U.S. patent application number 16/172266 was filed with the patent office on 2019-06-06 for method and apparatus for wafer outgassing control.
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 | 20190172728 16/172266 |
Document ID | / |
Family ID | 61618044 |
Filed Date | 2019-06-06 |
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United States Patent
Application |
20190172728 |
Kind Code |
A1 |
BAO; Xinyu ; et al. |
June 6, 2019 |
METHOD AND APPARATUS FOR WAFER OUTGASSING CONTROL
Abstract
Embodiments disclosed herein generally relate to apparatus and
methods for controlling substrate outgassing such that hazardous
gasses are eliminated from a surface of a substrate after a Si:As
process has been performed on a substrate, and prior to additional
processing. The apparatus includes a purge station including an
enclosure, a gas supply coupled to the enclosure, an exhaust pump
coupled to the enclosure, a first purge gas port formed in the
enclosure, a first channel operatively connected to the gas supply
at a first end and to the first purge gas port at a second end, a
second purge gas port formed in the enclosure, and a second channel
operatively connected to the second purge gas port at a third end
and to the exhaust pump at a fourth end. The first channel includes
a particle filter, a heater, and a flow controller. The second
channel includes a dry scrubber.
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: |
61618044 |
Appl. No.: |
16/172266 |
Filed: |
October 26, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15267232 |
Sep 16, 2016 |
10115607 |
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16172266 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/673 20130101;
H01L 21/677 20130101; H01L 21/67 20130101; H01L 21/67393
20130101 |
International
Class: |
H01L 21/67 20060101
H01L021/67; H01L 21/677 20060101 H01L021/677; H01L 21/673 20060101
H01L021/673 |
Claims
1. A semiconductor processing system, comprising: a purge station,
comprising: an enclosure; a gas supply coupled to the enclosure; an
exhaust pump coupled to the enclosure; a first purge gas port
formed in the enclosure; a first channel operatively connected to
the gas supply at a first end and to the first purge gas port at a
second end, wherein the first channel comprises: a heater; and a
flow controller; a second purge gas port formed in the enclosure;
and a second channel operatively connected to the second purge gas
port at a third end and to the exhaust pump at a fourth end,
wherein the second channel comprises a dry scrubber.
2. The semiconductor processing system of claim 1, further
comprising a divider disposed between the first purge gas port and
the second purge gas port.
3. The semiconductor processing system of claim 2, wherein the
divider comprises a quartz material, a polytetrafluoroethylene
material, or a thermoplastic material.
4. The semiconductor processing system of claim 1, further
comprising a first valve disposed between the first channel and the
first purge gas port and a second valve disposed between the second
purge gas port and the second channel.
5. The semiconductor processing system of claim 1, further
comprising a Front Opening Unified Pod (FOUP) coupled to an outside
of the purge station.
6. The semiconductor processing system of claim 5, wherein the FOUP
is operatively connected to the first purge gas port and to the
second purge gas port.
7. The semiconductor processing system of claim 5, further
comprising a non-metal divider disposed between the first purge gas
port and the second purge gas port, wherein the FOUP comprises at
least one substrate support disposed horizontally therein, and
wherein the divider is oriented vertically and extends along the at
least one substrate support.
8. The semiconductor processing system of claim 7, wherein the
divider comprises a quartz material, a polytetrafluoroethylene
material, or a thermoplastic material.
9. The semiconductor processing system of claim 1, further
comprising: a gas detector disposed within the second purge gas
port.
10. The semiconductor processing system of claim 1, further
comprising: a controller operatively connected to the purge station
to control operation of the gas supply, the heater, the flow
controller, the exhaust pump, and the dry scrubber.
11. A semiconductor processing system, comprising: a purge station,
comprising: an enclosure; a gas supply coupled to the enclosure; an
exhaust pump coupled to the enclosure; a first purge gas port
formed in the enclosure; a first channel operatively connected to
the gas supply at a first end and to the first purge gas port at a
second end, wherein the first channel comprises at least one of: a
heater; and a flow controller; a second purge gas port formed in
the enclosure and having a gas detector disposed therein; a second
channel operatively connected to the second purge gas port at a
third end and to the exhaust pump at a fourth end; and a Front
Opening Unified Pod (FOUP) coupled to the purge station, wherein
the FOUP is operatively connected to the first purge gas port and
to the second purge gas port and the FOUP comprises at least one
horizontal substrate support.
12. The semiconductor processing system of claim 11, wherein the
second channel comprises a dry scrubber.
13. The semiconductor processing system of claim 11, further
comprising a divider disposed between the first purge gas port and
the second purge gas port.
14. The semiconductor processing system of claim 13, wherein the
divider comprises a quartz material, a polytetrafluoroethylene
material, or a thermoplastic material.
15. The semiconductor processing system of claim 11, further
comprising a first valve disposed between the first channel and the
first purge gas port and a second valve disposed between the second
purge gas port and the second channel.
16. The semiconductor processing system of claim 11, further
comprising: a controller operatively connected to the purge station
to control operation of the gas supply, the heater, the flow
controller, and the exhaust pump.
17. A semiconductor processing method, comprising: (a) operatively
connecting a Front Opening Unified Pod (FOUP) to a purge station
having a purge gas inlet and a purge gas outlet separated by a
divider; (b) disposing a semiconductor substrate in the FOUP; (c)
supplying a purge gas to the FOUP via the purge gas inlet by
directing the purge gas through a heater prior to entering the FOUP
and directing the purge gas through a flow controller prior to
entering the FOUP; (d) passing the purge gas through the FOUP; (e)
removing the purge gas from the FOUP via the purge gas outlet; (f)
measuring a toxic gas outgassing level after the purge gas is
removed from the FOUP; and (g) flowing the purge gas through a dry
scrubber after removing the purge gas from the FOUP.
18. (canceled)
19. The method of claim 17, wherein the directing the purge gas
through the heater prior to entering the FOUP heats the purge gas
to a temperature between about 30 degrees Celsius and about 100
degrees Celsius.
20. The method of claim 17, wherein the directing the purge gas
through a flow controller prior to entering the FOUP controls the
flow of the purge gas to a flow rate between about 1 CFM and about
350 CFM.
21. The method of claim 17, wherein the directing the purge gas
through the heater prior to entering the FOUP heats the purge gas
to a temperature from about 30 degrees Celsius to about 100 degrees
Celsius, and wherein the directing the purge gas through a flow
controller prior to entering the FOUP controls the flow of the
purge gas to a flow rate from about 1 CFM to about 350 CFM.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/267,232 filed Sep. 9, 2016, which is hereby
incorporated by reference in its entirety.
BACKGROUND
Field of the Disclosure
[0002] Embodiments of the present disclosure generally relate to
the fabrication of integrated circuits. More specifically,
embodiments disclosed herein relate to methods and apparatus for
controlling substrate outgassing.
Description of the Related Art
[0003] The manufacture of modern logic, memory, or integrated
circuits typically requires more than four hundred process steps. A
number of these steps 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 implantation 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 other members of the chamber. This deposition
may interfere with temperature sensor 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 to remove the
deposits.
[0006] A major challenge in some semiconductor processes relates to
arsenic outgassing from substrates after arsenic doped silicon
processes (Si:As). In such arsenic doped silicon processes the
arsenic outgassing from the substrates is higher, for example 2
parts per billion per substrate, than the arsenic outgassing from
substrates after a III-V epitaxial growth process and/or an etch
clean process (e.g., a CMOS, FinFET, TFET process), for example 0.2
parts per billion per substrate. Previous cycle purge approaches
developed for III-V epitaxial growth process and/or etch clean
processes are not effective for Si:As processed substrates. Testing
has been performed on the prior known III-V methods, apparatus, and
results indicate that outgassing levels are not altered after ten
cycles of pump/purge, as arsenic outgassing was still detected at
about 2.0 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 an
improved method and apparatus for controlling substrate outgassing
for Si:As processed substrates.
SUMMARY
[0008] Embodiments disclosed herein generally relate to apparatus
and methods for semiconductor processing that control substrate
outgassing such that hazardous gasses are eliminated from a surface
of a substrate after an Si:As process and prior to additional
processing. In one embodiment, an semiconductor processing system
is disclosed. The system includes a purge station. The purge
station includes an enclosure, a gas supply coupled to the
enclosure, an exhaust pump coupled to the enclosure, a first purge
gas port formed in the enclosure, a first channel operatively
connected to the gas supply at a first end and to the first purge
gas port at a second end, a second purge gas port formed in the
enclosure, and a second channel operatively connected to the second
purge gas port at a third end and to the exhaust pump at a fourth
end. The first channel includes a particle filter, a heater, and a
flow controller. The second channel comprises a dry scrubber.
[0009] In another embodiment, a semiconductor processing system is
disclosed. The system includes a purge station and a Front Opening
Unified Pod (FOUP) coupled to the purge station. The purge station
includes an enclosure, a gas supply coupled to the enclosure, an
exhaust pump coupled to the enclosure, a first purge gas port
formed in the enclosure, a first channel operatively connected to
the gas supply at a first end and to the first purge gas port at a
second end, a second purge gas port formed in the enclosure and
having a gas detector disposed therein, and a second channel
operatively connected to the second purge gas port at a third end
and to the exhaust pump at a fourth end. The first channel includes
at least one of a particle filter, a heater, and a flow controller.
The FOUP is operatively connected to the first purge gas port and
to the second purge gas port and the FOUP comprises at least one
horizontal substrate support.
[0010] In another embodiment, a semiconductor processing method is
disclosed. The method includes (a) operatively connecting a Front
Opening Unified Pod (FOUP) to a purge station having a purge gas
inlet and a purge gas outlet separated by a divider; (b) disposing
a semiconductor substrate in the FOUP; (c) supplying a purge gas to
the FOUP via the purge gas inlet; and (d) passing the purge gas
through the FOUP. The method further includes (e) removing the
purge gas from the FOUP via the purge gas outlet; (f) measuring a
toxic gas outgassing level after the purge gas is removed from the
FOUP; and (g) flowing the purge gas through a dry scrubber after
removing the purge gas from the FOUP via the purge gas outlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of
the disclosure can be understood in detail, a more particular
description of the disclosure, 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 disclosure and
are therefore not to be considered limiting of its scope, for the
disclosure may admit to other equally effective embodiments.
[0012] FIG. 1 schematically illustrates a top via of an outgassing
control system, according to one embodiment.
[0013] FIG. 2 illustrates a schematic flow diagram of a method for
controlling outgassing, according to one embodiment.
[0014] FIG. 3 illustrates a schematic flow diagram of a method for
controlling outgassing, according to one embodiment.
[0015] 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
[0016] Embodiments disclosed herein generally relate to an
outgassing control system and methods for controlling outgassing
such that hazardous gasses are eliminated from a surface of a
substrate after an arsenic doped silicon process (Si:As) and prior
to additional processing. The system includes a purge station
having an enclosure, a gas supply coupled to the enclosure, an
exhaust pump coupled to the enclosure, a first purge gas port
formed in the enclosure, a first channel operatively connected to
the gas supply at a first end and to the first purge gas port at a
second end, a second purge gas port formed in the enclosure, and a
second purge gas port operatively connected to the second purge gas
port at a third end and to the exhaust pump at a fourth end. The
first channel includes a heater for heating the purge gas, a
particle filter, and/or a flow controller. The second channel
includes a dry scrubber. It is observed that the outgassing is more
effectively reduced when a heated purge gas is utilized. As such,
hazardous gases and outgassing residuals are decreased and/or
removed from the substrate such that further processing may be
performed.
[0017] A "substrate" or "substrate surface," as described herein,
generally refers to any substrate surface upon which processing is
performed. For example, a substrate surface may include silicon,
silicon oxide, doped silicon, silicon germanium, germanium, gallium
arsenide, glass, sapphire, and any other materials, such as metals,
metal nitrides, metal alloys, and other conductive or
semi-conductive materials, depending on the application. A
substrate or substrate surface may also include dielectric
materials such as silicon dioxide, silicon nitride,
organosilicates, and carbon dopes silicon oxide or nitride
materials. The term "substrate" may further include the term
"wafer." The substrate itself is not limited to any particular size
or shape. Although the implementations described herein are
generally made with reference to a round substrate, other shapes,
such as polygonal, squared, rectangular, curved, or otherwise
non-circular workpieces may be utilized according to the
implementations described herein.
[0018] FIG. 1 is a schematic top view of an outgassing control
system 100. The outgassing control system 100 may be a standalone
unit, thus being separate from a load lock chamber. In some
embodiments, however, the outgassing control system 100 may be part
of a cluster tool station, and, for example, utilized to increase
throughput of an epitaxial tool.
[0019] The outgassing control system 100 includes a purge station
102 and a Front Opening Unified Pod (FOUP) 104. The FOUP 104 is an
enclosure configured to hold a plurality of substrates securely and
safely in a controlled environment. The FOUP may hold about 25
substrates, each in or on a substrate support disposed therein in a
vertical orientation such that each substrate is relatively
horizontal or flat on a major axis of the substrate. It is
contemplated, however, that any number of substrates may be held in
the FOUP. The FOUP 104 is portable thus allowing the substrates to
be transferred between machines for processing or measurement. In
some embodiments, the FOUP 104 may be coupled to the purge station
102. The FOUP 104, however, is transferred to the purge station 102
after processing of the substrates disposed inside the FOUP 104 has
been completed.
[0020] The purge station 102 includes an enclosure 103 and a gas
supply 106 coupled to the enclosure 103. In some embodiments, the
gas supply 106 may be disposed in the purge station 102. In other
embodiments, the gas supply 106 may be operatively connected to the
purge station 102. The gas supply 106 may store and/or supply
clean, dry air (CDA), oxygen, nitrogen, or an oxygen containing
gas, among other suitable gases. In certain embodiments, the gas
supply 106 may store and/or supply a gas comprising between about
10% oxygen and about 60% oxygen, such as a gas comprising about 20%
oxygen.
[0021] A first channel 108 is operatively connected to the gas
supply 106 at a first end 110 of the first channel 108. The first
channel 108 is operatively connected to a first purge gas port 114
of the purge station 102 at a second end 112 of the first channel
108. The first purge gas port 114 is formed in the enclosure 103.
The first channel 108 may be any suitable channel or tube for
directing the flow of the purge gas from the gas supply 106 to the
first purge gas port 114. The first channel 108 directs the flow of
the purge gas from the gas supply 106 to the first purge gas port
114, as shown by reference arrows A in FIG. 1. After the purge gas
flows from the gas supply to the first channel 108, the first
channel 108 may direct the purge gas through a particle filter 116,
a heater 118, and/or a flow controller 120 prior to directing the
flow of the purge gas to the first purge gas port 114. In some
embodiments, the first channel 108 may direct the purge gas through
any one or more of the particle filter 116, the heater 118, and the
flow controller 120. Further, in certain embodiments, the first
channel 108 directs the purge gas through each of the particle
filter 116, the heater 118, and the flow controller 120, the
directing of which may occur in any order. In certain embodiments,
however, the purge gas may be heated by the heater 118 after the
purge gas has been filtered by the filter 116. In certain
embodiments, the purge gas may first flow through the particle
filter 116, followed by the heater 118, and ultimately flowing to
the flow controller 120.
[0022] The particle filter 116 filters the purge gas at a rate
between about 1 CFM and about 350 CFM, for example between about
200 CFM and about 300 CFM. The particle filter 116 may include
pores therein of various sizes for filtering different sized
particles.
[0023] The heater 118 heats the purge gas to a temperature between
about 150 degrees Celsius and about 450 degrees Celsius, for
example between about 200 degrees Celsius and about 400 degrees
Celsius. In some embodiments, the heater 118 may be a coil heater,
a heater jacket, or a resistively heated jacket. It is contemplated
however that the heater 118 may be any suitable heating unit for
heating a gas.
[0024] The flow controller 120 controls a flow rate of the purge
gas. In some embodiments, the flow controller 120 further controls
the oxygen level of the purge gas entering the first purge gas port
114 such that the oxygen level of the purge gas is between about 1%
and about 40%, for example between about 1% and about 21% oxygen.
In some implementations, the flow controller 120 dilutes and/or
tunes the oxygen level of the purge gas by adding a second gas
thereto. In some embodiments, the second gas may be a nitrogen gas
or a nitrogen containing gas. The flow controller 120 may be a
pneumatic flow meter, a manually adjustable flow meter, an electric
flow meter, a mass flow controller, among others.
[0025] After directing the purge gas through the particle filter
116, the heater 118, and/or the flow controller 120 the first
channel 108 directs the purge gas to the first purge gas port 114.
A first valve 122 is disposed between the first channel 108 and the
first purge gas port 114. The first valve 122 may be a gate valve,
a pneumatic valve, a ball valve, or any other suitable open/close
valve. The first purge gas port 114 is disposed adjacent a FOUP
connection location 124. Upon opening of the first valve 122 the
purge gas is directed into and/or enters into the FOUP 104.
[0026] A second purge gas port 126 is formed in the enclosure 103
and is further disposed adjacent the first purge gas port 114 at
the FOUP connection location 124. The purge gas is directed to the
second purge gas port 126 after passing through the FOUP 104. The
second purge gas port 126 is operatively connected to a second
channel 128 at a third end 130 of the second channel 128. The
second channel 128 is substantially similar to the first channel
108, discussed supra. A second valve 144 is disposed between the
second purge gas port 126 and the second channel 128. The second
valve 144 may be a gate valve, a pneumatic valve, a ball valve, or
any other suitable open/close valve. Upon opening of the second
valve 144 the purge gas is directed into and/or enters into the
second channel 128. The second channel 128 is also operatively
connected to an exhaust pump 134 at a fourth end 132 of the second
channel 128, wherein the fourth end 132 is opposite the third end
130. The exhaust pump 134 pumps the purge gas out of the second
channel 128 and draws purge gas out of the FOUP 104. The second
channel 128 comprises a dry scrubber 136. The dry scrubber 136 is
disposed upstream of the second purge gas port 126. The dry
scrubber 136 cleans the purge gas of toxic gases, such as arsenic.
After passing through the dry scrubber 136, the purge gas continues
in the second channel 128 to an exhaust 142. The second channel 128
directs the flow of the purge gas from the second purge gas port
126 to an exhaust 142, as shown by reference arrows C in FIG.
1.
[0027] The second purge gas port 126 includes a gas detector 140
disposed therein. The gas detector 140 is a toxic gas monitor or
sensor which measures the concentration of toxic gases, such as
arsenic. In some embodiments, the gas detector 140 may be an
electrochemical sensor, an infrared sensor, a chemical detector, a
chemical tape, or any other suitable gas sensor. In order to
receive an accurate gas detection reading, a hot purge gas may be
supplied into the FOUP 104 for a first time period, for example
between about one minute and about eight minutes, for example five
minutes. Subsequently, a room temperature nitrogen purge gas may be
supplied to the FOUP 104 for approximately the same first time
period. In some embodiments, the nitrogen purge gas may have a
temperature higher or lower than room temperature. Subsequently,
the purge gas flow is ceased and the gas detector measures the
arsenic concentration.
[0028] A divider 138 is disposed between the first purge gas port
114 and the second purge gas port 126. In some embodiments, the
divider 138 comprises a quartz material, a polytetrafluoroethylene
material, a thermoplastic material, or the like. The divider is a
non-metal material. The divider 138 influences the flow path of the
purge gas from the first purge gas port 114 into the FOUP 104, as
shown by reference arrows B in FIG. 1. The divider 138 prevents the
purge gas from directly entering the second purge gas port 126
after being supplied to the FOUP 104 via the first purge gas port
114. As such, the divider 138 directs the purge gas through and/or
around the inside of the FOUP 104 such that a substrate disposed in
the FOUP 104 is exposed to the purge gas. The divider 138 extends
outward from the purge station 102 towards the FOUP 104 such that
upon coupling of the FOUP 104 to the purge station 102 the divider
138 is immediately next to an edge of the substrate, for example
the divider is disposed between about 1 mm and about 10 mm from the
edge of a substrate disposed inside the FOUP 104. The divider 138
extends vertically along each substrate disposed in the FOUP. In
some embodiments, the divider 138 is oriented vertically and
extends along at least one substrate support of the FOUP 104.
[0029] During operation of the purge station 102, both the first
valve 122 and the second valve may be in an open position such that
each of the first valve 122 and the second valve 144 are each open
during operation of the purge station 102 as the operation may be a
continuous process. With each of the first valve 122 and the second
valve 144 open during operation of the purge station kinetic energy
may allow for the purge gas to continuously flow through the purge
station 102, including the FOUP 104, thus allowing for mechanical
agitation of the substrates.
[0030] The outgassing control system 100 may also include a
controller 146. The controller 146 facilitates the control and
automation of the outgassing control system 100, including the
purge station 102. The controller 146 may be coupled to or in
communication with one or more of the purge station 102, the gas
supply 106, the particle filter 116, the heater 118, the flow
controller 120, the first valve 122, the second valve 144, the
exhaust pump 134, the gas detector 140, the dry scrubber 136,
and/or the exhaust 142. In some embodiments, the purge station 102
may provide information to the controller regarding substrate
outgassing, purge gas flow, toxic gas levels, gas flow rates, gas
temperatures, among other information.
[0031] The controller 146 may include a central processing unit
(CPU) 148, memory 150, and support circuits (or I/O) 152. The CPU
148 may be one of any form of computer processors that are used in
industrial settings for controlling various processes and hardware
(e.g., pattern generators, motors, and other hardware) and monitor
the processes (e.g., processing time and substrate position or
location). The memory 150 is connected to the CPU 148, 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 148. The support circuits 152 are also
connected to the CPU 148 for supporting the processor in a
conventional manner. The support circuits 152 may include
conventional cache, power supplies, clock circuits, input/output
circuitry, subsystems, and the like. A program (or computer
instructions) readable by the controller 146 implements the method
described herein (infra) and/or determines which tasks are
performable. The program may be software readable by the controller
146 and may include code to monitor and control, for example, the
processing time and substrate outgassing or position within the
FOUP 104.
[0032] In certain embodiments, the controller 146 may be a PC
microcontroller. The controller 146 may also automate the sequence
of the process performed by the outgassing control system 100, such
that an outgassing reduction process is performed until a desired
outgassing level is reached.
[0033] FIG. 2 is a schematic flow diagram of a method 200 for
controlling and reducing outgassing. Substrate outgassing generally
relates to the releasing of gas or vapor product from the substrate
or from a surface of the substrate. Controlling outgassing relating
to the reduction and/or elimination of residual outgassed
materials, for example, arsenic, from a substrate prior to
transferring the substrate for downstream processing. In some
embodiments, controller 146 facilitates the control and automation
of the method 200.
[0034] At operation 210, a Front Opening Unified Pod (FOUP) is
operatively connected to a purge station having a purge gas inlet
and a purge gas outlet separated by a divider.
[0035] At operation 220, a purge gas is supplied to the FOUP via
the purge gas inlet. The gas is supplied from a gas supply disposed
upstream from the FOUP. The gas supply may hold more than one purge
gas. In some embodiments, the purge gas may include clean dry air
(CDA), an oxygen containing gas, or any other suitable purge gas.
In certain embodiments, the purge gas is a gas comprising between
about 10% oxygen and about 40% oxygen, such as air. In some
embodiments, the gas supply may store an oxygen containing gas in a
first storage unit and nitrogen containing gas in a second storage
area. It is contemplated however, that the gas supply may also
store other suitable purge gases.
[0036] Supplying the purge gas to the FOUP via the purge gas inlet
includes directing the purge gas through a filter prior to entering
the FOUP, directing the purge gas through heater prior to entering
the FOUP, and/or directing the purge gas through a flow controller
prior to entering the FOUP. The filter filters the purge such that
unwanted particles are removed from the purge gas. The heater heats
the purge gas to a temperature between about 30 degrees Celsius and
about 100 degrees Celsius. The flow controller controls the flow of
the purge gas to a flow rate between about 1 CFM and about 350
CFM.
[0037] At operation 230, the purge gas is passed through the FOUP.
Passing the purge gas through the FOUP allows each substrate
disposed in the FOUP to be exposed to the purge gas. In some
embodiments, the purge gas may be clean dry air, or any other
suitable oxygen containing gas. The exposure of the substrate to
oxygen allows for the outgassing of toxic gases, such as arsenic,
to be reduced to safe levels. Furthermore, the purge gas breaks
down arsenic residuals to either stable oxides and/or byproducts
which have a high vapor pressure, and therefore, evaporate quickly.
As such, the deliberate pulsing and/or providing of an oxygen
containing purge gas into the FOUP may remove arsenic in a
controlled manner in order to appropriately abate the arsenic.
[0038] Furthermore, the flowing of an oxygen containing purge gas
into the FOUP may allow for stable oxides to form on the surface of
the substrate. Also, the oxygen containing purge gas may allow high
vapor pressure byproducts may be removed from the substrate.
Moreover, oxidation may have various effects on the substrate. The
oxidation may break the bond of the arsenic species (for example
between arsenic and OH groups) to carbon to form arsenic oxide
which may leave the surface of the substrate more quickly.
[0039] At operation 240, the purge gas is removed from the FOUP via
the purge gas outlet. The purge gas is removed from the FOUP by the
use of an exhaust pump disposed downstream of the FOUP.
[0040] At operation 250, a toxic gas outgassing level is measured
after the purge gas is removed from the FOUP. In some embodiments,
a toxic gas outgassing level is measured by a gas detector. The gas
detector monitors, senses, and/or measures the toxic gas outgassing
level, for example, the concentration of arsenic therein. The gas
detector may be an electrochemical sensor, a chemical detector, a
chemical tape, an infrared sensor, or any other suitable sensor or
detector.
[0041] At operation 260, the purge gas is flowed through a dry
scrubber after removing the purge gas from the FOUP via the purge
gas outlet. The dry scrubber cleans the exhausted purge gas of
outgassing toxic gases, such as arsenic.
[0042] In certain embodiments, the a purge gas, such as CDA, is
supplied into the FOUP for between about three minutes and about
seven minutes, for example about five minutes. Subsequently, a
nitrogen containing gas is supplied into the FOUP for between about
three minutes and about seven minutes. After the CDA purge and the
nitrogen purge are each complete, the purge is complete and a
concentration of toxic gas (e.g., arsenic) is measured via the gas
detector.
[0043] In some embodiments, operation 210, operation 220, operation
230, operation 240, operation 250, and/or operation 260 may be
repeated for at least one additional cycle after an initial
completion of operation 260. By repeating the flowing of the purge
gas into the FOUP, ceasing the flow of the purge gas into the FOUP,
and/or removing the purge gas from the FOUP, outgassing is further
driven down towards the zero ppb level. Testing has been completed
and results indicate that exposure of a substrate disposed in a
FOUP after a Si:As process, outgassing is reduced to zero ppb after
exposure to heated CDA.
[0044] FIG. 3 is a schematic flow diagram of a method 300 for
controlling and reducing outgassing. In some embodiments,
controller 146 facilitates the control and automation of the method
300.
[0045] At operation 310, a FOUP is transferred to a purge station.
The FOUP may comprise one or more substrates therein.
[0046] At operation 320, a door to the FOUP is opened and the FOUP
is operatively connected to a purge gas box. The FOUP is
operatively connected to the purge gas box at the door of the FOUP
such that the opened door is adjacent the purge gas box. The purge
gas box is divided into two channels such that the purge gas box
includes a purge gas inlet and a purge gas outlet each separated by
a divider.
[0047] At operation 330, clean dry air (CDA) is supplied from a gas
supply and is filtered, heated, and controlled by a flow
controller. In some embodiments, the CDA is heated to a temperature
between about 30 degrees Celsius and about 100 degree Celsius, for
example, a temperature between about 50 degrees Celsius and about
80 degrees Celsius. In some embodiments the CDA is controlled by
the flow controller to a flow rate between about 1 CFM and about
350 CFM, for example between about 1 CFM and about 100 CFM.
[0048] At operation 340, the heated CDA is flowed through the purge
box inlet into the FOUP. At operation 350, the heated CDA is
removed from the FOUP by flowing the CDA through the purge gas
outlet and through a dry scrubber. At operation 360, a toxic gas
detector mounted in the purge gas outlet measures the arsenic level
in the purge gas during the purge. It is also contemplated that the
toxic gas detector may also measure arsenic levels when a purge gas
is not present in the purge gas outlet. In certain embodiments, the
method 300 is repeated until outgassing levels drop to zero parts
per billion.
[0049] Benefits of the present disclosure include improved
substrate throughput, as well as substrates in which residual
arsenic outgassing gasses are eliminated before further processing.
Furthermore, fume hoods are not necessary to control outgassing.
Outgassing is controlled and removed prior to subsequent processes
between chambers and/or tools.
[0050] Additional benefits include reduced contaminations and
cross-contaminations. Also, the present disclosure may be applied
to all arsenic and/or phosphate implantations.
[0051] To summarize, the embodiments disclosed herein relate to
apparatus and methods for controlling substrate outgassing such
that hazardous gasses are eliminated from a surface of a substrate
after a Si:As process has been performed on a substrate, and prior
to additional processing. A heated purge gas, generally an oxygen
containing gas, is flowed to a substrate disposed in a FOUP. A
toxic gas detector continuously measures arsenic level during the
purge as well as before or after the purge. As such, hazardous
gases and outgassing residuals are decreased and/or removed from
the substrate such that further processing may be performed.
[0052] While the foregoing is directed to embodiments of the
present disclosure, other and further embodiments of the disclosure
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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