U.S. patent application number 10/990162 was filed with the patent office on 2006-05-18 for method and apparatus for selectively filtering residue from a processing chamber.
This patent application is currently assigned to Supercritical Systems, Inc.. Invention is credited to Douglas Michael Scott.
Application Number | 20060102282 10/990162 |
Document ID | / |
Family ID | 36384948 |
Filed Date | 2006-05-18 |
United States Patent
Application |
20060102282 |
Kind Code |
A1 |
Scott; Douglas Michael |
May 18, 2006 |
Method and apparatus for selectively filtering residue from a
processing chamber
Abstract
The processing system comprises a pump assembly, a bypass
assembly, and a processing chamber, which together form a
circulation path. The bypass assembly is configured so that in a
first mode, a filter does not form part of the circulation path,
and in a second mode the filter does form part of the circulation
path. Thus, the processing system is placed in the first mode when
a processing material circulated over the circulation path does not
need to be filtered. The processing system is placed in the second
mode when a processing material circulated over the circulation
path must be filtered.
Inventors: |
Scott; Douglas Michael;
(Gilbert, AZ) |
Correspondence
Address: |
HAVERSTOCK & OWENS LLP
162 NORTH WOLFE ROAD
SUNNYVALE
CA
94086
US
|
Assignee: |
Supercritical Systems, Inc.
|
Family ID: |
36384948 |
Appl. No.: |
10/990162 |
Filed: |
November 15, 2004 |
Current U.S.
Class: |
156/345.18 ;
216/93 |
Current CPC
Class: |
B08B 9/00 20130101; C23G
5/00 20130101 |
Class at
Publication: |
156/345.18 ;
216/093 |
International
Class: |
C23F 1/00 20060101
C23F001/00 |
Claims
1. An apparatus, comprising: a processing chamber having a
processing chamber inlet and a processing chamber outlet; a
recirculation subassembly having an inlet coupled to the processing
chamber outlet and an outlet coupled to the processing chamber
inlet, wherein the recirculation subassembly comprises a pump
assembly and a bypass assembly coupled to the pump assembly, the
bypass assembly comprising a first branch and a second branch; and
a controller coupled to the bypass assembly for switching the
bypass assembly between a first mode and a second mode, wherein
when the bypass circuit is in a first mode, a first path is
establish through the recirculation subassembly that includes the
pump assembly and the first branch, and when the bypass circuit is
in a second mode, a second path is establish through the
recirculation subassembly that includes the pump assembly and the
second branch.
2. The apparatus of claim 1, wherein the second branch contains a
filter and the first branch contains a bypass line.
3. The apparatus of claim 1, further comprising: a fluid supply
system coupled to the processing chamber, wherein a fluid contained
in the fluid supply system is provided to the processing chamber
and flows through the pump assembly, through the bypass assembly,
and through the processing chamber.
4. The apparatus of claim 3, wherein the pump assembly, the bypass
assembly, and the processing chamber form a circulation loop.
5. The apparatus of claim 2, wherein the bypass assembly comprises:
a first valve having an input, a first output, and a second output,
the first output coupled to the filter the second output coupled to
the bypass line; and a second valve having a first input coupled to
the filter, a second input coupled to the bypass line, and an
output coupled to the processing chamber.
6. The apparatus of claim 1, wherein the processing chamber is a
supercritical processing chamber.
7. The apparatus of claim 3, wherein the fluid comprises
substantially pure CO.sub.2.
8. An apparatus, comprising: means for circulating a supercritical
fluid over a substrate in a processing chamber, thereby creating a
contaminated process fluid; means for filtering the contaminated
process fluid coupled to the means for circulating and the
processing chamber; means for bypassing coupled to the means for
circulating and the processing chamber, wherein the means for
bypassing comprises means for bypassing the means for filtering;
and means for controlling the means for bypassing, wherein when the
means for bypassing is in a first mode, the means for circulating,
the means for bypassing and the processing chamber define a first
path containing a bypass line, and when the means for bypassing is
in a second mode, the means for circulating, the means for
filtering, and the processing chamber define a second path
containing a filter.
9. A method of circulating a first material and a second material
in a processing system, comprising: circulating the first material
through a processing chamber over a first processing path through a
recirculation subassembly during a first processing cycle; and
circulating a second material through the processing chamber over a
second processing path through a recirculation subassembly during a
second processing cycle, the second processing path different from
the first processing path.
10. The method of claim 9, wherein the second processing path
comprises a filter and the first processing path comprises a bypass
line.
11. The method of claim 9, wherein one of the first processing
cycle and the second processing cycle comprises supercritical
processing.
12. The method of claim 9, wherein the second material is carbon
dioxide.
13. The method of claim 12, wherein the carbon dioxide is in a
supercritical state.
14. The method of claim 12, wherein the second material further
comprises a surfactant.
15. The method of claim 12, wherein the second material further
comprises an amide or an amine.
Description
FIELD OF THE INVENTION
[0001] This invention relates to the field of processing systems.
More particularly, this invention relates to the field of
selectively filtering residue from a semiconductor processing
chamber.
BACKGROUND OF THE INVENTION
[0002] During a processing cycle, a semiconductor processing system
introduces photoresist and other materials into a processing
chamber to process a semiconductor wafer. During a later cleaning
cycle, cleaning materials are introduced into the processing
chamber to remove particles, such as etch residue, and other
contaminants generated, for example, during the processing cycle.
The processing chamber forms part of a circulation path used to
circulate both processing materials and cleaning materials over a
wafer in the processing chamber in one or more processing cycles.
To ensure that the particles removed from the wafer surface are not
reintroduced into the processing chamber, circulation paths
generally employ a filter to trap and remove these particles before
they can reenter the processing chamber.
[0003] As part of the circulation path, filters are exposed to
materials during cleaning cycles and processing cycles, even those
cycles that do not require filtration. For example, during an
etching or a chemical vapor deposition process cycle, a filter is
not needed. A filter placed in the circulation path is exposed to
harsh chemicals and operating conditions used in the processing
cycle. These harsh chemicals and operating conditions can shorten a
filter's life, requiring that it be replaced more often than
necessary. Replacing filters increases the time and cost of the
entire device fabrication process because the processing system
must be shut down to allow the filters to be replaced.
[0004] Accordingly, what is needed is a system and method for
extending the life of a filter used in a circulation path.
SUMMARY OF THE INVENTION
[0005] One embodiment of the invention includes a processing system
that includes a processing chamber having a processing chamber
inlet and a processing chamber outlet; a recirculation subassembly
having an inlet coupled to the processing chamber outlet and an
outlet coupled to the processing chamber inlet, where the
recirculation subassembly comprises a pump assembly and a bypass
assembly coupled to the pump assembly, the bypass assembly
comprising a first branch and a second branch; and a controller
coupled to the bypass assembly for switching the bypass assembly
between a first mode and a second mode, wherein when the bypass
circuit is in a first mode, a first path is establish through the
recirculation subassembly that includes the pump assembly and the
first branch, and when the bypass circuit is in a second mode, a
second path is establish through the recirculation subassembly that
includes the pump assembly and the second branch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] A more complete appreciation of various embodiments of the
invention and many of the attendant advantages thereof will become
readily apparent with reference to the following detailed
description, particularly when considered in conjunction with the
accompanying drawings, in which:
[0007] FIG. 1 shows an exemplary block diagram of a processing
system in accordance with an embodiment of the invention;
[0008] FIG. 2 illustrates a simplified block diagram of a
recirculation subassembly in accordance with an embodiment of the
invention; and
[0009] FIG. 3 illustrates an exemplary graph of pressure versus
time for a supercritical process step in accordance with an
embodiment of the invention.
DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS
[0010] The invention is a processing system having a circulation
path that selectively includes one or more filters. The processing
system comprises a pump assembly, a bypass assembly, and a
processing chamber, which together form a circulation path. The
bypass assembly is configured so that in a first mode, a filter
does not form part of the circulation path, and in a second mode
the filter does form part of the circulation path. Thus, the
processing system is placed in the first mode when a processing
material circulated over the circulation path does not need to be
filtered. The processing system is placed in the second mode when a
processing material circulated over the circulation path must be
filtered. The second mode can be used, for example, when a
processing material has collected residue and other contaminants
generated while processing a semiconductor wafer. This structure
advantageously extends the life of the filter.
[0011] FIG. 1 shows an exemplary block diagram of a processing
system in accordance with an embodiment of the invention. In the
illustrated embodiment, processing system 100 comprises a process
module 110, a recirculation system 120, a process chemistry supply
system 130, a carbon dioxide supply system 140, a pressure control
system 150, an exhaust system 160, and a controller 180. The
processing system 100 can operate at pressures that can range from
1000 psi. to 10,000 psi. In addition, the processing system 100 can
operate at temperatures that can range from 40 to 300 degrees
Celsius.
[0012] The controller 180 can be coupled to the process module 110,
the recirculation system 120, the process chemistry supply system
130, the carbon dioxide supply system 140, the pressure control
system 150, and the exhaust system 160. Alternately, controller 180
can be coupled to one or more additional controllers/computers (not
shown), and controller 180 can obtain setup and/or configuration
information from an additional controller/computer.
[0013] In FIG. 1, singular processing elements (110, 120, 130, 140,
150, 160, and 180) are shown, but this is not required for the
invention. The semiconductor processing system 100 can comprise any
number of processing elements having any number of controllers
associated with them in addition to independent processing
elements.
[0014] The controller 180 can be used to configure any number of
processing elements (110, 120, 130, 140, 150, and 160), and the
controller 180 can collect, provide, process, store, and display
data from processing elements. The controller 180 can comprise a
number of applications for controlling one or more of the
processing elements. For example, controller 180 can include a GUI
component (not shown) that can provide easy to use interfaces that
enable a user to monitor and/or control one or more processing
elements.
[0015] The process module 110 can include an upper assembly 112, a
frame 114, and a lower assembly 116. The upper assembly 112 can
comprise a heater (not shown) for heating the process chamber, the
substrate, or the processing fluid, or a combination of two or more
thereof. Alternately, a heater is not required. The frame 114 can
include means for flowing a processing fluid through the processing
chamber 108. In one example, a circular flow pattern can be
established, and in another example, a substantially linear flow
pattern can be established. Alternately, the means for flowing can
be configured differently. The lower assembly 116 can comprise one
or more lifters (not shown) for moving the chuck 118 and/or the
substrate 105. Alternately, a lifter is not required.
[0016] In one embodiment, the process module 110 can include a
holder or chuck 118 for supporting and holding the substrate 105
while processing the substrate 105. The holder or chuck 118 can
also be configured to heat or cool the substrate 105 before,
during, and/or after processing the substrate 105. Alternately, the
process module 110 can include a platen for supporting and holding
the substrate 105 while processing the substrate 105.
[0017] A transfer system (not shown) can be used to move a
substrate into and out of the processing chamber 108 through a slot
(not shown). In one example, the slot can be opened and closed by
moving the chuck, and in another example, the slot can be
controlled using a gate valve.
[0018] The substrate can include semiconductor material, metallic
material, dielectric material, ceramic material, or polymer
material, or a combination of two or more thereof. The
semiconductor material can include Si, Ge, Si/Ge, or GaAs. The
metallic material can include Cu, Al, Ni, Pb, Ti, Ta, or W, or
combinations of two or more thereof. The dielectric material can
include Si, O, N, or C, or combinations of two or more thereof. The
ceramic material can include Al, N, Si, C, or O, or combinations of
two or more thereof.
[0019] The recirculation system can be coupled to the process
module 110 using one or more inlet lines 122 and one or more outlet
lines 124. The recirculation system 120 can comprise one or more
valves for regulating the flow of a supercritical processing
solution through the recirculation system and through the process
module 110. The recirculation system 120 can comprise any number of
back-flow valves, filters, pumps, and/or heaters (not shown) for
maintaining a supercritical processing solution and flowing the
supercritical process solution through the recirculation system 120
and through the processing chamber 108 in the process module
110.
[0020] Processing system 100 can comprise a chemistry supply system
130. In the illustrated embodiment, the chemistry supply system is
coupled to the recirculation system 120 using one or more lines
135, but this is not required for the invention. In alternate
embodiments, the chemical supply system can be configured
differently and can be coupled to different elements in the
processing system. For example, the chemistry supply system 130 can
be coupled to the process module 110.
[0021] The chemistry supply system 130 can comprise a cleaning
chemistry assembly (not shown) for providing cleaning chemistry for
generating supercritical cleaning solutions within the processing
chamber. The cleaning chemistry can include peroxides and a
fluoride source. For example, the peroxides can include hydrogen
peroxide, benzoyl peroxide, or any other suitable peroxide, and the
fluoride sources can include fluoride salts (such as ammonium
fluoride salts), hydrogen fluoride, fluoride adducts (such as
organic-ammonium fluoride adducts) and combinations thereof.
[0022] Further details of fluoride sources and methods of
generating supercritical processing solutions with fluoride sources
are described in U.S. patent application Ser. No. 10/442,557, filed
May 10, 2003, and titled "TETRA-ORGANIC AMMONIUM FLUORIDE AND HF IN
SUPERCRITICAL FLUID FOR PHOTORESIST AND RESIDUE REMOVAL", and U.S.
patent application Ser. No. 10/321,341, filed Dec. 16, 2002, and
titled "FLUORIDE IN SUPERCRITICAL FLUID FOR PHOTORESIST POLYMER AND
RESIDUE REMOVAL," both incorporated by reference herein.
[0023] In addition, the cleaning chemistry can include chelating
agents, complexing agents, oxidants, organic acids, and inorganic
acids that can be introduced into supercritical carbon dioxide with
one or more carrier solvents, such as N,N-dimethylacetamide (DMAc),
gamma-butyrolactone (BLO), dimethyl sulfoxide (DMSO), ethylene
carbonate (EC), N-methylpyrrolidone (NMP), dimethylpiperidone,
propylene carbonate, and alcohols (such a methanol, ethanol and
1-propanol).
[0024] The chemistry supply system 130 can comprise a rinsing
chemistry assembly (not shown) for providing rinsing chemistry for
generating supercritical rinsing solutions within the processing
chamber. The rinsing chemistry can include one or more organic
solvents including, but not limited to, alcohols and ketones. In
one embodiment, the rinsing chemistry can comprise sulfolane, also
known as thiocyclopenatne-1,1-dioxide, (Cyclo)tetramethylene
sulphone and 1,3,4,5-tetrahydrothiophene-1,1-dioxide, which can be
purchased from a number of venders, such as Degussa Stanlow
Limited, Lake Court, Hursley Winchester SO21 1LD UK.
[0025] The chemistry supply system 130 can comprise a curing
chemistry assembly (not shown) for providing curing chemistry for
generating supercritical curing solutions within the processing
chamber.
[0026] The processing system 100 can comprise a carbon dioxide
supply system 140. As shown in FIG. 1, the carbon dioxide supply
system 140 can be coupled to the process module 110 using one or
more lines 145, but this is not required. In alternate embodiments,
carbon dioxide supply system 140 can be configured differently and
coupled differently. For example, the carbon dioxide supply system
140 can be coupled to the recirculation system 120.
[0027] The carbon dioxide supply system 140 can comprise a carbon
dioxide source (not shown) and a plurality of flow control elements
(not shown) for generating a supercritical fluid. For example, the
carbon dioxide source can include a CO.sub.2 feed system, and the
flow control elements can include supply lines, valves, filters,
pumps, and heaters. The carbon dioxide supply system 140 can
comprise an inlet valve (not shown) that is configured to open and
close to allow or prevent the stream of supercritical carbon
dioxide from flowing into the processing chamber 108. For example,
controller 180 can be used to determine fluid parameters such as
pressure, temperature, process time, and flow rate.
[0028] The processing system 100 can also comprise a pressure
control system 150. As shown in FIG. 1, the pressure control system
150 can be coupled to the process module 110 using one or more
lines 155, but this is not required. In alternate embodiments,
pressure control system 150 can be configured differently and
coupled differently. The pressure control system 150 can include
one or more pressure valves (not shown) for exhausting the
processing chamber 108 and/or for regulating the pressure within
the processing chamber 108. Alternately, the pressure control
system 150 can also include one or more pumps (not shown). For
example, one pump may be used to increase the pressure within the
processing chamber, and another pump may be used to evacuate the
processing chamber 108. In another embodiment, the pressure control
system 150 can comprise means for sealing the processing chamber.
In addition, the pressure control system 150 can comprise means for
raising and lowering the substrate and/or the chuck.
[0029] Furthermore, the processing system 100 can comprise an
exhaust control system 160. As shown in FIG. 1, the exhaust control
system 160 can be coupled to the process module 110 using one or
more lines 165, but this is not required. In alternate embodiments,
exhaust control system 160 can be configured differently and
coupled differently. The exhaust control system 160 can include an
exhaust gas collection vessel (not shown) and can be used to remove
contaminants from the processing fluid. Alternately, the exhaust
control system 160 can be used to recycle the processing fluid.
[0030] Controller 180 can use pre-process data, process data, and
post-process data. For example, pre-process data can be associated
with an incoming substrate. This pre-process data can include lot
data, batch data, run data, composition data, and history data. The
pre-process data can be used to establish an input state for a
wafer. Process data can include process parameters. Post processing
data can be associated with a processed substrate.
[0031] The controller 180 can use the pre-process data to predict,
select, or calculate a set of process parameters to use to process
the substrate. For example, this predicted set of process
parameters can be a first estimate of a process recipe. A process
model can provide the relationship between one or more process
recipe parameters or set points and one or more process results. A
process recipe can include a multi-step process involving a set of
process modules. Post-process data can be obtained at some point
after the substrate has been processed. For example, post-process
data can be obtained after a time delay that can vary from minutes
to days. The controller can compute a predicted state for the
substrate based on the pre-process data, the process
characteristics, and a process model. For example, a cleaning rate
model can be used along with a contaminant level to compute a
predicted cleaning time. Alternately, a rinse rate model can be
used along with a contaminant level to compute a processing time
for a rinse process.
[0032] It will be appreciated that the controller 180 can perform
other functions in addition to those discussed here. The controller
180 can monitor the pressure, temperature, flow, or other variables
associated with the processing system 100 and take actions based on
these values. For example, the controller 180 can process measured
data, display data and/or results on a GUI screen, determine a
fault condition, determine a response to a fault condition, and
alert an operator. The controller 180 can comprise a database
component (not shown) for storing input and output data.
[0033] In a supercritical cleaning/rinsing process, the desired
process result can be a process result that is measurable using an
optical measuring device. For example, the desired process result
can be an amount of contaminant in a via or on the surface of a
substrate. After each cleaning process run, the desired process
result can be measured.
[0034] FIG. 2 illustrates a simplified block diagram of a
recirculation subassembly in accordance with an embodiment of the
invention. In the illustrated embodiment, a recirculation
subassembly 210 is shown that includes an input 212, an output 214,
a pump assembly 220, and a bypass assembly 230. In alternate
embodiments, different configurations can be used. For example, the
recirculation subassembly 210 can be a portion of the recirculation
system 120 (FIG. 1).
[0035] As shown in FIG. 2, an input 212 of the recirculation
subassembly 210 can be coupled to one or more of the lines (122
FIG. 1), and an output 214 of the recirculation subassembly 210 can
be coupled to one or more of the lines (124 FIG. 1). In addition,
the input 212 of the recirculation subassembly 210 can be coupled
to the pump assembly inlet 221; the pump assembly outlet 222 can be
coupled to the input 231 of the bypass assembly 230; the output 214
of the recirculation subassembly 210 can be coupled to the bypass
assembly outlet 232. In an alternate embodiment, input 212 and/or
output 214 may not be required.
[0036] The pump assembly 220, which can include a pump (not shown)
and a motor (not shown), can have an operating pressure up to 5,000
psi. The pump assembly can have an operating temperature up to 250
degrees Celsius. The pump assembly 220 can be used to pump a
supercritical fluid that can include supercritical carbon dioxide
or supercritical carbon dioxide admixed with an additive or
solvent. A coolant fluid can be flowed through the pump
assembly.
[0037] The pump assembly 220 can include a centrifugal impeller
(not shown) that can rotate within the pump assembly 220 to pump
fluid from a pump inlet 221 to a pump outlet 222. The pump assembly
220 can be coupled to a controller (180 FIG. 1) using control line
225 to control the operation of the pump assembly 220. In an
alternate embodiment, the pump assembly 220 may include a
controller (not shown) suitable for operating the pump assembly
220. In another embodiment, the pump assembly 220 may include one
or more filters (not shown). For example, a filter may be included
in an input path, an output path, or in both paths.
[0038] Bypass assembly 230 can include at least two multi-port
valves (340 and 250), at least one filter 260, and at least one
bypass line 270. The multi-port valve 240 can be coupled to a
controller (180 FIG. 1) using control line 245 to control the
operation of the multi-port valve 240. The multi-port valve 250 can
be coupled to a controller (180 FIG. 1) using control line 255 to
control the operation of the multi-port valve 250. For example, a
multi-port valve can include a measuring device (not shown) for
measuring flow and/or pressure. In an alternate embodiment, a
multi-port valve may include a controller (not shown) suitable for
operating the multi-port valve.
[0039] Multi-port valve 240 can include an input 241 coupled to the
bypass assembly input 231, a first output 242 coupled to an input
end of the bypass line 270, and a second output 243 coupled to the
input 261 of the filter 260. Multi-port valve 250 can include an
output 251 coupled to the bypass assembly output 232, a first input
252 coupled to an output end of the bypass line 270, and a second
input 253 coupled to the output 262 of the filter 260. In alternate
embodiments, a different number of multi-port valves may be used, a
different number of filters may be used, a different number of
bypass lines may be used, and the multi-port valves may be
configured differently.
[0040] Filter 260 can be constructed to filter particles that are
larger than approximately 0.050 microns. Filter 260 is intended for
non-continuous operation and is not intended to operate when the
supercritical fluid includes a large amount of process chemistry,
process residues, and/or particles. For example, the filter 260 can
be switch into the recirculation loop during one or more of the
decompression cycles during time T.sub.4 shown in FIG. 2. In this
example, the small amount of process chemistry, process residues,
and/or particles that remain in the fluid circulating in the
recirculation loop can be removed by the filter.
[0041] In one embodiment, the flow path length for the bypass line
270 can be made to be substantially equal to the flow path length
for the filter 260 and the associated piping. Alternately, the flow
path length for the bypass line 270 may be made as short as
possible to reduce particle contamination.
[0042] Bypass line 270 can be used for continuous operation or
substantially continuous operation. For example, the bypass line
270 can be switch out of the recirculation loop during one or more
of the decompression cycles during time T.sub.4 shown in FIG.
2.
[0043] During substrate processing, having a filter in the
recirculation loop can have a negative affect on the process. For
example, a filter can affect the process chemistry, the process
pressure, the process flow, the process temperature, and the
process uniformity. In one embodiment, the bypass line 270 is
coupled into the recirculation loop during a major portion of the
substrate processing so that the filter's impact on the process is
minimized.
[0044] In another embodiment, filter 260 can be used during a
maintenance or system cleaning operation in which cleaning
chemistry is used to remove process by-products and/or particles
from the interior surfaces of the system. This is a preventative
maintenance operation that prevents material from adhering to the
interior surfaces of the system that can be dislodged later during
processing and that can cause unwanted particle deposition on a
substrate. In addition, the filter 260 can be replaced and/or
cleaned during the bypass mode.
[0045] FIG. 3 illustrates an exemplary graph of pressure versus
time for a supercritical process step in accordance with an
embodiment of the invention. In the illustrated embodiment, a graph
300 of pressure versus time is shown, and the graph 300 can be used
to represent a supercritical cleaning process step, a supercritical
rinsing process step, or a supercritical curing process step, or a
combination thereof. Alternately, different pressures, different
timing, and different sequences may be used for different
processes.
[0046] Now referring to both FIGS. 1, 2, and 3, prior to an initial
time T.sub.0, the substrate to be processed can be placed within
the processing chamber 108 and the processing chamber 108 can be
sealed. For example, during cleaning and/or rinsing processes, a
substrate can have post-etch and/or post-ash residue thereon. The
substrate, the processing chamber, and the other elements in the
recirculation loop 115 (FIG.1) can be heated to an operational
temperature. For example, the operational temperature can range
from 40 to 300 degrees Celsius.
[0047] From the initial time T.sub.0 through a first duration of
time T.sub.1, the processing chamber 108 and the other elements in
the recirculation loop 115 (FIG.1) can be pressurized. For example,
a supercritical fluid, such as substantially pure CO.sub.2, can be
used to pressurize the processing chamber 108 and the other
elements in the recirculation loop 115 (FIG.1). During time
T.sub.1, a pump, such as pump 220 (FIG. 2), can be started and can
be used to circulate the supercritical fluid through the processing
chamber 108 and the other elements in the recirculation loop 115
(FIG.1).
[0048] During a first portion of the time T.sub.1, a filter, such
as filter 260 (FIG. 2), can be switched into the flow path and can
be used to filter the supercritical fluid circulating through the
processing chamber 108 and the other elements in the recirculation
loop 115 (FIG.1). For example, the recirculation subassembly can be
operated in a filter mode. In addition, during a second portion of
the time T.sub.1, the filter can be switched out of the flow path
and a bypass line, such as bypass line 270 (FIG. 2), can be used as
an element in the recirculation loop. For example, the
recirculation subassembly can be operated in a bypass mode.
[0049] In one embodiment, when the pressure in the processing
chamber 108 exceeds a critical pressure Pc (1,070 psi), process
chemistry can be injected into the processing chamber 108, using
the process chemistry supply system 130. In addition, the filter
can be switched out of the recirculation loop and the bypass line
can be switched into the recirculation loop before the process
chemistry is injected. In alternate embodiments, process chemistry
may be injected into the processing chamber 108 before the pressure
exceeds the critical pressure Pc (1,070 psi) using the process
chemistry supply system 130. For example, the injection(s) of the
process chemistries can begin upon reaching about 1100-1200 psi. In
other embodiments, process chemistry is not injected during the
T.sub.2 period.
[0050] In one embodiment, process chemistry is injected in a linear
fashion, and the injection time can be based on a recirculation
time. For example, the recirculation time can be determined based
on the length of the recirculation path and the flow rate. In other
embodiments, process chemistry may be injected in a non-linear
fashion. For example, process chemistry can be injected in one or
more steps.
[0051] The process chemistry can include a cleaning agent, a
rinsing agent, or a curing agent, or a combination thereof that is
injected into the supercritical fluid. One or more injections of
process chemistries can be performed over the duration of time
T.sub.1 to generate a supercritical processing solution with the
desired concentrations of chemicals. The process chemistry, in
accordance with the embodiments of the invention, can also include
one more or more carrier solvents.
[0052] Still referring to both FIGS. 1, 2, and 3, during a second
time T.sub.2, the supercritical processing solution can be
re-circulated over the substrate and through the processing chamber
108 using the recirculation system 120, such as described above. In
one embodiment, process chemistry is not injected during the second
time T.sub.2. Alternatively, process chemistry may be injected into
the processing chamber 108 during the second time T.sub.2 or after
the second time T.sub.2.
[0053] The processing chamber 108 can operate at a pressure above
1,500 psi during the second time T.sub.2. For example, the pressure
can range from approximately 2,500 psi to approximately 3,100 psi,
but can be any value so long as the operating pressure is
sufficient to maintain supercritical conditions. The supercritical
processing solution is circulated over the substrate and through
the processing chamber 108 using a pump in the recirculation system
120, such as described above. The supercritical conditions within
the processing chamber 108 and the other elements in the
recirculation loop 115 (FIG.1) are maintained during the second
time T.sub.2, and the supercritical processing solution continues
to be circulated over the substrate and through the processing
chamber 108 and the other elements in the recirculation loop 115
(FIG.1). A pump, such as pump 220 (FIG. 2), can be used to regulate
the flow of the supercritical processing solution through the
processing chamber 108 and the other elements in the recirculation
loop 115 (FIG.1).
[0054] In one embodiment, during the second time T.sub.2, the
filter can be switched out of the flow path and a bypass line, such
as bypass line 270 (FIG. 2), can be used as an element in the
recirculation loop. For example, the recirculation subassembly 210
can be operated in a bypass mode. Alternately, the recirculation
subassembly 210 may be operated in a filter mode during a portion
of the second time T.sub.2.
[0055] Still referring to both FIGS. 1, 2, and 3, during a third
time T.sub.3 a push-through process can be performed. During the
third time T.sub.3, a new quantity of supercritical carbon dioxide
can be fed into the processing chamber 108 and the other elements
in the recirculation loop 115 from the carbon dioxide supply system
140, and the supercritical cleaning solution along with process
residue suspended or dissolved therein can be displaced from the
processing chamber 108 and the other elements in the recirculation
loop 115 through the exhaust control system 160. In an alternate
embodiment, supercritical carbon dioxide can be fed into the
recirculation system 120 from the carbon dioxide supply system 140,
and the supercritical cleaning solution along with process residue
suspended or dissolved therein can also be displaced from the
processing chamber 108 and the other elements in the recirculation
loop 115 through the exhaust control system 160.
[0056] In one embodiment, during the third time T.sub.3, the filter
can be switched out of the flow path and a bypass line, such as
bypass line 270 (FIG. 2), can be used as an element in the
recirculation loop. For example, the recirculation subassembly 210
can be operated in a bypass mode. Alternately, the recirculation
subassembly 210 may be operated in a filter mode during a portion
of the third time T.sub.3.
[0057] In the illustrated embodiment shown in FIG. 2, a single
second time T.sub.2 is followed by a single third time T.sub.3, but
this is not required. In alternate embodiments, other time
sequences may be used to process a substrate.
[0058] After the push-through process is complete, a decompression
process can be performed. In an alternate embodiment, a
decompression process is not required. During a fourth time
T.sub.4, the processing chamber 108 can be cycled through a
plurality of decompression and compression cycles. The pressure can
be cycled between a first pressure P.sub.3 and a second pressure
P.sub.4 one or more times. In alternate embodiments, the first
pressure P.sub.3 and a second pressure P.sub.4 can vary. In one
embodiment, the pressure can be lowered by venting through the
exhaust control system 160. For example, this can be accomplished
by lowering the pressure to below approximately 1,500 psi and
raising the pressure to above approximately 2,500 psi. The pressure
can be increased by adding high-pressure carbon dioxide.
[0059] In one embodiment, during a first portion of the fourth time
T.sub.4, the filter can be switched out of the flow path and a
bypass line 270 can be used as an element in the recirculation
loop. For example, the recirculation subassembly 210 can be
operated in a bypass mode. During a second portion of the time
T.sub.4, a filter 260 can be switched into the flow path and can be
used to filter the supercritical fluid circulating through the
processing chamber 108 and the other elements in the recirculation
loop 115 (FIG.1). For example, the recirculation subassembly can be
operated in a filter mode.
[0060] Alternately, the recirculation subassembly can be operated
in a bypass mode during the fourth time T.sub.4.
[0061] During a fifth time T.sub.5, the processing chamber 108 can
be returned to lower pressure. For example, after the decompression
and compression cycles are complete, then the processing chamber
can be vented or exhausted to atmospheric pressure. For substrate
processing, the chamber pressure can be made substantially equal to
the pressure inside of a transfer chamber (not shown) coupled to
the processing chamber. In one embodiment, the substrate can be
moved from the processing chamber into the transfer chamber, and
moved to a second process apparatus or module to continue
processing.
[0062] In one embodiment, during the fifth time T.sub.5, the filter
can be switched out of the flow path and a bypass line 270 can be
used as an element in the recirculation loop. For example, the
recirculation subassembly 210 can be operated in a bypass mode.
[0063] In the illustrated embodiment shown in FIG. 3, the pressure
returns to an initial pressure P.sub.0, but this is not required
for the invention. In alternate embodiments, the pressure does not
have to return to P.sub.0, and the process sequence can continue
with additional time steps such as those shown in time steps
T.sub.1, T.sub.2, T.sub.3, T.sub.4, or T.sub.5
[0064] The graph 300 is provided for exemplary purposes only. It
will be understood by those skilled in the art that a supercritical
processing step can have any number of different time/pressures or
temperature profiles without departing from the scope of the
invention. Further, any number of cleaning and rinse processing
sequences with each step having any number of compression and
decompression cycles are contemplated. In addition, as stated
previously, concentrations of various chemicals and species within
a supercritical processing solution can be readily tailored for the
application at hand and altered at any time within a supercritical
processing step.
[0065] While the invention has been described in terms of specific
embodiments incorporating details to facilitate the understanding
of the principles of construction and operation of the invention,
such reference herein to specific embodiments and details thereof
is not intended to limit the scope of the claims appended hereto.
It will be apparent to those skilled in the art that modifications
may be made in the embodiments chosen for illustration without
departing from the spirit and scope of the invention.
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