U.S. patent application number 09/802692 was filed with the patent office on 2001-12-27 for wafer processing apparatus and method.
This patent application is currently assigned to Semix Incorporated. Invention is credited to Chang, Arin, Kelly, Tom, Mendez, Guy, Tran, Khanh.
Application Number | 20010055823 09/802692 |
Document ID | / |
Family ID | 22693834 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010055823 |
Kind Code |
A1 |
Tran, Khanh ; et
al. |
December 27, 2001 |
Wafer processing apparatus and method
Abstract
A method and apparatus are described for transferring processing
structures between first and second processing environments. The
apparatus includes a first apparatus compartment configured to
provide the first processing environment and a second apparatus
compartment configured to provide the second processing
environment. The apparatus is preferably configured for
transferring wafer structures between the processing environments.
The first and second processing environments are coupled together
through a transfer passage that is opened and closed in order to
isolate the wafer in a small transfer volume between the processing
environments. Preferably, the transfer passage is opened and closed
with first and second movable tables to create the small volume
transfer cavity. In operation, the wafer is isolated within the
small volume transfer cavity and the first and second tables are
individually raised and lowered to expose the wafer to the first
and second processing environments without opening the transfer
passage between the first and second apparatus compartments.
According to an embodiment of the invention, the apparatus is
configured with a chemical delivery system that monitors the
chemical composition or chemical concentration within the second
apparatus compartment and supplies the appropriate quantity of
chemical or chemicals to maintain a selected composition or
concentration therein. According to a preferred embodiment the
apparatus is configured for processing wafers coated with
silicon-based materials to produce porous low-k coatings.
Inventors: |
Tran, Khanh; (San Jose,
CA) ; Kelly, Tom; (Milipitas, CA) ; Chang,
Arin; (San Jose, CA) ; Mendez, Guy; (Fremont,
CA) |
Correspondence
Address: |
Jonathan O. Owens
HAVERSTOCK & OWENS LLP
260 Sheridan Avenue, Suite 420
Palo Alto
CA
94306
US
|
Assignee: |
Semix Incorporated
|
Family ID: |
22693834 |
Appl. No.: |
09/802692 |
Filed: |
March 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60188605 |
Mar 9, 2000 |
|
|
|
Current U.S.
Class: |
438/14 |
Current CPC
Class: |
H01L 21/67751
20130101 |
Class at
Publication: |
438/14 |
International
Class: |
G01R 031/26; H01L
021/66 |
Claims
What is claimed is:
1. An apparatus comprising: a) a first compartment with a first
processing environment; b) a second compartment with a second
processing environment; c) a transfer passage through which the
first and the second compartments are coupled; and d) a transfer
mechanism for transferring a structure between the first processing
environment and the second processing environment through the
transfer passage, the transfer mechanism comprising a closing
mechanism configured to close the first compartment and the second
compartment at the transfer passage in order to form a transfer
cavity, wherein the structure is isolated within the transfer
cavity prior to transferring the structure between the first
processing environment and the second processing environment.
2. The apparatus of claim 1, wherein the volume of the transfer
cavity is less than 10% of the volume of at least one of the first
and the second compartments.
3. The apparatus of claim 2, wherein the closing mechanism
comprises a first movable table structure within the first
compartment and a second movable table structure within the second
compartment, wherein the first movable table structure caps the
transfer passage from within the first compartment and a second
movable table structure caps the transfer passage from within the
second compartment.
4. The apparatus of claim 3, wherein at least one of the first and
second movable table structures is configured to hold the structure
while transferring the structure between the first process
environment and the second processing environment.
5. The apparatus of claim 2, further comprising a purging system
coupled to the transfer passage to purge the transfer cavity.
6. The apparatus of claim 1, wherein at least one of the first and
the second compartments has a chemical sensor unit comprising at
least one chemical sensor for monitoring at least one of the first
and the second processing environments.
7. The apparatus of claim 6, further comprising a controllable
chemical supply system for controlling the chemical composition of
the at least one of the first and the second processing
environments.
8. The apparatus of claim 7, wherein the controllable chemical
supply comprises an ammonia source, wherein the chemical sensor
senses the concentration of ammonia and supplies ammonia to the at
least one of the first and second compartments to maintain a
predetermined concentration of ammonia.
9. The apparatus of claim 4, further comprising a structure support
for supporting the structure in the at least one of the first and
the second compartments.
10. The apparatus of claim 9, wherein the structure support
comprises pin structures that pass through the at least one of the
first and second movable table structures such that when the at
least one of the first and second movable table structures is
lowered, the structure is released onto the pin structures and when
the at least one of the first and second movable table structures
is raised, the structure is released onto the table configured to
hold the structure.
11. The apparatus of claim 3, wherein at least one of the first and
the second movable table structures is capable of being raised and
lowered to provided convection.
12. The apparatus of claim 1, wherein the second compartment is
contained within the first compartment.
13. A wafer processing apparatus configured for transferring a
wafer from a first compartment with a first environment to a second
compartment with a second environment by a transfer mechanism, the
transfer mechanism comprising: a. a first movable table within the
first compartment for opening and closing a transfer passage
between the first and the second compartment; and b. a second
movable table within the second compartment for opening and closing
the transfer passage between the first and the second compartment;
wherein the first and the second movable table close together to
create a transfer cavity for isolating the wafer within a small
transfer volume prior to transferring the wafer between the first
environment and the second environment.
14. The wafer process apparatus of claim 13, further comprising a
control system controlling the chemical composition of the second
environment.
15. The wafer process apparatus of claim 13, wherein the control
system comprises a chemical senor and chemical supply source,
wherein the chemical sensor signals the chemical supply source to
dispense a chemical into the second compartment when the chemical
composition of the second environment is at a predetermined
value.
16. The wafer process apparatus of claim 13, wherein the first
movable table is configured to hold and transfer the wafer between
the first environment and the second environment.
17. The wafer process apparatus of claim 16, further comprising a
wafer support for supporting the wafer in the first
compartment.
18. The wafer process apparatus of claim 17, wherein the wafer
support comprises pin structures that pass through the first
movable table such that when the first movable table is lowered,
the wafer is released onto the pins and when the first movable
table is raised the wafer is released onto the first movable
table.
19. The wafer process apparatus of claim 13, wherein the second
movable table is configured to be being raised and lowered while
the first movable table seals the transfer passage.
20. The wafer process apparatus of claim 13, wherein the second
compartment is contained within the first compartment.
21. The wafer process apparatus of claim 13, further comprising a
vacuum system coupled to the transfer cavity to purge the transfer
volume between transfers of the wafer from the first compartment to
the second compartment and from the second compartment to the first
compartment.
22. A method of transferring a wafer from a first processing
environment to a second processing environment comprising the steps
of: a. placing the wafer in a first compartment containing the
first processing environment; b. isolating the wafer between the
first compartment and a second compartment in a transfer cavity
having a small transfer volume containing a portion of the first
processing environment; and c. opening the transfer cavity to the
second compartment with the transfer cavity closed to the first
compartment.
23. The method of claim 22, further comprising the step of purging
the transfer volume prior to the step of opening the transfer
cavity to the second compartment with the transfer cavity closed to
the first compartment.
24. The method of claim 23, wherein the step of purging the
transfer cavity comprises the additional steps of: a. drawing a
vacuum on the transfer cavity; and b. backfilling the transfer
cavity.
25. The method of claim 24, wherein small transfer volume is 10% or
less than the volume of the second processing environment.
26. The method of claim 23, further comprising the additional steps
of: a. monitoring the chemical composition of the processing
environment in the second compartment; and b. adjusting the
chemical composition of the processing environment in the second
compartment when the chemical composition reaches a threshold
value.
27. The method of claim 26, wherein the chemical composition of the
processing environment in the second compartment is monitored with
an infrared sensor that monitors the concentration of ammonia.
28. A wafer processing apparatus configured for selectively
exposing a reaction surface of a wafer to a first processing
environment supplied by a first apparatus compartment and a second
processing environment supplied by a second apparatus compartment,
wherein the first and the second apparatus compartments are coupled
through a transfer passage, the apparatus comprising: a. means for
opening and closing a transfer passage between the first and the
second compartment to form a small volume transfer cavity with the
wafer contained therein; and b. means for selectively opening the
small volume transfer cavity to a selective one of the first
processing environment and the second processing environment to
expose the reaction surface of the wafer to the selective one of
the first and the second processing environment.
Description
Related Application(s)
[0001] This Patent Application claims priority under 35 U.S.C. 119
(e) of the co-pending U.S. Provisional Patent Application, Ser. No.
60/188,605, filed Mar. 9, 2000, and entitled "AGING CHAMBER FOR
LOW-K CHEMICAL". The Provisional Patent Application, Ser. No.
60/188,605, filed Mar. 9, 2000, and entitled "AGING CHAMBER FOR
LOW-K CHEMICAL" is also hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention is related to wafer processing. More
particularly, the present invention relates to an apparatus and
method for processing wafers in multiple processing
environments.
BACKGROUND OF THE INVENTION
[0003] State of the art integrated circuits can contain up to 6
million transistors and more than 800 meters of wiring. There is a
constant push to increase the number of transistors on wafer-based
integrated circuits. As the number of transistors is increased
there is a need to reduce the cross-talk between the closely packed
wire in order to maintain high performance requirements. The
semiconductor industry is continuously looking for new processes
and new materials that can help to improve the performance of
wafer-based integrated circuits. For example, there is considerable
excitement within the industry surrounding the use and application
of a group of materials generically referred to as low-k materials
or low-dielectric materials. Low-k materials have been shown to
reduce cross-talk and provide a transition into the fabrication of
even smaller geometry integrated circuitry.
[0004] Low-k materials are required to be compatible with other
wafer fabrication processes, they must exhibit good adhesion, high
thermal stability and low film stress. The k value of a material
depends on several factors including how the materials is deposited
on the wafer. SiO.sub.2 has a k-value of approximately 4.0 and air
has a k-value of 1.0. An ideal low-k material will have a k-value
that approaches that of air. However, materials that exhibit
k-values below 3.5 are considered low-k materials. Post treatment
of coated materials can significantly reduce their observed
k-value. For example, spin on glass materials and polymers can be
treated to make porous siloxane coatings with k-values as low or
below 2.0.
[0005] While low-k materials provide a promise for the fabrication
of advanced micro circuitry, the deposition and subsequent
treatment steps of low-k material in the wafer fabrication
processing can lead to low throughput, increases in cost and low
processing consistency. The wafer fabrication industry is
continuously trying to balance state-of-the-art chip performance
with the throughput, cost and consistency of wafer processing.
SUMMARY OF THE INVENTION
[0006] A wafer processing apparatus and method provides an
apparatus and method for transferring a structure with a reaction
surface from one processing environment to another processing
environment. Preferably, the apparatus is configured to transfer a
wafer from one processing environment to another processing
environment. The wafer processing apparatus and method of the
present invention transfers wafers with reaction surfaces from one
processing environment to another processing environment while
minimizing cross-contamination between processing environments and
minimizing the depletion of processing chemicals during the
transfer process. Further, the wafer processing apparatus and
method transfers a reaction surface of a wafer into a chemical
environment, while exposing the entire reaction surface to the
processing environment quickly and with minimal initial convection
during the transfers, thereby enhancing the consistency and
uniformity of the wafer processing.
[0007] The apparatus of the instant invention has a first apparatus
compartment configured to provide a first processing environment
and a second apparatus compartment configured to provide a second
processing environment. The first and the second apparatus
compartments are coupled through a transfer passage that is capable
of being opened and closed to create a transfer cavity and
isolating a small transfer volume. The transfer volume is
preferably less than five times the volume of the wafer, or wafers,
being transferred and is most preferably less than twice the volume
of the wafer, or wafers, being transferred in order to reduce the
potential for cross-contamination between the first processing
environment and the second processing environment during the
transfer processes between the first and second apparatus
compartments. According to an embodiment of the instant invention,
the apparatus is provided with a vacuum source or a gas purge
coupled to the transfer cavity for purging the transfer volume
between transfers further reducing cross-contamination between the
first processing environment and the second processing environment
during the transfer process. The small transfer volume, utilized in
the apparatus and method of the present invention, also reduces
depletion of chemicals in a processing environment of the first
and/or second apparatus compartment resulting from multiple
transfers.
[0008] Preferably, the transfer cavity is formed from the transfer
passage, a first movable table within the first apparatus
compartment and a second movable table within the second apparatus
compartment. The movable tables open and close ports of the
transfer passage from within their respective compartments. The
first and the second movable tables are configured to close
together and isolate the wafer within the small transfer volume
prior to exposing or transferring the wafer between the first
processing environment and the second processing environment.
[0009] The apparatus preferably has a controllable chemical
delivery system that maintains a chemical processing environment
within the second compartment. Preferably, the chemical delivery
system has a chemical sensor unit with one or more chemical
sensors. The chemical sensor unit monitors the chemical
composition, concentration or concentrations within the second
apparatus compartment. The sensor unit controls a chemical supply,
via feed back control circuitry, to deliver a processing chemical,
or processing chemicals, to the second apparatus compartment in
order to maintain a predetermined or selected composition or
concentration value of the processing chemical in the second
apparatus compartment.
[0010] According to an embodiment of the instant invention the
chemical supply system is configured to deliver hydrated ammonia to
the second apparatus compartment and the apparatus is configured
for the treatment and aging of wafers coated with low-k
spin-on-glass materials. At least one of the sensors is preferably
a short path infrared sensor that measures the concentration of
ammonia, water or both. If the measured concentration of ammonia or
water is low, water or hydrated ammonia is supplied to the second
apparatus compartment to reestablish the predetermined or selected
concentration of hydrated ammonia within the second apparatus to
compartment. If the measured concentration of ammonia or water is
high, the second apparatus compartment is purged with inert gas, or
a vacuum is drawn on the second apparatus compartment, until the
predetermined or selected concentration of hydrated ammonia is
reestablished within the second apparatus compartment.
[0011] In operation, the wafer is placed on the first movable table
within the first apparatus compartment with the second movable
table in the closed position and capping the transfer passage
between the first and second apparatus compartments. The processing
environment within the first apparatus compartment is adjusted or
maintained by any means known in the art to produce the desired
outcome.
[0012] To expose and transfer the reaction surface of the wafer to
the second processing environment, the second movable table is
raised. Because the pressure and the chemical composition within
the second processing environment is held substantially constant
and because the entire reaction surface is exposed quickly to the
chemical processing environment, the reaction surface of the wafer
does not experience large fluctuations in chemical composition or
exposure time to the surrounding processing environment. Thus, the
method and apparatus of the present invention provides for
consistent processing not only from wafer to wafer, but also
throughout the surface of each wafer processed.
[0013] According to an alterative embodiment, prior to the step of
exposing the wafer to the second processing environment, the
transfer volume within the transfer cavity is purged to reduce
contamination of the second processing environment with the small
volume of the first processing environment captured within the
transfer cavity.
[0014] According to a preferred embodiment of the invention, the
second movable table is capable of being raised and lowered while
the wafer is being exposed to the second processing environment.
Moving the second movable table in an upward and downward motion
creates a small amount of post exposure convection within the
second processing environment and helps to quickly replenish
processing chemicals at the reaction surface of the wafer and,
thereby, helps to improve the throughput of the chemical processing
step.
[0015] To transfer the wafer back to the first processing
environment, the second movable table is placed in the closed
position, thereby, capping the transfer passage and isolating the
wafer in the transfer cavity. The first movable table is then
lowered to expose and transfer the wafer back to the first
processing environment. Alternatively, prior to the step of
exposing and transferring the wafer back to the first processing
environment, the transfer volume within the transfer cavity is
purged to reduce contamination of the first processing environment
with the small volume of the second processing environment captured
within the transfer cavity. The purging includes steps such as
drawing a vacuum on the transfer cavity and/or back filling the
transfer cavity with a suitable processing environment or inert
gas.
[0016] Preferably, the first movable table is configured to hold
and support the wafer between transfers and support the wafer in
the first apparatus compartment. Alternatively, the apparatus is
configured with a wafer support for supporting the wafer above the
first movable table, when the first movable table is in a lowered
position. Within this embodiment, the wafer support comprises pin
structures that pass through the first movable table, such that
when the first movable table is lowered, the wafer is released onto
the pins and when the first movable table is raised, the wafer is
supported by the first movable table.
[0017] Preferably, the operation of the apparatus is automatically
controlled by a controller or a computer, wherein a user selects a
time of exposure of the wafer to the first and second processing
environment, time of isolation of the wafer within the transfer
cavity, concentrations of chemicals and the like. The at least one
chemical sensor preferably continuously monitors the chemical
composition or chemical concentration within the second process
environment and is utilized to control the supply of the
appropriate quantity of chemical or chemicals to maintain the
selected composition or concentration.
[0018] The transfer mechanism of the instant invention is not
limited to a two compartment wafer processing system. Any number of
processing stations can be included within the apparatus, whereby
wafers are moved from one station to the next and transferred
between processing compartments by the mechanism described herein.
Further, any number of more complex systems can be implemented to
control the chemical environments within apparatus compartments.
For example, each compartment can be equipped with an independently
controllable chemical delivery system and monitoring system. Also,
the transfer cavity itself can serve as a processing compartment
and provide a separate and unique processing environment. According
to the preferred embodiment of the invention, the apparatus is a
modular processing station that is integrated into a multi-station
wafer processing system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIGS. 1a-c are schematic cross-sectional views of a
multi-compartment wafer processing apparatus configured with
movable tables for transferring a wafer from a first processing
environment to a second processing environment, in accordance with
the current invention.
[0020] FIGS. 2a-b are flow block diagrams outlining the steps of
the method for transferring a wafer from a first processing
environment to a second processing environment, in accordance with
the method of the current invention.
[0021] FIG. 3 is a schematic cross-sectional view of a
multi-compartment wafer processing apparatus with a controllable
chemical delivery system and a transfer mechanism in accordance
with the preferred embodiment of the instant invention.
[0022] FIG. 4 is a schematic block diagram of a robotic wafer
processing machine with a modular low-k processing station in
accordance with the instant invention.
DESCRIPTION OF THE INVENTION
[0023] A wafer processing apparatus and method of the present
invention includes an apparatus and method for transferring
materials from one processing environment to another processing
environment. The wafer processing apparatus and method expose the
reaction surface of the structure to the processing environments
with minimal initial fluctuation in the environment and such that
the entire reaction surface of the structure is exposed at
substantially the same time. Referring to FIG. 1a, the apparatus
100 of the instant invention is preferably configured to transfer a
wafer 307 from a first apparatus compartment 101 with a first
processing environment 109 to a second apparatus compartment 201
with a second processing environment 209. The apparatus has a first
apparatus compartment 101 configured to supply the first processing
environment 109 and a second apparatus compartment 201 configured
to supply the second processing environment 209. The compartments
101 and 201 are coupled through a transfer passage 301 that is
capable of being opened and closed to create a transfer cavity
301', shown in FIG. 1b, wherein the transfer cavity 301' has a
relatively small transfer volume. The transfer volume is preferably
less than 10% of the volume of the second apparatus compartment 201
and less than five times the volume occupied by the wafer 307. The
small transfer volume helps to ensure that cross-contamination
between the first processing environment 109 and the second
processing environment 209 is reduced during the transfer process.
Preferably, the transfer cavity 301' is formed from the walls 303
and 305 of the transfer passage 301, a first movable table 103,
within the first apparatus compartment 101, and a second movable
table 203, within the second apparatus compartment 201.
[0024] Now referring to FIG. 1b, the first movable table 103 is
configured to move up and down with a first drive motor 105. The
first drive motor preferably moves the first movable table 103 up
and down through a first shaft structure 107. A second drive motor
205 is coupled to the second movable table 203 and moves the second
movable table 203 up and down through a second shaft structure 207.
In operation, the first drive motor 105 and the second drive motor
205 are controlled so that preferably one of the first movable
table 103 and the second movable table 203 is always in the closed
position. Further, the first movable table 103 and the second
movable table 203 are controlled so that both of the tables 103 and
203 are in a closed position and isolate the wafer 307 in the
transfer passage 301, between the first apparatus compartment 101
and the second apparatus compartment 201 (as shown in FIG. 1b).
Preferably, the first movable table 103 is configured to hold and
support the wafer 307 while transferring the wafer 307 between the
first processing environment 109 and the second processing
environment 209 and while the wafer 307 is isolated within the
small transfer volume 301'. While the second movable table 203 is
preferable for closing the port of the transfer passage 301, it
will be clear for the ensuing description that other means for
closing the port of the transfer passage are within the scope of
the invention. For example, instead of the second movable table 203
which moves up and down, the apparatus could also be configured
with a cover that moves from side-to-side in order to close the
transfer passage 301 and isolate the wafer 307 within the transfer
cavity 301'.
[0025] Now referring to FIG. 1c, after the wafer 307 is isolated
within the small transfer volume 301', then the second movable
table 203 is moved to an upward position, thereby, exposing and
transferring the wafer 307 to the second processing environment
209. Still referring to FIG. 1c, the second movable table 203 is
preferably configured to move up and down through a distance 204 in
order to create post exposure convection within the second
processing environment 209. The convection helps to ensure that the
second processing environment 209 is quickly replenished at the
wafer 307 surface and helps to improve the throughput of the
chemical processing steps.
[0026] FIG. 2 is a block diagram outlining the steps of the method
for transferring a wafer from a first processing environment to a
second processing environment, in accordance with the method of the
current invention. In the step 401, a wafer is placed within the
first apparatus compartment on the first movable table with the
transfer passage sealed to the second apparatus compartment,
preferably with a second movable table. In the step 403, the first
movable table is raised, thereby isolating the wafer within the
transfer cavity formed from the transfer passage, the first movable
table and the second movable table. After the wafer is isolated
within the transfer cavity in the step 403, then in the step 405,
the second movable table is raised, thereby exposing and
transferring the wafer to the second processing environment.
[0027] In an alternative embodiment, illustrated in FIG. 2b, prior
to the step 405 of exposing the wafer to the second processing
environment, in the step 404 the transfer volume within the
transfer cavity is purged to reduce the contamination of the second
processing environment with the small volume of the first
processing environment captured within the transfer cavity. The
step 404 of purging the transfer environment includes drawing a
vacuum on the transfer cavity or back filling the transfer cavity
with any suitable processing environment or inert gas.
[0028] After the step 405 of exposing the wafer to the second
processing environment, in the step 407, the wafer is processed.
The processing step 407 includes any appropriate processing step,
but is preferably a chemical processing step of the wafer, whereby
a processing chemical within the second processing environment is
monitored and maintained by a controllable chemical delivery
system. It is also preferred that the chemical processing
environment is provided with convection by moving the second table
up and down, as described in detail above. After the wafer is
processed by the processing environment in the step 407, then in
the step 409 the second movable table is placed in the closed
position to cap the transfer passage and isolate the wafer within
the transfer cavity. After the wafer is isolated within the
transfer cavity in the step 409, then in the step 411 the first
movable table is lowered to expose and transfer the wafer to the
first processing environment. After the step 411 of exposing the
wafer to the first processing environment, then in the step 413 the
wafer is removed from the first movable table for additional
processing steps or is transferred to a different processing
station within the apparatus.
[0029] Alternatively, in the embodiment illustrated in FIG. 2b,
prior to the step 411 of exposing the wafer to the first processing
environment, in the step 410 the transfer volume within the
transfer cavity is purged to reduce contamination of the first
processing environment with the small volume of the second
processing environment captured within the transfer cavity.
[0030] According to a preferred embodiment of the invention, the
chemical supply system is configured to deliver hydrated ammonia to
the second apparatus compartment and the apparatus is configured
for the treatment and aging of wafers coated with low-k, or low
dielectric, spin-on-glass materials. The wafer is prepared with the
spin on glass material by coating the wafer with a glass material
that is suspended in a suitable solvent. Suitable solvents include,
but are not limited to, Tetradecane, for applications where a
higher boiling point solvent is preferred, and Methyl-Isobutyl
Ketone (MIBK), for applications where a lower boiling point solvent
is preferred. Commercially available glass materials include
XLK.TM. Spin, manufactured by Dow Corning at 20 W. Salzburg Rd.,
Midland Mich. 48686 and Nanoglass.TM. manufactured by GE/Allied
Signal at 1349 Moffett Park Dr., Sunnyvale, Calif. 94089. The
spin-on-glass suspension is applied to the processing surface of
the wafer while the wafer is spinning preferably in the range of
2000-4000 rpm. The resultant film is preferably 5000-6000 angstroms
thick. The wafer with the spin-on-glass film is then placed in the
apparatus of the instant invention to process the spin-on-glass
film to achieve a low-k value.
[0031] The treatment of the spin-on-glass material with the
hydrated ammonia results in a porous spin on glass coating that has
a low-k value. The process of creating the porous spin-on-glass
coating is preferably performed in a temperature range of 15 to 25
degrees Celsius. The wafer is held within the chemical processing
environment of the apparatus for a period of time between 40 and 60
seconds and with an ammonia concentration that is preferably in the
range of 70 to 90%. Wafers processed in similar conditions with
spin-on-glass materials and the apparatus described herein, have
produced wafers with low-k coating that 60 to 90% Si-H remaining
and which exhibit k-values between 2.0 and 2.5.
[0032] FIG. 3 is a schematic cross-sectional view of a
multi-compartment wafer processing apparatus 500 with a
controllable chemical delivery system and a transfer mechanism
according to the preferred embodiment of the instant invention. The
apparatus has a primary compartment 501 with a first processing
environment 502 and a secondary compartment 503 with a second
processing environment 504. The compartments 501 and 503 are
coupled through a transfer passage 610 that is capable of being
opened and closed to isolate a wafer 527 within a small volume
transfer cavity by moving the tables 505 and 507. The tables 505
and 507 are moved up and down with the drive motors 509 and 511
that are coupled to the tables 505 and 507 through the shaft
structures 513 and 515, respectively. The drive motors 509 and 511
are operated to isolate the first processing environment 502 from
the second processing environment 504 through the transfer passage
610 and to isolate the wafer 527 with a small transfer volume
between transfers, as described in detail above.
[0033] The controllable chemical delivery system comprises a
chemical source 601, that is preferably ammonia, coupled to the
secondary compartment 503. At any time during the transfer process
or processing of the wafer, the sensor unit 607 monitors the
chemical composition or chemical concentration of the secondary
processing environment and signals the regulators 603 and 605 to
deliver an appropriate quantity of processing chemical or chemicals
to maintain a predetermined composition or concentration within the
secondary processing environment. In an alterative embodiment of
the invention, the primary compartment 501 is also configured with
a chemical delivery and monitoring system with a feedback loop for
maintaining a predetermined composition or concentration of a
processing chemical in the first processing environment 502. Also,
in other embodiments, the primary compartment 501 and/or the
secondary compartment 503 are equipped with a vacuum source 609 for
purging their respective processing environments.
[0034] The controllable chemical delivery system preferably has a
filtration station and/or hydration station 604. In the case where
the processing chemical 601 is ammonia, the station 604 is a
hydration station with water containing a predetermined
concentration ammonium hydroxide coupled to the secondary
compartment 503 through the regulator 605. The chemical sensor unit
607 is preferably has a short path infrared sensor that measures
the concentration of the ammonia, water or both within the
secondary compartment 503. The chemical senor is coupled to a feed
back control loop that signals the delivery of additional ammonia
and or water to the compartment when the concentration of ammonia
is below a selected value.
[0035] Preferably, the movable table 505 is configured to hold and
support the wafer 527 between transfers. In a further embodiment,
the apparatus is configured with a wafer support structure having a
plurality of pins structures 517 and 519 for supporting the wafer
527 while the wafer is at rest within the compartment 501. The pin
structures 517 and 519 pass through the movable table 505 such that
when the movable table 505 is lowered, the wafer 527 is released
from the table 505 onto the pin structures 517 and 519, as shown.
When the table movable 505 is raised, the wafer 527 is released
from the pin structures 517 and 519 onto the table 505.
[0036] According an alternative embodiment of the instant
invention, the apparatus 500 is equipped with a vacuum or purging
system 611 coupled to the transfer passage 610 such that when the
tables 505 and 507 are in the closed position, the transfer cavity
is capable of being purged to reduce cross-contamination between
the primary and secondary process environments.
[0037] Preferably, the feed back control loop includes a computer
system 625 module in communication with the sensor unit 607 and the
regulators 603 and 605. The chemical sensor unit 607 measures the
chemical concentration or composition of the processing environment
504 within the secondary compartment 503 and provides this
information to the computer system 625. When the chemical
concentration or composition of the processing environment 504 is
measured to be below a threshold value, then the computer system
625 signals the regulators to 603 and 605 to open and deliver a
regulated amount of the processing chemical 601 to the secondary
compartment 503 thereby replenishing chemical concentration or
composition of the processing environment 504 to the desired value.
When the chemical concentration or composition of the processing
environment 504 is measured to be above a threshold value, then the
computer system 625 signals the vacuum 609 to purge an appropriate
amount of the processing chemical from the secondary compartment
503.
[0038] According to a further embodiment of the invention, the
operation of the apparatus 500 is automated with th assistance of
the computer system 625. Accordingly, the computer system 625 is
also coupled to the first table motor 509, the second table motor
511 and the vacuum systems 609 and 611. The computer system 625 is
operated with software having the appropriate computer code to
operate the apparatus in accordance with the method of the instant
invention. Preferably, a user is able to select and adjust
processing parameters including, but not limited to, the
concentration of processing chemical within the processing
environment 504, the temperature of the processing environment 504
and the duration of time that the wafer is exposed to the
processing environment 504.
[0039] Referring now to FIG. 4, according to a preferred embodiment
of the invention, a processing station 707, configured in
accordance with the description, is one wafer processing station
within a multi-station wafer processing system 700. The wafer
processing system 700 has any number of processing stations such as
a wafer storage station 709, a wafer annealing or bake station 711
and a wafer coating station 713. The wafers are moved between the
processing stations 707, 709, 711 and 713 with a robotic arm 715.
The system conditions and each of the station are controlled by a
computer system 703 coupled to system body 701 and coupled to each
of the stations 707, 709, 711 and 713. Software runs the computer
to execute the appropriate processing sequence to accomplish the
intended result. For example, the computer system 703 is used to
select appropriate ammonia and water concentration within the
chemical processing environment of the station 707. Preferably, the
robotic arm 715 is configured to directly move wafers on and off of
the first movable table 705.
[0040] The present invention has been described relative to a
preferred embodiment. Improvements or modifications that become
apparent to persons of ordinary skill in the art only after reading
this disclosure are deemed within the spirit and scope of the
application. Specifically, the operation of the apparatus is
described, herein, in terms of two processing environments and two
processing compartments. However, it is understood that the
apparatus may be configured with any number of processing
compartments and corresponding processing environments and that
practicing the method of the instant invention does not depend on
the number of processing compartments or processing environments.
Further, practice of the invention is not limited to wafer
processing applications. The apparatus and the method of the
instant invention are useful for any number of applications that
require constant and controllable surface processing by
transferring a reaction surface of a structure between distinct
processing environments.
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