Note: Descriptions are shown in the official language in which they were submitted.
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COMBINATORIAL SYSTEMS AND METHODS FOR COATING WITH ORGANIC MATERIALS
BACKGROUND OF THE INVENTION
This invention was made with government support under Contract No.
70NANB9H3038 awarded by NIST. The government may have certain rights to the
invention.
This disclosure relates generally to methods and apparatus for
generating and screening coating libraries, and more particularly, to methods
and
systems for the parallel deposition of layers of materials onto a substrate to
form a
coating library.
Coatings are widely used in industry to enhance the functionality and
add-on value of bulk materials. There are generally two types of functional
coating
materials: inorganic and organic coatings. Inorganic coatings have been used
in both
the semiconductor industry, for example in various thin film integrated
circuit
devices, as well as in conventional industry, such as thermal barrier coatings
for
steam turbines and aircraft engine airfoils. Organic coatings are also widely
used in
many industrial protective/decorative applications, such as in automobile top
clear
coatings, paints, etc. Other types of coatings include, for example,
protective and
anticorrosive coatings, adhesive and release coatings, environmental barrier
coatings,
electric conductive/optic transparent coatings, scratch resistance hard
coatings, etc.
Discovery of an advanced coating formula promises huge value for a
manufacturer.
The development of generic tools to accelerate the discovery process
for various coating systems may be of even higher value, however, as the
search and
optimization of advanced coatings is more of an art than a science. The power
of
. 25 theoretical guidance in the search and optimize advanced coatings is
limited, largely
because of the complexity of a typical coating system and multiplicity of
quality
requirements that need to be met. Typically, industrial coating formulations
have to
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meet multiple functional requirements, and multiple compatible functional
groups or
blends are necessary to obtain a balanced formulation. In addition, the
properties of a
coating system depend not only on the formula/composition, but also on the
processing conditions and the coating application method. For example, the
degree of
thickness uniformity and surface roughness, which depends on the application
method
and processing of a coating, are important in the quality and reproducibility
of the
coating. Further, different processing conditions, including exposure to ultra-
violet(UV)/electron curing; varying temperature/pressure, and the sequence of
application of each layer of multiple layer coatings, are highly important
factors in
determining the structure/composition of the final coating. Additionally, the
structure/composition of the final coating impacts the functionality of the
coating.
Thus, because of the multitude of variables, most of the usable industrial
coating
systems developed to date have been a result of serendipitous trial-and-error
experimental processes.
BRIEF SUMMARY OF THE INVENTION
Therefore, there is a need for an approach that accelerates the rate at
which functional coatings are generated and studied for various manufacturing
applications. Thus, the present invention provides systems and methods for
high
throughput fabrication and analysis of an array of coated materials.
A system of one embodiment for making an array of coated materials
includes a plurality of organic materials and a delivery mechanism for
delivering each
of the plurality of organic materials to a delivery area. The delivery
mechanism has a
plurality of sources each associated with a corresponding one of the plurality
of
organic materials. Each of the plurality of sources provides a thickness
distribution
profile of the corresponding organic material at least partially positioned in
the
delivery area, where at least one of the thickness distribution profiles
varies across the
delivery area.
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A method of one embodiment for making an array of coated materials
includes providing a plurality of organic materials and selectively delivering
each of
the plurality of organic materials to a delivery area. Each of the delivered
plurality of
organic materials has a thickness distribution profile at least partially
positioned in the
delivery area, where at least one of the thickness distribution profiles
varies across the
delivery area.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic diagram of a system for making an array of
coating materials;
Fig. 2 is a schematic diagram of a coating library formed from the
system of Fig. 1;
Fig. 3 is a schematic diagram of an envelope of a vaporized material
being delivered from a delivery mechanism source to the surface of a substrate
within
a delivery area;
Fig. 4 is a graph of a thickness profile distributed across a dimension
of a delivery area from a normal, focused set up of the delivery mechanism; ,
Fig. 5 is a graph of a thickness profile distributed across a dimension
of a delivery area from an angled, focused set up of the delivery mechanism
source;
Fig. 6 is a graph of a thickness profile distributed across a dimension
of a delivery area from a normal, off focus set up of the delivery mechanism
source;
Fig. 7 is a graph of a thickness profile distributed across a dimension
of a delivery area from an angled, off focus set up of the delivery mechanism
source;
Fig. 8 is a side view of one embodiment of a combinatorial coating
system having two opposing delivery sources;
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Fig. 9 is a top view of a coating library formed from the system of Fig.
8;
Fig. 10 is a perspective view of one embodiment of a ternary
combinatorial coating system;
Fig. 11 is a top view of a coating library formed from the system of
Fig. 10;
Fig. 12 is a schematic diagram of another embodiment of a
combinatorial coating system;
Fig. 13 is a top view of a mask having a plurality of patterns, as may
be utilized in the system of Fig. 12;
Fig. 14 is a top view of a coating library formed using the mask of Fig.
13 in the system of Fig. 12; and
Fig. 15 is a side view showing the cross-section of one embodiment of
a vapor deposition combinatorial coating system.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Figs. 1 and 2~ a system 10 for making an array of coating
materials that form a coating library includes a delivery mechanism 12
delivering one
or a combination of a plurality of materials 14 to a surface 16 of a substrate
18 to
form a coating 20. The substrate surface 16 has a plurality of predefined
regions 22
that are positioned within a delivery area 24, which is preferably at a fixed
location
within the system 10. The delivery mechanism 12 and/or the plurality of
materials 14
are positioned to simultaneously deliver, or deliver in parallel, each of the
plurality of
materials to the delivery area 24. A controller 26 controls the selection,
quantity and
sequence of delivery of each of the plurality of materials 14 such that the
composition
of the coating 20 may vary between each of the regions 22 on the substrate
surface 16
to form a coating library 28. As such, each of the plurality of predefined
regions 22 is
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coated with one of a plurality of predefined coatings 30. The plurality of
predefined
coatings 30 include: a single layer coating of one of the plurality of
materials 14; a
single layer coating of a combination of the plurality of materials; a
multiple layer
coating, where each layer is one of the plurality of materials; and a multiple
layer
coating, where each layer is a combination of the plurality of materials.
Additionally,
the system 10 may include a mask 32 in communication with the controller 26 to
permit delivery of the materials 14 to different combinations of the plurality
of
predefined regions 22 form the plurality of predefined coatings 30. The system
10
may also include a curing source 34 for curing the plurality of materials 14,
either as
they are being delivered to the substrate 18 or once they have been deposited
on the
substrate. Further, the system 10 may include a testing device 36 to perform
analytical tests on the coated substrate or coating library 28, to determine
the
properties of each of the plurality of predefined coatings 30. The mask 32 may
be
secured by a mounting device 35, which optionally may movably position the
mask
within the system 10. Similarly, the substrate 18 may be secured by a holding
device
37, which optionally may movably position the substrate within the system 10.
Thus,
the present invention provides a system and method for manufacturing and
testing a
coating library having an array of coatings established from a plurality of
materials
simultaneously focused, or focused in parallel, on a substrate.
The delivery mechanism 12 is configured such that each of the
plurality of materials 14 may be simultaneously delivered, or delivered in
parallel, to
the delivery area 24 from a variety of angles. As such, the delivery mechanism
12 is
positioned or focused so that at least a portion of the delivered material
reaches the
delivery area 24, as is discussed in more detail below. The delivery mechanism
12
may be a single device, or it may be a plurality of individual devices each
corresponding to one of the plurality of materials 14. The position of each of
the one
or more delivery mechanisms 12 is preferably fixed within the system 10
relative to
the delivery area 24 and relative to the other delivery mechanisms.
Preferably, the
delivery mechanism 12 projects each of the plurality of materials 14 to the
delivery
area 24 in, a vaporized or atomized form. Suitable examples of a delivery
mechanism
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12 include: a spray nozzle or gun of any type, such as ultrasonic, air,
thermal, airless
guns, such as those using hydraulic force; microwave or radio frequency ("RF")
delivery mechanisms; an ink jet print head; a vapor deposition device,
including
sputtering, thermal/electron/laser evaporation, chemical vapor deposition
(CVD),
molecular beam epitaxy, plasma spray; and ion beam deposition.
The plurality of materials 14 include inorganic materials and organic
materials in various states, such as solid, liquid, gaseous and
vaporizedlatomized
materials. Suitable examples of inorganic coatings include metals, alloys,
ceramics,
oxides, nitrides, and sulfides. Suitable examples of organic coatings include
polymeric, oligomeric and small molecules, where small molecules are
individual
monomers that react to form a coating. The polymeric materials include, but
are not
limited to, polycarbonates, acrylics, silicones, cellulose esters, polyesters,
alkyds,
polyurethanes, and vinyl polymers and alike. Preferably, the plurality of
organic
materials include organic polymeric materials, such as "architectural"
materials
derived from organic materials having protective or decorative functionality,
especially including thermoplastic ar thermosetting polymers. Preferably, the
plurality of inorganic materials include oxides. Further, the plurality of
materials 14
preferably can be vaporized or atomized, individually or in combination, and
directed
to or deposited on a substrate, where the vaporized/atomized material
coalesces and
forms a continuous coating if a sufficient amount of the material is delivered
to the
substrate. Additionally, the material or combination of materials may form a
coating
having a plurality of layers, where the coating may be a mufti-functional
coating
having an overall function dictated by a predefined functional role of each
layer. The
materials may be combined such that multiple organic materials, or multiple
inorganic materials, or a combination of organic and inorganic axe combined
into a
coating. Additionally, by providing these various combinations of materials,
the
interaction and compatibility of various combinations of materials may be
determined.
The coating 20 is a material or a combination of materials deposited on
the substrate 18. These materials may remain as separate homogenous materials,
or
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they may react, interact, diffuse, mix or otherwise combine to form a new
homogeneous material, a mixture, a composite or a blend. As mentioned above,
the
coating 20 may include a single layer or multiple layers. In general, coating
20 has a
lateral measure, i.e. a measured length across the surface of the substrate,
much
greater than a thickness, i.e. a measure of the coating normal to the surface
of the
substrate. Preferably, each layer is a thin film layer. The coating 20 may
vary in
composition, optionally in a continuous manner, from one predefined region 22
to
another to thereby form an array of coatings that define the plurality of
predefined
coatings 30 of the coating library 28. Each of the array of coatings are
distinguishable
from each other based on their location. Further, each of the array of
coatings may be
processed under the same conditions and analyzed to determine their
performance
relative to functional or useful properties, and then compared with each other
to
determine their relative utility.
Each of the plurality of predefined regions 22 is a fixed area on the
substrate 18 for receiving one or a combination of the plurality of materials
14 to
form a single or multiple layer coating. Each of the predefined regions 22 may
have
any shape sufficient for receiving and analyzing the coating deposited
thereon, such
as rectangular, linear, arcuate, circular, elliptical, combinations thereof,
etc. Each
predefined region 22 typically has an area in the range of about 0.01 mm2 to
about
100 cm2, preferably in the range of about 1 mm2 to about 1 cm2, and more
preferably
in the range of about 10 mm2 to about 50 mm2. Other areas may be utilized, and
the
area of each predefined region 22 may be determined by the capability of
deposition
and analytical devices and by a preferred density of the coating library.
The substrate 18 is a rigid or semi-rigid material suitable for receiving
and supporting at least one of the plurality of materials 14. The substrate 18
has at
least one substantially flat surface 16 that includes the plurality of
predefined regions
22. This substantially flat surface, however, may have raised portions to
physically
separate each of the plurality of predefined regions 22. The substrate 18 may
be of
any size and shape, but preferably is in a disk shape, plate shape, or
elongated shape,
such as in a tape or roll. The substantially flat surface 16 of the substrate
18,
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corresponding to the delivery area 24, typically has an area in the range of
about 1
mm2 to about 1 m2, preferably in the range of about 50 mm2 to about 750 cm2,
and
more preferably in the range of about 1 cm2 to about 500 cmz.
The substrate 18 may be secured within the system 10 and positioned
in the delivery area 24 by the holding device 37. The holding device 37 may
movably
position the substrate 18. For example, for a substrate 18 in the form of an
elongated
tape, the holding device 37 may include a tape pay-out device and a tape take-
up
device that are both rotatable and that support the tape, possibly in
combination with
rollers, in the delivery area 24. In another example, the holding device 37
may be a
ZO plate on which the substrate is placed and secured, where the plate is
connected to a
motor or other actuator-type device that controls the position of the plate
relative to
the delivery area 24. As such, the controller 26 may control the movement of
the
holding device 37 to control the predefined regions 22 onto which the
materials 14 are
delivered. For example, the controller 26 may move the holding device 37 such
that
predetermined ones of the plurality of predefined regions 22 are outside of
the
delivery area 24 and therefore do not receive one or more of the materials 14.
The delivery area 24 is an area at a fixed position within the system 10.
The delivery area 24 may be of any shape or size and typically, but not
necessarily,
substantially corresponds in shape and size to the plurality of predefined
regions 22
on the surface 16 of the substrate 18. However, the plurality of predefined
regions 22
may be much larger or much smaller than the delivery area 24. The fixed
positioning
of the delivery area 24 provides a known, constant locale for the system 10 to
deliver
the plurality of materials 14 and the surface 16 of the substrate 18.
The controller 26 is a computer system having inputs, outputs, a
memory and a processor for receiving, sending, storing and processing signals
and
data to operate, monitor, record and otherwise functionally control the
operation of
the system 10. The controller 26 includes a computer system having an
interface
board for integrating all of the components of the system and a motion
controller for
controlling the movements of the mask 32 and substrate 18. The controller 26
may
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include a keyboard for inputting data and commands, a video display for
displaying
information, and a printer for printing information. The controller 26 may
include
software, hardware, firmware, and other similar components and circuitry for
operating the system 10. The controller 26 may be a single device, or it may
be a
plurality of devices working in concert. The controller 26 is preferably in
communication with all of the other components of the system 10, including the
delivery mechanism 12, the plurality of materials 14, the substrate 18, the
mask 32,
the curing source 34, the testing device 36, the mounting device 35 and the
holding
device 37, to coordinate the operations of the system. For example, the
controller
controls the delivery of the materials to the substrate, recording the exact
combination
of materials that make up the coating at each predefined region. By
controlling the
delivery, the controller may control one or more of the material volume, the
combination of materials, the projective power, the coating speed, the
projective
angle, the spacing between the delivery mechanism and the substrate, the
masking,
etc. Further, the controller 26 controls, synchronizes, combines and records
the
delivery and curing of the delivered materials, the testing of the coating
library, and
the analysis of the test results.
The mask 32 is a material having one or more patterns of open areas
and blocked areas, where the open areas allow delivery of the plurality of
materials 14
to the substrate 18 and the blocked areas block the delivery. The pattern may
be in
any shape. The mask 32 is utilized to define the spatial variation of
materials in the
coating library 28. In a binary masking system, for example, the mask includes
a
plurality of patterns that are sequentially arranged to allow delivery to
alternating half
areas on the substrate 18, as will be described below in more detail. The mask
32
may be positioned anywhere in between the plurality of materials 14 and the
substrate
18, including positioned directly on top of and in contact with the substrate,
along the
line of delivery of the materials. By increasing the spacing between the mask
32 and
the substrate 18, an effect called "shadowing" is produced which may be
undesirable
in some instances. In shadowing, the pattern of material delivered to the
substrate is
proportional to the pattern of the mask, but larger, as the spacing between
the mask
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and the substrate allows the delivered pattern to expand until it reaches the
substrate.
The mask 32 may be formed of a rigid or semi-rigid material, or the mask may
be a
chemical formed on the surface of the substrate. Preferably, the material of
the mask
insures that the mask is as flat as possible and resists bending and/or
folding. Suitable
examples of mask materials include: silicon, silicon oxide and glass for rigid
or
relatively non-bendable materials; plastics, metals and alloys for semi-rigid
or
relatively bendable materials in the form of sheets, films or foils; and
lithographic-
polyacrylate ("PMMA") and other chemical materials that form negative and
positive
chemical masks.
The mask 32 may be secured within the system 10 and positioned
relative to the delivery area 24 by the mounting device 35. The mounting
device 35
may movably position the mask 32. For example, for a mask 32 in the form of an
elongated semi-rigid material having a plurality of patterns, the mounting
device 35
may include a tape pay-out device and a tape take-up device that are both
rotatable
and that support the tape, possibly in combination with rollers, relative to
the delivery
area 24. In another example, for a mask 32 in the form of a rigid material,
the
mounting device 35 may be a platform or other supporting structure connected
to a
motor or other actuator-type device that controls the position of the platform
and
mask relative to the delivery area 24. This allows one pattern or a number of
patterns
to be utilized to mask different predefined regions 22 on the substrate 18 by
movement of the mask 32. As such, the controller 26 may control the movement
of
the mounting device 35 to control the predefined regions 22 onto which the
materials
14 are delivered.
The curing source 34 is a device in communication with each of the
plurality of materials 14 to cause a reaction or a solvent evaporation with
one or a
combination of the materials. For example, the reaction may be a
polymerization, a
cross-linking reaction, a small molecule reaction, an inorganic phase
reaction, and
other similar reactions appropriate for the delivered material(s). Suitable
examples of
a curing source 34 include a heating device in communication with the
substrate 18, a
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radiation device in communication with the delivered materials or the
deposited
materials, a microwave device, a plasma device and combinations thereof.
The testing device 36 is a system for analyzing the performance of
each of the plurality of predefined coatings 30 on the substrate 18. The
testing device
36 subjects the entire coating library 28 to the same conditions in order to
determine
the relative performance of each one of the predefined coatings 30. The
testing
device 36 is in communication with the controller 26 in order to compile and
analyze
the test data. Suitable examples of a testing device 36 include a thickness
profiler, a
surface analyzer, an ultra violet ("UV") absorbance tester, a scratch
resistance tester,
a permeability tester, and other similar devices that test architectural,
protective,
decorative and other functional features of a coating.
Referring to Fig. 3, a source 38 of the delivery of the materials from
the delivery mechanism 12 delivers one of the plurality of materials 14 in a
vaporized
or atomized state within an envelope 40 that preferably encompasses the
delivery area
24 in order to obtain coating coverage over the entire delivery area. The
source 12 is
the point of exit of the material from the delivery mechanism. For example,
the
source 12 may be the nozzle on a spray gun. It may be desired in some cases,
however, not to have coating coverage over the entire delivery area 24. For
example,
the envelope 40 may only encompass a portion of the delivery area 24 when a
portion
of the predetermined regions 22 of the substrate 18 are not to be coated and a
mask 32
is not being used to prevent delivery of the material to those regions. The
envelope
40 may be of any convenient shape, including: conical with various cross-
sections
such as round, elliptical and rectangular; semi-conical with various cross-
sections;
and a thin line shape. The shape of the envelope 40 may be dictated by the
shape of
the delivery area 24, the shape of the surface 16 of the substrate 18, the
delivery
mechanism 12, the desired composition of each of the plurality of predefined
coatings
30, the shape and number of the predetermined regions 22, the number of
sources 38,
the number of materials 14 being delivered to the substrate 18, and similar
factors.
The shape of the envelope 40 may be controlled by the shape of a nozzle on the
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delivery mechanism 12, by an air shroud associated with the delivery
mechanism, or
by other shape-defining structures or devices associated with the delivery
mechanism.
Referring to Figs. 3 and 4, in a normal focused set up 41, the source 38
has a point of focus 42 for delivering the material 14 coinciding with a
center point 44
of the delivery area 24. The source 38 is positioned to direct the material 14
along a
delivery angle having a centerline 46 substantially perpendicular to the
surface of the
delivery area 24 at the center point 44. Referring to Fig. 4, the cross-
sectional
thickness profile 48 along one of the dimensions 50 (such as the lateral
dimension of
Fig. 3) of the delivery area 24 of a coating delivered from the set-up of Fig.
3, with
the delivery angle a substantially perpendicular to the plane 49 of the
delivery area,
typically has a 2-dimensional substantially Gaussian or normal distribution.
The
thickness profile 48 therefore has an apex 52 coinciding with the centerline
46 above
the center point 44, with two equal, mirror-image tails 54 on each side of the
centerline. Further, the source 38 is positioned at a vertical spacing 60
relative to the
plane 49 of the delivery area 24 (Fig. 3). The vertical spacing 60 affects the
total
width 51 of the thickness profile 48 and thereby the thickness of the coating
at any
given point along the thickness profile distribution. Thus, in this case, the
thickness
profile 48 is centered within the dimension 50 of the delivery area 24, the
thickness
being largest at the apex 52 and gradually reducing in all directions from the
centerline 46.
Referring to Fig. 5, in an angled focused set up 55, the source 38 has
the point of focus 42 for delivering the material 14 coinciding with the
center point 44
of the delivery area 24, however, the source is positioned such that the
centerline 46
of the material is at a delivery angle a between about 0 degrees and about 90
degrees
relative to the plane 49 of the delivery area. Further, because of the angled
but
focused delivery, the source 38 is located at a horizontal. spacing distance
53 from the
center point 44. The horizontal spacing distance 53 is a distance in the plane
of the
source 38 parallel to the plane 49 of the delivery area and spaced away from
the
normal focused set up position. The horizontal spacing distance 53, vertical
spacing
distance 60, and delivery angle a are all mathematically interrelated and may
be
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varied to position the thickness profile 48 within the delivery area 24. In
this
embodiment, the thickness profile 48 has a distorted Gaussiari distribution
with an
inclined tail 56 closer to the source 38 and an elongated tail end 58 trailing
away from
the source. Within the elongated tail 58 is typically a region where the
thickness
profile 48 varies substantially linearly with the length along the dimension
50. Thus,
in this case, the thickness profile 48 is distorted within the dimension 50 of
the
delivery area 24, the thickness being largest toward the end of the dimension
having
the inclined tail 56 and reducing in thickness from the apex 52 toward the
edge of the
dimension corresponding to the elongated tail 58.
Referring to Fig. 6, in an normal off focus set up 57, the source 38 has
the point of focus 42 for delivering the material 14 positioned at an offset
distance 59
in the plane of the delivery area 24 along the dimension 50 from the center
point 44.
In this case, where the centerline 46 is at a delivery angle a substantially
perpendicular to the plane 49 of the delivery area 24, the offset distance 59
is
substantially equivalent to the horizontal spacing of the source 38 from the
normal
focused set up position (Fig. 4). Also, note that the point of focus for a
delivery
mechanism may be positioned within the delivery area or outside of the
delivery area.
Thus, in this case, the thickness profile 48 is offset within the dimension 50
of the
delivery area 24, the thickness being largest at the offset position of the
apex 52 and
gradually reducing in all directions from the centerline 46.
Referring to Fig. 7, in an angled off focus set up 61, the source 38 has
the point of focus 42 for delivering the material 14 positioned at the offset
distance 59
along the dimension 50 from the center point 44, where the centerline 46 is at
a
delivery angle a between about 0 degrees and about 90 degrees relative to the
plane
49 of the delivery area 24. In this case, because of the delivery angle a and
off focus
point of focus 42, the horizontal spacing 53 of the source 38 from the normal
focused
delivery point is greater than the offset distance 59 of the point of focus to
the center
point 44. Thus, in this case, the thickness profile 48 is even more distorted
within the
dimension SO of the delivery area 24 than the set up of Fig. 5.
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In each of the set ups of Figs. 4-7, the flatness of the thickness profile
48 within the delivery area 24 will vary depending on the vertical spacing 60
between
the source 38, where the flatness will increase with increased spacing.
Further, the
flatness of the thickness profile 48 will vary within the delivery area 24
depending on
the delivery angle a, horizontal spacing 53, and offset distance 59, where the
smaller
the angle and greater the horizontal spacing and offset distance will increase
the
flatness. For example, referring to Fig. 4, the thickness profile 48 may be
substantially flat in the dimension 50 of the delivery area 24 with the proper
combination of delivery angle, horizontal spacing and offset distance. With
closer
spacing, however, the thickness profile 48 in the dimension 50 of the delivery
area 24
may gradually change from a largest thickness at the apex 52 to a smallest
thickness
at the edges of the dimension of the delivery area. Preferably, a coating
library
having a substantially constant thickness is desired so that the thickness
variable can
be ruled out of the analysis of the plurality of predefined coatings 30
associated with
1 S each predefined region 22 in order to focus the study on the effect of the
coating
composition. In operation, a substantially constant thickness coating library
is
achieved by calibrating each delivery mechanism such that a linear thickness
profile
is distributed across the delivery area. When multiple delivery mechanisms are
utilized, preferably the same portion of the thickness profile is positioned
within the
delivery area for each delivery mechanism. Therefore, the present invention
allows
the manufacture of coating libraries having virtually infinite variations in
compositions, layers and thicknesses of coating materials within the plurality
of
predefined regions 30 of the substrate 18 by varying the vertical spacing 60,
the
delivery angle a and the offset distance 59, for each source 38 of each of the
plurality
of materials 14.
Referring to Figs. 8 and 9, in one embodiment of a combinatorial
coating system 62, a continuously varying coating library 64 is formed on the
substrate 18 by the simultaneous deposition of at least two (A and B) of the
plurality
of materials 14 from sources 38. The relative thickness and composition of
each of
the plurality of predefined coatings 30 may individually or both continuously
vary as
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the result of the thickness_profile 48 (see Figs. 4-7) of each of the
materials A and B
as they are delivered to the substrate 18. This continuous variation may be
linear or
non-linear, depending on variables such as the delivery angle a, the
projective power
of the delivery mechanism 12 (not shown) associated with each source 38, the
coating
speed or amount of material deposited per unit time, the feed rate and
concentration
of the material input into the delivery mechanism, the vertical spacing 60,
the offset
distance 59 of the source 38 relative to the center point 44, the horizontal
spacing 53
of each source 38 to the center point 44, the shape of the envelope 40 (not
shown), the
atmosphere and power per area and pressure and species of gas in vapor
deposition,
and other similar factors. Each of these variables may be varied individually
or in
combination to produce a predefined coating in each predefined region 30.
Further,
although not shown, a mask 32 may be positioned between each of the sources 38
and
the substrate 18, preferably adjacent to or touching the substrate to assist
in forming
the coating library.
Additionally, referring to Fig. 8, the delivery angle a may have a value
in the range of about 0° to about 90°, more preferably from
about 15° to about 75°, and
most preferably from about 30° to about 60°. The vertical
spacing 60 may vary from
about 0 cm to about 90 cm, more preferably from about 3 cm to about 30 cm, and
most preferably from about 10 cm to about 20 cm. The horizontal spacing 53 may
vary from about 0 cm to about 60 cm, more preferably from about 3 cm to about
30
cm, and most preferably from about 10 cm to about 20 cm. The coating thickness
may vary from about 1 nanometer to about 1 millimeter, more preferably from
about
1 micrometer (or microns) to about 500 micron, and most preferably from about
5
microns to about 100 microns.
Referring to Fig. 9, one embodiment of the coating library 64 produced
by the combinatorial coating system 62 (Fig. 8) includes opposing gradients of
materials A and B, ranging continuously from about 100% to about 0% of
material A
and from about 0% to about 100% of material B moving laterally across the
coating
library from the side adjacent to the source 38 of material A. Depending on
the
variables discussed above with regard to the delivery of the materials to the
substrate,
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the coating library 64 may have a substantially constant or a variable
thickness across
the substrate. Preferably, the sources of materials A and B have respective
points of
focus 42 having a predefined offset distance S3 from the center point 44 of
the
delivery area so that the thickness of the coating library is substantially
constant
S across the substrate. Further, by allowing a sufficient time for diffusion
of materials
A and B by controlling the rate of evaporation, a new material may be formed
by the
in-situ diffusion/mixing or by the reaction of A and B. Alternatively, the
substrate 18
of Fig. 8 may be movable, such as rotationally, longitudinally and laterally,
to obtain
multiple variations in the composition of each of the predefined coatings 30.
Further,
the sources 38 may be sequentially fed with new and different materials, which
in
combination with a laterally moving elongated substrate, results in a
continuously
varying coating along a longitudinal length of the substrate. Additionally,
each
source 38 preferably is positioned within a delivery plane 6S that is
substantially
parallel to, but spaced a vertical distance 60 from, the plane 49 of the
delivery area.
1S In an alternate embodiment, however, the vertical spacing 60 of each source
38 may
independently vary to provide a different thickness profile 48 within the
delivery area
24. Thus, the system 62 of provides for the simultaneous delivery of at least
two of a
plurality of materials onto the substrate to obtain a continuously varying
coating
having gradients of the at least two materials.
Referring to Figs. 10-11, in another embodiment similar to that of Figs.
8-9, a ternary combinatorial,coating system 68 provides a continuous ternary
coating
library 70. At least three materials (A, B and C) of a plurality of materials
14 (Fig. 1)
may be simultaneously or sequentially delivered from sources 38. The sources
38 are
each positioned in a substantially identical angled off focus setup 61 (Fig.
7), as
2S described above. The sources 38 are preferably equally spaced about a
circle 74
having a center 76 on the same axis 78 as center point 44. Preferably, the
circle 74
has a diameter larger than the diameter of the delivery area. For example, the
circle
74 preferably has a diameter of about 30 cm while the delivery area has a
diameter in
the range of about 10 cm to about 1S cm. The coating library 70 formed by
system 68
may be a continuously varying combination of each of the three materials A, B
and C,
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mimicking a ternary phase diagram. The same variables affecting the formation
of
the coating library 64 (Figs. 8-9), described above, similarly apply to the
coating
library 70 of the system 68. For example, the relative composition of the
coating
library 70 at any point is a function of the horizontal spacing 53, offset
distance 59,
the delivery angle a, the shape of the envelope 40 of the spray of each
material, the
point of focus 42 of each source, etc. Further, the preferred spacing and
angles are
the same as those described above with reference to Figs. 8-9. In one working
example, three airbrush guns were simultaneously focused to deliver a fine
spray of
three different materials to the substrate utilizing an angled, off focus set
up 61 (Fig.
7). All of the guns were positioned in a delivery plane parallel to and
vertically
spaced about 15 cm from the delivery area. Further, each gun was positioned to
have
a delivery angle a of about 45° and a horizontal spacing 53 of about 18
cm. The
substrate 18 was a substantially circular disk of silicon wafer material
having a
diameter of about 8 cm. Each of the plurality of predefined regions were sized
to
I S form a coating library having 66 predefined coatings. The coating material
included
2% polyethylmethyl acrylate (PEMA) in iso-propanol solvent mixed with an
organic
pigment. After deposition through a ternary or triangle mask (not shown) and
thermal
curing, a ternary coating library having 66 distinct compositions was
generated in a
few minutes. The coating was about 2 microns in thickness, and the coating
thickness
scales linearly with the coating time.
Referring.to Figs. 12-14, in another embodiment, a combinatorial
coating system 72 includes a plurality of co-focused or simultaneously focused
delivery mechanisms 12 each fixedly positioned to simultaneously or
sequentially
deliver one of the plurality of materials 14 to the substrate 18 through a
mask 32.
Each of the plurality of delivery mechanisms 12 produces a mist of atomized
material
within an envelope 40 (Fig. 3) that intersects with the surface 16 of the
substrate 18.
Each source 38 is preferably positioned in an angled, off focus set up 61
(Fig. 7).
Preferably, each delivery mechanism 12 is equally spaced about a circle 74
having a
center 76 on the same axis 78 as center point 44. Further, each delivery
mechanism
12 preferably has a horizontal spacing 53 (Fig. 7) radially from the center 76
a
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distance less than the distance from the center point 44 to the edge of the
delivery area
24. Preferably, the point of focus 42 (not shown) of each delivery mechanism
12 is
focused a substantially equivalent offset distance 59 (Fig. 7) from the center
point 44,
thereby positioning the same portion of the thickness profile 48 (Fig. 7) for
each
material in the delivery area 24. However, the point of focus 42 for each
delivery
mechanism 12 is not required to be offset from the center point 44 or to have
equivalent offset distances 53. In fact, each delivery mechanism 12 may have a
unique point of focus 42, including one that results in the centerline 46
(Fig. 3) being
normal or angled relative to the surface 16 while the delivery mechanism is in
line
with or radially spaced away from the center point 44, as long as the envelope
40
(Fig. 3) of the delivered material 14 coincides with at least a portion of the
delivery
area 24, and hence the surface 16 of the substrate 18. Further, the delivery
mechanisms 12 need not be positioned about a circle, but may be in any
relative
position that allows the parallel or simultaneous delivery of a plurality of
materials 14
to at least a portion of the delivery area 24.
The mask 32 preferably comprises a plurality of patterns 80 (Fig. 13),
which may be moved in and out of the line of delivery of the materials 14 in
order to
control the coating of different predefined regions 22 (Fig. 2) with different
materials
to form a coating library 82 (Fig. 13). Although depicted in Fig. 12 as being
spaced
apart from substrate 18, preferably the mask is a physical contact mask that
is
touching or in close proximity to the substrate to eliminate shadowing. For
example,
refernng to Fig. 14, the system 72 may produce a coating library 82 having
sixteen
predefined coatings 30 using four (A, B, C and D) of the plurality of
materials 14 in
combination with the first four patterns 80 of the mask 32 (Fig. 13).
In a working example of the system 72, each delivery mechanism 12 is
a sprayer nozzle that atomizes a liquid precursor material 14 into a fine
spray and
directs it individually or in combination with other nozzles/materials to the
substrate
18 to make a coating layer. Compressed air, superheated steam, or an
ultrasonic wave
may be applied to the liquid material to generate the fme mist of the liquid
material.
A coating library 82 having multiple coating layers may be developed by
sequencing
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the delivery of the materials 14 from the plurality of sprayers 12 in
combination with
a sequence of masking patterns and curing steps (if necessary) to provide a
predetermined coating 30 in a predefined region 22 (Fig. 2) of the substrate.
This
may be desirable, for instance, when searching for a coating having multi-
functional
properties where each one or a combination of the coating layers provides at
least one
of the functional properties. In this particular example, which should not be
construed as limiting, eight different liquid coatings (A-H) are fed to eight
individually controlled spray guns. For example, suitable liquid coating
materials
include polyacrylides, polycarbonates, vinyl polymer, silicones, and silica
gel.
Further, for example, suitable spray guns include those manufactured by
SonoTech.
If the materials require curing, then suitable examples of a curing source 34
(Fig. 1)
include a hot plate and a UV lamp capable of curing the materials at
temperatures of
about 80 to about 200, and more preferably about 100 to about 150, for time
periods
of about 10 min to about 10 hours, and more preferably about 1 hour about 4
hours.
Thus, a coating library having a plurality of predefined mufti-layer coatings
is made
in a parallel fashion, either by combining different masking patterns with
different
liquid precursor materials, or by a maskless "continuous phase spreading" of
the
materials, taking advantage of the variation in spacing and volume of the
liquid
precursor material being delivered from each sprayer nozzle to form the
coating
library.
Refernng to Fig. 15, in another embodiment, a vapor deposition
combinatorial coating system 90 includes multiple delivery mechanisms 12 each
co-
focused, or simultaneously focused, for simultaneously or sequentially
delivering one
of a plurality of solid materials 14 to the substrate 18 positioned on a
movable stage
92 within a deposition housing 94. To withstand the high temperature of vapor
deposition, the substrate comprises a stable high temperature material such as
magnesium oxide or lanthanum aluminate (LaAl03). The deposition housing 94 is
sealable to form a vacuum chamber 96 within its interior surfaces. In this
case, the
delivery mechanisms 12 are vapor deposition devices, such as sputter guns
powered
by RF power, preferably matched for optimum output. The stage 92 supports the
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substrate 18 in a known position, where the stage may adjust vertically,
rotationally or
linearly to position the substrate within the delivery area. Positioned
between the
delivery mechanisms 12 and the substrate 18 is a mask 32 having an array of
different
patterns 80. The mask 32 is preferably substantially in contact with the
substrate 18
during vapor deposition, to minimize the "shadowing effect." The mask 32 is
movably positioned within a vacuum chamber 98 of a mask housing 100. The mask
housing 100 is in communication with the main housing 94 in a manner to
maintain
the atmosphere of both vacuum chambers 96 and 98. Further, the mask housing
100
includes a gear box 102 and micrometer 104 for moving and measuring,
respectively,
the position of the mask patterns 80 with respect to the substrate 18.
Further, the system 90 may optionally may include a shutter 106
having one or more apertures 108 to select one or more materials for
simultaneous or
sequential delivery and prevent intermixing of materials. The shutter 106 is
movably
connected to a rotor 110 that rotates the shutter and aperture 108 to select
the solid
material 14 to vaporize, while the mask pattern 80 is changed in-vacu with
linear
motion vacuum feed-through. The quantity of deposition of the materials 14 'is
monitored with a thickness monitoring device 112, such as a quartz crystal
oscillator.
By vapor deposition of different solid precursors through different patterns
of masks,
a substrate with more than 100 different coating composition/layer structures
can be
fabricated in a day without need to break vacuum to change solid materials
and/or
mask patterns.
The vacuum atmosphere within the vacuum chambers 96 and 98 are
maintained by a back-pump station 114 connected to a turbo-molecular pump 116.
For example, the back-pump station 114 may provide a vacuum of about 10-3
torr,
while the turbo-molecular pump 1 l6may provide a vacuum of 10-6 torr. The
pumps
114 and 116 are in communication with the vacuum chamber 96 through a gate
valve
118.
For example, this system 90 may generate coating libraries of any
ceramic, metallic and/or semiconductor materials, with surface roughness and
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accuracy of thickness measured in nanometers. Besides the sputter devices
described
above, other suitable delivery mechanisms 12 include laser ablation, electron
beam
evaporation, CVD, etc., that may be used with the masking system to generate
inorganic coating libraries. To fabricate an organic coating library, a co-
focusing
multiple source thermal evaporation apparatus coupled with a masking system
may be
set up. The same system may be utilized to fabricate small molecule libraries
such as
for use in organic light emitting diode ("LED") devices.
It is apparent that there has been provided in accordance with this
invention, a combinatorial coating system and method. While the invention has
been
, particularly shown and described in conjunction with preferred embodiments
thereof,
it will be appreciated that variations and modifications can be effected by a
person of
ordinary skill in the art without departing from the scope of the invention.
Further, it
is to be understood that the principles of the positioning of the delivery
mechanisms
and the delivery of the materials to form the coating thickness profiles
described
herein apply in a similar manner, where applicable, to all embodiments.
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