plasma in
the processing chamber, pulsing substrate RF bias power, forming a
plasma that contains light atomic species, using a plasma shield to
confine the plasma, adjusting processing position of the substrate
relative to the plasma, and/or a combination thereof.
Cleaning Chamber
[0021] FIG. 1 schematically illustrates a cross-sectional side view
of a cleaning chamber 100 in accordance with one embodiment of the
present invention. The cleaning chamber 100 is an inductively
coupled plasma processing chamber that is able to clean a substrate
102, in a processing region 122. In one embodiment, the cleaning
chamber 100 is a modified Decoupled Plasma Nitridation (DPN)
Chamber that is available from Applied Materials of Santa Clara,
which uses an inductively coupled radio frequency (RF) source.
Detailed description of a DPN chamber may be adapted to perform one
or more of the processes described herein can be found in U.S. Pat.
No. 6,660,659, entitled "Plasma Method and Apparatus for Processing
a Substrate" and U.S. Pat. No. 7,122,454, entitled "Method for
improving nitrogen profile in plasma nitrided gate dielectric
layers," which are both incorporated herein by reference.
[0022] The cleaning chamber 100 generally comprises an RF source
assembly 191, a process chamber assembly 193, and a substrate
support assembly 194. The process chamber assembly 193 generally
comprises multiple components that are used to form a vacuum in the
processing region 122 so that a plasma process can be performed
therein. In general the process chamber assembly 193 comprises a
chamber base 127, chamber walls 128 and a chamber lid 129 that
sealably enclose the processing region 122. The processing region
122 can be evacuated to a desired vacuum pressure by the use of a
vacuum pump 110 that is connected to the processing region 122
through the chamber base 127 and/or chamber walls 128. Generally,
the chamber walls 128 and chamber base 127 may be formed from a
metal, such as aluminum, or other suitable material.
[0023] In one embodiment, the chamber walls 128 and chamber lid 129
may be temperature controlled. Conventional methods and/or heat
exchanging devices may be used to heat and cool various chamber
components. For example, the chamber walls 128 and chamber lid 129
may be heated by heaters (not shown), such as lamp arrays,
positioned outside the process chamber assembly 193. In another
example, cooling gases may be circulated out side the process
chamber assembly 193 to cool the chamber walls 128 and chamber lid
129. In another example, heating and/or cooling conduits, which may
be embedded in the chamber walls 128 and chamber lid 129, may be
connected to a fluid heater/chiller device to control the
temperature. A method and apparatus that may be used to control the
temperature of the process chamber assembly 193 may be found in the
U.S. Pat. No. 6,083,323, entitled "Method for Controlling the
Temperature of the Walls of a Reaction Chamber During Processing,"
which is incorporated herein by reference.
[0024] In one embodiment, the RF source assembly 191 is an
inductive type RF source that generally contains an RF generator
108 and an RF match circuit 108A that are connected to a coil 109.
The coil 109 is positioned adjacent to the chamber lid 129. In one
embodiment, the RF generator 108 may operate at between about 0 and
about 3000 W at a frequency between about 400 kHz and about 60 MHz.
In one example, the RF generator 108 operates at a frequency of
13.56 MHz. In one embodiment, the RF generator 108 may provide
pulses of RF energy to the coil 109 to generate a plasma that has a
reduced energy level and/or plasma density.
[0025] The chamber lid 129 is generally a dielectric component
(e.g., quartz, ceramic material (e.g., alumina)) that is adapted to
allow the RF energy delivered from the inductive RF source assembly
191 to form a plasma in the processing region 122.
[0026] In one embodiment, the process chamber assembly 193 also
contains a gas delivery system 150 that is adapted to deliver one
or more process gasses into the processing region 122, which is
defined by the chamber base 127, the chamber walls 128 and the
chamber lid 129. In one embodiment, the processing region 122 is
circumscribed with one or more shields 130 that are intended to
protect the chamber walls 128 and/or the chamber lid 129 from the
generated plasma and preparation processes performed in the
chamber. In one embodiment, the gas delivery system 150 comprises
an ozonator configured to generate a stream of gas containing high
concentration ozone (O.sub.3). In one embodiment, the gas delivery
system is adapted to deliver a reactive gas, such as a silicon
containing gas (e.g., silane), a hydrogen containing gas (e.g.,
H.sub.2), a germanium containing gas, a chlorine containing gas, an
oxygen containing gas (e.g., O.sub.2), nitrogen trifluoride
(NF.sub.3), a boron containing gas (e.g., diborane), and/or a
phosphorus containing gas (e.g., phosphine) to name just a few. In
one embodiment, the gas delivery system is adapted to deliver an
inert gas, such as argon (Ar), helium (He), krypton (Kr) and/or
nitrogen (N.sub.2). The pressure in the processing region 122 can
be controlled by adjusting the flow rate of gas delivered by the
gas delivery system 150 and the pumping speed of the vacuum pump
110. A throttle valve 111 may be used to adjust the pumping speed
of the vacuum pump 110.
[0027] The substrate support assembly 194 generally includes a
substrate support 162 that contains a substrate supporting member
162A. The substrate supporting member 162A may be a conventional
electrostatic chuck that can be used to actively hold the substrate
during processing, or comprise a simple substrate support. A
temperature controller 161 is generally adapted heat and/or cool
the substrate supporting member 162A to a desired temperature by
use of temperature controller 161 and a heat exchanging device,
such embedded resistive heating elements or fluid cooling channels
that are coupled to a conventional heat exchanger (not shown). In
one embodiment, the temperature controller 161 is adapted to
operate and heat a substrate 102 positioned on the substrate
supporting member 162A to a temperature between about 20.degree. C.
and about 800.degree. C.
[0028] During processing the substrate support 162 may be connected
to a RF generator 123 so that an RF bias can be applied to a
conductive element disposed within a portion of the substrate
support 162 to pull the ions present in the plasma formed in the
processing region 122 to a surface of the substrate 102. In one
embodiment, the RF generator 123 is adapted to generate a cathodic
or anodic bias on the substrate during one or more portions of the
substrate cleaning process to adjust the retained charge on the
substrate and/or control the amount of ion and plasma bombardment
of the substrate surface. In one embodiment, the substrate
supporting member 162A is grounded, or DC (direct current) biased.
In another embodiment, the substrate supporting member 162A and
substrate are electrically floating during the plasma process in
order to minimize ion bombardment damage of substrate 102.
[0029] Referring to FIG. 1, delivering RF energy from the RF
generator 108 to the processing region 122 causes the gas atoms in
the processing region 122 to become ionized. When the substrate is
exposed to plasma generated in the processing region 122 during the
cleaning process, contamination on the surface of the substrate 102
may be knocked off or desorbed from the surface due to the energy
transferred by the ionized atoms in the plasma striking the surface
of the substrate 102. In one embodiment, the ionized gas atoms in
the plasma may be attracted to surface of the substrate 102 due to
a bias applied to the substrate 102 via the substrate supporting
member 162A.
[0030] In one embodiment, the RF power delivered to the coil 109 by
the RF generator 108 is pulsed to form a low energy plasma. In one
embodiment, a pulsed plasma process is generally a series of
sequential energy pulses delivered to the processing region 122 as
a function of time by use of the coil 109 by the RF generator 108.
Pulsing an inductive RF source to excite a plasma formed in the
processing region 122 will minimize the amount of damage caused to
the surface of the substrate due to the plasma potentials commonly
formed in conventional plasma processing chambers. The need to
minimize or eliminate any damage caused to the substrate surface by
the cleaning process is critical for single crystal substrates that
are being prepared for the formation of an epitaxial layer thereon.
Damage to the surface of the substrate needs to be minimized to
reduce the number of defects and stress in the formed epitaxial
layer. Therefore, pulsing the inductive RF source power allows one
to create and sustain a low electron temperature, and a low ion
energy plasma. Generally, the ions generated by a pulsed RF
inductive plasma, which produces ions with low ion energies (e.g.,
<10 eV) that will not damage a substrate positioned within the
plasma. An example of a method of pulsing RF power that can be
adapted to benefit one or more of the embodiments described herein
is further discussed in the commonly assigned U.S. Pat. No.
6,831,021, filed Jun. 12, 2003, which is incorporated herein by
reference.
[0031] FIG. 2A schematically illustrates a cross-sectional side
view of a cleaning chamber 100a in accordance with another
embodiment of the present invention. The cleaning chamber 100a is a
capacitively coupled plasma chamber. The cleaning chamber 100a
comprises a chamber lid 129 sealably coupled to the process chamber
assembly 196 and defining a process region 133. In this
configuration, the chamber lid assembly 130 comprises a gas
distribution plate (also known as a shower head) 132 and a base
plate 131 having a blocker plate 134 substantially parallel to the
gas distribution plate 132. The gas distribution plate 132 is
isolated from the chamber walls 128 using an electric insulator
135. The chamber lid assembly 130 is connected to the gas delivery
assembly 150. Reactant and/or cleaning gases from the gas delivery
system 150 may be flown to the process region 133 through a gas
passage 136. The RF source assembly 191 is coupled to the base
plate 131 providing RF power source for plasma generation. A RF
source for capacitive plasma generation generally comprises a radio
frequency (RF) power source, for example, a 13.56 MHz RF generator.
During processing, the substrate supporting member 162A may be
grounded. The bias potential between the substrate supporting
member 162A and the base plate 131 may ignite a plasma in the
process region 133. Activated species in the plasma can be used to
process the substrate 102. During processing the substrate support
162A may be connected to a RF generator 123 so that an RF bias can
be applied to a conductive element disposed in portions of the
substrate support member 162A to pull the ions present in the
plasma that has been generated in the processing region 122 to a
surface of the substrate 102. A more detailed description of a
capacitively coupled plasma reactor may be found in U.S. Pat. No.
6,495,233, entitled "Apparatus for distributing gases in a chemical
vapor deposition system," which is incorporated by reference
herein.
[0032] The cleaning chambers 100 and 100a (FIGS. 1 and 2) described
above may be used to clean a semiconductor substrate. Particularly,
the cleaning chambers 100 and 100a of the present invention may be
used to perform a damage free cleaning to a silicon surface.
[0033] In another embodiment, a cleaning chamber may use microwave
energy source (not shown) to generate a plasma that is used to
perform the cleaning process discussed herein.
Method for Cleaning a Substrate Surface
[0034] FIG. 3 illustrates a flow chart of a method 200 for cleaning
a semiconductor substrate in accordance with one embodiment of the
present invention. In one embodiment, the method 200 may be
performed in the cleaning chambers 100 or 100a described above. In
one embodiment, the cleaning process generally provides a method
for forming a clean and damage free surface on a semiconductor
substrate by use of plasma cleaning process.
[0035] In step 212, inner surfaces of a cleaning chamber, such as
the cleaning chamber 100 or cleaning chamber 100a, may be
regenerated. In one embodiment, step 212 comprises running an
etching process to remove any unwanted residual material and/or
contamination found on various inner surfaces of the cleaning
chamber. Conventional sputter etching and/or chemically assisted
etching processes may be performed to regenerate the inner surfaces
of the cleaning chamber, such as the chamber walls or shields
130.
[0036] In one embodiment, remote or in-situ plasma of a reactive
gas may be used to remove contaminations on the inner surface of
the cleaning chamber. The reactive gas may be selected from a wide
range of gases, including the commonly used halogens and halogen
compounds. For example, the reactive gas may be chlorine, fluorine
or compounds thereof, such as nitrogen trifluoride (NF.sub.3),
carbon tetrafluoride (CF.sub.4), sulfur hexafluoride (SF.sub.6),
hexafluoroethane (C.sub.2F.sub.6), carbon tetrachloride
(CCl.sub.4), hexachloroethane (C.sub.2Cl.sub.6), or combination
thereof depending on the deposited material to be removed.
[0037] In one embodiment, a carrier gas, such as argon, nitrogen,
helium, hydrogen or oxygen, etc, may be delivered to the processing
region of the cleaning chamber to aid the removal of the unwanted
species and/or to assist in the etching process, or help initiating
and/or stabilizing the plasma in the cleaning chamber.
[0038] In one embodiment, a cleaning gas may be delivered into the
cleaning chamber to etch a coating comprising a gettering material
(discussed below), such as silicon (Si) on the inner surface of the
cleaning chamber. The cleaning gas may comprise heated nitrogen
trifluoride (NF.sub.3), hydrogen chloride (HCl), or the combination
thereof. In one embodiment, a conventional remote plasma source
(RPS) may be coupled to the processing region of the process
chamber. RPS generally provides a reactive cleaning agent, such as
disassociated fluorine, that removes deposition and other process
byproducts from the chamber components, which is evacuated by the
vacuum pump 110.
[0039] In step 214, a shutter disk or a dummy substrate may be used
to cover a top surface of a substrate support member, such as the
substrate supporting member 162A of FIGS. 1 and 2A. The shutter
disk or dummy substrate is used to prevent any deposition on the
substrate support member during the subsequent deposition, such as
step 216, so that a substrate being processed will not be in
contact with any coatings formed inside the cleaning chamber.
Covering the substrate support member may also avoid chucking
problems when the substrate support member is an electrostatic
chuck configured to hold the substrate during processing.
[0040] In step 216, in one embodiment, one or more of the cleaning
chamber components, such as the chamber walls 128, shields 130,
shadow rings 138, chamber lid 129 may be conditioned by depositing
a gettering coating thereon. The gettering coating may comprise one
or more gettering materials. The term gettering materials generally
refers to any material that used to immobilize and/or adsorb (i.e.,
physiosorb, or chemisorb) any impurities found in the cleaning
chamber prior to or during the cleaning process. Gettering
materials are chosen to remove unwanted byproducts in the cleaning
chamber while presenting no other complications, such as generation
of new byproducts, generating particles, the unwanted dissipation
of RF power, or removal of desired species found in the processing
region 122. The thickness of the deposited gettering coating formed
during step 216 may be between about 10 .ANG. to about 1 .mu.m. The
coating on the inner surfaces may be used to reduce or prevent
contamination of subsequently processed substrates. The coating may
comprise a pure silicon material (e.g., epitaxial Si layer,
polycrystalline Si layer, amorphous Si layer), a silicon containing
layer, a germanium containing layer, and/or a silicon or germanium
layer that contains a desired level of one or more common dopant
materials (e.g., boron (B), phosphorus (P)), or the combinations
thereof. It is believed that coatings that are formed from pure
silicon will have a strong gettering affect for most contamination
commonly found on silicon substrates that are about to have an
epitaxial layer formed thereon. The use of silicon may also be
beneficial to minimize the effect of particle contamination on
device yield that would be caused by the metal contamination or
poisoning of a subsequently formed epitaxial layer on the cleaned
surface of the substrate. In one example, the gettering coating is
deposited using a silane (SiH.sub.4) containing gas that is
delivered into the processing region of the processing chamber to a
pressure of about 0.1 to about 5.0 Torr and an RF power between
about 200 watts and about 2 kW, while the chamber component
temperatures are maintained in a range between about 200.degree. C.
and about 500.degree. C.
[0041] In one embodiment, a layer of a gettering material that is
configured to getter oxygen may be deposited on the inner surfaces
of the cleaning chamber. In one embodiment, the coating comprises a
silicon (Si) layer of a thickness between about 10 .ANG. to about 1
.mu.m. The silicon coating may be deposited by use of a typical CVD
or ALD type processes that deliver a silicon containing precursor
to heated components that are positioned in the processing region
of the chamber. The components that are to receive the gettering
material may be heated by use of external lamps, embedded resistive
heating elements, and/or are heated by use of the RF plasma.
[0042] The coating of gettering material deposited in step 216 is
capable of immobilizing, absorbing or adsorbing undesired species
created during the cleaning process. Eventually, the gettering
capability of the coating will be reduced as the active surfaces
are covered or become less reactive. To compensate for this problem
a fresh coating of gettering material may be formed on the
components in the processing region 122 by repeating steps 212,
214, 216. In one embodiment, steps 212, 214, 216 may be repeated
prior to processing each substrate in the cleaning chamber. In
another embodiment, steps 212, 214, 216 may be repeated after
processing multiple substrates in the cleaning chamber.
[0043] After depositing the layer of gettering material, the
shutter disk, dummy disk, or dummy substrate is removed from the
cleaning chamber. Next, a substrate that is to be cleaned is
disposed in the cleaning chamber. Since the cleaning chamber is
generally kept in a vacuum state, contaminations and particles
found on the substrate surface, such as oxygen, carbon, fluorine,
silicon, and chlorine, may desorb or be moved so that they can be
gettered by the coating formed on the inner surface of the cleaning
chamber.
[0044] The substrate is then cleaned by performing one or more
oxidation and etching steps which are discussed below. The
oxidation process is used to consume contaminated or damaged
silicon found on the surface of the substrate. The formed oxidized
layer is then removed to expose a fresh and clean silicon surface.
The oxidation process is described in step 220, and the etching
step is described in step 222.
[0045] In step 220, an oxidizing agent is delivered to the cleaning
chamber to generate oxide on a top layer of the substrate being
cleaned. In one embodiment, the oxidizing agent comprises ozone
(O.sub.3), which enables oxidation of silicon at a relatively low
temperature. In one embodiment, ozone may be generated in an
ozonator from exposing oxygen to plasma, ultra violet (UV) energy,
or the combination of plasma and UV energy. In one embodiment, UV
lamps 145 are positioned to deliver energy to the surface of the
substrate during processing. In one embodiment (not shown), the UV
lamps are positioned so that it can deliver UV light through a port
formed in one of the chamber walls 128. Detailed description of
method for oxidation may be found in United States Patent
Application Publication No. 2006/0223315, entitled "Thermally
Oxidizing Silicon Using Ozone" and United States Patent Application
Publication No. 2002/0115266, entitled "Method and a System For
Sealing An Epitaxial Silicon Layer On A Substrate," which are both
incorporated herein by reference.
[0046] In one embodiment, the substrate surface is oxidized using a
high temperature oxidation process. In this case the substrate may
be heated on a substrate support member, such as the substrate
supporting member 162A of FIG. 1, to a temperature between about
400.degree. C. to about 700.degree. C. During oxidization, the
cleaning chamber is maintained at a lower temperature than the
substrate. For example, the cleaning chamber components (e.g.,
walls, shields), including the gas delivery paths, is maintained at
a temperature less than 400.degree. C., or substantially lower than
400.degree. C. In one embodiment, the substrate support
member/heater is maintained at about 700.degree. C., and the
cleaning chamber is maintained at about 350.degree. C. In one
embodiment, the walls are temperature controlled using fluid
flowing through channels formed in the walls of the processing
chamber.
[0047] In step 222, an etching process is then performed to remove
the oxide formed in step 220. The etching process may be achieved
by the use of physical, chemical, or a combination of physical and
chemical etching techniques.
[0048] In case of chemical etching, an etching gas may be delivered
into the cleaning chamber and a plasma may be ignited to generate
reactive species that chemically reacts with the material on the
substrate. Volatile byproducts of the reaction are removed by a
vacuum system connected to the cleaning chamber and/or gettered by
the coating formed on the surface of the chamber components in step
216. The etching gas may comprise chlorine, fluorine or other
compounds that are suitable for the removal of the oxides formed on
the substrate surface during step 220. In one embodiment, the
etching gas comprises nitrogen trifluoride (NF.sub.3), chlorine ion
(Cl.sup.-), and a carrier gas, such as argon.
[0049] A physical etching is performed by generating a plasma that
provides energetic species that are used to bombard the substrate
surface to physically remove the material from the substrate
surface. In some cases it is desirable to provide a bias to the
substrate support to accelerate ions formed in the plasma towards
the substrate surface. The bombarding ions physically remove
material on the substrate surface by a sputter-etching action. Low
energy physical bombardment of the substrate surface is generally
desirable to reduce the amount damage to the silicon lattice at the
substrate surface. A low power bias may be used to remove the
oxidized layer and minimize the damage to the surface of the
substrate. Conventional dry etching processes are generally used to
rapidly remove material without need to be concerned about the
substrate material lattice damage created by plasma assisted
material removal process. Conventional sputter etching techniques
are generally not desirable for cleaning substrates prior to
performing epitaxial deposition steps due to the high energy of the
bombarding ions and/or byproducts. More particularly, the etching
process of the present invention comprises adjusting the energy of
the ions formed during the etching process to minimize the damage
to the crystalline material exposed at the substrate surface during
step 222. In one embodiment, by use of a low RF power material
removal process in a chamber that has a gettering layer disposed
therein the material removal process performed in step 222 will
form a damage-free and clean surface on the substrate, which is
important to assure a high quality epitaxial layer is formed during
the subsequent deposition process step(s). In one embodiment, the
RF generator 123 is adapted to deliver an average RF bias power
between about 25 W and about 500 W to the conductive element
disposed in the substrate support 162 to perform the etching
process.
[0050] In an alternate embodiment of the method 200, step 216 is
performed after step 220, but prior to performing step 222. In one
aspect of this alternate embodiment, steps 220 and 222 are
performed in different chambers so that the gettering layer is not
deposited on the surface of the oxidized substrate (step 216) prior
to performing step 222. In another aspect of the alternate
embodiment, in which a single cleaning chamber is used, step 220 is
performed on the substrate, then the substrate is removed from the
cleaning chamber so that a dummy substrate can be inserted to allow
step 216 to be performed without coating the surface of the
oxidized substrate with the gettering material, and then the dummy
substrate is removed and the oxidized substrate is reinserted so
that step 222 can be performed.
[0051] FIG. 4 schematically illustrates a partial sectional side
view of a cleaning chamber 300 that generally illustrates a
mechanism that may cause the physical etching process. The cleaning
chamber 300 having a chamber body 301 defining a process region
302. A substrate 303 to be cleaned may be disposed in the process
region 302 on a substrate support 304. A coil 305 is positioned
outside an upper portion of the chamber body 301 to generate a
plasma 308 in an upper portion of the process region 302. A RF
source 306 may be connected to the coil 305 to provide RF energy
for plasma generation. A bias source 307 may be coupled to the
substrate support 304 to provide a bias potential to the substrate
303 and/or the substrate support 304. Activated species 309 or ions
310 generated in the plasma 308 may be attracted to a top surface
303A of the substrate 303 to remove materials thereon.
[0052] In one embodiment, energy of the activated species 309
and/or ions 310 may be adjusted so that no physical damage will
occur to the top surface 303A during material removal. The
adjustment may be achieved by lowering the substrate RF bias power,
adjusting bias potential applied across the substrate, pulsing RF
power delivered to the plasma generating components (e.g.,
inductive coupled device (e.g., coil), capacitively coupled device
(e.g., showerhead, microwave source), pulsing substrate RF bias
power, forming a plasma that contains light atomic species in
etching gas, using a plasma shield to confine the plasma, adjusting
processing position of the substrate relative to the plasma, and/or
a combination thereof.
[0053] In one embodiment, the energy of the activated species may
be reduced by using a lowered RF bias power delivered to the
substrate support. In one embodiment, the power of a bias source,
such as the bias source 307 in FIG. 4, may be set at about 50 W for
removing silicon dioxide from a top surface of the a substrate.
[0054] In one embodiment, the potential of a bias source, such as
the bias source 307 in FIG. 4, may be adjusted to be less cathodic
to reduce the bias on the substrate. In one embodiment, the bias
source may be eliminated and the substrate is positioned on a
grounded substrate support. In another embodiment, a reversed bias
may be applied to apply a repelling force to ions and reactive ion
species in the plasma. For example, a reversed bias may be used
when cleaning a silicon-on-insulator substrate.
[0055] In one embodiment, the plasma energy may be reduced by
pulsing the RF source and/or the substrate bias source. The degree
of energy reduction may be controlled by adjusting duty cycle of
the RF pulses delivered to the plasma generating components (e.g.,
coil, showerhead, microwave source). Pulsing the RF source reduces
density of activated species in a plasma generated by the RF
source. In one embodiment, a RF source is pulsed to maintain a low
energy plasma in a cleaning chamber during a cleaning process.
Pulsing the RF source reduces the overall plasma and activated
species density in the plasma processing region, and therefore
reduces the energy and number of bombarding species to avoid
damages to the substrate. A detailed discussion on pulsed plasma
processes may be found in the U.S. patent application Ser. No.
11/614,019 (Docket No. APPM 10983), filed Dec. 20, 2007, entitled
"Method and Apparatus for Fabricating a High Dielectric Constant
Transistor Gate Using a Low Energy Plasma Apparatus," which is
incorporated herein by reference.
[0056] In one embodiment, the etching gas comprises one or more
lighter species that used to generate the low energy plasma to
reduce or minimize any damage created on the substrate surface by
physical etching processes. In one embodiment, a lighter gas
species, such as helium (He), neon (Ne), hydrogen (H.sub.2), or
combinations thereof may be added to an etching gas that contains
other process gases, such as argon (Ar). In one embodiment, the
etching gas comprises argon and helium. In another embodiment, the
etching gas substantially comprises argon, helium, and hydrogen
gas. In another embodiment, the etching gas comprises argon and
hydrogen. In another embodiment, the etching gas comprises argon
and nitrogen. In yet another embodiment, the etching gas
substantially comprises helium (He), neon (Ne), or hydrogen
(H.sub.2).
[0057] In another embodiment, a plasma shield 140 (FIG. 2B) may be
positioned near the surface of a substrate during processing. FIG.
2B schematically illustrates a cross-sectional side view of one
embodiment of the cleaning chamber 100 that contains a plasma
shield 140. The plasma shield is used to reduce or minimize the
amount of and/or the energy of the bombarding species near the
surface of the substrate. The plasma shield 140 may be a perforated
or porous material that allows portions of the plasma and/or
process gases to pass through during processing. In one embodiment,
the perforations are a plurality of holes 141 that pass through the
plasma shield. In one embodiment, the plasma shield is made of a
dielectric material, or is coated with a dielectric material, that
is compatible with the plasma and process gases (e.g., quartz,
SiO.sub.2). In one embodiment, the plasma shield is made from the
same material as other components in the chamber, such as the
material from which the chamber lid 129 or chamber walls 128 are
made. In one embodiment, the plasma shield is made from a material
selected from a group consisting of silicon, yttrium, yttrium
oxide, germanium, boron, phosphorus, and silicon germanium
compounds.
[0058] In another embodiment, relative position of a substrate
being processed and the plasma generated in a cleaning chamber may
be adjusted to adjust amount of bombardment of the substrate
surface by the ions or active species in the plasma. Similar
adjustment is described in the commonly assigned United States
Patent Application Publication No. 2006/0105114, entitled
"Multi-Layer High Quality Gate Dielectric for Low-Temperature
Poly-Silicon TFTs," which is incorporated herein by reference.
[0059] Returning back to FIG. 3, the exemplary etching process of
step 222 may be performed in a cleaning chamber similar to the
cleaning chamber 100 of FIG. 1 to remove silicon oxides formed on a
top surface of a substrate. During processing, the chamber pressure
may be maintained at about 1 mTorr to about 1 Torr. In one
embodiment, the chamber pressure may be maintained at between about
20 mTorr to about 800 mTorr. An etching gas comprising helium and
argon may be provided to the process region. In one embodiment, the
chamber pressure may be about 5 mTorr to about 20 mTorr and the
etching gas comprises primarily helium. The substrate being
processed may also be heated to a temperature up to about
700.degree. C. The cleaning chamber may be maintained at a
temperature between about 20.degree. C. to about 400.degree. C. In
one embodiment, the chamber is maintained at a temperature of about
30.degree. C. It is believed that maintaining the chamber walls at
a lower temperature may help reduce the erosion of the chamber
walls.
[0060] Returning to FIG. 3, steps 220, 222 may be repeated one or
more times until the substrate is cleaned. Once the substrate
surface is cleaned then step 224 and/or step 226 may then be
performed on the clean substrate surface.
[0061] In step 224, a passivation treatment is performed to the
cleaned substrate so that the substrate remains clean until a
subsequent epitaxial deposition process. In one embodiment, the
passivation treatment comprises flowing a passivation gas and
generating a plasma of the passivation gas. In one embodiment, the
passivation gas comprises a dilute concentration of hydrogen gas
(H.sub.2) that is used to terminate the cleaned silicon surface
with hydrogen. In one embodiment, the passivation treatment
comprises delivering a hydrogen containing gas comprising about 1%
of hydrogen gas while the substrate is maintained at a temperature
between about 50 and about 500.degree. C.
[0062] In step 226, an epitaxial silicon layer may be grown on the
cleaned substrate in an epitaxial chamber. To grow a silicon
epitaxial layer using a CVD process, a substrate is positioned in a
epitaxial chamber set to an elevated temperature, for example,
about 500.degree. C. to 800.degree. C., and a reduced pressure
state or atmospheric pressure. While maintaining in the elevated
temperature and reduced pressure state, a silicon containing gas,
such as monosilane gas or dichlorosilane gas, is supplied to the
epitaxial chamber and a silicon epitaxial layer is grown by vapor
phase growth to form a semiconductor layer having the same
crystalline orientation as the substrate on which it is grown. The
processes may operate at a range of pressures from about 0.1 Torr
to about 760 Torr. Hardware that may be used to deposit
silicon-containing films includes the Epi Centura.RTM. system and
the Poly Gen.RTM. system available from Applied Materials, Inc.,
located in Santa Clara, Calif. A detailed description of an
epitaxial chamber may be found in U.S. patent application Ser. No.
11/767,619 (Docket No. 10394), entitled "Modular CVD EPI 300 mm
Reactor," filed Jun. 25, 2007, which is incorporated herein by
reference.
[0063] The method 200 may be performed in a cluster tool comprising
a cleaning chamber and an epitaxial chamber. In conventional
configurations, a substrate may be wait a period of time after
performing a conventional cleaning process (e.g., wet clean
processes) before it is it is transferred into an epitaxial
deposition chamber to form an epitaxial layer. The process of
waiting can affect the cleanliness of the substrate surface, which
can affect the wafer to wafer process results. In one embodiment,
the timing between the completion of step 224 and the subsequent
epitaxial layer deposition process (i.e., step 226) is scheduled
such that the substrate is transferred to the epitaxial chamber
immediately after passivation process has been completed. The use
of a controller 147 that controls the process timing, or
scheduling, can improve the process repeatability and device yield.
In one embodiment, a queuing step may be added before step 224 to
eliminate waiting after passivation. In another embodiment, step
222 and/or step 224 are not started until the controller 147 is
sure that the epitaxial deposition chamber will be ready to receive
the substrate when step 222 and/or step 224 is completed.
[0064] In one embodiment, steps 220 is performed in a first
cleaning chamber 100, and step 222 is performed in a second
cleaning chamber 100 to reduce any process affect that step 220 may
have step 222 or vice versa. In one embodiment, the first cleaning
chamber 100 may perform steps 212-220 and the second cleaning
chamber 100 may perform steps 212-216 and steps 222-224.
[0065] The controller 147 is generally designed to facilitate the
control and automation of the first cleaning chamber 100 and system
400 (FIG. 5) and typically may include a central processing unit
(CPU) (not shown), memory (not shown), and support circuits (or
I/O) (not shown). The CPU may be one of any form of computer
processors that are used in industrial settings for controlling
various chamber processes and hardware (e.g., detectors, motors,
fluid delivery hardware, etc.) and monitor the system and chamber
processes (e.g., substrate position, process time, detector signal,
etc.). The memory is connected to the CPU, and may be one or more
of a readily available memory, such as random access memory (RAM),
read only memory (ROM), floppy disk, hard disk, or any other form
of digital storage, local or remote. Software instructions and data
can be coded and stored within the memory for instructing the CPU.
The support circuits are also connected to the CPU for supporting
the processor in a conventional manner. The support circuits may
include cache, power supplies, clock circuits, input/output
circuitry, subsystems, and the like. A program (or computer
instructions) readable by the controller 147 determines which tasks
are performable on a substrate. Preferably, the program is software
readable by the controller 147, which includes code to generate and
store at least process recipe sequencing, substrate positional
information, the sequence of movement of the various controlled
components, process control, process timing, scheduling, queuing
steps, and any combination thereof.
Cluster Tool
[0066] FIG. 5 illustrates a plan view of a cluster tool 400 for
semiconductor processing in accordance with one embodiment of the
present invention. A cluster tool is a modular system comprising
multiple chambers which perform various functions in a
semiconductor fabrication process. The cluster tool 400 comprises a
central transfer chamber 401 connected to a front end environment
404 via a pair of load locks 405. Factory interface robots 408A and
408B are disposed in the front end environment 404 and are
configured to shuttle substrates between the load locks 405 and a
plurality of pods 403 mounted on the front end environment 404.
[0067] A plurality of chambers 407, 408, 409, and 410 are mounted
to the central transfer chamber 401 for performing a desired
process. A central robot 406 disposed in the central transfer
chamber 401 is configured to transfer substrates between the load
locks 405 and the chambers 407, 408, 409, 410, or among the
chambers 407, 408, 409, 410.
[0068] In one embodiment, the cluster tool 400 comprises a cleaning
chamber, such as the cleaning chamber 100 of FIG. 1, and two
epitaxial chambers 407, 408. The chamber 410 may be a cleaning
chamber, such as the cleaning chamber 100 described in FIG. 1. The
chamber 410 is configured to clean a substrate prior to an
epitaxial growth process. The chambers 407, 408 may be epitaxial
chambers capable of perform an epitaxial growth process. An
exemplary epitaxial chamber may be found in U.S. patent application
Ser. No. 11/767,619 (Docket No. 10394), entitled "Modular CVD EPI
300 mm Reactor," filed Jun. 25, 2007, which is incorporated herein
by reference.
[0069] The cluster tool 400 may be used to performed the method 200
described above. During processing, a substrate that is to be
processed may arrive to the cluster tool 400 in a pod 403. The
substrate is transferred from the pod 403 to the vacuum compatible
load lock 405 by the factory interface robot 408A or 408B. The
substrate is then picked by the central robot 406 in the transfer
chamber 401 which is generally kept in a vacuum state. The central
robot 406 then loads the substrate into the cleaning chamber 410,
whose inner surface has been regenerated and coated as described in
step 212, 214, 216 of the method 200. A clean process including
steps 220, 222, 224 of the method 200 may be performed in the
cleaning chamber 410 to the substrate. The central robot 406 then
picks up the substrate from the cleaning chamber 410 and loads the
substrate into the epitaxial chamber 407 or 408 whichever is
available. An epitaxial layer may be grown on the cleaned substrate
in the epitaxial chamber 407 or 408.
[0070] In one embodiment, the cluster tool 400 is configured such
that it contains two cleaning chambers 100 (or 100a) that are
positioned in the chamber 409 and chamber 410 positions (FIG. 5)
and two epitaxial chambers positioned in the chamber 407 or chamber
408 positions. As noted above, in this configuration it may
desirable to perform step 220 in one cleaning chamber (e.g.,
chamber 410) and perform steps 222 and 224 in the other cleaning
chamber (e.g., chamber 409) before performing the epitaxial layer
deposition step 226 in either of the epitaxial chambers 407,
408.
[0071] In another embodiment, the cluster tool comprises a plasma
immersion ion implantation (P3I) chamber. For example, the chamber
409 may be a P3I chamber configured to implant one or more dopant
into the epitaxial layer on the substrate. Exemplary P3I chamber
may be found in U.S. Pat. No. 6,939,434, entitled "Externally
Excited Torroidal Plasma Source with Magnetic Control of Ion
Distribution," and U.S. Pat. No. 6,893,907, entitled "Fabrication
of Silicon-on-Insulator Structure Using Plasma Immersion Ion
Implantation," which are incorporated herein by reference.
[0072] While the foregoing is directed to embodiments of the
present 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.
* * * * *