U.S. patent application number 15/413534 was filed with the patent office on 2018-03-15 for degassing chamber for arsenic related processes.
The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Xinyu BAO, Schubert S. CHU, Hua CHUNG, Chun YAN.
Application Number | 20180073162 15/413534 |
Document ID | / |
Family ID | 61559499 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180073162 |
Kind Code |
A1 |
BAO; Xinyu ; et al. |
March 15, 2018 |
DEGASSING CHAMBER FOR ARSENIC RELATED PROCESSES
Abstract
Implementations of the present disclosure generally relate to
the fabrication of integrated circuits. More specifically,
implementations disclosed herein relate to apparatus, systems, and
methods for reducing substrate outgassing. A substrate is processed
in an epitaxial deposition chamber for depositing an
arsenic-containing material on a substrate and then transferred to
a degassing chamber for reducing arsenic outgassing on the
substrate. The degassing chamber includes a gas panel for supplying
hydrogen, nitrogen, and oxygen and hydrogen chloride or chlorine
gas to the chamber, a substrate support, a pump, and at least one
heating mechanism. Residual or fugitive arsenic is removed from the
substrate such that the substrate may be removed from the degassing
chamber without dispersing arsenic into the ambient
environment.
Inventors: |
BAO; Xinyu; (Fremont,
CA) ; YAN; Chun; (San Jose, CA) ; CHUNG;
Hua; (San Jose, CA) ; CHU; Schubert S.; (San
Francisco, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
61559499 |
Appl. No.: |
15/413534 |
Filed: |
January 24, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62394282 |
Sep 14, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C30B 25/12 20130101;
C23C 16/481 20130101; C30B 25/165 20130101; H01L 21/30 20130101;
C23C 16/56 20130101; H01L 21/67201 20130101; C30B 25/00 20130101;
C30B 29/06 20130101; H01L 21/2252 20130101; H01L 21/67196 20130101;
C30B 25/105 20130101; C30B 25/14 20130101; C23C 16/301 20130101;
C30B 25/08 20130101; C30B 33/00 20130101; H01L 21/67167 20130101;
H01L 21/67253 20130101; C23C 16/4405 20130101; H01L 21/67207
20130101; C30B 29/40 20130101; C30B 35/00 20130101; C23C 16/24
20130101 |
International
Class: |
C30B 25/08 20060101
C30B025/08; C30B 25/12 20060101 C30B025/12; C30B 25/10 20060101
C30B025/10; C30B 25/14 20060101 C30B025/14; C30B 29/40 20060101
C30B029/40; C23C 16/30 20060101 C23C016/30; C23C 16/48 20060101
C23C016/48; C23C 16/56 20060101 C23C016/56; H01L 21/67 20060101
H01L021/67 |
Claims
1. A system, comprising: an epitaxial deposition chamber for
depositing an arsenic-containing material on a substrate; a
transfer chamber; and a degassing chamber for reducing arsenic
outgassing on the substrate, wherein each of the epitaxial
deposition chamber and the degassing chamber is connected to the
transfer chamber, and wherein the degassing chamber comprises: a
plurality of chamber walls; a gas panel; at least one heating
mechanism; a substrate support; a pump; and an arsenic detecting
device, wherein each of the gas panel, the at least one heating
mechanism, the substrate support, the pump, and the arsenic
detecting device is connected to at least one of the plurality of
chamber walls.
2. The system of claim 1, wherein the at least one heating
mechanism is an infrared lamp.
3. The system of claim 1, wherein the at least one heating
mechanism is a resistive heater.
4. The system of claim 1, wherein the substrate support supports a
single substrate.
5. The system of claim 1, wherein the substrate support supports a
plurality of substrates.
6. The system of claim 1, further comprising a second epitaxial
deposition chamber.
7. The system of claim 1, wherein a first substrate may be
processed in the epitaxial deposition chamber and a second
substrate may be processed in the degassing chamber in
parallel.
8. A method for reducing arsenic outgassing, comprising:
transferring a substrate from an epitaxial deposition chamber for
depositing an arsenic-containing material on a substrate to a
degassing chamber for reducing arsenic outgassing on the substrate;
flowing hydrogen or nitrogen gas into the degassing chamber;
ceasing the flow of hydrogen or nitrogen gas into the degassing
chamber; flowing a mixture of oxygen and nitrogen gas into the
degassing chamber to reduce arsenic outgassing on the substrate to
a first amount; ceasing the flow of oxygen and nitrogen gas into
the degassing chamber; flowing a chlorine-containing gas into the
degassing chamber to clean the degassing chamber after the
substrate is removed; and ceasing the flow of the
chlorine-containing gas into the degassing chamber.
9. The method of claim 8, further comprising detecting the first
amount of arsenic outgassing using an arsenic detecting device.
10. The method of claim 8, wherein the temperature in the degassing
chamber is between about 100.degree. C. and about 300.degree.
during flowing a mixture of oxygen and nitrogen gas into the
degassing chamber to reduce arsenic outgassing on the substrate to
a first amount.
11. The method of claim 8, wherein the flowing hydrogen or nitrogen
gas into the degassing chamber occurs for between about 1 minute
and about 10 minutes at a flow rate between about 10 slm and about
30 slm at a pressure between about 1 Torr and about 100 Torr.
12. The method of claim 8, wherein the flowing a mixture of oxygen
and nitrogen gas into the degassing chamber to reduce arsenic
outgassing on the substrate to a first amount comprises: flowing
nitrogen gas into the degassing chamber; flowing oxygen gas into
the degassing chamber after flowing nitrogen gas into the degassing
chamber; and flowing nitrogen into the degassing chamber after
flowing oxygen gas into the degassing chamber.
13. The method of claim 12, wherein flowing oxygen gas into the
degassing chamber occurs at a pressure between about 80 Torr and
about 300 Torr.
14. The method of claim 13, wherein flowing nitrogen into the
degassing chamber after flowing oxygen gas into the degassing
chamber occurs at a pressure less than about 20 Torr.
15. A method for reducing arsenic outgassing, comprising:
depositing an arsenic-containing material on a first substrate in
an epitaxial deposition chamber; transferring the first substrate
from the epitaxial deposition chamber to a degassing chamber;
reducing arsenic outgassing on the first substrate, wherein the
reducing arsenic outgassing comprises: flowing hydrogen or nitrogen
gas into the degassing chamber; ceasing the flow of hydrogen or
nitrogen gas into the degassing chamber; flowing a mixture of
oxygen and nitrogen gas into the degassing chamber to reduce
arsenic outgassing on the first substrate to a first amount;
ceasing the flow of oxygen and nitrogen gas into the degassing
chamber; flowing a chlorine-containing gas into the degassing
chamber to clean the degassing chamber after the substrate is
removed; ceasing the flow of the chlorine-containing gas into the
degassing chamber; and detecting the amount of arsenic outgassing
using an arsenic detecting device; and depositing an
arsenic-containing material on a second substrate in the epitaxial
deposition chamber while reducing arsenic outgassing on the first
substrate in the degassing chamber.
16. The method of claim 15, wherein a temperature in the degassing
chamber is between about 100.degree. C. and about 300.degree.
during flowing a mixture of oxygen and nitrogen gas into the
degassing chamber to reduce arsenic outgassing on the substrate to
a first amount.
17. The method of claim 15, wherein flowing hydrogen or nitrogen
gas into the degassing chamber occurs for between about 1 minute
and about 10 minutes at a flow rate between about 10 slm and about
30 slm at a pressure between about 1 Torr and about 100 Torr.
18. The method of claim 15, wherein flowing a mixture of oxygen and
nitrogen gas into the degassing chamber to reduce arsenic
outgassing on the substrate to a first amount comprises: flowing
nitrogen gas into the degassing chamber; flowing oxygen gas into
the degassing chamber after flowing nitrogen gas into the degassing
chamber; and flowing nitrogen into the degassing chamber after
flowing oxygen gas into the degassing chamber.
19. The method of claim 18, wherein the flowing oxygen gas into the
degassing chamber occurs at a pressure between about 80 Torr and
about 300 Torr.
20. The method of claim 19, wherein the flowing nitrogen into the
degassing chamber after flowing oxygen gas into the degassing
chamber occurs at a pressure less than about 20 Torr.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Patent
Application Ser. No. 62/394,282, filed on Sep. 14, 2016, which is
herein incorporated by reference in its entirety.
BACKGROUND
Field
[0002] Implementations of the present disclosure generally relate
to the fabrication of integrated circuits. More specifically,
implementations disclosed herein relate to systems, methods, and
apparatus for reducing substrate outgassing.
Description of the Related Art
[0003] The manufacture of modern logic, memory, or integrated
circuits typically includes more than four hundred process
operations. A number of these operations are thermal processes that
raise the temperature of the semiconductor substrate to a target
value to induce rearrangement in the atomic order or chemistry of
thin surface films (e.g., diffusion, oxidation, recrystallization,
salicidation, densification, flow).
[0004] Ion implementation is a method for the introduction of
chemical impurities in semiconductor substrates to form the p-n
junctions necessary for field effect or bipolar transistor
fabrication. Such impurities include P-type dopants, such as boron,
aluminum, gallium, beryllium, magnesium, and zinc, and N-type
dopants such as phosphorus, arsenic, antimony, bismuth, selenium,
and tellurium. Ion implantation of chemical impurities disrupts the
crystallinity of the semiconductor substrate over the range of the
implant. At low energies, relatively little damage occurs to the
substrate. However, the implanted dopants will not come to rest on
electrically active sites in the substrate. Therefore, an anneal is
required to restore the crystallinity of the substrate and drive
the implanted dopants onto electrically active crystal sites.
[0005] During the processing of the substrate in, for example, an
RTP chamber, the substrate may tend to outgas impurities implanted
therein. These outgassed impurities may be the dopant material, a
material derived from the dopant material, or any other material
that may escape the substrate during the annealing process, such as
the sublimation of silicon. The outgassed impurities may deposit on
the colder walls and on the reflector plate of the chamber. This
deposition may interfere with temperature pyrometer readings and
with the radiation distribution fields on the substrate, which in
turn affects the temperature at which the substrate is annealed.
Deposition of the outgassed impurities may also cause unwanted
particles on the substrates and may also generate slip lines on the
substrate. Depending on the chemical composition of the deposits,
the chamber is taken offline for a wet clean process.
[0006] Furthermore, one of the biggest challenges is to control the
outgassing from the substrates after an arsenic doped silicon
process, which is greater than the outgassing from the substrates
during a III-V epitaxial growth process. Limitations in current
outgassing control include that the thermal back process (>200
degrees Celsius) in either a process chamber or an etch chamber is
not suitable after an arsenic doped silicon process, or other
arsenic related process, as longer bake times for each substrate is
necessary to drive out arsenic related outgassing gasses from the
substrate surface and throughput is lowered. Furthermore, a long
N.sub.2 purge/pump cycle is less efficient and has a large impact
on throughput. Testing has been performed on the prior known
methods and results indicate that after ten cycles of pump/purge,
arsenic outgassing was still detected at 1.9 parts per billion.
[0007] Absolute zero parts per billion (ppb) outgassing is
typically desired for arsenic residuals due to arsenic toxicity. To
minimize toxicity from arsenic outgassing during subsequent
handling and processing of substrates, there is a need for improved
systems, methods, and apparatus for reducing substrate
outgassing.
SUMMARY
[0008] In one implementation, a system is disclosed. The system
includes an epitaxial deposition chamber for depositing an
arsenic-containing material on a substrate, a transfer chamber, and
a degassing chamber for reducing arsenic outgassing on the
substrate. Each of the epitaxial deposition chamber and the
degassing chamber is connected to the transfer chamber. The
degassing chamber for reducing arsenic outgassing on the substrate
includes a plurality of chamber walls, a gas panel, at least one
heating mechanism, a substrate support, a pump, and an arsenic
detecting device. Each of the gas panel, the at least one heating
mechanism, the substrate support, the pump, and the arsenic
detecting device is connected to at least one of the plurality of
chamber walls.
[0009] In another implementation, a method for reducing arsenic
outgassing is disclosed. The method includes transferring a
substrate from an epitaxial deposition chamber for depositing an
arsenic-containing material on a substrate to a degassing chamber
for reducing arsenic outgassing on the substrate, flowing hydrogen
or nitrogen gas into the degassing chamber, ceasing the flow of
hydrogen or nitrogen gas into the degassing chamber, flowing a
mixture of oxygen and nitrogen gas into the degassing chamber to
reduce arsenic outgassing on the substrate to a first amount,
ceasing the flow of oxygen and nitrogen gas into the degassing
chamber, flowing a chlorine-containing gas into the degassing
chamber to clean the degassing chamber after the substrate is
removed, and ceasing the flow of the chlorine-containing gas into
the degassing chamber.
[0010] In yet another implementation, a method for reducing arsenic
outgassing is disclosed. The method includes depositing an
arsenic-containing material on a first substrate in an epitaxial
deposition chamber, transferring the first substrate from the
epitaxial deposition chamber to a degassing chamber, reducing
arsenic outgassing on the first substrate, and depositing an
arsenic-containing material on a second substrate in the epitaxial
deposition chamber while reducing arsenic outgassing on the first
substrate in the degassing chamber. The reducing arsenic outgassing
includes flowing hydrogen or nitrogen gas into the degassing
chamber, ceasing the flow of hydrogen or nitrogen gas into the
degassing chamber, flowing a mixture of oxygen and nitrogen gas
into the degassing chamber to reduce arsenic outgassing on the
substrate to a first amount, ceasing the flow of oxygen and
nitrogen gas into the degassing chamber, flowing a
chlorine-containing gas into the degassing chamber clean the
degassing chamber after the substrate is removed, ceasing the flow
of the chlorine-containing gas into the degassing chamber, and
detecting the amount of arsenic outgassing using an arsenic
detecting device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of
the present disclosure can be understood in detail, a more
particular description of the disclosure, briefly summarized above,
may be had by reference to implementations, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical implementations
of this disclosure and are therefore not to be considered limiting
of its scope, for the disclosure may admit to other equally
effective implementations.
[0012] FIG. 1 illustrates a schematic view of a system for
performing a method according to one implementation described
herein.
[0013] FIG. 2 illustrates a schematic, plan view of a substrate
support according to one implementation described herein.
[0014] FIG. 3 illustrates a schematic, plan view of a system for
performing a method according to one implementations described
herein.
[0015] FIG. 4 illustrates a flow diagram summarizing a method
according to one implementation described herein.
[0016] To facilitate understanding, identical reference numerals
have been used, wherever possible, to designate identical elements
that are common to the Figures. Additionally, elements of one
implementation may be advantageously adapted for utilization in
other implementations described herein.
DETAILED DESCRIPTION
[0017] Implementations of the present disclosure generally relate
to the fabrication of integrated circuits. More specifically,
implementations disclosed herein relate to apparatus, systems, and
methods for reducing substrate outgassing. A substrate is processed
in an epitaxial deposition chamber for depositing an
arsenic-containing material on a substrate and then transferred to
a degassing chamber for reducing arsenic outgassing on the
substrate. The degassing chamber includes a gas panel for supplying
hydrogen, nitrogen, and oxygen and hydrogen chloride or chlorine
gas to the chamber, a substrate support, a pump, and at least one
heating mechanism. Residual or fugitive arsenic is removed from the
substrate such that the substrate may be removed from the degassing
chamber without dispersing arsenic into the ambient
environment.
[0018] FIG. 1 illustrates a schematic, cross-sectional view of a
degassing chamber 100 according to one implementation. The
degassing chamber 100 includes a gas panel 102, at least one
heating mechanism 106, a substrate support 120, and a pump 110.
Each of the gas panel 102, the at least one heating mechanism 106,
the substrate support 120, and the pump 110 is connected to at
least one of the plurality of degassing chamber walls 108a, 108b,
108c, and 108d. The gas panel 102 is coupled to at least one of the
chamber walls 108a, 108b, 108c, or 108d. In a preferred
implementation, the gas panel 102 is configured to flow hydrogen,
nitrogen, oxygen and chlorine gases into the degassing chamber 100.
The at least one heating mechanism is configured to provide gentle
heat to the chamber 100. In one implementation, the at least one
heating mechanism 106 is a lamp used for Infrared (IR) heating. In
another implementation, the at least one heating mechanism 106 is a
resistive heater in an overhead appliance. In one implementation,
the substrate support 120 is configured to support a single
substrate. In another implementation, the substrate support 120 may
be configured to support a plurality of substrates, as shown in
FIG. 2 and discussed below. In one implementation, the one or more
substrates may be circular substrates. For example, the substrate
may be a 200 millimeter (mm) circular substrate, a 300 mm circular
substrate, or a 450 mm circular substrate. In another
implementation, the one or more substrates may be non-circular
substrates. In one implementation, the pump 110 is configured to
remove residual gases and materials from the degassing chamber
100.
[0019] Additionally, in one implementation, the degassing chamber
100 includes an arsenic detecting device 104, which is coupled to
at least one of the chamber walls 108a, 108b, 108c, or 108d. The
arsenic detecting device 104 may be used to detect arsenic
concentration. More particularly, the arsenic detecting device 104
may be used for example, for detecting an arsenic endpoint based on
a concentration of arsenic, based on a concentration of arsenic
over a period of time (integral), or based on a rate of change of
arsenic (derivative).
[0020] FIG. 2 illustrates a schematic, plan view of a substrate
support 220 according to one implementation. The substrate support
220 may be the substrate support 120 shown in FIG. 1. As
illustrated, the annular ring 224 is configured to support a
plurality of substrates 228 in positions discrete from one another.
In one implementation, the annular ring 224 is disc-shaped.
Although four substrates 228 are illustrated, it is contemplated
that a greater or lesser number of substrates 228 may be supported
by the annular ring 224. In an alternative implementation, the
substrate support 220 may be arranged as a barrel-style substrate
support configured to support a plurality of substrates. If the
substrate support 220 were a barrel-style substrate support, the
entire substrate support may be heated using the heating mechanism
106 such that all substrates in the barrel-style substrate support
are adequately heated to reduce arsenic outgassing.
[0021] FIG. 3 illustrates a schematic view of a system 340 for
performing a method according to one implementation described
herein. More specifically, the system 340 is a cluster tool for
fabricating semiconductor devices according to the methods
described above. The system 340 includes an epitaxial deposition
chamber 350, a degassing chamber 300, and a central portion of the
system 340, which is a transfer chamber 342. Within the transfer
chamber 342 is a substrate transferring mechanism 344. Additionally
a load lock chamber 346 is included for loading substrates into the
system 340. The epitaxial deposition chamber 350 and the degassing
chamber 300 are connected to the transfer chamber 342. The load
lock chamber 346 is connected to the transfer chamber 342 through a
substrate alignment chamber 348. In a preferred implementation, the
epitaxial deposition chamber 350 may be a commercially available
process chamber, such as the Centura.RTM. RP Epi reactor, available
from Applied Materials, Inc. of Santa Clara, Calif., the
Producer.RTM. Epi reactor, available from Applied Materials, Inc.
of Santa Clara, Calif., or any suitable semiconductor process
chamber adapted for performing epitaxial deposition processes. In a
preferred implementation, the degassing chamber 300 may be the
degassing chamber 100 described above and shown in FIG. 1, or any
suitable degassing chamber adapted for reducing arsenic
outgassing.
[0022] In operation, once a substrate is processed in the epitaxial
deposition chamber 350, the substrate will be directly transferred
to the degassing chamber 300. While the epitaxial deposition
chamber 350 may be depositing on one substrate, the degassing
chamber 300 may be degassing, as described below and shown in FIG.
4, another substrate that has already been processed by an
epitaxial deposition chamber, such as the epitaxial deposition
chamber 350. Thus, throughput is increased because the epitaxial
deposition chamber 350 may not need down time for cleaning, as may
be necessary if both the depositing and degassing were being
performed in the epitaxial deposition chamber 350.
[0023] While the foregoing contemplates a single epitaxial
deposition chamber 350 and a single degassing chamber 300, the
system 340 may further include additional epitaxial deposition
chambers, additional degassing chambers, and any additional
substrate processing chambers.
[0024] In another implementation, the epitaxial deposition chamber
350 may be incorporated onto a first platform and the degassing
chamber 300, which may be the degassing chamber 100, may be
incorporated onto a second platform rather than being incorporated
into a single cluster tool system. In this alternative
implementation, the substrate may be transferred from the epitaxial
deposition chamber 350 to a Front Opening Unified Pod (FOUP) and
then to the degassing chamber 300.
[0025] FIG. 4 illustrates a flow diagram summarizing a method 460
according to one implementation described herein. Prior to the
first operation, operation 462, of the method 460, a substrate may
be processed in an epitaxial deposition chamber, for example the
epitaxial deposition chamber 350 shown in FIG. 3. During the
processing, outgassing may occur. More specifically, the substrate
may tend to outgas impurities implanted therein, for example, the
arsenic dopant material deposited during an arsenic doped silicon,
or other arsenic-related process. This outgassing may cause
unwanted particles on the substrate.
[0026] At operation 462, a substrate is transferred from an
epitaxial deposition chamber for depositing an arsenic-containing
material on the substrate, such as the epitaxial deposition chamber
350 shown in FIG. 3, to a degassing chamber for reducing arsenic
outgassing on the substrate, such as the degassing chamber 300
shown in FIG. 3, which may be the degassing chamber 100 described
above and shown in FIG. 1.
[0027] At operation 464, a hydrogen or nitrogen gas is flowed into
the degassing chamber 300. By flowing the hydrogen or nitrogen gas
into the degassing chamber 300, arsenic may be volatilized from the
surface of the substrate. During operation 464, heat may be used to
remove arsenic from the substrate and then the hydrogen or nitrogen
gas may remove the arsenic from the chamber 300. In one
implementation, the hydrogen or nitrogen gas may be a hydrogen gas,
such as H.sub.2. In another implementation, the hydrogen or
nitrogen gas may be a nitrogen gas, such as N.sub.2. In yet another
implementation, the hydrogen or nitrogen gas may be an inert gas,
which may be non-reactive to an epitaxially deposited film. Prior
to operation 464, the substrate is heated to a temperature between
about 500 degrees Celsius (.degree. C.) to about 700.degree. C.,
for example about 600.degree. C. The temperature may be then be
maintained at a constant temperature of about 600.degree. C. for
the remainder of the method 460, which increases system throughput
by reducing the time lost to ramping the temperature up or
down.
[0028] In one implementation, during operation 464, the hydrogen or
nitrogen gas may be continuously flowed into the degassing chamber
300. In another implementation, during operation 464, the hydrogen
or nitrogen gas may be discontinuously flowed into the degassing
chamber 300. The flow rate of the hydrogen or nitrogen gas, in one
implementation, may be between about 10 standard liters per minute
(slm) and about 30 slm. A higher flow rate may be used to create a
large concentration gradient to drive arsenic into the purge gas.
During this process, the pressure in the degassing chamber 300 may
be a low pressure. In one implementation, the pressure may be
between about 1 Torr and about 100 Torr. The hydrogen or nitrogen
gas may be flowed into the degassing chamber 300 for between about
1 minute and about 10 minutes.
[0029] One implementation may feature a short pressure reduction
operation to accelerate removal of arsenic from the substrate
surface. A pressure control member, such as a throttle valve used
to control back pressure in the chamber 300, may be opened for
about 5 to about 30 seconds, gas flow may be stabilized to remove
the additional arsenic extracted from the substrate, and the
throttle valve may then be pinched back to restore pressure in the
chamber 300. The hydrogen or nitrogen gas flow into the degassing
chamber 300 may then be ceased.
[0030] At operation 466, a mixture of oxygen and nitrogen gas, or
oxidation gas, is flowed into the degassing chamber, such as the
degassing chamber 300 shown in FIG. 3, which may be the degassing
chamber 100 described above and shown in FIG. 1 to reduce arsenic
outgassing on the substrate to a first amount. During this
operation, heat and exposure to oxygen-containing gas adds oxygen
to the substrate surface to form silicon (or other semiconductor)
oxides. This encases any residual arsenic in an oxide matrix and
substantially passivates the surface. In one implementation, the
mixture of oxygen gas and nitrogen gas, or oxidation gas, may be an
oxygen gas, such O.sub.2 or a nitrogen gas, such as N.sub.2, or a
mixture of O.sub.2 and N.sub.2. In another implementation, the
mixture of oxygen and nitrogen gas may be NO.sub.2 or H.sub.2O. In
one implementation the O.sub.2 percentage by volume in N.sub.2 may
be between about 0.1% and about 1%. In one implementation, N.sub.2
may be flowed into the degassing chamber 300 and then O.sub.2 may
be flowed into the degassing chamber 300 for several minutes.
During this operation, the temperature may be between about
100.degree. C. and about 300.degree., While O.sub.2 is flowing into
the degassing chamber 300, the pressure may be raised to between
about 80 Torr and about 300 Torr. Raising the pressure while
O.sub.2 is flowing into the degassing chamber 300 allows O.sub.2 to
remain on the substrate surface for a longer period of time, thus
resulting in increased oxidation. N.sub.2 may then be flowed into
the degassing chamber 300 at a lower pressure of less than about 20
Torr to purge the chamber 300. The flow of oxygen and nitrogen gas
into the degassing chamber may then be ceased.
[0031] At operation 468, a chlorine-containing gas is flowed into
the degassing chamber 300 to clean the degassing chamber 300 after
the substrate is removed. More specifically, the
chlorine-containing gas removes the residual arsenic adsorbed
inside the surface of the degassing chamber 300 during the
degassing process. This cleaning assures low arsenic background in
the degassing chamber 300. High arsenic background in the degassing
chamber 300 may reduce the degassing effectiveness.
[0032] Thus, apparatus, systems, and methods for reducing substrate
outgassing are provided. The disclosed separate degassing chamber
enables reduced arsenic outgassing. Benefits of this disclosure
include reduction of arsenic outgassing to zero (i.e., undetectable
levels) while increasing throughput because substrates may be
processed in parallel. Specifically, epitaxial deposition may be
performed on one substrate in the epitaxial deposition chamber
while another substrate undergoes degassing to reduce arsenic
outgassing in the dedicated degassing chamber in parallel.
[0033] While the foregoing is directed to implementations of the
present disclosure, other and further implementations of the
disclosure may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims that
follow.
* * * * *