U.S. patent application number 10/313549 was filed with the patent office on 2004-06-10 for system for producing patterned deposition from compressed fluids.
This patent application is currently assigned to Eastman Kodak Company. Invention is credited to Irvin, Glen C. JR., Jagannathan, Ramesh, Jagannathan, Seshadri, Mehta, Rajesh V., Nelson, David J., Rueping, John E., Sadasivan, Sridhar, Sunderrajan, Suresh.
Application Number | 20040108060 10/313549 |
Document ID | / |
Family ID | 32312289 |
Filed Date | 2004-06-10 |
United States Patent
Application |
20040108060 |
Kind Code |
A1 |
Sunderrajan, Suresh ; et
al. |
June 10, 2004 |
System for producing patterned deposition from compressed
fluids
Abstract
A system (10) produces patterned deposition on a substrate (14)
from compressed fluids. A delivery system (12) cooperates with a
controlled environment (30, 100, 200) retaining a substrate (14)
for receiving precipitated functional material (44) along a fluid
delivery path (13) from the delivery system (12). A mask (22) is
arranged in close proximity to the substrate (14) for forming the
patterned deposition on the substrate (14).
Inventors: |
Sunderrajan, Suresh;
(Rochester, NY) ; Nelson, David J.; (Rochester,
NY) ; Jagannathan, Ramesh; (Rochester, NY) ;
Jagannathan, Seshadri; (Pittsford, NY) ; Irvin, Glen
C. JR.; (Rochester, NY) ; Sadasivan, Sridhar;
(Rochester, NY) ; Mehta, Rajesh V.; (Rochester,
NY) ; Rueping, John E.; (Rochester, NY) |
Correspondence
Address: |
Thomas H. Close
Patent Legal Staff
Eastman Kodak Company
343 State Street
Rochester
NY
14650-2201
US
|
Assignee: |
Eastman Kodak Company
|
Family ID: |
32312289 |
Appl. No.: |
10/313549 |
Filed: |
December 6, 2002 |
Current U.S.
Class: |
156/345.11 |
Current CPC
Class: |
H01L 21/67017 20130101;
B05D 1/32 20130101; B05D 1/12 20130101; B05D 2401/90 20130101; B05D
1/04 20130101 |
Class at
Publication: |
156/345.11 |
International
Class: |
C23F 001/00 |
Claims
What is claimed is:
1. System for producing a patterned deposition on a substrate from
a compressed fluid, comprising: means for controllably delivering a
functional material in a compressed state and then converting said
functional material into a precipitate functional material; and, a
controlled environment for receiving said precipitated functional
material, said controlled environment exposing said substrate
bearing at least one shadow mask to said patterned deposition of
charged precipitated functional material.
2. The system recited in claim 1 wherein said controlled
environment comprises a pressure modulator for maintaining pressure
inside said controlled environment at a predetermined pressure
level.
3. The system recited in claim 2 wherein said controlled
environment comprises a temperature modulator for maintaining
temperature inside said controlled environment at a predetermined
temperature level.
4. The system recited in claim 3 wherein said temperature modulator
comprises an electric heater.
5. The system recited in claim 3 wherein said temperature modulator
comprises a water jacket in contact with a portion of said
controlled environment.
6. The system recited in claim 3 wherein said temperature modulator
comprises a refrigeration coil in fluid contact with a portion of
said controlled environment.
7. The system recited in claim 1 wherein said controlled
environment comprises means for monitoring temperature and pressure
levels inside said controlled environment.
8. The system recited in claim 1 wherein said substrate is provided
with an electrical charge thereby forming an electrically charged
substrate to attract charged precipitated functional material in
said controlled environment.
9. The system recited in claim 8 wherein said substrate comprises a
material selected from the group consisting of: an organic solid
material, an inorganic solid material, a metallo-organic material,
a ceramic material, an alloy material, a synthetic material, a
natural polymeric material, a gel material, a vitreous material, a
porous material, a non-porous material, and a composite
material.
10. The system recited in claim 8 wherein said electrically charged
substrate has a polarity opposite that of said charged precipitated
functional material.
11. The system recited in claim 1 wherein said at least one shadow
mask is provided with an electrical charge forming an electrically
charged shadow mask, said electrically charged shadow mask and said
charged precipitated functional material having the same
polarity.
12. The system recited in claim 1 further comprising means for
orienting the substrate relative to a stream of charged
precipitated functional material.
13. The system recited in claim 12 wherein said substrate has an
orientation relative to said stream of precipitate functional
material that indirectly exposes said substrate to said stream of
precipitated functional material.
14. The system recited in claim 12 wherein said substrate has an
orientation relative to said stream of precipitated functional
material that exposes said substrate directly to said stream of
precipitated functional material.
15. The system recited in claim 1 wherein said controlled
environment is provided with an access port for inserting and
removing said substrate.
17. The system recited in claim 1 wherein said means for
controllably delivering a functional material exposes said
precipitated functional material to a pressure higher than the
pressure inside said controlled environment.
18. The system recited in claim 2 wherein said pressure modulator
is a piston-like element.
18. The system recited in claim 2 wherein said pressure modulator
is a pump.
19. The system recited in claim 2 wherein said pressure modulator
is a vent arranged in said controlled environment and a pressure
control means cooperatively associated with said vent.
20. The system recited in claim 1 wherein said controlled
environment is further provided with a first electrostatic charging
element for imparting a charge on said precipitated functional
material.
21. The system recited in claim 20 wherein said controlled
environment is further provided with a second electrostatic
charging element for imparting an electrostatic charge on said
substrate.
22. The system recited in claim 20 wherein said controlled
environment is further provided with a third electrostatic charging
element for imparting an electrostatic charge on said shadow
mask.
23. The system recited in claim 21 wherein said electrostatic
charge on said substrate is determinate of the amount of
precipitated functional material deposited on said substrate.
24. The system recited in claim 23 wherein the charge applied to
said substrate is applied for a predetermined duration, said
predetermined duration being determinate of the amount of
precipitated functional material deposited on said substrate.
25. The system recited in claim 1 wherein said functional material
comprises a material selected from the group consisting of:
electroluminescent molecules, imaging dyes, ceramic nano-particles,
and polymeric materials.
26. The system recited in clam 1 wherein said compressed fluid
comprises materials selected from the group consisting of: carbon
dioxide, nitrous oxide, ammonia, xenon, ethane, ethylene, propane,
propylene, butane, isobutane, chlorotrifluoromethane,
monofluromethane, sulfur hexafluoride, and mixtures thereof.
27. The system recited in claim 1 wherein said controlled
environment is electrostatically charged to prevent deleterious
particles from adhering thereto.
28. The system recited in claim 1 wherein an optical emitter
cooperates with an optical detector determining the concentration
of functional material inside said controlled environment.
29. The system recited in claim 28 wherein said controlled
environment has at least one viewing port for observing the process
inside said controlled environment.
30. The system recited in claim 28 wherein a reflective surface is
arranged in said controlled environment opposite said optical
emitter for reflecting energy from said optical emitter which is
detected by said optical detector.
31. The system recited in claim 30 wherein said optical detector
transmits an electrical signal to a microprocessor thereby
generating data for future processing.
32. The system recited in claim 1 wherein said means for
controllably delivering comprises a discharge assembly having a
nozzle for ejecting a stream of precipitated formulation material
into said controlled environment.
33. The system recited in claim 32 wherein said nozzle is a
divergent nozzle.
34. The system recited in claim 32 wherein said precipitated
formulation material is further propelled from said nozzle in the
presence of an electromagnetic field in said controlled
environment.
35. The system recited in claim 32 wherein said precipitated
formulation material is further propelled from said nozzle in the
presence of at least one mechanical shield arranged in said
controlled environment.
36. The system recited in claim 32 wherein said precipitated
formulation material is further propelled from said nozzle in the
presence of at least one magnetic lens arranged in said controlled
environment.
37. The system recited in claim 32 wherein said precipitated
formulation material is further propelled from said nozzle in the
presence of at least one electrostatic lens arranged in said
controlled environment.
38. The system recited in claim 32 wherein said nozzle is provided
with a heating means to promote a predetermined fluid flow
rate.
39. The system recited in claim 1 wherein said substrate and a
discharge assembly in said means for controllably delivering are
spaced apart by a predetermined distance that enables said
compressed fluid to evaporate from a liquid or a compressed phase
to a gas phase prior to depositing on said substrate.
40. The system recited in claim 1 wherein said functional material
is dissolved in said compressed state.
41. The system recited in claim 1 wherein said functional material
is dispersed in said compressed state.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to deposition from
compressed fluids and, more particularly, to patterned deposition
from compressed fluids onto suitable substrates with the use of
masks.
BACKGROUND OF THE INVENTION
[0002] Processes that enable patterned deposition of materials onto
a substrate have a number of applications, especially in the
electronic microcircuit industry. Microfabrication of electronic
circuits relies on the ability to create multi-layer patterns of
numerous functional materials, with varying electrical properties.
The technologies used for creating these multi-layer patterns may
be additive, subtractive, or a combination of the two. Additive
technologies deposit the functional material on the substrate in
the desired pattern, i.e., the pattern is generated directly on the
substrate during the deposition/layering process. Subtractive
processes, on the other hand, first create a continuous layer of
the functional material on the substrate. The desired pattern is
then subsequently created by the selective removal of functional
material from the deposited layer, i.e., the pattern is created
subsequent to the deposition/layering process. A detailed
description of various patterned deposition/layering processes used
in the microfabrication industry may be found in "The Physics of
Micro/Nano-Fabrication" by Ivor Brodie and Julius J. Murray, Plenum
Press, NY, 1992.
[0003] Traditional micro-fabrication processes utilize either or
both the additive and subtractive processes depending upon the
specific application, and are generally carried out in a high
vacuum (low-pressure) environment. The high vacuum process
generally involves the evaporation of functional material by
heating or by ion bombardment followed by deposition onto the
substrate by condensation or by a chemical reaction. In these
deposition processes, the functional material is required to be
thermally stable or to have a thermally stable precursor that can
generate the functional material on the substrate by a chemical
reaction. As skilled artisans will appreciate, these processes are
not useful in generating patterned layers of thermally unstable
materials.
[0004] Further, those skilled in the art will appreciate that it is
common to use a mask technique for patterned deposition. Typically,
the mask employed for patterning on a planar substrate surface is a
photoresist material. However, when the surface is nonplanar,
difficulties can be encountered in depositing and cleaning off the
photoresist material, necessitating the use of shadow masks or
stencils. For example, U.S. Pat. No. 4,218,532 titled
"Photolithographic Technique For Depositing Thin Films," issued
Aug. 19, 1980 to Dunkleberger discloses a method for patterned
deposition of thin films of metals, such as lead alloys, by vacuum
evaporation onto a substrate through openings in a mask fabricated
with a predetermined pattern. A shortcoming of this development is
that it cannot be used for the patterned deposition of thermally
unstable materials since these are not suitable for vacuum
evaporation.
[0005] In U.S. Pat. No. 4,013,502 titled "Stencil Process For High
Resolution Pattern Replication," issued Mar. 22, 1977 to Staples, a
process for obtaining high-resolution pattern replication using
stencils is disclosed. The stencil in Staples is a mask effecting
molecular beam deposition of thin films onto a substrate through
openings in the stencil. In this deposition process, the molecular
beam source is an electron-beam evaporator. Much like the
Dunkleberger development, a shortcoming of Staples' technology is
that it cannot be used for patterned deposition of thermally
unstable materials that are not suitable for evaporation using an
electron beam evaporator.
[0006] Furthermore, it is well known that patterned deposition of
thermally unstable materials on substrates may be achieved by
liquid phase processes such as electroplating, electrophoresis,
sedimentation, or spin coating but these processes are system
specific. For example, in the case of electroplating, it is
necessary that an electrochemically active solution of the
functional material precursor is available. In the case of
sedimentation and spin coating, a stable colloidal dispersion is
necessary. In the case of electrophoresis, it is also necessary
that the stable colloidal dispersion be charged. Microfabrication
of multi-layer structures usually requires multiple stages,
necessitating the complete removal of residual liquids/solvents at
the end of every stage, which can be very energy, time, and cost
intensive. Further, many of these liquid-based processes require
the use of non-aqueous liquids/solvents, which are hazardous to
health and the disposal of which can be prohibitively expensive.
For example, in U.S. Pat. No. 5,545,307 titled "Process For
Patterned Electroplating," issued Aug. 13, 1996 to Doss et al., a
process is disclosed for patterned electroplating of metals onto a
substrate 14 through a mask. The Doss et al. process, however, has
at least two major shortcomings. First, it is only applicable to
materials that have electrochemically active precursors. Second, it
uses an aqueous electroplating bath for the process that requires
the coated substrate be cleaned and then dried at the end of the
coating process.
[0007] Moreover, it is well known that to eliminate the need for
potentially harmful solvents that need drying, it is possible to
use environmental and health-benign supercritical fluids such as
carbon dioxide as solvents. For example, in U.S. Pat. No. 4,737,384
titled "Deposition Of Thin Films Using Supercritical Fluids,"
issued Apr. 12, 1988 to Murthy et al., a process is disclosed for
depositing thin films of materials that are soluble in
supercritical fluids onto a substrate. Murthy et al. include the
steps of exposing a substrate at supercritical temperatures and
pressures to a solution comprising a metal or polymer dissolved in
water or a non-polar organic solvent. The metal or polymer is
substantially insoluble in the solvent under sub-critical
conditions and is substantially soluble in the solvent under
supercritical conditions. Reducing the pressure alone, or
temperature and pressure together, to sub-critical values cause the
deposition of a thin coating of the metal or polymer onto the
substrate. Nonetheless, a shortcoming of the process of Murthy et
al. is its limited applicability to materials that can be dissolved
in compressed fluids, severely limiting the choice of materials
that can be deposited on a substrate using this technology. Another
shortcoming of the process of Murthy et al. is that it does not
teach a process for the patterned deposition of functional
materials.
[0008] In U.S. Pat. No. 4,582,731 titled "Supercritical Fluid
Molecular Spray Film Deposition and Powder Formation," issued Apr.
15, 1986 to Smith, and U.S. Pat. No. 4,734,227 titled "Method Of
Making Supercritical Fluid Molecular Spray Films, Powder And
Fibers," issued Mar. 29, 1988 to Smith, independent processes are
disclosed for producing solid films on a substrate by dissolving a
solid material into supercritical fluid solution at an elevated
pressure. In both cases, the supercritical fluid solution is then
rapidly expanded in a region of relatively low pressure through a
heated nozzle having a relatively short orifice. Both of the
aforementioned Smith processes have similar shortcomings to those
indicated above, i.e., they are only applicable to materials that
are soluble in compressed fluids and do not teach a process for
patterned deposition.
[0009] Therefore, a need persists in the art for a patterned
deposition system that permits the patterned deposition of
thermally unstable/labile materials and that eliminates the use of
expensive and both environmentally and human health-hazardous
solvents. A further need exists for a patterned deposition system
that eliminates the need for post-deposition drying for
solvent-elimination. Moreover, there is an additional need for a
patterned deposition technique that is applicable for a wide range
of functional materials and that is not limited by specific
properties of the functional materials.
SUMMARY OF THE INVENTION
[0010] It is, therefore, an object of the invention to provide a
coating deposition system that permits the patterned deposition of
thermally unstable/labile materials.
[0011] Another object of the invention is to provide a coating
deposition system that eliminates the need for post-deposition
drying for solvent elimination.
[0012] Yet another object of the invention is to provide a coating
deposition system that is applicable for a wide range of functional
materials.
[0013] To achieve these and other objects and advantages of the
invention, there is provided, in one aspect of the invention, a
system for producing patterned deposition from compressed fluids.
The system includes a means for delivering a functional material
that is dissolved and/or dispersed in a compressed fluid and then
precipitating the functional material by decompressing the
compressed fluid to a state where the functional material is no
longer soluble and/or dispersible in the compressed fluid. A
controlled environment retains a substrate bearing a shadow mask.
The controlled environment exposes the substrate bearing the shadow
mask to receive precipitated functional material as a patterned
deposition on the substrate.
[0014] There are numerous advantageous effects of the present
invention over prior developments. More particularly, the present
system has the ability to deposit thermally unstable/labile
materials and is useful for a wider range of materials unlike prior
art developments. Further, the present system is considerably more
efficient and controllable than existing systems. Moreover, the
present invention eliminates the need for harmful and expensive
materials used for drying.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the detailed description of the preferred embodiments of
the invention presented below, reference is made to the
accompanying drawings, in which:
[0016] FIG. 1 is a schematic view of a preferred embodiment made in
accordance with the present invention;
[0017] FIG. 2 is enlarged schematic view of a controlled
environment in one embodiment of the invention;
[0018] FIG. 3 is a schematic view of an alternative embodiment of
an enclosure of the invention
[0019] FIG. 4 is a diagram schematically representing the operation
of the present invention;
[0020] FIG. 5 is a schematic view of an alternative embodiment of a
controlled environment or deposition chamber useful in the
invention; and,
[0021] FIG. 6 is a schematic view of an alternative embodiment of
another controlled environment or deposition chamber useful in the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Turning now to the drawings, and more particularly to FIG.
1, system 10, broadly defined, for producing patterned deposition
from compressed fluids includes a delivery system 12, a deposition
chamber, or alternatively controlled environment, 30, and a
substrate 14 retained in the deposition chamber, or alternatively,
controlled environment 30. Controlled environment 30 is more
typically a deposition chamber, as described in detail below. A
typical delivery system 12 contemplated by the invention is one
disclosed, for instance, in commonly assigned in U.S. Patent
Application Publication No. 2002/01184245A1 titled "Apparatus And
Method Of Delivering A Focused Beam Of A Thermodynamically
Stable/Metastable Mixture Of A Function Material In A Dense Fluid
Onto A Receiver," by Ramesh Jagannathan, published Aug. 29, 2002,
hereby incorporated herein by reference. Each of the disclosed
delivery systems is capable of delivering a precipitate functional
material (as described below) and can be used in the invention.
[0023] Referring to FIG. 1, delivery system 12, capable of
delivering fluids along fluid delivery path 13 in a compressed
state, generally includes a source 16 of compressed fluid, a
formulation reservoir 18 for containing a formulation material, a
discharge assembly 20, each being described in detail in the above
U.S. Patent Applications. Delivery system 12 serves several
important functions in the invention. It enables the dissolution
and/or dispersal of a selected material into a compressed fluid
with density greater than 0.1 g/cc.sup.3. Further, a solution
and/or dispersion of an appropriate functional material or
combination of functional materials in the chosen compressed fluid
is produced in delivery system 12. Moreover, delivery system 12
delivers the functional materials as a beam or spray into a
deposition chamber 30 in a controlled manner. In this context, the
chosen materials taken to a compressed fluid state with a density
greater than 0.1 g/cc.sup.3 are gases at ambient pressure and
temperature. Ambient conditions are preferably defined as
temperature in the range from -100 to +100.degree. C., and pressure
in the range from 1.times.10.sup.-8-100 atm for this
application.
[0024] As depicted in FIG. 1, controlled environment 30, such as a
deposition chamber, is arranged proximate to delivery system 12.
Controlled environment 30 is positioned at one end of the fluid
delivery path 13 and adjacent the discharge assembly 20 of delivery
system 12. As illustrated in FIG. 2, substrate 14 to be patterned
with deposition material and is suitably arranged within deposition
chamber 30. In close proximity to substrate 14, a mask 22 is
preferably used (but not required) to control the location of the
deposited functional material on the substrate 14.
[0025] Referring to FIG. 3, in many applications, it is desirable
to maintain an exact concentration of functional material within
the controlled enclosure 31. Whilst open loop systems relying on
valve opening times can be used, for greater precision and
reliability it is desirable to use a system such as the one
illustrated in FIG. 3. According to FIG. 3, enclosure 31 (applies
to enclosures of FIGS. 2, 5 and 6) is fitted with at least one
viewing window or port 33. Viewing window 33 can be used alone to
provide a visual indication of the conditions inside the enclosure
31. On the other hand, a viewing window 33 is also required to
facilitate the use of optical emitters 35 and optical detectors 37
for the purpose of a more accurate assessment of the concentration
of functional material inside the enclosure 31. The optical emitter
35 emits a beam of light that travels across the inside of the
enclosure 31 and is detected by optical detector 37. This optical
detector 37 sends an electrical signal to the microprocessor 39 in
proportion to the amount of light received (which is a function of
the amount of functional material inside the controlled enclosure
31). This information can be used in many ways, most simply as a
check of the process, but also as an input to a closed loop control
of the input valve 24. For example, if the concentration in the
controlled enclosure 31 is low, the valve 24 is opened allowing
more functional material to enter the controlled enclosure 31. This
method relies on the cleanliness of the viewing windows 33 to be
effective, and therefore either by routine maintenance,
calibration, or the application of a like charge as the particles
to the viewing windows 33, the viewing windows 33 themselves must
be kept free of debris. Skilled artisans will appreciate that there
are many variations and other detection methods that could be
applied to a closed loop concentration monitoring and control
method described above. For example, in an optical detection
scheme, the optical emitter 35 and optical detector 37 could be on
the same side of the controlled enclosure 31 relying on a
reflective surface on the opposite side to reflect the beam. The
scope is not limited to optical detection, any method that provides
an indication of the amount of functional material such as
electrical properties, physical properties, or chemical properties
could be used.
[0026] Referring back to FIG. 1, a compressed fluid carrier
contained in the source 16 of compressed fluid is any material that
dissolves/solubilizes/disperses a functional material. Source 16 of
compressed fluids, containing compressed fluid delivers the
compressed fluid carrier at predetermined conditions of pressure,
temperature, and flow rate as a compressed fluid. Compressed fluids
are defined in the context of this application as those fluids that
have a density of greater than 0.1 grams per cubic centimeter in
the defined range of temperature and pressure of the formulation
reservoir, and are gases at ambient temperature and pressure.
Materials in their compressed fluid state that exist as gases at
ambient conditions find application here because of their unique
ability to solubilize and/or disperse functional materials of
interest in the compressed fluid state, and precipitate the
functional material under ambient conditions.
[0027] Fluids of interest that may be used to transport the
functional material include but are not limited to carbon dioxide,
nitrous oxide, ammonia, xenon, ethane, ethylene, propane,
propylene, butane, isobutane, chlorotrifluoromethane,
monofluoromethane, sulphur hexafluoride, and mixtures thereof. Due
to environmental compatibility, low toxicity, low cost, wide
availability, and non-flammability, carbon dioxide is generally
preferred.
[0028] Referring again to FIG. 1, formulation reservoir 18 is
utilized to dissolve and/or disperse functional materials in
compressed liquids or compressed fluids with or without cosolvents
and/or dispersants and/or surfactants, at desired formulation
conditions of temperature, pressure, volume, and concentration. The
formulation may include additives to modify surface tension for
charging and wetting viscosity through the use of rheology
modifiers and/or thickeners, stabilizers, binders, and dopants.
Functional materials may be any material that needs to be delivered
to a substrate 14, for example electroluminescent molecules,
imaging dyes, nanoparticles, polymers etc.
[0029] In addition, the formulation reservoir 18 can include a
source that electrically charges the material particles prior to
the material being ejected from the discharge assembly 20. Charging
the particles is an important step in many of the preferred
embodiments. Alternatively, the marking materials can also be
chosen such that the marking material stream becomes charged as it
is ejected from the discharge assembly 20 and does not need
additional charging. Additionally, additives that can promote
charging of the marking materials can also be chosen such that the
marking material stream becomes charged as it is ejected from the
discharge assembly 20. Such additives may include surfactants such
as those disclosed in U.S. patent application Ser. No. 10/033,458
filed Dec. 27, 2001, titled "A Compressed Fluid Formulation" by
Glen C. Irvin, Jr., et al.
[0030] Further, formulation reservoir 18 can be made out of any
suitable materials that can withstand the formulation conditions.
An operating range from 0.001 atmospheres (1.013.times.10.sup.2 Pa)
to 1000 atmospheres (1.013.times.10.sup.8 Pa) in pressure and from
-25.degree. Centigrade to 1000.degree. Centigrade is preferred.
Typically, the preferred materials of construction include various
grades of high pressure stainless steel. However, the material of
choice is determined by temperature and pressure range of
operation.
[0031] Formulation reservoir 18 should be precisely controlled with
respect to the operating conditions, i.e., pressure, temperature,
and volume. The solubility/dispersability of functional materials
depends upon the conditions within the formulation reservoir 18 and
even small changes in the operating conditions within the
formulation reservoir 18 can have undesired effects on functional
material solubility/dispersabili- ty.
[0032] Any suitable surfactant and dispersant material that is
capable of solubilizing/dispersing the functional materials in the
compressed liquid for the required application can be used in this
method. Such materials include but are not limited to fluorinated
polymers such as perfluoropolyether and silane and siloxane
compounds.
[0033] Referring to FIGS. 1 and 4, delivery system 12 is shown in
fluid communication through orifices/nozzles 28 with enclosed,
controlled environment 30 that contains substrate 14 and mask 22.
According to FIG. 1, valve 24 may be designed to actuate with a
specific frequency or for a fixed time period so as to permit the
controlled release of formulation from formulation reservoir 18
into enclosed environment 30 via orifices/nozzles 28. According to
FIG. 4, the controlled release of functional material 40 into
enclosed environment 30 results in the evaporation of the
compressed fluid 41 and the precipitation and/or aggregation of the
dissolved and/or dispersed functional material 40. The
precipitated/aggregated functional material may be allowed to
gravity-settle or may be settled using an electric, electrostatic,
electromagnetic, or magnetic assist. Mask 22 in close proximity to
substrate 14 results in the patterned deposition of functional
material 40 on the substrate 14.
[0034] Substrate 14 may be any solid including an organic, an
inorganic, a metallo-organic, a metallic, an alloy, a ceramic, a
synthetic and/or natural polymeric, a gel, a glass, and a composite
material. Substrate 14 may be porous or non-porous. Additionally,
the substrate 14 can have more than one layer. Additionally, the
substrate 14 may be flexible or rigid.
[0035] As best illustrated in FIGS. 2 and 4, mask 22 may be
physical (separate) or integral. The purpose of the mask 22 is to
provide a pattern for the deposition of functional solute material.
Those skilled in the art will appreciate that mask design and
manufacture is well established. Physical masks require direct
contact between mask 22 and substrate 14. Their advantage is that
they are relatively inexpensive and can be re-used for multiple
substrates 14. However, if the substrate 14 is delicate, the
physical contact may damage the substrate 14. Precise alignment is
also difficult. Integral masks 22 are structures formed on the
substrate 14 prior to coating/deposition. Alignment and spacing is
easier because the mask 22 is a part of the substrate 14. However,
because of the potential need to remove the mask 22 after
deposition, a subsequent etching step may be necessary, potentially
making this more expensive and time-consuming.
[0036] Referring to FIG. 4, nozzle 28 directs the flow of the
functional material 40 from formulation reservoir 18 via delivery
system 12 into enclosed environment 30. Nozzle 28 is also used to
attenuate the final velocity with which the functional material 40
enters the enclosed environment 30. In our preferred application,
it is desirable to rapidly spread the stream of precipitated
functional material 40 using a divergent nozzle geometry. Skilled
artisans will however appreciate that nozzle geometry can vary
depending on a particular application, as described in U.S. Patent
Application Publication No. 2002/011842A1, incorporate herein by
reference.
[0037] In Operations
[0038] Operation of system 10 will now be described. FIG. 4 is a
diagram schematically representing the operation of delivery system
10 and should not be considered as limiting the scope of the
invention in any manner. The description below uses a single nozzle
28 although multiple nozzles and/or multiple nozzle shapes and/or
multiple delivery devices and shapes are within the contemplation
of the invention. (See for instance other nozzle exemplars
disclosed in U.S. Patent Application Publication No.
2002/0118245A1.
[0039] Referring to FIG. 4, a formulation 42 of functional material
40 in a compressed liquid 41 is prepared in the formulation
reservoir 18 of the invention. Functional material 40, which may be
any material of interest in solid or liquid phase, can be dispersed
(as shown in FIG. 4) and/or dissolved in a supercritical fluid
and/or compressed liquid 41 making a mixture or formulation 42.
Functional material 40 may have various shapes and sizes depending
on the type of the functional material 40 used in the
formulation.
[0040] According to FIG. 4, the supercritical fluid and/or
compressed liquid 41 form a continuous phase and functional
material 40 forms a dispersed and/or dissolved single phase. The
formulation 42 (i.e., the functional material 40 and the
supercritical fluid and/or compressed liquid 41) is maintained at a
suitable temperature and a suitable pressure for the functional
material 40 and the supercritical fluid and/or compressed liquid 41
used in a particular application. The shutter 32 is actuated to
enable the ejection of a controlled quantity of the formulation
42.
[0041] With reference to FIGS. 1 and 4, functional material 40 is
controllably introduced into the formulation reservoir 18. The
compressed fluid 41 is also controllably introduced into the
formulation reservoir 18. The contents of the formulation reservoir
18 are suitably mixed using a mixing device (not shown) to ensure
intimate contact between the functional material 40 and compressed
fluid 41. As the mixing process proceeds, functional material 40 is
dissolved and/or dispersed within the compressed fluid 41. The
process of dissolution/dispersion, including the amount of
functional material 40 and the rate at which the mixing proceeds,
depends upon the functional material 40 itself, the particle size
and particle size distribution of the functional material 40 (if
the functional material 40 is a solid), the compressed fluid 41
used, the temperature, and the pressure within the formulation
reservoir 18. When the mixing process is complete, the mixture or
formulation 42 of functional material and compressed fluid is
thermodynamically stable/metastable in that the functional material
is dissolved or dispersed within the compressed fluid in such a
fashion as to be indefinitely contained in the same state as long
as the temperature and pressure within the formulation reservoir 18
are maintained constant or in the same state for the period of the
efficient operation of the process (metastable). This
thermodynamically stable state is distinguished from other physical
mixtures in that there is no settling, precipitation, and/or
agglomeration of functional material particles within the
formulation reservoir 18 unless the thermodynamic conditions of
temperature and pressure within the formulation reservoir 18 are
changed. As such, the functional material 40 and compressed fluid
41 mixtures or formulations 42 of the present invention are said to
be thermodynamically stable.
[0042] The functional material 40 can be a solid or a liquid.
Additionally, the functional material 40 can be an organic
molecule, a polymer molecule, a metallo-organic molecule, an
inorganic molecule, an organic nanoparticle, a polymer
nanoparticle, a metallo-organic nanoparticle, an inorganic
nanoparticle, an organic microparticle, a polymer micro-particle, a
metallo-organic microparticle, an inorganic microparticle, and/or
composites of these materials, etc. After suitable mixing with the
compressed fluid 41 within the formulation reservoir 18, the
functional material 40 is uniformly distributed within a
thermodynamically stable/metastable mixture, that can be a solution
or a dispersion, with the compressed fluid 41. This
thermodynamically stable/metastable mixture or formulation 42 is
controllably released from the formulation reservoir 18 through the
discharge assembly 20.
[0043] Referring again to FIG. 4, during the discharge process, the
functional material 40 is precipitated from the compressed fluid 41
as the temperature and/or pressure conditions change. The
precipitated functional material 44 is ejected into the deposition
chamber or controlled environment 30 by the discharge assembly 20.
The particle size of the functional material 40 ejected into the
chamber 30 and subsequently deposited on the substrate 14 is
typically in the range from 1 nanometer to 1000 nanometers. The
particle size distribution may be controlled to be more uniform by
controlling the formulation (functional solute materials and their
concentrations) rate of change of temperature and/or pressure in
the discharge assembly 20, and the ambient conditions inside the
controlled environment 30.
[0044] Although not specifically shown, delivery system 12 (FIG.
4), contemplated by the invention, is also designed to
appropriately change the temperature and pressure of the
formulation 42 to permit a controlled precipitation and/or
aggregation of the functional material 40 (see for instance U.S.
Patent Application Publication No. 2002/0118245A1). As the pressure
is typically stepped down in stages, the formulation 42 fluid flow
is self-energized. Subsequent changes to the conditions of
formulation 42, for instance, a change in pressure, a change in
temperature, etc., result in the precipitation and/or aggregation
of the functional material 40 coupled with an evaporation of the
compressed fluid 41. The resulting precipitated and/or aggregated
functional material 44 deposits on the substrate 14 evenly.
According to FIG. 4, evaporation of the compressed fluid 41 can
occur in a region located outside of the discharge assembly 20
within deposition chamber 30. Alternatively, evaporation of the
compressed fluid 41 can begin within the discharge assembly 20 and
continue in the region located outside the discharge assembly 20
but within deposition chamber 30. Alternatively, evaporation can
occur within the discharge assembly 20.
[0045] According to FIG. 4, a stream 43 of the functional material
40 and the compressed fluid 41 is formed as the formulation 42
moves through the discharge assembly 20. When the size of the
stream 43 of precipitated and/or aggregated functional material 44
is substantially equal to an exit diameter of the nozzle 28 of the
discharge assembly 20, the stream 43 of precipitated and/or
aggregated functional material 44 has been collimated by the nozzle
28. When the size of the stream 43 of precipitated and/or
aggregated functional material 44 is less than the exit diameter of
the nozzle 28 of the discharge assembly 20, the stream 43 of
precipitated and/or aggregated functional material 44 has been
focused by the nozzle 28. It may be desirable for a deposition
chamber input to be a diverging beam to quickly spread the
precipitated and/or aggregated functional material 44 and dissipate
its kinetic energy. Such an input is possible without a nozzle
28.
[0046] Referring again to FIGS. 2, 4 & 5, substrate 14 resides
within deposition chamber 30 such that the stream 43 of
precipitated and/or aggregated functional material stream 44 is
deposited onto the substrate 14. The distance of the substrate 14
from the discharge assembly 20 is chosen such that the compressed
fluid 41 evaporates prior to reaching the substrate 14. Hence,
there is no need for subsequent substrate 14 drying processes.
Further, subsequent to the ejection of the formulation 42 from the
nozzle 28 and the precipitation of the functional material 44,
additional focusing and/or collimation may be achieved using
external devices such as electromagnetic fields, mechanical
shields, magnetic lenses, electrostatic lenses, etc. Alternatively,
the substrate 14 can be electrically or electrostatically charged
such that the position of the functional material 40 can be
controlled.
[0047] Referring again to FIG. 4, it is also desirable to control
the velocity with which individual particles 46 of functional
material 40 are ejected from the nozzle 28. Since there may be a
sizable pressure drop from within the delivery system 10 to the
operating environment, the pressure differential converts the
potential energy of the delivery system 10 into kinetic energy that
propels the functional material particles 46 onto the substrate 14.
The velocity of these particles 46 can be controlled by suitable
nozzle design (see discussion above) and by controlling the rate of
change of operating pressure and temperature within the system.
Further, subsequent to the ejection of the formulation 42 from
nozzle 28 and the precipitation of the functional material 40,
additional velocity regulation of the functional material 40 may be
achieved using external devices such as electromagnetic fields,
mechanical shields, magnetic lenses, electrostatic lenses, etc. The
nozzle design will depend upon the particular application
addressed. (See, for instance, U.S. Patent Application Publication
No. 2002/0118245A1).
[0048] Moreover, the temperature of nozzle 28 may also be
controlled. Referring to FIG. 4, the temperature of nozzle 28 may
be controlled as required by specific applications to ensure that
the nozzle opening 47 maintains the desired fluid flow
characteristics. Nozzle temperature can be controlled through the
nozzle heating module (not shown) using a water jacket, electrical
heating techniques, etc. (See, for instance, U.S. Patent
Application Publication No. 2002/0118245A1). With appropriate
nozzle design, the exiting stream temperature can be controlled at
a desired value by enveloping the exiting stream with a co-current
annular stream of a warm or cool inert gas.
[0049] Embodiment I
[0050] Referring to FIG. 2, controlled environment 30 is designed
for use at extremes of pressure. Incorporated in the controlled
environment 30 is a pressure modulator 105. The pressure modulator
105, as shown, resembles a piston. This is for illustration only.
Skilled artisans will also appreciate that pressure modulator 105
could also be a pump or a vent used in conjunction with an
additional pressure source. An example of an additional pressure
source is the source 109 of compressed fluid. This source 109 is
modulated with a flow control device or valve 108 to enable
functional material to enter the deposition chamber 30 via a fluid
delivery path 13. The pressure inside the deposition chamber 30 is
carefully monitored by a pressure sensor 103 and can be set at any
pressure less than that of the delivery system 12 (including levels
of vacuum) to facilitate precipitation/aggregation. In addition,
the deposition chamber 30 is provided with temperature sensor 104
and temperature modulator 106. Temperature modulator 106 is shown
as an electric heater but could consist of any of the following
(not shown): heater, a water jacket, a refrigeration coil, and a
combination of temperature control devices.
[0051] Referring to FIGS. 1, 2, and 4, deposition chamber 30
generally serves to hold the substrate 14 and the mask 22 and
facilitates the deposition of the precipitated functional material
44. To enable a more complete and even distribution of the
functional material 40, electric or electrostatic charges can be
applied to the substrate 14 and/or mask 22. Through the ejection
process in the discharge assembly 20, the particles are known to
become charged. If desired, additional charge can be applied to
them using a particle charging device 107 (FIG. 2). The functional
material 40, now charged can be attracted or repelled from various
surfaces to aid in the deposition process. According to FIG. 2,
charging devices 102a, 102b are provided for both the substrate 14
and mask 22, respectively. For illustrative purposes only, a
positive charge (+) is shown on substrate 14 and a negative charge
(-) is shown on mask 22. The polarity may be changed to suit the
application. A charge equal to that of the functional material 40
is applied to the mask 22, whereas a charge opposite of that of the
functional material 40 is applied to the substrate 14 to attract
the functional material. Obviously there can be no electrical
conduction between the two to maintain the charge differential.
This may limit the material selection of one or both, or add the
requirement for an additional insulating layer (not shown). In a
similar manner, it may be beneficial to create other electric or
electrostatic charges on the deposition chamber 30 or on any other
mechanical elements within the deposition chamber 30. As shown in
FIG. 6, an internal baffle 122 may be used to provide a more even
distribution of functional material 40 within the deposition
chamber 200. A charge may be applied to the internal baffling by a
baffle charging device 123.
[0052] Referring again to FIG. 2, deposition chamber 30 also
provides easy access for the insertion and removal of the substrate
14 through access port 101. This process will potentially be
automated by mechanical devices which are not shown. Access port
101 of deposition chamber 30 also provides access for the insertion
and removal of the mask 22 as well as for the proper placement of
the mask 22. Mask alignment relative to the substrate 14 is key to
this application and may be manual or preferably, automated. Though
it is shown oriented with the substrate 14 facing upwards, this is
not a requirement of the invention. When attracting particles
electrostatically, it may be advantageous to orient the substrate
14 facing downward. In this manner, no debris from the deposition
chamber 30 could inadvertently fall onto the substrate 14.
[0053] The controlled environment can be used for post deposition
processing of the deposited material on the substrate. Post
deposition processing may involve the control of humidity,
temperature, atmospheric conditions including pressure, and
chemical composition of the atmosphere. As an example, many
processes require the curing of the materials to obtain desired
functionality at elevated temperature. The thermal control that is
already built into the enclosure can be utilized for this purpose.
Alternatively, the post processing required can be done outside the
enclosure.
[0054] It should be appreciated that deposition chamber 30 should
also be designed so that there are no dead volumes that may result
in the accumulation of precipitated functional materials 44 and so
that it may be easily cleaned. As such, it may be further
partitioned into more than one sub-chamber to facilitate the above
(not shown). It may also be equipped with suitable mechanical
devices to aid the precipitation and deposition of functional
material 40. An example of such a device would be a mechanical
agitator.
[0055] Embodiment II
[0056] Turning now to FIG. 5, another embodiment of deposition
chamber 100, contemplated by the invention, is shown. It contains
many of the same features previously described in the discussion of
FIG. 2, with the addition of a medium 111 which divides the
deposition chamber 100 into a preparation sub-chamber 100a and a
deposition sub-chamber 100b. The materials in these sub-chambers
100a, 100b are allowed to flow through controllable dual chamber
interface valve 110. Each sub-chamber 100a, 100b is configured with
independent control of pressure and temperature through the use of
pressure sensors 103, temperature sensors 104, pressure modulators
105, and temperature modulators 106. The preparation sub-chamber
100a differs from the formulation reservoir 18 (FIG. 1) in that the
functional material 40 can be (but is not necessarily)
precipitated. The addition of a preparation sub-chamber 100a to the
system allows for a potentially large volume of prepared deposition
material to be ready and maintained at a higher than ambient
pressure while still allowing the changing of substrate 14 and
deposition material through the access port 101.
[0057] Embodiment III
[0058] In FIG. 6, a simplified deposition chamber 200 is
illustrated. In this embodiment, no provision is made for
maintaining a pressure above that of ambient. Many of the other
features described in FIGS. 2 and 5 are still possible, but by no
longer requiring the deposition chamber 200 to support an elevated
pressure, certain additional advantages can be realized. For
example, the substrate 14 no longer is required to be contained in
deposition chamber 200. This is illustrated in FIG. 6 by showing a
moving substrate in the form of a web 120 that is transported by
conveyors 121. In such a system, it is possible to perform
continuous coating operations. In this case, a separate mask would
likely not be used except for the case of a step and repeat
process. Rather, a mask integral to the substrate, as previously
described, is the preferred method of achieving patterned
deposition. Alternatively, a similar approach, illustrated in FIGS.
2 and 5, could be used also without need for access port 101.
[0059] Additional aspects of the invention may include multiple
deposition chambers 30, 100, or 200, as illustrated in FIGS. 2, 5,
and 6, for coating multiple layers onto substrate 14.
Alternatively, multiple masks 22 may be used such that a mask with
a specific configurational structure of aperture patterns is used
and subsequently replaced with another shadow mask of different
configurational structure of aperture patterns on the same
substrate 14. Multiple masks, indexing of a mask, multiple layers,
and multiple material processes are commonly used in the
manufacture of displays, therefore details and methods to provide
proper registration such as through the use of optical fiducials
are well known. The sequential process used for deposition of
colored material(s) for display products applications may be
interspersed with other processes, including deposition of other
material(s) and/or post treatment of deposited material(s), as
needed, to create a desired product.
[0060] It is to be understood that elements not specifically shown
or described may take various forms well known to those skilled in
the art. Additionally, materials identified as suitable for various
facets of the invention, for example, functional materials. These
are to be treated as exemplary, and are not intended to limit the
scope of the invention in any manner.
Parts List
[0061] 10 system
[0062] 12 delivery system
[0063] 13 fluid delivery path
[0064] 14 substrate
[0065] 16 source of compressed fluid
[0066] 18 formulation reservoir
[0067] 20 discharge assembly
[0068] 22 mask
[0069] 24 closed loop control of the input valve
[0070] 28 orifices/nozzles
[0071] 30 deposition chamber or controlled environment
[0072] 31 enclosure
[0073] 32 shutter
[0074] 33 viewing window
[0075] 35 optical emitter
[0076] 37 optical detector
[0077] 39 microprocessor
[0078] 40 functional material
[0079] 41 compressed fluids
[0080] 42 formulation of functional material 40
[0081] 43 stream of functional material 40
[0082] 44 precipitated and/or aggregated functional material
[0083] 46 functional material particles
[0084] 47 nozzle opening
[0085] 100 alternative embodiment of deposition chamber or
controlled environment
[0086] 100a preparation sub-chamber
[0087] 100b deposition sub-chamber
[0088] 101 access port
[0089] 103 pressure sensor
[0090] 102a charging device
[0091] 102b charging device
[0092] Parts List--Continued
[0093] 104 temperature sensor
[0094] 105 pressure modulator
[0095] 106 Temperature Modulator
[0096] 107 particle charging device
[0097] 108 flow control valve
[0098] 109 source of compressed fluids
[0099] 110 interface valve
[0100] 111 medium
[0101] 120 web
[0102] 121 conveyor
[0103] 122 internal baffle
[0104] 123 baffle charging device
[0105] 200 another alternative embodiment of deposition chamber or
controlled environment
* * * * *