U.S. patent application number 12/393851 was filed with the patent office on 2009-06-25 for high efficiency uv curing system.
Invention is credited to Sanjeev Baluja, Josephine Chang, Tom Cho, Scott A. Hendrickson, Dustin W. Ho, Andrzej Kaszuba, Hichem M'saad, Thomas Nowak, Juan Carlos Rocha-Alvarez.
Application Number | 20090162259 12/393851 |
Document ID | / |
Family ID | 37392958 |
Filed Date | 2009-06-25 |
United States Patent
Application |
20090162259 |
Kind Code |
A1 |
Nowak; Thomas ; et
al. |
June 25, 2009 |
HIGH EFFICIENCY UV CURING SYSTEM
Abstract
An ultraviolet (UV) cure chamber enables curing a dielectric
material disposed on a substrate and in situ cleaning thereof. A
tandem process chamber provides two separate and adjacent process
regions defined by a body covered with a lid having windows aligned
respectively above each process region. One or more UV sources per
process region that are covered by housings coupled to the lid emit
UV light directed through the windows onto substrates located
within the process regions. The UV sources can be an array of light
emitting diodes or bulbs utilizing a source such as microwave or
radio frequency. The UV light can be pulsed during a cure process.
Using oxygen radical/ozone generated remotely and/or in-situ
accomplishes cleaning of the chamber. Use of lamp arrays, relative
motion of the substrate and lamp head, and real-time modification
of lamp reflector shape and/or position can enhance uniformity of
substrate illumination.
Inventors: |
Nowak; Thomas; (Sunnyvale,
CA) ; Rocha-Alvarez; Juan Carlos; (Cupertino, CA)
; Kaszuba; Andrzej; (San Jose, CA) ; Hendrickson;
Scott A.; (Brentwood, CA) ; Ho; Dustin W.;
(Fremont, CA) ; Baluja; Sanjeev; (San Francisco,
CA) ; Cho; Tom; (Palo Alto, CA) ; Chang;
Josephine; (Sunnyvale, CA) ; M'saad; Hichem;
(Santa Clara, CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP - - APPM/TX
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Family ID: |
37392958 |
Appl. No.: |
12/393851 |
Filed: |
February 26, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11124908 |
May 9, 2005 |
|
|
|
12393851 |
|
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Current U.S.
Class: |
422/186.3 |
Current CPC
Class: |
B05D 3/0493 20130101;
H01L 21/31058 20130101; B05D 3/0209 20130101; B05D 3/067
20130101 |
Class at
Publication: |
422/186.3 |
International
Class: |
B01J 19/08 20060101
B01J019/08 |
Claims
1. An ultraviolet (UV) curing chamber for curing dielectric
materials disposed on substrates, comprising: a body defining first
and second process regions that are separate and adjacent to one
another; a lid coupled to a top of the body to cover the first and
second process regions, wherein the lid includes first and second
quartz windows aligned respectively above the first and second
process regions; first and second UV sources disposed respectively
above the first and second windows; first and second housings
coupled to the lid and respectively covering the first and second
UV sources; and first and second reflectors disposed respectively
in the first and second housings and each of the first and second
reflectors are movable to adjust patterns of UV light directed by
the reflectors into the process regions.
2. The UV curing chamber of claim 1, wherein gas inlets into the
first and second process regions are adapted to supply ozone to the
process regions for a cleaning process.
3. The UV curing chamber of claim 1, further comprising a central
air source in fluid communication with an interior of the first
housing and an interior of the second housing to cool the first and
second UV sources disposed therein.
4. The UV curing chamber of claim 3, further comprising a common
exhaust system in fluid communication with the interior of the
first housing and the interior of the second housing to collect
heated air therein and remove ozone from the air.
5. The UV curing chamber of claim 1, further comprising first and
second heated and movable pedestals disposed respectively within
the first and second process regions for supporting the
substrates.
6. The UV curing chamber of claim 1, further comprising at least
one power source for activation of the first and second UV sources
and each of the at least one power source being at least one
microwave generator.
7. The UV curing chamber of claim 1, further comprising at least
one power source for activation of the first and second UV sources,
each power source being at least one radio frequency generator.
8. The UV curing chamber of claim 1, wherein each of the first and
second UV sources comprise one or more UV bulbs.
9. The UV curing chamber of claim 8, wherein each of the one or
more UV bulbs have long axes oriented vertically with respect to
first and second substrates located respectively in the first and
second process regions.
10. The UV curing chamber of claim 8, wherein the UV curing chamber
is mounted on a transfer chamber.
11. The UV curing chamber of claim 1, wherein the first and second
housings have respective first and second quartz linings coated
with dichroic films.
12. The UV curing chamber of claim 8, wherein of the first and
second UV sources each comprise a first UV bulb and a second UV
bulb.
13. The UV curing chamber of claim 12, wherein the first UV bulb
emits UV light of a first wavelength distribution different from a
second wavelength distribution emitted by the second UV bulb.
14. The UV curing chamber of claim 12, wherein the first UV bulb is
capable of being turned on independently of the second UV bulb.
15. An ultraviolet (UV) curing chamber for curing dielectric
materials disposed on substrates, comprising: a body defining first
and second process regions that are separate and adjacent to one
another; a lid coupled to a top of the body to cover the first and
second process regions, wherein the lid includes first and second
quartz windows aligned respectively above the first and second
process regions; first and second UV sources disposed respectively
above the first and second windows; and first and second housings
coupled to the lid and respectively covering the first and second
UV sources and the first and second housings have respective first
and second quartz linings coated with dichroic films.
16. The UV curing chamber of claim 15, wherein the dichroic film
comprises a periodic multilayer film composed of non-metallic
dielectric materials having alternating high and low refractive
index.
17. The UV curing chamber of claim 15, further comprising first and
second heated and movable pedestals disposed respectively within
the first and second process regions for supporting the
substrates.
18. The UV curing chamber of claim 15, further comprising at least
one power source for activation of the first and second UV sources,
each power source being at least one microwave generator or at
least one radio frequency generator.
19. The UV curing chamber of claim 15, wherein the first and second
UV sources comprise one or more UV bulbs having long axes oriented
vertically with respect to first and second substrates located
respectively in the first and second process regions.
20. The UV curing chamber of claim 15, wherein the UV curing
chamber is mounted on a transfer chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 11/124,908 (APPM/009433), filed May 9,
2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the invention generally relate to an
ultraviolet (UV) cure chamber. More particularly, embodiments of
the invention relate to a tandem UV chamber for performing cure
processes of dielectric films on substrates and clean processes of
surfaces within the tandem chamber.
[0004] 2. Description of the Related Art
[0005] Silicon oxide (SiO), silicon carbide (SiC) and carbon doped
silicon oxide (SiOC) find extremely widespread use in the
fabrication of semiconductor devices. One approach for forming
silicon containing films on a semiconductor substrate is through
the process of chemical vapor deposition (CVD) within a chamber.
Organosilicon supplying materials are often utilized during CVD of
the silicon containing films. As a result of the carbon present in
such a silicon supplying material, carbon containing films can be
formed on the chamber walls as well as on the substrate.
[0006] Water is often a by-product of the CVD reaction of
organosilicon compounds and can be physically absorbed into the
films as moisture. Moisture in the air inside the substrate fab
provides another source of moisture in un-cured films. The ability
of the film to resist water uptake while in queue for subsequent
manufacturing processes is important in defining a stable film. The
moisture is not part of stable films, and can later cause failure
of dielectric material during device operation.
[0007] Accordingly, undesirable chemical bonds and compounds such
as water are preferably removed from a deposited carbon containing
film. More importantly, thermally unstable organic fragments of
sacrificial materials (resulting from porogens used during CVD to
increase porosity) need to be removed. It has been suggested to
utilize ultraviolet radiation to aid in the post treatment of CVD
silicon oxide films. For example, U.S. Pat. Nos. 6,566,278 and
6,614,181, both to Applied Materials, Inc. and incorporated herein
in their entirety, describe use of UV light for post treatment of
CVD carbon-doped silicon oxide films.
[0008] Therefore, there exists a need in the art for a UV curing
chamber which can be used to effectively cure films deposited on
substrates. A further need exists for a UV curing chamber that can
increase throughput, consume a minimum of energy and be adapted for
in situ cleaning processes of surfaces within the chamber
itself.
SUMMARY OF THE INVENTION
[0009] Embodiments of the invention generally relate to an
ultraviolet (UV) cure chamber for curing a dielectric material
disposed on a substrate. In one embodiment, a tandem process
chamber provides two separate and adjacent process regions defined
by a body covered with a lid having bulb isolating windows aligned
respectively above each process region. The bulb isolating windows
are implemented with either one window per side of the tandem
process chamber to isolate one or many bulbs from the substrate in
one large common volume, or with each bulb of an array of bulbs
enclosed in its own UV transparent envelope which is then in direct
contact with the substrate treating environment. One or more UV
bulbs per process region are covered by housings coupled to the lid
and emit UV light that is directed through the windows onto
substrates located within the process regions.
[0010] The UV bulbs can be an array of light emitting diodes or
bulbs utilizing any of the state of the art UV illumination sources
including but not limited to microwave arcs, radio frequency
filament (capacitively coupled plasma) and inductively coupled
plasma (ICP) lamps. Additionally, the UV light can be pulsed during
a cure process. Various concepts for enhancing uniformity of
substrate illumination include use of lamp arrays which can also be
used to vary wavelength distribution of incident light, relative
motion of the substrate and lamp head including rotation and
periodic translation (sweeping), and real-time modification of lamp
reflector shape and/or position.
[0011] Residues formed during the curing process are
organic/organosilicon and are removed using an oxygen radical and
ozone based clean. Production of the necessary oxygen radicals can
be done remotely with the oxygen radicals transported to the curing
chamber, generated in-situ or accomplished by running these two
schemes simultaneously. Since the oxygen radicals generated
remotely recombine very rapidly back into molecular oxygen
(O.sub.2), the key to remote oxygen based clean is to generate
ozone remotely and to transfer this ozone into the curing chamber
where the ozone is then allowed to dissociate into oxygen radicals
and oxygen molecules when it comes into contact with heated
surfaces inside the curing chamber. Consequently, the ozone is
essentially a vehicle for transporting oxygen radicals into the
curing chamber. In a secondary benefit of the remote ozone clean,
ozone that does not dissociate in the cure chamber can also attack
certain organic residues thereby enhancing the oxygen radical
clean. Methods of generating the ozone remotely can be accomplished
using any existing ozone generation technology including, but not
limited to dielectric barrier/corona discharge (e.g., Applied
Materials Ozonator) or UV-activated reactors. According to one
embodiment, the UV bulbs used for curing the dielectric material
and/or additional UV bulb(s) that can be remotely located are used
to generate the ozone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0013] FIG. 1 is a plan view of a semiconductor processing system
in which embodiments of the invention may be incorporated.
[0014] FIG. 2 is a view of a tandem process chamber of the
semiconductor processing system that is configured for UV
curing.
[0015] FIG. 3 is a partial section view of the tandem process
chamber that has a lid assembly with two UV bulbs disposed
respectively above two process regions.
[0016] FIG. 4 is a partial section view of a lid assembly with a UV
bulb having a long axis oriented vertically above a process
region.
[0017] FIG. 5 is a partial view of a bottom surface of a lid
assembly that utilizes an array of UV lamps.
[0018] FIG. 6 is a schematic of a process chamber with a first
array of UV lamps selected for curing and a second array of UV
lamps selected for activating a cleaning gas.
[0019] FIG. 7 is an isomeric view of a lid assembly for disposal on
a tandem process chamber with exemplary arrays of UV lamps arranged
to provide UV light to two process regions of the chamber.
DETAILED DESCRIPTION
[0020] FIG. 1 shows a plan view of a semiconductor processing
system 100 in which embodiments of the invention may be
incorporated. The system 100 illustrates one embodiment of a
Producer.TM. processing system, commercially available from Applied
Materials, Inc., of Santa Clara, Calif. The processing system 100
is a self-contained system having the necessary processing
utilities supported on a mainframe structure 101. The processing
system 100 generally includes a front end staging area 102 where
substrate cassettes 109 are supported and substrates are loaded
into and unloaded from a loadlock chamber 112, a transfer chamber
111 housing a substrate handler 113, a series of tandem process
chambers 106 mounted on the transfer chamber 111 and a back end 138
which houses the support utilities needed for operation of the
system 100, such as a gas panel 103, and a power distribution panel
105.
[0021] Each of the tandem process chambers 106 includes two
processing regions for processing the substrates (see, FIG. 3). The
two processing regions share a common supply of gases, common
pressure control and common process gas exhaust/pumping system.
Modular design of the system enables rapid conversion from any one
configuration to any other. The arrangement and combination of
chambers may be altered for purposes of performing specific process
steps. Any of the tandem process chambers 106 can include a lid
according to aspects of the invention as described below that
includes one or more ultraviolet (UV) lamps for use in a cure
process of a low K material on the substrate and/or in a chamber
clean process. In one embodiment, all three of the tandem process
chambers 106 have UV lamps and are configured as UV curing chambers
to run in parallel for maximum throughput.
[0022] In an alternative embodiment where not all of the tandem
process chambers 106 are configured as UV curing chambers, the
system 100 can be adapted with one or more of the tandem process
chambers having supporting chamber hardware as is known to
accommodate various other known processes such as chemical vapor
deposition (CVD), physical vapor deposition (PVD), etch, and the
like. For example, the system 100 can be configured with one of the
tandem process chambers 106 as a CVD chamber for depositing
materials, such as a low dielectric constant (K) film, on the
substrates. Such a configuration can maximize research and
development fabrication utilization and, if desired, eliminate
exposure of as-deposited films to atmosphere.
[0023] FIG. 2 illustrates one of the tandem process chambers 106 of
the semiconductor processing system 100 that is configured for UV
curing. The tandem process chamber 106 includes a body 200 and a
lid 202 that can be hinged to the body 200. Coupled to the lid 200
are two housings 204 that are each coupled to inlets 206 along with
outlets 208 for passing cooling air through an interior of the
housings 204. The cooling air can be at room temperature or
approximately twenty-two degrees Celsius. A central pressurized air
source 210 provides a sufficient flow rate of air to the inlets 206
to insure proper operation of any UV lamp bulbs and/or power
sources 214 for the bulbs associated with the tandem process
chamber 106. The outlets 208 receive exhaust air from the housings
204, which is collected by a common exhaust system 212 that can
include a scrubber to remove ozone potentially generated by the UV
bulbs depending on bulb selection. Ozone management issues can be
avoided by cooling the lamps with oxygen-free cooling gas (e.g.,
nitrogen, argon or helium).
[0024] FIG. 3 shows a partial section view of the tandem process
chamber 106 with the lid 202, the housings 204 and the power
sources 214. Each of the housings 204 cover a respective one of two
UV lamp bulbs 302 disposed respectively above two process regions
300 defined within the body 200. Each of the process regions 300
includes a heating pedestal 306 for supporting a substrate 308
within the process regions 300. The pedestals 306 can be made from
ceramic or metal such as aluminum. Preferably, the pedestals 306
couple to stems 310 that extend through a bottom of the body 200
and are operated by drive systems 312 to move the pedestals 306 in
the processing regions 300 toward and away from the UV lamp bulbs
302. The drive systems 312 can also rotate and/or translate the
pedestals 306 during curing to further enhance uniformity of
substrate illumination. Adjustable positioning of the pedestals 306
enables control of volatile cure by-product and purge and clean gas
flow patterns and residence times in addition to potential fine
tuning of incident UV irradiance levels on the substrate 308
depending on the nature of the light delivery system design
considerations such as focal length.
[0025] In general, embodiments of the invention contemplate any UV
source such as mercury microwave arc lamps, pulsed xenon flash
lamps or high-efficiency UV light emitting diode arrays. The UV
lamp bulbs 302 are sealed plasma bulbs filled with one or more
gases such as xenon (Xe) or mercury (Hg) for excitation by the
power sources 214. Preferably, the power sources 214 are microwave
generators that can include one or more magnetrons (not shown) and
one or more transformers (not shown) to energize filaments of the
magnetrons. In one embodiment having kilowatt microwave (MW) power
sources, each of the housings 204 includes an aperture 215 adjacent
the power sources 214 to receive up to about 6000 W of microwave
power from the power sources 214 to subsequently generate up to
about 100 W of UV light from each of the bulbs 302. In another
embodiment, the UV lamp bulbs 302 can include an electrode or
filament therein such that the power sources 214 represent
circuitry and/or current supplies, such as direct current (DC) or
pulsed DC, to the electrode.
[0026] The power sources 214 for some embodiments can include radio
frequency (RF) energy sources that are capable of excitation of the
gases within the UV lamp bulbs 302. The configuration of the RF
excitation in the bulb can be capacitive or inductive. An
inductively coupled plasma (ICP) bulb can be used to efficiently
increase bulb brilliancy by generation of denser plasma than with
the capacitively coupled discharge. In addition, the ICP lamp
eliminates degradation in UV output due to electrode degradation
resulting in a longer-life bulb for enhanced system productivity.
Benefits of the power sources 214 being RF energy sources include
an increase in efficiency.
[0027] Preferably, the bulbs 302 emit light across a broad band of
wavelengths from 170 nm to 400 nm. The gases selected for use
within the bulbs 302 can determine the wavelengths emitted. Since
shorter wavelengths tend to generate ozone when oxygen is present,
UV light emitted by the bulbs 302 can be tuned to predominantly
generate broadband UV light above 200 nm to avoid ozone generation
during cure processes.
[0028] UV light emitted from the UV lamp bulbs 302 enters the
processing regions 300 by passing through windows 314 disposed in
apertures in the lid 202. The windows 314 preferably are made of an
OH free synthetic quartz glass and have sufficient thickness to
maintain vacuum without cracking. Further, the windows 314 are
preferably fused silica that transmits UV light down to
approximately 150 nm. Since the lid 202 seals to the body 200 and
the windows 314 are sealed to the lid 202, the processing regions
300 provide volumes capable of maintaining pressures from
approximately 1 Torr to approximately 650 Torr. Processing or
cleaning gases enter the process regions 300 via a respective one
of two inlet passages 316. The processing or cleaning gases then
exit the process regions 300 via a common outlet port 318.
Additionally, the cooling air supplied to the interior of the
housings 204 circulates past the bulbs 302, but is isolated from
the process regions 300 by the windows 314.
[0029] In one embodiment, each of the housings 204 include an
interior parabolic surface defined by a cast quartz lining 304
coated with a dichroic film. The quartz linings 304 reflect UV
light emitted from the UV lamp bulbs 302 and are shaped to suit
both the cure processes as well as the chamber clean processes
based on the pattern of UV light directed by the quartz linings 304
into the process regions 300. For some embodiments, the quartz
linings 304 adjust to better suit each process or task by moving
and changing the shape of the interior parabolic surface.
Additionally, the quartz linings 304 preferably transmit infrared
light and reflect ultraviolet light emitted by the bulbs 302 due to
the dichroic film. The dichroic film usually constitutes a periodic
multilayer film composed of diverse dielectric materials having
alternating high and low refractive index. Since the coating is
non-metallic, microwave radiation from the power sources 214 that
is downwardly incident on the backside of the cast quartz linings
304 does not significantly interact with, or get absorbed by, the
modulated layers and is readily transmitted for ionizing the gas in
the bulbs 302.
[0030] In another embodiment, rotating or otherwise periodically
moving the quartz linings 304 during curing and/or cleaning
enhances the uniformity of illumination in the substrate plane. In
yet another embodiment, the entire housings 204 rotate or translate
periodically over the substrates 308 while the quartz linings 304
are stationary with respect to the bulbs 302. In still another
embodiment, rotation or periodic translation of the substrates 308
via the pedestals 306 provides the relative motion between the
substrates 308 and the bulbs 302 to enhance illumination and curing
uniformity.
[0031] For cure processes for carbon containing films, the
pedestals 306 are heated to between 350.degree. C. and 500.degree.
C. at 1-10 Torr, preferably 400.degree. C. The pressure within the
processing regions 300 is preferably not lower than approximately
0.5 Torr in order to enhance heat transfer to the substrate from
the pedestals 306. Substrate throughput increases by performing the
cure processes at low pressure in order to accelerate porogen
removal as evidenced by the fact that the rate of shrinkage of the
deposited films increases as pressure decreases. Further, the
stability of the resulting dielectric constant upon exposure to
moisture in the ambient atmosphere of the fab improves when the
cure process occurs at a lower pressure. For example, under the
same conditions a cure process at 75 Torr created a film with a
dielectric constant, .kappa., of 2.6 while a cure process at 3.5
Torr created a film with a .kappa. of 2.41. After completion of a
standard accelerated stability test, the dielectric constant of the
film cured at 75 Torr increased to 2.73 while the .kappa. of the
film cured at 3.5 Torr increased approximately half as much to
2.47. Thus, the lower pressure cure produced a lower dielectric
constant film with approximately half the sensitivity to ambient
humidity.
Example 1
[0032] A cure process for a carbon doped silicon oxide film
includes introduction of fourteen standard liters per minute (slm)
of helium (He) at eight Torr for the tandem chamber 106 (7 slm per
side of the twin) via each inlet passage 316. For some embodiments,
the cure processes use nitrogen (N.sub.2) or argon (Ar) instead or
as mixtures with He since primary concern is absence of oxygen
unless other components are desired for reactive UV surface
treatments. The purge gas essentially performs two main functions
of removing curing byproducts and promoting uniform heat transfer
across the substrate. These non-reactive purge gases minimize
residue build up on the surfaces within the processing regions
300.
[0033] Additionally, hydrogen can be added to beneficially remove
some methyl groups from films on the substrates 300 and also
scavenge oxygen which is released during curing and tends to remove
too many methyl groups. The hydrogen can getter residual oxygen
remaining in the chamber after the oxygen/ozone based clean and
also oxygen out-gassed from the film during the cure. Either one of
these sources of oxygen can potentially damage the curing film by
photo-induced reactions of oxygen radicals formed by the short
wavelength UV potentially used in the cure and/or by binding with
methyl radicals to form volatile byproducts that can leave the
final film poor in methyl, yielding poor dielectric constant
stability and/or excessively high film stress. Care must be
exercised in the amount of hydrogen introduced into the cure
process since with a UV radiation wavelength less than
approximately 275 nm the hydrogen can form hydrogen radicals that
can attack carbon-carbon bonds in the film and also remove methyl
groups in the form of CH.sub.4.
[0034] Some cure processes according to aspects of the invention
utilize a pulsed UV unit which can use pulsed xenon flash lamps as
the bulbs 302. While the substrates 308 are under vacuum within the
processing regions 300 from approximately 10 milliTorr to
approximately 700 Torr, the substrates 308 are exposed to pulses of
UV light from the bulbs 302. The pulsed UV unit can tune an output
frequency of the UV light for various applications.
[0035] For clean processes, the temperature of the pedestals 306
can be raised to between about 100.degree. C. and about 600.degree.
C., preferably about 400.degree. C. With the UV pressure in the
processing regions 300 elevated by the introduction of the cleaning
gas into the region through the inlet passages 316, this higher
pressure facilitates heat transfer and enhances the cleaning
operation. Additionally, ozone generated remotely using methods
such as dielectric barrier/corona discharge or UV activation can be
introduced into the processing regions 300. The ozone dissociates
into O.sup.- and O.sub.2 upon contact with the pedestals 306 that
are heated. In the clean process, elemental oxygen reacts with
hydrocarbons and carbon species that are present on the surfaces of
the processing regions 300 to form carbon monoxide and carbon
dioxide that can be pumped out or exhausted through the outlet port
318. Heating the pedestals 306 while controlling the pedestal
spacing, clean gas flow rate, and pressure enhances the reaction
rate between elemental oxygen and the contaminants. The resultant
volatile reactants and contaminants are pumped out of the
processing regions 300 to complete the clean process.
[0036] A cleaning gas such as oxygen can be exposed to UV radiation
at selected wavelengths to generate ozone in-situ. The power
sources 214 can be turned on to cause UV light emission from the
bulbs 302 in the desired wavelengths, preferably about 184.9 nm and
about 253.7 nm when the cleaning gas is oxygen, directly onto the
surfaces to be cleaned and indirectly by focusing with the quartz
linings 304. For example, UV radiation wavelengths of 184.9 nm and
253.7 nm optimizes cleaning using oxygen as the cleaning gas
because oxygen absorbs the 184.9 nm wavelength and generates ozone
and elemental oxygen, and the 253.7 nm wavelength is absorbed by
the ozone, which devolves into both oxygen gas as well as elemental
oxygen.
Example 2
[0037] For one embodiment, a clean process includes introduction of
5 slm of ozone and oxygen (13 wt % ozone in oxygen) into the tandem
chamber, split evenly within each processing region 300 to generate
sufficient oxygen radicals to clean deposits from surfaces within
the processing regions 300. The O.sub.3 molecules can also attack
various organic residues. The remaining O.sub.2 molecules do not
remove the hydrocarbon deposits on the surfaces within the
processing regions 300. A sufficient cleaning can occur with a
twenty minute clean process at 8 Torr after curing six pairs of
substrates.
[0038] FIG. 4 illustrates a partial section view of a lid assembly
402 with a UV bulb having a long axis 403 oriented vertically above
a process region 400. The shape of the reflector in this embodiment
is different than in any of the other embodiments. In other words,
the reflector geometry must be optimized to ensure maximum
intensity and uniformity of illumination of the substrate plane for
each lamp shape, orientation and combination of single or multiple
lamps. Only one half of a tandem process chamber 406 is shown.
Other than the orientation of the bulb 403, the tandem process
chamber 406 shown in FIG. 4 is similar to the tandem process
chamber 106 shown in FIGS. 2 and 3. Accordingly, the tandem process
chamber 406 can incorporate any of the aspects discussed above.
[0039] FIG. 5 shows a partial view of a bottom surface 500 of a lid
assembly that utilizes an array of UV lamps 502. The array of UV
lamps 502 can be disposed within a housing above a tandem process
chamber instead of single bulbs as depicted in the embodiments
shown in FIGS. 2-4. While many individual bulbs are depicted, the
array of UV lamps 502 can include as few as two bulbs powered by a
single power source or separate power sources. For example, the
array of UV lamps 502 in one embodiment includes a first bulb for
emitting a first wavelength distribution and a second bulb for
emitting a second wavelength distribution. The curing process can
thus be controlled by defining various sequences of illumination
with the various lamps within a given curing chamber in addition to
adjustments in gas flows, composition, pressure and substrate
temperature. In addition on a multi-curing chamber system, the
curing process can be further refined by defining sequences of
treatments in each of the tandem curing chambers each of which is
controlled independently with respect to parameters such as lamp
spectrum, substrate temperature, ambient gas composition and
pressure for the specific portion of the cure for which each is
used.
[0040] The array of UV lamps 502 can be designed to meet specific
UV spectral distribution requirements to perform the cure process
and the clean process by selecting and arranging one, two or more
different types of individual bulbs within the array of UV lamps
502. For example, bulbs may be selected from low pressure Hg,
medium pressure Hg and high pressure Hg. UV light from bulbs with a
wavelength distribution particularly suited for cleaning can be
directed to the entire process region while UV light from bulbs
with a wavelength distribution particularly suited for curing can
be directed specifically to the substrate. Additionally, bulbs
within the array of UV lamps 502 directed specifically at the
substrate may be selectively powered independently from other bulbs
within the array of UV lamps 502 such that select bulbs are turned
on for either the clean process or the cure process.
[0041] The array of UV lamps 502 can utilize highly efficient bulbs
such as UV light emitting diodes. UV sources powered by microwave
or pulsed sources have a conversion efficiency of five percent
compared to low power bulbs, such as 10 W-100 W, that can be in the
array of UV lamps 502 to provide a conversion efficiency of about
twenty percent. With the microwave power source ninety five percent
of the total energy is converted to heat that wastes energy and
necessitates extra cooling requirements while only five percent of
the energy is converted to UV emission. The low cooling requirement
of the low power bulbs can allow the array of UV lamps 502 to be
placed closer to the substrate (e.g., between one and six inches)
to reduce reflected UV light and loss of energy.
[0042] Furthermore, the bottom surface 500 of the lid assembly can
include a plurality of gas outlets 504 interleaved within the array
of UV lamps 502. Accordingly, curing and cleaning gases can be
introduced into a process region within a chamber from above (see,
FIGS. 6 and 7).
[0043] FIG. 6 schematically illustrates a process chamber 600 with
a first array of UV lamps 602 selected for curing and a second
array of UV lamps 604 remotely located and selected for activating
a cleaning gas. The first array of UV lamps 602 is divided into a
first group of bulbs 601 having a first wavelength distribution and
a second group of bulbs 603 having a second wavelength
distribution. Both groups of bulbs 601, 603 within the first array
of UV lamps 602 focus UV light (depicted by pattern 605) onto a
substrate 606 during a cure process. Thereafter, the cleaning gas
(depicted by arrows 608) is introduced through inlet 610 and
subjected to UV radiation from the second array of UV lamps 604 to
preferably generate ozone. Subsequently, ozone enters a process
region 612 where oxygen free radicals caused by activation of the
ozone clean the processing region 612 prior to being exhausted via
outlet 614.
[0044] FIG. 7 shows an isomeric view of a lid assembly 702 for
disposal on a tandem process chamber (not shown) with exemplary
arrays of individually isolated UV lamps 762 arranged to provide UV
light to two process regions of the chamber. Similar to the
embodiment shown in FIGS. 2 and 3, the lid assembly 702 includes a
housing 704 coupled to an inlet (not visible) along with a
corresponding outlet 208 oppositely located on the housing 704 for
passing cooling air across UV lamp bulbs 732 covered by the housing
704. In this embodiment with the arrays of individually isolated UV
lamps 762, the cooling air is directed into and passes through an
annulus defined between each bulb 732 and a window or UV
transmitting protective tube surrounding each bulb 732
individually. An interior roof 706 of the housing 704 can provide a
reflector for directing the UV light to a substrate and a blocker
to facilitate diffusion of gases supplied into a top of the housing
by gas inlet 716.
[0045] Any of the embodiments described herein can be combined or
modified to incorporate aspects of the other embodiments. While the
foregoing is directed to embodiments of the present invention,
other and further embodiments of the invention may be devised
without departing from the basic scope thereof, and the scope
thereof is determined by the claims that follow.
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