U.S. patent application number 12/139391 was filed with the patent office on 2008-12-18 for method and apparatus for depositing films.
This patent application is currently assigned to MASSACHUSETTS INSTITUTE OF TECHNOLOGY. Invention is credited to Vladimir Bulovic, Jianglong Chen, Conor Francis Madigan, Martin A. Schmidt.
Application Number | 20080311307 12/139391 |
Document ID | / |
Family ID | 40131159 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080311307 |
Kind Code |
A1 |
Bulovic; Vladimir ; et
al. |
December 18, 2008 |
METHOD AND APPARATUS FOR DEPOSITING FILMS
Abstract
The disclosure relates to a method for depositing films on a
substrate which may form part of an LED or other types of display.
In one embodiment, the disclosure relates to an apparatus for
depositing ink on a substrate. The apparatus includes a chamber for
receiving ink; a discharge nozzle having an inlet port and an
outlet port, the discharge nozzle receiving a quantity of ink from
the chamber at the inlet port and dispensing the quantity of ink
from the outlet port; and a dispenser for metering the quantity of
ink from the chamber to the inlet port of the discharge nozzle;
wherein the chamber receives ink in liquid form having a plurality
of suspended particles and the quantity of ink is pulsatingly
metered from the chamber to the discharge nozzle; and the discharge
nozzle evaporates the carrier liquid and deposits the solid
particles on the substrate.
Inventors: |
Bulovic; Vladimir;
(Lexington, MA) ; Chen; Jianglong; (Quincy,
MA) ; Madigan; Conor Francis; (San Francisco, CA)
; Schmidt; Martin A.; (Reading, MA) |
Correspondence
Address: |
Dianoosh Salehi;SNELL & WILMER L.L.P.
Suite 1400, 600 Anton Boulevard
Costa Mesa
CA
92626-7689
US
|
Assignee: |
MASSACHUSETTS INSTITUTE OF
TECHNOLOGY
Cambridge
MA
|
Family ID: |
40131159 |
Appl. No.: |
12/139391 |
Filed: |
June 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60944000 |
Jun 14, 2007 |
|
|
|
Current U.S.
Class: |
427/466 ;
347/47 |
Current CPC
Class: |
B41J 2/14 20130101; B05B
17/0638 20130101; B41J 2202/09 20130101; B41J 2/04581 20130101;
B41J 2202/16 20130101; B41J 2/04588 20130101; B41J 2/07 20130101;
H01L 51/56 20130101; H01L 51/0005 20130101; H05B 33/10
20130101 |
Class at
Publication: |
427/466 ;
347/47 |
International
Class: |
B05D 1/32 20060101
B05D001/32; B41J 2/14 20060101 B41J002/14 |
Claims
1. An apparatus for depositing ink on a substrate, the apparatus
comprising: a chamber for receiving ink; a discharge nozzle having
an inlet port and an outlet port, the discharge nozzle receiving a
quantity of ink from the chamber at the inlet port and dispensing
the quantity of ink from the outlet port; and a dispenser for
metering the quantity of ink from the chamber to the inlet port of
the discharge nozzle; wherein the chamber receives ink in liquid
form having a plurality of suspended particles and the quantity of
ink is pulsatingly metered from the chamber to the discharge
nozzle; and the discharge nozzle evaporates the carrier liquid and
deposits the substantially solid particles on the substrate.
2. The apparatus of claim 1, further comprising a housing for
receiving the chamber and the discharge nozzle.
3. The apparatus of claim 1, wherein the housing defines a conduit
between the chamber and the discharge nozzle.
4. The apparatus of claim 1, further comprising a duct for
introducing gas into the housing.
5. The apparatus of claim 1, further comprising an ink reservoir in
fluid communication with the chamber.
6. The apparatus of claim 1, wherein the dispenser further
comprises a heater for metering the quantity of ink.
7. The apparatus of claim 1, wherein the dispenser further
comprises a piezoelectric element for metering the quantity of
ink.
8. The apparatus of claim 1, wherein the dispenser meters a
quantity of liquid ink by delivering a pulse of energy at a first
frequency.
9. The apparatus of claim 1, wherein the discharge nozzle further
comprises a plurality of conduits spanning from the inlet port to
the outlet port, the plurality of conduits receiving ink in liquid
form at the inlet port and dispensing the plurality of particles
from the outlet port in substantially solid form.
10. The apparatus of claim 1, wherein the discharge nozzle further
comprises a plurality of conduits separated by a plurality of
partitions, each conduit having an opening surface area W which
holds the relationship 1/20,000<W/D<1/4, wherein D is the
inlet port surface area of the discharge nozzle.
11. A method for depositing ink on a substrate, the method
comprising: using a pulsating energy having a first frequency to
meter a quantity of ink to a discharge nozzle, the ink defined by a
plurality of solid particles in a carrier liquid; receiving the
metered quantity of ink at the discharge nozzle and evaporating the
carrier liquid from the metered quantity of ink to provide a
quantity of substantially solid ink particles; dispensing the
substantially solid ink particles from the discharge nozzle and
depositing the substantially solid ink particles on the substrate;
and wherein at least a portion of the substantially solid ink
particles are converted to a vapor phase during discharge from the
discharge nozzle, directed to the substrate as a vapor, and
condense on a surface of the substrate in substantially solid
form.
12. The method of claim 11, wherein the step of using the pulsating
energy to meter the quantity of ink further comprises heating the
quantity of ink with a plurality of heat pulses.
13. The method of claim 11, wherein the step of using the pulsating
energy to meter the quantity of ink further comprises activating a
piezoelectric element to meter the quantity of ink.
14. The method of claim 13, wherein the piezoelectric element is
activated by providing a pulse of energy at a first frequency.
15. The method of claim 11, wherein the step of dispensing the
substantially solid ink particles from the discharge nozzle further
comprises providing a plurality of conduits spanning from an inlet
port of the discharge nozzle to an outlet port of the discharge
nozzle, the plurality of conduits receiving the plurality of solid
particles and the carrier liquid at the inlet port and heating the
ink to be dispensed from the output port in substantially solid
form.
16. The method of claim 11, wherein the step of dispensing the
quantity of ink from the discharge nozzle in substantially solid
form further comprises providing a discharge nozzle having a
plurality of conduits separated by a plurality of partitions, each
conduit having an opening surface area W which holds the
relationship 1/20,000<W/D<1/4, wherein D is the inlet port
surface area of the discharge nozzle.
17. The method of claim 11, wherein the solid ink particles are
substantially solvent free.
18. A method for depositing ink on a substrate, the method
comprising: providing liquid ink to a chamber, the liquid ink
defined by a plurality of suspended particles in a carrier liquid;
pulsatingly energizing a dispenser to meter a quantity of liquid
ink from the chamber to a discharge nozzle, the quantity of liquid
ink metered as a function of a frequency of at least one of a pulse
amplitude, a pulse duration or a pulse frequency; receiving the
metered quantity of ink at a discharge nozzle, the discharge nozzle
having a plurality of conduits for directing the metered quantity
of ink; heating the metered quantity of ink at the plurality of
conduits to evaporate the carrier liquid; and discharging the
plurality of suspended particles from the discharge nozzle onto the
substrate; wherein the plurality of suspended particles are
deposited on the substrate in substantially solid form.
19. The method of claim 18, wherein the step of pulsatingly
energizing the dispenser results in heating the chamber with a
plurality of energy bursts.
20. The method of claim 18, wherein the step of pulsatingly
energizing the dispenser further comprises energizing a
piezoelectric element.
21. The method of claim 18, wherein the step of providing liquid
ink to the chamber further comprises supplying ink from a reservoir
to the chamber.
22. The method of claim 18, wherein the step of receiving the
metered quantity of ink at the discharge nozzle further comprises
receiving the metered quantity of ink at an inlet to the conduit,
transporting the metered quantity of ink through the conduit and
substantially evaporating the carrier liquid as the metered
quantity of ink is transported through the conduit.
23. The method of claim 18, wherein the step of discharging the
plurality of suspended particles from the discharge nozzle further
comprises selectively heating the discharge nozzle to discharge the
suspended particles.
24. The method of claim 23, wherein the step of heating the
discharge nozzle further comprises pulsatingly heating the
discharge nozzle.
25. The method of claim 18, wherein the step of discharging the
plurality of suspended particles further comprises using a
piezoelectric effect on the discharge nozzle to deposit the
suspended particles onto the substrate.
26. The method of claim 25, wherein using the piezoelectric effect
further comprises mechanically stressing the discharge nozzle.
27. The method of claim 18, wherein the step of pulsatingly
energizing the dispenser further comprises controlling the quantity
of dispensed ink by controlling at least one of duration,
intensity, or frequency of the pulse energy.
Description
[0001] The instant application claims priority to Provisional
Application No. 60/944,000 entitled "METHOD AND APPARATUS FOR
DEPOSITING FILMS," filed Jun. 14, 2007, which is incorporated
herein by reference in its entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The disclosure relates to a method and apparatus for
efficiently depositing patterns of films on a substrate. More
specifically, the disclosure relates to a method and apparatus for
depositing films on a substrate which may form part of an LED or
other types of display.
[0004] 2. Description of Related Art
[0005] The manufacture of organic light emitting devices (OLEDs)
requires depositing one or more organic films on a substrate and
coupling the top and bottom of the film stack to electrodes. The
film thickness is a prime consideration. The total layer stack
thickness is about 100 nm and each layer is optimally deposited
uniformly with an accuracy of better than .+-.1 nm. Film purity is
also important. Conventional apparatuses form the film stack using
one of two methods: (1) thermal evaporation of organic material in
a relative vacuum environment and subsequent condensation of the
organic vapor on the substrate; or, (2) dissolution of organic
material into a solvent, coating the substrate with the resulting
solution, and subsequent removal of the solvent.
[0006] Another consideration in depositing the organic thin films
of an OLED is placing the films precisely at the desired location.
There are two conventional technologies for performing this task,
depending on the method of film deposition. For thermal
evaporation, shadow masking is used to form OLED films of a desired
configuration. Shadow masking techniques require placing a
well-defined mask over a region of the substrate followed by
depositing the film over the entire substrate area. Once deposition
is complete, the shadow mask is removed. The regions exposed
through the mask define the pattern of material deposited on the
substrate. This process is inefficient, as the entire substrate
must be coated, even though only the regions exposed through the
shadow mask require a film. Furthermore, the shadow mask becomes
increasingly coated with each use, and must eventually be discarded
or cleaned. Finally, the use of shadow masks over large areas is
made difficult by the need to use very thin masks (to achieve small
feature sizes) that make said masks structurally unstable. However,
the vapor deposition technique yields OLED films with high
uniformity and purity and excellent thickness control.
[0007] For solvent deposition, ink jet printing can be used to
deposit patterns of OLED films. Ink jet printing requires
dissolving organic material into a solvent that yields a printable
ink. Furthermore, ink jet printing is conventionally limited to the
use of single layer OLED film stacks, which typically have lower
performance as compared to multilayer stacks. The single-layer
limitation arises because printing typically causes destructive
dissolution of any underlying organic layers. Finally, unless the
substrate is first prepared to define the regions into which the
ink is to be deposited, a step that increases the cost and
complexity of the process, ink jet printing is limited to circular
deposited areas with poor thickness uniformity as compared to vapor
deposited films. The material quality is also typically lower, due
to structural changes in the material that occur during the drying
process and due to material impurities present in the ink. However,
the ink jet printing technique is capable of providing patterns of
OLED films over very large areas with good material efficiency.
[0008] No conventional technique combines the large area patterning
capabilities of ink jet printing with the high uniformity, purity,
and thickness control achieved with vapor deposition for organic
thin films. Because ink jet processed single layer OLED devices
continue to have inadequate quality for widespread
commercialization, and thermal evaporation remains impractical for
scaling to large areas, it is a major technological challenge for
the OLED industry to develop a technique that can offer both high
film quality and cost-effective large area scalability.
[0009] Finally, manufacturing OLED displays may also require the
patterned deposition of thin films of metals, inorganic
semiconductors, and/or inorganic insulators. Conventionally, vapor
deposition and/or sputtering have been used to deposit these
layers. Patterning is accomplished using prior substrate
preparation (e.g., patterned coating with an insulator), shadow
masking as described above, and when a fresh substrate or
protective layers are employed, conventional photolithography. Each
of these approaches is inefficient as compared to the direct
deposition of the desired pattern, either because it wastes
material or requires additional processing steps. Thus, there is a
need for these materials as well for a method and apparatus for
depositing high-quality, cost effective, large area scalable
films.
SUMMARY
[0010] In one embodiment, the disclosure is directed to an
apparatus for depositing ink on a substrate, the apparatus
comprising: a chamber for receiving ink; a discharge nozzle having
an inlet port and an outlet port, the discharge nozzle receiving a
quantity of ink from the chamber at the inlet port and dispensing
the quantity of ink from the outlet port; and a dispenser for
metering the quantity of ink from the chamber to the inlet port of
the discharge nozzle; wherein the chamber receives ink in liquid
form having a plurality of suspended particles and the quantity of
ink is pulsatingly metered from the chamber to the discharge
nozzle; and the discharge nozzle evaporates the carrier liquid and
deposits the substantially solid particles on the substrate.
[0011] In another embodiment, the disclosure relates to a method
for depositing ink on a substrate, the method comprising: using a
pulsating energy having a first frequency to meter a quantity of
ink to a discharge nozzle, the ink defined by a plurality of solid
particles in a carrier liquid; receiving the metered quantity of
ink at the discharge nozzle and evaporating the carrier liquid from
the metered quantity of ink to provide a quantity of substantially
solid ink particles; dispensing the substantially solid ink
particles from the discharge nozzle and depositing the
substantially solid ink particles on the substrate; and wherein at
least a portion of the substantially solid ink particles are
converted to a vapor phase during discharge from the discharge
nozzle, directed to the substrate as a vapor, and condense on a
surface of the substrate in substantially solid form.
[0012] In still another embodiment, the disclosure relates to a
method for depositing ink on a substrate, the method comprising:
providing liquid ink to a chamber, the liquid ink defined by a
plurality of suspended particles in a carrier liquid; pulsatingly
energizing a dispenser to meter a quantity of liquid ink from the
chamber to a discharge nozzle, the quantity of liquid ink metered
as a function of a frequency of at least one of a pulse amplitude,
a pulse duration or a pulse frequency; receiving the metered
quantity of ink at a discharge nozzle, the discharge nozzle having
a plurality of conduits for directing the metered quantity of ink;
heating the metered quantity of ink at the plurality of conduits to
evaporate the carrier liquid; and discharging the plurality of
suspended particles from the discharge nozzle onto the substrate;
wherein the plurality of suspended particles are deposited on the
substrate in substantially solid form.
[0013] In still another embodiment, the disclosure relates to a
system for depositing ink on a substrate, the system comprising: a
chamber having a quantity of ink, the ink defined by a plurality of
suspended ink particles in a carrier liquid; a discharge nozzle
proximal to the chamber for receiving a metered quantity of ink
pulsatingly delivered from the chamber by a dispenser, the
discharge nozzle evaporating the carrier liquid to form a
substantially solid quantity of ink particles; and a controller in
communication with the discharge nozzle, the controller energizing
the discharge nozzle to communicate the substantially solid
quantity of ink particles from the discharge nozzle onto the
substrate.
[0014] In still another embodiment, the disclosure relates to a
system for depositing ink on a substrate, the system comprising: a
chamber for receiving a quantity of ink, the ink having a plurality
of suspended particles in a carrier liquid; an ink dispenser for
pulsatingly metering a quantity of ink delivered from the chamber;
a discharge nozzle for receiving a metered quantity of ink
delivered from the chamber and evaporating the carrier liquid from
the received quantity of ink to form a substantially solid quantity
of particles; a first controller in communication with the ink
dispenser, the first controller pulsatingly energizing the
dispenser to meter a quantity of ink delivered from the chamber;
and a second controller in communication with the discharge nozzle,
the second controller energizing the discharge nozzle to
communicate the metered quantity of particles from the discharge
nozzle onto the substrate.
[0015] In still another embodiment, the disclosure relates to a
method for providing accurate deposition of ink on a substrate, the
method comprising: providing a quantity of ink to a chamber, the
ink having a plurality of suspended particles in a carrier liquid;
metering at least a portion of the ink delivered from the chamber
to an inlet of a discharge nozzle by activating a dispenser;
receiving the metered ink at a discharge nozzle, the discharge
nozzle having an inlet port and an outlet port; transporting the
metered ink from the inlet port to the outlet port of the discharge
nozzle forming substantially solid particles; and depositing the
substantially solid particles from the outlet port of the discharge
nozzle onto a substrate by energizing the discharge nozzle to
pulsatingly eject at least a portion of the substantially solid
particles onto the substrate.
[0016] In yet another embodiment, the disclosure relates to a
system for accurate deposition of ink on a substrate, the system
comprising: a storage means for storing a composition of ink
particles in a carrier liquid; a metering means in communication
with the storage means to pulsatingly meter at least a portion of
the composition; a transporting means for transporting the ink from
the chamber to a discharge nozzle; an evaporating means for
evaporating the carrier liquid to form a substantially solid
quantity of ink particles at the discharge nozzle; and a
discharging means for discharging the substantially solid ink
particles from the discharge nozzle onto a substrate.
[0017] In still another embodiment, the disclosure relates to an
apparatus for depositing particles on a substrate, the apparatus
comprising: a chamber for receiving ink, the chamber receiving ink
in liquid form having a plurality of particles in a carrier liquid;
a dispenser associated with the chamber, the dispenser metering a
quantity of ink delivered from the chamber to a discharge nozzle,
the discharge nozzle evaporating the carrier liquid to form a
substantially solid quantity of ink particles; wherein the
discharge nozzle rotates axially relative to the chamber to
discharge the substantially solid quantity of ink particles; and
wherein the discharge nozzles deposits the substantially solid
particles onto a substrate.
[0018] In still another embodiment, the disclosure relates to a
system for controlling a printing device, the system comprising: a
first controller having a first processor circuit in communication
with a first memory circuit, the first memory circuit containing
instructions for directing the first processor to: identify a
plurality of chambers, each chamber receiving liquid ink having a
plurality of dissolved or suspended particles in a carrier liquid,
engage each of the plurality of chambers to meter a quantity of
liquid ink for dispensing; a second controller having a second
processor circuit in communication with a second memory circuit,
the second memory circuit containing instructions for directing the
second processor to: identify a plurality of discharge nozzles,
each of the plurality of discharge nozzles receiving the quantity
of liquid from a corresponding one of the plurality of chambers,
activate each of the plurality of the discharge nozzles to
evaporate at least a part of the carrier liquid, direct each of the
plurality of discharge nozzles to deposit substantially solid ink
particles onto a substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] These and other embodiments of the disclosure will be
discussed with reference to the following non-limiting and
exemplary illustrations, in which like elements are numbered
similarly, and where:
[0020] FIG. 1A is a schematic representation of an exemplary
print-head having a thermal ink dispensing mechanism according to
one embodiment of the disclosure;
[0021] FIG. 1B is a schematic representation of an exemplary
print-head having a piezo-electric ink dispensing mechanism
according to one embodiment of the disclosure;
[0022] FIG. 1C is a schematic representation of an exemplary
print-head having physically separated chamber housing and
discharge nozzle housing portions according to one embodiment of
the disclosure;
[0023] FIG. 1D is a schematic representation of an exemplary
print-head having physically separated chamber housing and
discharge nozzle housing portions, and isolation space between the
discharge nozzle and the associated housing, according to one
embodiment of the disclosure;
[0024] FIG. 1E shows a top view of an exemplary implementation of
the discharge nozzle;
[0025] FIGS. 2A-2D schematically illustrate the process of
depositing a solvent-free material using a print-head apparatus
according to an embodiment of the disclosure;
[0026] FIG. 3A schematically illustrates a print-head apparatus
having multiple discharge nozzles and using thermal ink dispensing
elements;
[0027] FIG. 3B schematically illustrates a print-head apparatus
having multiple discharge nozzles and using piezoelectric ink
dispensing elements;
[0028] FIG. 4 is a schematic representation of a print-head
apparatus with multiple reservoirs;
[0029] FIG. 5 schematically illustrates an apparatus for depositing
thin films of material using one or more print-heads, at least one
of which having one or more discharge nozzles, and a positioning
system;
[0030] FIG. 6 schematically illustrates a micro-porous discharge
nozzle having micro-pores with tapered sidewalls;
[0031] FIG. 7 shows exemplary micro-pore patterns for use in a
micro-porous discharge nozzle;
[0032] FIGS. 8A and 8B (collectively, FIG. 8) schematically
illustrate a dye sublimation printer in accordance with one
embodiment of the disclosure;
[0033] FIGS. 9A and 9B illustrate the use of the discharge
apparatus for spatially localized chemical synthesis;
[0034] FIGS. 9C and 9D depict the use of a discharge apparatus as a
micro reactor;
[0035] FIG. 10A is a schematic representation of an exemplary
print-head in accordance with an embodiment of the disclosure;
[0036] FIGS. 10B-10E illustrate a method for depositing a film
using the print-head shown in FIG. 10A;
[0037] FIG. 11A schematically illustrates a thermally activated
print-head according to one embodiment of the disclosure;
[0038] FIGS. 11B-11E illustrate a method for depositing a film
using the print-head apparatus shown in FIG. 11A;
[0039] FIG. 12 illustrates a method for depositing particles on a
substrate according to one embodiment of the disclosure; and
[0040] FIG. 13 is a schematic representation of a control system
for controlling a print-head having a discharge nozzle, according
to one embodiment of the disclosure.
DETAILED DESCRIPTION
[0041] In one embodiment, the disclosure relates to a method and
apparatus for depositing a film in substantially solid form on a
substrate. Such films can be used, for example, in the design and
construction of OLEDs and large area transistor circuits. In one
embodiment, the disclosure relates to a method and apparatus for
depositing a film of material in substantially solid form on a
substrate. In another embodiment, the disclosure relates to a
method and apparatus for depositing a film of material
substantially free of solvent of a substrate. Such films can be
used, for example, in the design and construction of OLEDs and
large area transistor circuits. The materials that may be deposited
by the apparatuses and methods described herein include organic
materials, metal materials, and inorganic semiconductors and
insulators, such as inorganic oxides, chalcogenides, Group IV
semiconductors, Group III-V compound semiconductors, and Group
II-VI semiconductors.
[0042] FIG. 1A is a schematic representation of an apparatus for
depositing material according to one embodiment of the disclosure.
Namely, FIG. 1A provides a schematic representation of a thermal
jet print-head according to one embodiment of the disclosure.
[0043] Referring to FIG. 1A, the exemplary apparatus for depositing
a material on a substrate comprises chamber 130, orifice 170,
nozzle 180, and micro-porous conduits 160. Chamber 130 receives ink
in liquid form and communicates the ink from orifice 170 to
discharge nozzle 180. The ink can comprise suspended or dissolved
particles in a carrier liquid. These particles can comprise single
molecules or atoms, or aggregations of molecules and/or atoms. The
path between orifice 170 and discharge chamber 180 defines a
delivery path. In the embodiment of FIG. 1A, discharge nozzle 180
comprises conduits 160 separated by partitions 165. Conduits 160
may include micro-porous material therein. A surface of discharge
nozzle 180 proximal to orifice 170 defines the inlet port to
discharge nozzle 180 while the distal surface of discharge nozzle
180 defines the outlet port. A substrate (not shown) can be
positioned proximal to the outlet port of discharge nozzle 180 for
receiving ink deposited from the nozzle.
[0044] The thermal jet print-head of FIG. 1 further includes bottom
structure 140, which receives discharge nozzle 180. Discharge
nozzle 180 can be fabricated as part of the bottom structure 140.
Alternatively, discharge nozzle 180 can be manufactured separately
and later combined with bottom structure 140 to form an integrated
structure. Top structure 142 receives chamber 130. Top structure
142 can be formed with appropriate cavities and conduits to form
chamber 130. Top structure 142 and bottom structure 140 are coupled
through bonds 120 to form a housing. The housing allows the thermal
jet print-head to operate under pressure or in vacuum. The housing
may further comprise an inlet port (not shown) for accepting a
transport gas for carrying the material from the discharge nozzle
to the substrate (not shown). Alternatively, a port (not shown) can
be integrated into top structure 142 to receive transport gases.
The port can include a flange adapted to receive a transport gas,
which according to one embodiment comprises a substantially inert
mixture of one or more gases. The mixture can include gases which
are substantially non-reactive with the materials being deposited
by the apparatus, such as nitrogen or argon when used with typical
organic materials. The transport gas can transport particles from
discharge nozzle 180 by flowing through micro-pores 160.
[0045] A heater 110 can be added optionally to chamber 130 for
heating and/or dispensing the ink. In FIG. 1A, heater 110 is
positioned inside chamber 130. Heater 110 can be any thermal energy
source coupled to chamber 130 for providing pulsating energy to the
liquid ink and thereby discharge a droplet of the liquid ink
through orifice 170. In one embodiment, heater 110 delivers heat in
pulses having a duration of one minute or less. For instance, the
heater can be energized with square pulses having a variable duty
cycle and a cycle frequency of 1 kHz. Thus, the heater energy can
be used to meter the quantity of ink delivered from chamber 130 to
discharge nozzle 180. Chamber 130 may also contain material, other
than ink, required for forming a film used in the fabrication of an
OLED or transistor. Orifice 170 can be configured such that surface
tension of the liquid in chamber 130 prevents discharge of the
liquid prior to activation of the mechanism for dispensing the
ink.
[0046] In the embodiment of FIG. 1A, discharge nozzle 180 includes
partitions (or rigid portions) 165 separated by conduits 160.
Conduits 160 and rigid portions 165 can collectively define a micro
porous environment. The micro-porous environment can be composed of
a variety of materials, including, micro-porous alumina or solid
membranes of silicon or silicon carbide and having micro-fabricated
pores. Micro-pores 160 prevent the material dissolved or suspended
in the liquid from escaping through discharge nozzle 180 until the
medium is appropriately activated. When the discharged droplet of
liquid encounters discharge nozzle 180, the liquid is drawn into
micro-pores 160 with assistance from capillary action. The liquid
in the ink may evaporate prior to activation of discharge nozzle
180, leaving behind a coating of the suspended or dissolved
particles on the micro-pore walls. The liquid in the ink may
comprise one or more solvents with a relatively-low vapor pressure.
The liquid in the ink may also comprise one or move solvents with a
relatively-high vapor pressure.
[0047] The evaporation of the liquid in the ink may be accelerated
by heating the discharge nozzle. The evaporated liquid can be
removed from the chamber and subsequently collected (not shown),
for instance, by flowing gas over one or more of the discharge
nozzle faces. Depending on the desired application, micro-pores 160
can provide conduits (or passages) having a maximum linear
cross-sectional distance W of a few nanometers to hundreds of
microns. The micro-porous region comprising discharge nozzle 180
will take a different a shape and cover a different area depending
on the desired application, with a typical maximum linear
cross-sectional dimension D ranging from a few hundred nanometers
to tens of millimeters. In one embodiment, the ratio of W/D is in a
range of about 1/10 to about 1/1000.
[0048] In the exemplary apparatus of FIG. 1A, discharge nozzle 180
is actuated by nozzle heater 150. Nozzle heater 150 is positioned
proximal to discharge nozzle 180. Nozzle heater 150 may comprise a
thin metal film. The thin metal film can be comprised of, for
example, platinum. When activated, nozzle heater 150 provides
pulsating thermal energy to discharge nozzle 180, which acts to
dislodge the material contained within micro-pores or conduits 160,
which can subsequently flow out from the discharge nozzle. In one
embodiment, the pulsations can be variable on a time scale of one
minute or less.
[0049] Dislodging the ink particles may include vaporization,
either through sublimation or melting and subsequent boiling. It
should be noted again that the term particles is used generally,
and includes anything from a single molecule or atom to a cluster
of molecules or atoms. In general, one can employ any energy source
coupled to the discharge nozzle that is capable of energizing
discharge nozzle 180 and thereby discharging the material from
micro-pores 160; for instance, mechanical (e.g., vibrational). In
one embodiment of the disclosure, a piezoelectric material is used
instead of, or in addition to, nozzle heaters 150.
[0050] FIG. 1B is a schematic representation of an apparatus for
depositing a film according to one embodiment of the disclosure.
Referring to FIG. 1B, the exemplary apparatus for depositing a
material on a substrate is similar to the embodiment of FIG. 1A,
except chamber 130 is shaped differently, and the ink is dispensed
by pulsatingly activating piezoelectric element 115. When
activated, piezoelectric elements 115 pulsate to discharge a
droplet of the liquid contained within chamber 130 through orifice
170 toward discharge nozzle 180. Thus, chamber heater 110 can be
replaced by piezoelectric elements 115. While not shown in FIG. 1B,
the piezoelectric elements can be used in addition to or in
combination with a chamber heater.
[0051] FIG. 1C is a schematic representation of an apparatus for
depositing a film according to another embodiment of the
disclosure. Referring to FIG. 1C, the exemplary apparatus for
depositing a material on a substrate comprises similar elements as
in FIG. 1B except bonds 120 are removed to illustrate that top
structure 142 and bottom structure 140 can be structurally distinct
components. In the configuration of FIG. 1C, top structure 142 and
bottom structure 140 may be accessed and positioned independently,
as may be desirable when performing maintenance on the
apparatus.
[0052] FIG. 1D is a schematic representation of an apparatus for
depositing a film according to still another embodiment of the
disclosure. The exemplary apparatus of FIG. 1D comprises similar
elements as the apparatus of FIG. 1C except confining well 145 is
introduced. This structure mechanically confines ink, or any other
material, supplied to discharge nozzle 180 from ink chamber 130
through chamber orifice 170. This structure can enhance the
uniformity of the loading of ink into micro-pores 160 and can
correct for positioning errors in the placement of ink material
supplied to discharge nozzle 180 from ink chamber 130.
[0053] Another distinction in the embodiment of FIG. 1D is the
presence of connective regions 155. In each of FIGS. 1A to 1C,
discharge nozzle 180 was shown as integrated with the bottom
structure 140. In contrast, discharge nozzle 180 of FIG. 1D is
manufactured to achieve a physically distinct bottom structure 140
and discharge nozzle 180 with connective regions 155 comprising a
different material. Regions 155 are used to connect discharge
nozzle 180 to bottom structure 140. Connective regions 155 extend
beyond bottom structure 140 to leave opening 156. Opening 156 can
be adjusted depending on the size of the housing and the objectives
in physically separating 180 from 140. For instance, this
configuration can provide improved thermal isolation of discharge
nozzle 180 from the surrounding structure. FIG. 1D also shows
heater 150 extending beneath brackets 155 to reach discharge nozzle
180. It should be noted that heater 150 can be replaced augmented
by or replaced with a piezoelectric element or other
electromechanical means for delivering pulsating energy.
[0054] FIG. 1E is an image of a discharge nozzle 180, as part of an
apparatus for depositing a film on a substrate. In FIG. 1E,
discharge nozzle heater 150 is comprised of a thin platinum film on
a silicon housing 140. In the center of discharge nozzle 180 are
also shown discharge nozzle micro-pores corresponding to
micro-pores 160 indicated in prior figures.
[0055] FIGS. 2A-2D schematically show the process of depositing ink
on a substrate according to one embodiment of the disclosure. While
different films and material can be deposited using the embodiments
disclosed herein, in one embodiment, the ink is deposited in
substantially solid form. In FIG. 2A, ink 101 is commissioned to
chamber 130. Ink 101 can have a conventional composition. In one
embodiment, ink 101 is a liquid ink defined by a plurality of
particles in a carrier liquid. The carrier liquid can comprise one
or more solvents having a vapor pressure such that during the
transportation and deposition process the solvent is substantially
evaporated and the plurality of particles in the carrier liquid are
deposited as solid particles. Thus, the deposited plurality of
solid particles are deposited comprise a film on the substrate.
[0056] Referring again to FIG. 2A, chamber heater 110 comprises the
ink dispensing mechanism and pulsatingly imparts thermal energy
into ink 101. The thermal energy drives at least a portion of ink
liquid 101 through orifice 170 to form ink droplet 102. Ink droplet
102 can define all of, or a portion of liquid ink 101. The
pulsating impartment of energy from an energy source (e.g., heater
110) determines the quantity of ink to be metered out from chamber
130. Once droplet 102 is metered out of chamber 130, it is directed
to discharge nozzle 180.
[0057] In another exemplary embodiment, piezoelectric elements (not
shown) can be positioned at or near chamber 130 to meter out the
desired quantity of ink 101 through orifice 170, thereby forming
droplet 101. In yet another exemplary embodiment, liquid can be
streamed out of chamber 130 through orifice 170 (by, for instance,
maintaining a positive ink pressure) and this stream can be
pulsatingly interrupted by a mechanical or electrostatic force such
that metered droplets created from this stream and further directed
onto discharge nozzle 180. If a mechanical force is utilized, this
force can be provided by introducing a paddle (not shown) that
pulsatingly intersects the stream. If an electrostatic force is
utilized, this force can be provided by introducing a capacitor
(not shown) around the stream that pulsatingly applies an
electromagnetic field across the stream. Thus, any pulsating energy
source that activates a dispensing mechanism and thereby meters
liquid 102 delivered from chamber 130 through orifice 170 and to
discharge nozzle 180 can be utilized. The intensity and the
duration of each energy pulse can be defined by a controller (not
shown) which is discussed below. Furthermore, as noted above, this
metering can occur primarily when the ink is ejected from chamber
130 through orifice 170; alternatively, this metering can occur
primarily wile the ink is traveling from orifice 170 to discharge
nozzle 180.
[0058] As discussed in relation to FIGS. 1A-1E, discharge nozzle
180 includes conduits for receiving and transporting metered
droplet 102. Discharge nozzle heater 150 is placed proximal to
discharge nozzle 180 to heat the discharge nozzle. In an exemplary
embodiment (not shown), a heater is integrated with the discharge
nozzle such that partitions 165 define the heating elements.
[0059] Discharge nozzle 180 has a proximal surface (alternatively,
inlet port) 181 and a distal surface (alternatively, outlet port)
182. Proximal surface 181 and distal surface 182 are separated by a
plurality of partitions 160 and conduits 165. Proximal surface 181
faces chamber 130 and distal surface 182 faces substrate 190.
Nozzle heater 150 can be activated such that the temperature of
discharge nozzle 180 exceeds the ambient temperature which enables
rapid evaporation of the carrier liquid from droplet 102 which is
now lodged in conduits 160. Nozzle heater 150 may also be activated
prior to energizing the ink dispenser (and metering ink droplet 102
as it travels from chamber 130 through orifice 170 to discharge
nozzle 180) or after droplet 102 lands on discharge nozzle 180. In
other words, chamber heater 110 and discharge heater 150 can be
choreographed to pulsate simultaneously or sequentially.
[0060] In the next step of the process, liquid ink 103 (previously
droplet 102) is directed to inlet port 181 of discharge nozzle 180
between confining walls 145. Liquid ink 103 is then drawn through
conduits 160 toward outlet port 182. As discussed, conduits 160 can
comprise a plurality of micro-pores. Liquid in ink 103, which may
fill conduits 160 extends onto the surrounding surface, with the
extent of this extension controlled in part by the engineering of
confining walls 145, may evaporate prior to activation of discharge
nozzle 180, leaving behind on the micro-pore walls the particles
104 (FIG. 2C) that are substantially solid and which can be
deposited onto substrate 190. Alternatively, the carrier liquid in
ink 103 (FIG. 2B) may evaporate during activation of nozzle heater
150.
[0061] Activating nozzle heater 150 in FIG. 2C, provides pulsating
energy to discharge nozzle 180 and dislodges material 104 from
conduits 160. The result is shown in FIG. 2D. The intensity and the
duration of each energy pulse can be defined by a controller (not
shown.) The activating energy can be thermal energy. Alternatively,
any energy source directed to discharge nozzle 180 which is capable
of energizing discharge nozzle 180 to thereby discharge material
104 from conduits 160 (e.g., mechanical, vibrational, ultrasonic,
etc.) can be used. Deposited film 105 is thus deposited in solid
form substantially free of the carrier liquid present in ink 101
(FIG. 2A). That is, substantially all of the carrier liquid is
evaporated from ink 103 while it travels through discharge nozzle
180. The evaporated carrier liquid, which typically comprises a
mixture of one or more solvents, can be transported away from the
housing by one or more gas conduits (not shown).
[0062] Substrate 190 is positioned proximal to discharge nozzle 180
for receiving the dislodged material to form thin film 105.
Simultaneous with steps shown in FIGS. 2B-2D, chamber 130 is
provided with a new quantity of liquid ink 101 for the next
deposition cycle.
[0063] FIG. 3A illustrates a discharge array using a heating
element for depositing material. The apparatus of FIG. 3A, includes
chamber 330 for housing liquid 301. Liquid 301 can comprise
dissolved or suspended particles for deposition on a substrate.
Chamber 330 also includes a plurality of chamber orifices 370. The
embodiment of FIG. 3A comprises ink dispensing heaters 310 for
pulsatingly metering liquid ink through each chamber orifice 370
and towards discharge nozzles 380. Discharge nozzles 380 are
arranged in an array such that each discharge nozzle 380
communicates with a corresponding chamber orifice 370. Nozzle
heaters 350 are positioned near discharge nozzles 380 to evaporate
substantially all of the carrier liquid and to allow solid
particles to be deposited by the discharge nozzle array.
[0064] FIG. 3B illustrates a discharge array using a piezoelectric
element. Specifically, FIG. 3B shows piezoelectric ink dispensing
elements 315 that pulsatingly meter out liquid ink 301 through
chamber orifices 370 and toward discharge nozzles 380. In general,
any energy source capable of metering the ink can be used.
Discharge nozzles 380 are also provided with nozzle heaters 350.
While not shown in FIGS. 3A and 3B, liquid ink is delivered to
chamber 330 through one or more conduits in fluid communication
with an ink reservoir. Additionally, one or more gas conduits (not
shown) can be configured to remove any vaporized carrier liquid
from the housing. In operation, piezoelectric elements 315 are
energized in bursts or pulses. With each pulse of energy,
piezoelectric elements vibrate and dispense liquid ink 301 which is
held in place through its molecular forces and surface tension. The
duration of the pulse energizing piezoelectric elements 370 can
determine the quantity of liquid ink 370 which is metered out from
each chamber orifice 370. Thus, increasing the amplitude or the
duration of, for example, a square pulse, can increase the quantity
of the dispensed liquid ink. The viscosity or thixotropic
properties of the chosen ink will impact the pulse shape, amplitude
and duration for a metered quantity of ink to be delivered from
chamber 330 to discharge nozzle 380.
[0065] In FIGS. 3A and 3B, discharge nozzles 380 include
micro-porous openings, intervening rigid regions, and heaters 350.
The exemplary apparatus may also include a housing configured for
operation in a vacuum or a pressurized environment. The housing can
further include an inlet port for receiving a transport gas which
carries the material from the discharge nozzle 380 to the substrate
(not shown). The inlet port can be defined by a flange adapted to
receive a transport gas, which according to one embodiment
comprises a substantially inert mixture of one or more gases, such
as nitrogen or argon. Nitrogen and argon are particularly suitable
when depositing conventional organic materials. The transport gas
may also transport the ink from the discharge nozzles 380 by
flowing through the conduits or the micro-pores. It should be noted
that the embodiments shown in FIGS. 3A and 3B define the
integration of multiple apparatus, or nozzles (shown in FIGS. 1A
and 1B) to form a multi-nozzle deposition system, or a print-head,
and that each individual nozzle can include all the features and
elements described in reference to the apparatus of FIGS.
1A-1E.
[0066] Also, in the embodiments of FIGS. 3A and 3B, the chamber
energy sources and discharge nozzles energy sources may be
independently and/or simultaneously pulsatingly activated, with the
intensity and the duration of each pulse defined by a controller
(not shown.) It can be an important consideration when using the
deposition apparatus of FIGS. 3A and 3B to utilize multiple
simultaneously and independently activated discharge nozzles.
[0067] FIG. 4 is a schematic representation of a print-head
apparatus with multiple reservoirs. FIG. 4 includes reservoirs 430,
431 and 423. Each reservoir contains a different deposition liquid.
Thus, reservoir 430 contains liquid ink 401, reservoir 431 contains
ink 402 and reservoir 432 contains ink 403. In addition, reservoir
401 communicates with chambers 410 and 412, reservoir 402
communicates with chambers 413 and 414, while reservoir 403
communicates with chambers 415, 416 and 417. In this manner,
different material can be printed simultaneously using a single
print-head. For example, liquids 401, 402, and 403 may contain the
OLED materials that determine the emission color, such that liquid
401 may contain the material for fabricating red OLEDs, liquid 402
may contain the material for fabricating green OLEDs, and liquid
403 may contain the material for fabricating blue OLEDs. Each of
chambers 410, 412, 413, 414, 415, 416 and 417 communicates with the
respective discharge nozzle 440, 442, 443, 444, 445, 446 and
447.
[0068] FIG. 5 illustrates an apparatus for depositing thin films of
material using one or more micro-porous print-heads and a
positioning system. Print-head unit 530 may comprise one or more of
the apparatuses discussed in relation to FIGS. 1A-1D or
permutations thereof as shown in FIGS. 3-4. Print-head unit 530 of
FIG. 5 can be connected to positioning system 520, which can adjust
the distance between print-head unit 530 and substrate 540 by
traveling along guide 522. In one embodiment, print-head unit 530
is rigidly connected to positioning system 520. Print-head unit
530, positioning system 520, and guide 522 can be collectively (and
optionally, rigidly) connected to positioning system 510, which can
adjust the position of print-head unit 530 relative to substrate
540 in the plane of substrate 540. The position adjustments
performed by positioning system 510 may be accomplished by travel
along guides 523 and 521. The exemplary apparatus of FIG. 5 may
further comprise combinations of multiple independent print-head
units and positioning systems (not shown). In the apparatus of FIG.
5, the location of the substrate can be fixed. A related apparatus
can be constructed in which the print-head unit position would be
fixed and the substrate would move relative to the print-head. Yet
another related apparatus can be constructed in which both the
print-head unit and substrate move simultaneously and relative to
each other.
[0069] Including a motion system with the multi-nozzle micro-porous
print-head has practical advantages as it provides for high speed
printing of arbitrary patterns. The positioning systems utilized in
the apparatus of FIG. 5 may control the distance between print head
unit 530 and substrate 540 so that the distance is between 1 micron
and 1 cm. Other tolerances can be designed without departure form
the principles disclosed herein. A control system may actively
maintain a constant separation distance, and may utilize optical or
capacitive feedback (not shown). The control may also be passive
based on prior calibration. The positioning system may also have
the capacity to register print-head unit 530 relative to a
particular position in the plane of substrate 540 by utilizing
optical feedback. The optical feedback may include a digital camera
and processing system for converting the digital image into
positioning instructions. The positioning system may have an
absolute position resolution of between 10 nm and 10 cm for each
direction, as appropriate for the application. For instance, for
some OLED applications, a positioning resolution of one micron for
each direction can be employed.
[0070] FIG. 6 illustrates a micro-porous discharge nozzle having
micro-pores with tapered sidewalls. Discharge nozzle 680,
intervening rigid segments 665, micro-porous openings 660, and
heating elements 650, correspond to elements 180, 165, 160, and 150
of FIG. 1A, except that the sidewalls of micro-pores 660 are
tapered. The taper may be engineered so that the wider section of
the micro-pore is closer to substrate 690 than the narrower
section. The tapered design can be advantageous because upon
activation of the discharge nozzle and the subsequent dislodging
material, the tapering allows discharge along the direction of the
wider section of micro-pores 660. In the exemplary embodiment of
FIG. 6, the taper is shown so that activation of discharge nozzle
680 with heating elements 650 can increase the fraction of material
that flows to substrate 690 as compared to micro-pores having
straight sidewalls. While the sidewalls of FIG. 6 have a
substantially straight taper, one can utilize any sidewall profile
designed to have a larger opening on one end as compared to the
other such that the fraction of material flowing out of the nozzle
in one direction or the other is altered. Another example of such a
tapered sidewall includes a side that widens monotonically from one
end to the other with a curved profile. Yet another profile for
rigid segments 665 can be a trapezoidal shape.
[0071] FIG. 7 shows exemplary micro-pore patterns for use in a
micro-porous discharge nozzle. Shapes 701, 702, and 703 represent
exemplary patterns. Complex pixel shape 701 defines a rectangle,
complex pixel shape 702 is defines an L-shape pattern, while
complex pixel shape 703 defines a triangle. Other complex pixel
shapes, such as ovals, octagons, asymmetric patterns, etc., can
also be devised without departing form the principles disclosed
herein. Each of the pixel patterns can comprise one or more
micro-pores 704. Such pixel patterns are advantageous in depositing
a uniform thin film of material with a micro-porous discharge
nozzle that covers a region that is not a simple square or circle.
Depositing a film using complex micro-pore patterns can be superior
to depositing an equivalent region with multiple depositions using
a circle or square micro-pore pattern because deposition by this
latter method yields a film with a non-uniform thickness where the
separate depositions overlap. Additionally, it may not be possible
to recreate small features in certain shapes (such as the points of
a triangle) except by using an impractically small square or
circular micro-pore pattern.
[0072] Referring to FIG. 7, each micro-pore 704 can have a width of
w1. In an exemplary embodiment, w1 is between 0.1 .mu.m to 100
.mu.m. Each micro-pore pattern can have a width w2 of between 0.5
.mu.m and 1 cm depending on the number, size, and spacing of the
micro-pores. The conversion of the complex micro-pore pattern into
a corresponding pattern of deposited material on a substrate by the
discharge apparatus can depend on the number of micro-pores in the
discharge apparatus, the diameter of each micro-pore, the spacing
of the micro-pores, the shape of the micro-pore sidewalls, and the
distance between the discharge apparatus and the substrate. For
example, the discharge apparatus can have complex micro-pore
pattern 701, each of the micro-pores can have a diameter (w1) of
1.0 .mu.m, have a center to center spacing of 2.0 microns, and have
a straight sidewall. The micro-pores can be positioned about 100
.mu.m from the substrate. It has been found that this approach can
be used to recreate an approximately rectangular pattern of
deposited material corresponding to complex micro-pore pattern
701.
[0073] In one embodiment, a discharge apparatus according to the
disclosure can be used to deposit ink in substantially solid form
on a substrate. The ink can be composed of the material to be
deposited on the substrate in the form of particles initially
suspended or dissolved in a carrier liquid. The carrier liquid can
be organic, for example, acetone, chloroform, isopropanol,
chlorbenzene, and toluene, or can be water. The carrier liquid can
also be a mixture of the materials identified above. One or more of
the components to be deposited on the substrate can be an organic
molecular compound, for example, pentacene, aluminum
tris-(8-hydroxyquinoline) (A1Q3),
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine
(TPD), bathocuproine (BCP), or fac tris(2-phenylpyridine) iridium
(Irppy). One or more of the components to be deposited on the
substrate may also be polymeric. One or more of the components to
be deposited on the substrate may be inorganic, such as a
semiconductor or insulator or conductor. One or more of the
deposited materials can be an electron injection material. One or
more of the deposited materials can be an electron transport
material. One or more of the deposited materials can be light
emitting material. One or more of the deposited materials can be a
hole transport material. One or more of the deposited materials can
be a hole injecting material. One or more of the deposited
materials can be an exciton blocking material. One or more of the
deposited materials can be a light absorbing material. One or more
of the deposited materials can be a chemical sensing material. The
deposited materials may be used as, for instance, conductors, light
emitters, light absorbers, charge blockers, exciton blockers, and
insulators, in, for instance, OLEDs, transistors, photodetectors,
solar cells, and chemical sensors.
[0074] The properties of the ink can define an important factor in
depositing the film. One of the important performance criteria for
the ink can be the efficient, reliable, and uniform loading of the
ink material from the chamber into the discharge nozzles. Relevant
performance criteria include the ability of the ink: (1) to wet one
or more of the discharge nozzle surfaces; (2) to be drawn rapidly
into the discharge nozzle holes; and (3) to spread rapidly over the
area of the discharge nozzle containing the discharge nozzle holes.
Another important performance criterion for the ink is the
consistent delivery of the desired mass of material into the
discharge nozzle, so the desired amount of material is consistently
deposited each time the discharge nozzle discharges its material.
The ink can be adapted so that the ink is reliably delivered from
the chamber orifice to the discharge nozzle with a consistent ink
volume. These adaptations have been carried out by the inventors
for target inks by designing the physical and chemical properties
of the ink liquids and the material dissolved or suspended in the
ink. These properties include, but are not limited to, viscosity,
thixotropy, boiling point, material solubility, surface energy, and
vapor pressure.
[0075] In one embodiment, the discharge apparatus according to the
disclosed embodiments can be used to deposit metal material on a
substrate. The deposited metal material can be deposited in
substantially solid form. The deposited material can include metal
synthesis utilizing organo-metallic precursor materials dissolved
or suspended in a solvent, or metal dissolved or suspended in a
solvent. The metal dissolved or suspended in a solvent may
comprise, at least partially, nanoparticles, which can be coated
with organic compounds. The metal can be, for instance, gold,
silver, aluminum, magnesium, or copper. The metal can be an alloy
or mixture of multiple metals. Such metal material is useful in
many applications, for instance, as thin film electrodes,
electrical interconnections between electronic circuit elements,
and passive absorptive or reflective patterns. Metal films
deposited by the discharge apparatus can be used to deposit the
electrodes and electrical interconnections utilized in circuits
including organic electronic devices such as OLEDs, transistors,
photodetectors, solar cells, and chemical sensors. Organo-metallic
or metallic material can be delivered to the discharge nozzle, and
upon activation of the discharge nozzle can be delivered to the
substrate. A reaction converting the organo-metallic material into
metallic material can be carried out prior to or during delivery of
the liquid from the chamber to the discharge nozzle, during
delivery from the discharge nozzle to the substrate, or following
deposition on the substrate. When delivering metal material from
the discharge nozzle to the substrate, it is advantageous to
utilize nanoparticles because this reduces the energy required to
dislodge the metal from the micro-pores. Metal deposited on a
substrate utilizing the discharge apparatus has the advantage of
efficiently utilizing material and employing a deposition technique
that may not damage the material onto which the metal film is
deposited, including both the underlying substrate and any other
deposited layers.
[0076] In another embodiment, the discharge apparatus is used to
deposit inorganic semiconductor or insulator material in
substantially solid form on a substrate. The deposition material
can include synthesis utilizing organic and inorganic precursor
materials dissolved or suspended in a carrier liquid, or inorganic
semiconductor or insulator dissolved or suspended in a carrier
liquid. The inorganic semiconductor or insulator dissolved or
suspended in a liquid may be comprised of all, or in part,
nanoparticles, which can be coated with organic compounds. The
inorganic semiconductor or insulator can be, for instance, group IV
semiconductors (for instance, Carbon, Silicon, Germanium), group
III-V compound semiconductors (for instance, Gallium Nitride,
Indium Phosphide, Gallium Arsenide), II-VI compound semiconductors
(for instance, Cadmium Selenide, Zinc Selenide, Cadmium Sulfide,
Mercury Telluride), inorganic oxides (for instance, Indium Tin
Oxide, Aluminum Oxide, Titanium Oxide, Silicon Oxide), and other
chalcogenides. The inorganic semiconductor or insulator can be an
alloy or mixture of multiple inorganic compounds. The semiconductor
or insulator material can be useful in many applications, for
instance, as transparent conductors for electrodes and electrical
interconnections between electronic circuit elements, insulating
and passivation layers, and as active layers in electronic and
optoelectronic devices. When integrated together, these layers can
be utilized in circuits containing organic electronic devices such
as OLEDs, transistors, photodetectors, solar cells, and chemical
sensors.
[0077] In another embodiment, precursor or inorganic semiconductor
or insulator material can be delivered to the discharge nozzle, and
upon activation of the discharge nozzle can be delivered to the
substrate. A reaction converting the precursor material into the
desired inorganic semiconductor or insulator material can be
carried out prior to or during delivery of the liquid from the
chamber to the discharge nozzle, during delivery from the discharge
nozzle to the substrate, or following deposition on the substrate.
When delivering inorganic semiconductor or insulator material from
the discharge nozzle to the substrate, it can be advantageous to
utilize nanoparticles for reducing energy required to dislodge the
material from the micro-pores. Inorganic semiconductor or insulator
material deposited on a substrate utilizing the discharge apparatus
has the advantage of efficiently utilizing material and employing a
deposition technique that may not damage the material onto which
the film is deposited, including both the underlying substrate and
any other deposited layers.
[0078] FIGS. 8A and 8B (collectively, FIG. 8) schematically
illustrate a dye sublimation printer in accordance with one
embodiment of the disclosure. In FIG. 8A, ink droplet 809 comprises
ink pigments dissolved or suspended in a carrier liquid. The
carrier liquid can comprise one or more components, including
organic solvents and water. Ink droplet 809 is directed to the
backside of the discharge apparatus 850. Droplet 809 is drawn into
micro-pores 840 where the solvent portion of the liquid ink
evaporates, leaving pigment particles 810 deposited on micro pore
840 walls.
[0079] Next, and with reference to FIG. 8B, heater 830 can be
activated to vaporize pigment particles 810 from micro-pores 840
and discharge the pigment particles from discharge nozzle 825. The
discharged pigment particles condense on substrate surface 860,
forming pixel pattern 870 of a printed pigment. Heater 830 can also
be used to evaporate any remaining solvent in pixel pattern
870.
[0080] FIGS. 9A and 9B illustrate the use of the discharge
apparatus for spatially localized chemical synthesis. In the
embodiment of FIG. 9A, reactant gas 910 is flown over discharge
nozzle 825. Reactant gas 910 can additionally help vaporize and
remove evaporated solvents. The gas flow, along with deposition ink
809, can be drawn into the discharge nozzle micro-pores 840.
[0081] In FIG. 9B, vaporizable reactant 920 is directed to
discharge nozzle 825 and pressed through micro-pores 840.
Vaporizable reactant 920 may optionally contain the suspended
particles which form synthesized material 930. Heater 830 can be
activated to heat reactant gas flow 909 containing solid ink
particles to be deposited. Vaporizable reactant (not shown) from
micro-pores 840 can be transported out of the system using an
effluent gas (not shown). The heat from heater 830 can then
activate the desired chemical reaction to produce the desired
material 930 on a substrate 860. In another embodiment, the
discharge apparatus 850 can be employed as an efficient, spatially
localized heating element, submerged in either a gaseous or liquid
environment in which heat from heater 830 is used to activate the
chemical syntheses process.
[0082] In still another embodiment, an ink having dissolved or
suspended particles in a carrier liquid (not shown) is delivered to
discharge nozzle 825. Discharge nozzle 825 comprises micro-pores
840 for receiving the ink. After the carrier liquid is evaporated,
heater 830 heats the particles deposited on pore walls of the
micro-pores 840, where the particles are vaporized and mixed with
ambient gaseous and/or liquid environment. In another embodiment
the discharge apparatus can be employed as an efficient, spatially
localized heating element, in which heat from heater 830 is used to
activate the chemical syntheses process on a defined area of the
substrate.
[0083] FIGS. 9C and 9D depict the use of a discharge apparatus as a
micro reactor. As shown in FIG. 9C, optional reactant gas flow or
ink deposition 909 or vaporizable reactant 911 can be deposited on
the backside of the discharge apparatus 850. Discharge apparatus
850 can be integrated into a micro-scale chamber with micro-scale
chamber valves 922 and 924 for controlling the in- and out-flux of
gaseous and liquid products, reactants, and analytic or synthetic
product 970. In FIG. 9C, optional reactant gas flow or ink
deposition 909 or vaporizable reactant 911 is drawn into
micro-pores 840. Heater 830 is activated to heat optional reactant
gas flow or ink deposition 909, or vaporizable reactant 911 from
micro-pores 840 and discharge them from discharge nozzle 825. The
heat from heater 830 can then activate the desired chemical
synthesis process to produce analytic or synthetic product 970 on
substrate 860.
[0084] In another embodiment, the discharge apparatus can be used
to create sub-pixels for displays such as Red, Green, or Blue
sub-pixels. Each sub-pixel can have lateral dimensions from 20
.mu.m to 5 mm wide. Other dimensions are available without
departing from the principles disclosed herein. The subpixels can
include one or more films deposited using one or more of the
apparatuses discussed in relation to FIGS. 1A-1D or variations
thereof (e.g., as shown in FIGS. 3-4, or in FIGS. 10-11, as
discussed further below), referred to here as the "thermal jet" and
the corresponding deposition method as the "thermal jet deposition
method." A plurality of these sub-pixels can be deposited over a
substrate to form one or more displays. When multiple displays are
deposited on a substrate, the substrate can be subdivided into
individual displays. Deposition using the thermal jet deposition
method can be advantageous over shadow masking because shadow
masking can require long thin pieces of metal with holes which can
twist and bend over large areas and/or which can be difficult to
keep clean and/or which generate dust particles.
[0085] FIG. 10A is a schematic representation of an exemplary
print-head. Referring to FIG. 10A, the exemplary apparatus for
depositing a material on a substrate comprises chamber 1030 for
housing ink with containing particles of material to be deposited
on a substrate suspended or dissolved in a carrier liquid. Chamber
1030 includes orifice 1070 and a delivery path from orifice 1070 to
a discharge nozzle 1080. Discharge nozzle 1080 is defined by a
surface that may contain a plurality of micro-porous conduits 1060
for receiving the material communicated through orifice 1070 from
chamber 1030. These conduits extend into, but not through,
supporting material 1040 which provides mechanical support for the
discharge nozzle 1080. Housing 1040 may be joined to the housing
for chamber 1030 using bracket or connecting material 1020.
[0086] Chamber activator 1015 also includes a piezoelectric
actuator 1015 coupled to chamber 1030 for providing pulsating
energy to activate the ink dispensing mechanism and thereby meter a
droplet of the liquid from chamber 1030 through orifice 1070
towards discharge nozzle 1080. The pulsating energy can be variable
on a time scale of one minute or less. For instance, the
piezoelectric actuator 1015 can be energized with square pulses
having a variable duty cycle and a cycle frequency of 1 kHz.
Chamber 1030 may contain material required for forming a film used
in the fabrication of an OLED or a transistor. Orifice 1070 is
configured such that surface tension of the liquid in chamber 1030
prevents discharge of the liquid prior to activation of the
piezoelectric ink dispensing mechanism.
[0087] Discharge nozzle 1080 may include rigid portions
(interchangeably, partitions) 1065 separated by micro-pores 1060.
The micro-pores region can be composed of a variety of materials,
such as micro-porous alumina or solid membranes of silicon or
silicon carbide and having micro-fabricated pores. In one
embodiment, micro-pores 1060 receive the material dissolved or
suspended in the liquid and prevent the material from being
released again from discharge nozzle 1080 until the medium is
appropriately activated. Discharge nozzle 1080 may also comprise a
rough surface (not shown) for receiving the material dissolved or
suspended in the carrier liquid and delivered from chamber orifice
1070. The surface can similarly contain the material until the
discharge nozzle is properly actuated. Alternatively, discharge
nozzle 1080 may comprise a smooth surface (not shown) for receiving
the material dissolved or suspended in the liquid and delivered
from chamber orifice 1070. The smooth surface can be adapted to
contain the material until the discharge nozzle is properly
actuated. Such adaptations can comprise modification of the surface
chemistry or proper selection of the discharge nozzle material with
respect to the choice of liquid.
[0088] In the exemplary device of FIG. 10A, when the discharged
droplet of liquid encounters discharge nozzle 1080, the liquid is
drawn into micro-pores 1060 with the assistance of the capillary
action. The liquid in the ink may evaporate prior to activation of
discharge nozzle 1080, leaving behind a coating of the suspended or
dissolved material on the micro-pore walls. The evaporation of the
liquid in the ink may be accelerated by heating discharge nozzle
1080. The evaporated liquid can be removed from the chamber and
subsequently collected (not shown) by flowing gas over one or more
of the discharge nozzle faces.
[0089] Depending on the desired application, micro-pores 1060 can
provide containers having a maximum cross-sectional distance W of a
few nanometers to hundreds of microns. The micro-porous region
comprising discharge nozzle 1080 will take a different shape and
cover a different area depending on the desired application, with a
typical dimension D ranging from a few hundred nanometers to tens
of millimeters. If discharge nozzle 1080 is adapted so that the
micro-porous region is replaced by a roughened surface region or a
smooth surface region (not shown), the discharge nozzle 1080
behaves in substantially the same manner, whereby the material
delivered in a liquid from the chamber 1030 to discharged nozzle
1080 is retained on the surface (by surface tension through proper
control of surface and material properties) until activation of
discharge nozzle 1080. The evaporation of the liquid in the ink may
be accelerated by heating the discharge nozzle. Again, the
evaporated liquid can be removed from the chamber and subsequently
collected (not shown) by flowing gas over one or more of the
discharge nozzle faces.
[0090] In the exemplary apparatus of FIG. 10A, the relative
orientation of the chamber nozzle orifice 1070 and the surface of
discharge nozzle 1080 are such that the liquid in chamber 1030 can
be delivered directly from the chamber orifice 1070 (for instance,
by firing a droplet at a controlled velocity and trajectory out of
chamber orifice 1070) onto the discharge nozzle surface.
Furthermore, the discharge nozzle surface is also positioned such
that when activated, the material delivered to the discharge nozzle
surface can flow substantially towards the substrate. In the
exemplary embodiment of FIG. 10A, this is accomplished by aligning
the discharge nozzle surface to an intermediate angle relative to
both the incoming trajectory of the liquid supplied through chamber
orifice 1070 and the angle of the substrate, which would be placed
below the print-head (shown in FIG. 10B).
[0091] Also, in the exemplary embodiment of FIG. 10A, the discharge
nozzle is activated by heater 1050 which is positioned proximal to
the discharge nozzle 1080. Nozzle heater 1050 may comprise a thin
metal film, composed of, for instance, platinum. When activated,
nozzle heater 1050 provides pulsating thermal energy to discharge
nozzle 1080, which dislodges the material contained within
micro-pores 1060 allowing the material to flow out from the
discharge nozzle. Dislodging the material may include vaporization
of the substantially solid ink particles, either through
sublimation or melting and subsequent boiling. In general, one can
employ any energy source coupled to the discharge nozzle capable of
energizing discharge nozzle 1080 and thereby discharging the
material from micro-pores 1060. For example, mechanical (e.g.,
vibrational) energy may be used.
[0092] FIGS. 10B-10E illustrate a method for depositing a film
using the print-head shown in FIG. 10A. The method of FIG. 10B is
referred to herein as the thermal surface jet deposition method.
Referred to FIG. 10B, chamber 1030 is commissioned with ink 1002,
comprising particles of material to be deposited on a substrate,
dissolved, or suspended in a carrier liquid. Piezoelectric elements
1015 pulsatingly meter liquid 1002 as it travels from chamber 1030
through orifice 1070 to form free droplet 1001. In an alternative
embodiment (not shown), a heater is positioned in place of
piezoelectric element 1015 for pulsatingly activating a thermal ink
dispensing mechanism and thereby driving at least a portion of
liquid 1002 in chamber 1030 through orifice 1070 to form free
droplet 1001. In general, any pulsating energy source that
activates the ink dispensing mechanism to thereby meter liquid 1002
as it travels through orifice 1070 towards discharge nozzle 1080
can be utilized. The intensity and the duration of each energy
pulse can be defined by a controller (not shown).
[0093] Referring to FIG. 10B, discharge nozzle heater 1050 may be
activated so that the discharge nozzle temperature is elevated
above ambient temperature. The heating cycle assists in rapidly
evaporating the liquid in the ink after it is deposited on the
discharge nozzle. Discharge nozzle heater 1050 may also be
activated prior to energizing the ink dispensing mechanism (and
discharging ink droplet 1001 from chamber 1030 through orifice
1070) or after droplet 1001 lands on discharge nozzle 1080.
[0094] In FIG. 10C, droplet 1001 travels from chamber orifice 1070
to discharge nozzle 1080, where the ink is drawn into micro-pores
1060. The solvent or carrier liquid in ink 1003, which may fill the
micro-pores, may evaporate prior to activation of discharge nozzle
1080, leaving behind on the micro-pore walls the material 1004 that
is substantially solvent-free and in substantially solid form and
which is to be deposited onto the substrate. This is shown in FIG.
10D. Alternatively, the solvent or liquid 1003 may evaporate during
activation of discharge nozzle 1080.
[0095] FIG. 10E shows the step of activating nozzle heater 1030 to
provide pulsating energy to discharge nozzle 1080 dislodges the
material in micro-pores 1060. The intensity and the duration of
each pulse can be defined by a controller (not shown). The
activating energy can be thermal energy, but alternatively the
energy source can be coupled to discharge nozzle 1080 to energize
discharge nozzle 1080 and discharge the material from micro-pores
1060. For example, mechanical (e.g., vibrational) energy may also
be used for this step. Substrate 1090 can be positioned proximal to
discharge nozzle 1080 to receive the dislodged material to thereby
form thin film 1005.
[0096] FIG. 11A schematically illustrates a thermally activated
print-head according to one embodiment of the disclosure. The
apparatus shown in FIG. 11A comprises chamber 1130 for housing ink,
chamber orifice 1170 and a delivery path from orifice 1170 to a
discharge nozzle 1180. Discharge nozzle 1180 includes a surface
that containing a plurality of micro-porous conduits 1160 for
receiving the liquid ink, containing particles of material to be
deposited on a substrate dissolved or suspended in a carrier
liquid, communicated through orifice 1170 from chamber 1130.
Conduits 1160 extend into, but not through, bracket 1142 which
structurally supports discharge nozzle 1180. Bracket 1142 is joined
to supporting sidewalls 1140 through rotating joints 1141.
Sidewalls 1140 may then be connected to a larger frame to form a
housing for chamber 1130 (not shown).
[0097] Chamber activator 1110 optionally defines a heater coupled
to chamber 1130 for providing pulsating energy which activates the
ink dispensing mechanism to meter a droplet of the liquid from
within chamber 1130 through orifice 1170 towards discharge nozzle
1180. As stated, pulsating energy can be variable on a time scale
of one minute or less. For example, the actuator 1110 can be
energized with square pulses having a variable duty cycle and a
cycle frequency of 1 kHz. Chamber 1130 may contain material
required for forming a film used in the fabrication of an OLED or
transistor. Orifice 1170 can be configured such that surface
tension of the liquid in chamber 1130 would prevent liquid
discharge prior to activation of the ink dispensing mechanism.
[0098] Discharge nozzle 1180 may includes rigid portions
(interchangeable, partitions) 1165 separated by micro-pores (or
conduits) 1160. The micro-porous region can be composed of a
variety of materials, such as micro-porous alumina or solid
membranes of silicon or silicon carbide and having micro-fabricated
pores. Micro-pores 1160 receive ink and prevent the material from
being released again from discharge nozzle 1180 until the medium is
appropriately activated. Discharge nozzle 1180 may also include a
rough surface for receiving the material dissolved or suspended in
the liquid and delivered from chamber orifice 1170. Such surfaces
can retain the material until the discharge nozzle is properly
actuated. Alternatively, discharge nozzle 1180 may also contain a
smooth surface for receiving the material dissolved or suspended in
the liquid and delivered from chamber orifice 1170. Such surfaces
can retain the material until the discharge nozzle is properly
actuated. It should be noted that such adaptations may require
modifying the surface chemistry or selecting appropriate discharge
nozzles configuration given the surface chemistry of the
liquid.
[0099] In FIG. 11A, when the discharged droplet of liquid
encounters discharge nozzle 1180, the liquid is drawn into
micro-pores 1160 with assistance from capillary action and
molecular surface tension. The liquid may evaporate prior to
activation of discharge nozzle 1180, leaving behind a substantially
solid coating of the suspended or dissolved particles on the
micro-pore walls 1160. The evaporation of the liquid in the ink may
be accelerated by heating discharge nozzle 1180. The evaporated
liquid can be removed from the chamber and subsequently collected
(not shown) by flowing gas over one or more of the discharge nozzle
surfaces.
[0100] Depending on the desired application, micro-pores 1160 can
provide containers having a maximum cross-sectional distance W of a
few nanometers to hundreds of microns. The micro-porous region
comprising discharge nozzle 1180 will take a different shape and
cover a different area depending on the desired application, with a
typical dimension D ranging from a few hundred nanometers to tens
of millimeters. If discharge nozzle 1180 is adapted so that the
micro-porous region is replaced by a roughened surface region or a
smooth surface region (not shown), the discharge nozzle 1180
behaves in substantially the same manner, whereby the material
delivered in a liquid from the chamber 1130 to discharged nozzle
1180 is retained on the surface (by surface tension through proper
control of surface and material properties) until activation of
discharge nozzle 1180. The liquid may evaporate prior to activation
of discharge nozzle 1180, leaving behind a substantially solid
coating of the suspended or dissolved material on the discharge
nozzle surface. The evaporation process may be accelerated by
heating the discharge nozzle. Again, the evaporated liquid can be
removed from the chamber and subsequently collected (not shown) by
flowing gas over one or more of the discharge nozzle faces.
[0101] The relative orientation of the chamber nozzle orifice 1170
and the surface of discharge nozzle 1180 are such that the liquid
in chamber 1130 can be delivered directly from the chamber orifice
1170 (for instance, by firing a droplet at a controlled velocity
and trajectory through chamber orifice 1170) onto the discharge
nozzle surface. Discharge nozzle 1180 can be integrated in 1142 so
that it can be rotated relative to side walls 1140 through 1141.
The rotation is used to reorient the surface of discharge nozzle
1180 so that when activated, the material delivered to the
discharge nozzle surface can flow directly, or at an angle, towards
the substrate.
[0102] In FIG. 11A, the discharge nozzle can be activated by a
heater. The discharge nozzle heater 1150 can be positioned proximal
to the discharge nozzle 1180. Nozzle heater 1150 may comprise a
thin metal film, composed of, for instance, platinum. When
activated, nozzle heater 1150 provides pulsating thermal energy to
discharge nozzle 1180, which acts to dislodge the material
contained within micro-pores 1160, which can subsequently flow out
from the discharge nozzle. Dislodging said material may include
vaporization, either through sublimation or melting and subsequent
boiling. Any energy source coupled to the discharge nozzle capable
of energizing discharge nozzle 1180 to discharge the material from
micro-pores 1160 may be used. Confining well 1145 operates in the
same manner disclosed in relation to FIG. 1D.
[0103] FIGS. 11B-11E show an exemplary implementation of the
print-head apparatus of FIG. 11A. Referring to FIG. 11B, the first
step is filing chamber 1130 with ink 1102. The liquid ink may
contain material dissolved or suspended in a liquid and can be
deposited as a thin film. Chamber heater 1110 pulsatingly
introduces thermal energy into the ink 1102 in chamber 1130 and
thereby meters at least a portion of liquid 1102 through orifice
1170 to form free droplet 1101. In another exemplary embodiment
(not shown), chamber piezoelectric elements 1115 pulsatingly
introduce mechanical energy into the ink 1102 in chamber 1130 and
thereby meter at least a portion of liquid 1102 through orifice
1170 to form free droplet 1101. The discharge nozzle heater 1150
may be activated so that the discharge nozzle temperature is
elevated above ambient temperature. This can assist in rapidly
evaporating the liquid in the ink once deposited on the discharge
nozzle. The discharge nozzle heater 1150 may also be activated
prior to energizing the ink chamber (and discharging ink droplet
1101 from chamber 1130 through orifice 1170) or after droplet 1101
lands on discharge nozzle 1180.
[0104] In FIG. 11C, droplet 1101 travels from chamber orifice 1170
to discharge nozzle 1180, where the ink is drawn into micro-pores
1160. Liquid in ink 1103, which may fill the micro-pores and extend
onto the surrounding surface, with the extent of this extension
controlled in part by the engineering of the surrounding surface,
may evaporate prior to activation of discharge nozzle 1180, leaving
behind on the micro-pore walls the material 1104 substantially
discharge nozzle 1180, leaving behind on the micro-pore walls the
material 1104 substantially free of solvent. This step of the
process is illustrated in FIG. 11D. The solvent in liquid 1103 may
also evaporate during activation of discharge nozzle 1180.
[0105] Prior to activating discharge nozzle 1180, the discharge
nozzle is rotated 180 degrees relative to sidewalls 1140. As
discussed in relation to FIG. 11A, bracket 1142 rotates relative to
sidewalls 1140 along joints 1141. This rotation brings the
discharge nozzle surface closer to and substantially parallel to
substrate 1190, so that there is a direct path from the discharge
nozzle surface to the substrate. This step of the process is shown
in FIG. 11E. Thereafter, activating nozzle heater 1130 to provide
pulsating energy to discharge nozzle 1180 dislodges the material in
micro-pores 1160. The intensity and the duration of each pulse can
be defined by a controller (not shown). In this exemplary example,
the activating energy is thermal energy; one can alternatively
employ any energy source coupled to discharge nozzle 1180 that is
capable of energizing discharge nozzle 1180 and thereby discharging
the material from micro-pores 1160. Substrate 1190 can be
positioned proximal to discharge nozzle 1180 to receive the
dislodged material and thin film 1105 can be formed.
[0106] FIG. 12 illustrates a method for depositing particles on a
substrate according to one embodiment of the disclosure. Referring
to FIG. 12, in step 1200, liquid ink is provided from a reservoir
to the chamber of a thermal jet printing device. The liquid ink can
be a combination of a liquid carrier and a plurality of ink
particles. In step 1210 a desired quantity of liquid ink is metered
from the chamber. A dispenser can be used to meter the desired
quantity of liquid ink. The dispenser can comprise an
electromechanical or vibrational device configured to direct energy
to the chamber. In an alternative embodiment, the dispenser
comprises a heater. In another embodiment, the dispenser comprises
a piezoelectric element. Pulsating energy can be provided to the
dispenser to meter the desired quantity of ink. In step 1220, the
metered quantity of ink is directed from the chamber to a discharge
nozzle. The ink can be directed to the discharge nozzle using
gravity feed, forced air conduction or through any conventional
means. In step 1230, the liquid carrier is evaporated to leave
behind substantially solid particles of ink.
[0107] In one embodiment, the evaporation step is implemented as
soon as the metered quantity of ink leaves the chamber. In another
embodiment, evaporation commences once the liquid ink has reached
the discharge nozzle. In still another embodiment, the evaporation
step continues until substantially all of the carrier liquid has
evaporated. In step 1240, the substantially-solid ink particles are
dispensed from the discharge nozzle and deposited on the substrate
in step 1250.
[0108] FIG. 13 is a schematic representation of a control system
for controlling a dispensing device. In FIG. 13, chamber 1330 is in
fluid communication with reservoir 1399. Reservoir 1399 provides
liquid ink to chamber 1330. The liquid ink comprises carrier liquid
1391 and dissolved or suspended particles 1396. Dispenser 1310 is
positioned proximal to chamber 1330 to agitate the chamber and
thereby meter a desired quantity of liquid ink from the chamber.
Dispenser 1310 can comprise, among others, a heater. Dispenser 1310
is in electrical communication with controller 1395 through wiring
1353 and 1352.
[0109] Controller 1395 comprises processor 1397 and memory 1398.
Memory 1398 can contain instructions for directing the processor to
activate dispenser 1310 in order to meter an exact quantity of
liquid ink from chamber 1330. For example, memory 1398 can
comprises a program to pulsatingly activate dispenser 1310 in order
to dispense a desired quantity of ink onto discharge nozzle 1380.
Controller 1395 may also activate chamber 1330 in order to dispense
a desired quantity of ink onto discharge nozzle 1380.
[0110] Discharge nozzle 1380 receives the metered quantity of
liquid ink from chamber 1330. Heaters 1348 and 1349 are positioned
proximal to the discharge nozzle 1380 and configured to heat the
metered quantity of ink to thereby evaporate substantially all of
the carrier liquid 1391, leaving behind substantially solid ink
particles. Heaters 1348 and 1349 can further heat the substantially
solid ink particles and thereby boil or sublime the material, so
that discharge nozzle 1380 can dispense ink particles 1396 towards
substrate 1390. As particles 1396 land on substrate 1390 and
condense they form a substantially solid film. Heaters 1348, 1349
are positioned about discharge nozzle 1380 to help evaporate liquid
carrier 1391 and dispense solid particles 1396.
[0111] In the embodiment of FIG. 13, controller 1395 also controls
activation and operation of heaters 1348 and 1349 through electric
lines 1350 and 1351, respectively. Memory 1398 can be configured
with instructions to direct processor 1397 to engage and disengage
heaters 1348 and 1349 to thereby evaporate liquid carrier 1391 and
deposit particles 1396 onto substrate 1390.
[0112] While the schematic representation of FIG. 13 provides a
single controller (i.e., controller 1395), the principles disclosed
are not limited thereto. In fact, a plurality of controllers, with
each controller having one or more independent processors and
memory circuits can be used to accurately control the thermal
dispensing system. For example, a first controller (not shown) can
be used to control metering liquid ink delivered from chamber 1330
by controlling the pulse parameters supplied to dispenser 1310. A
second controller (not shown) can be used to control heaters 1348
and 1349. The second controller can be used to energize the
discharge nozzle 1380 to evaporate the carrier liquid. The second
controller can receive an input identifying an attribute of the
ink. Exemplary attributes of the ink include the ink's viscosity,
thixotropic properties, and molecular weight.
[0113] While the principles of the disclosure have been illustrated
in relation to the exemplary embodiments shown herein, the
principles of the disclosure are not limited thereto and include
any modification, variation or permutation thereof.
* * * * *