U.S. patent application number 11/871135 was filed with the patent office on 2008-09-11 for melt-based patterning for electronic devices.
Invention is credited to Siegfried F. Karg, Heike E. Riel, Walter H. Riess.
Application Number | 20080220561 11/871135 |
Document ID | / |
Family ID | 33566319 |
Filed Date | 2008-09-11 |
United States Patent
Application |
20080220561 |
Kind Code |
A1 |
Karg; Siegfried F. ; et
al. |
September 11, 2008 |
MELT-BASED PATTERNING FOR ELECTRONIC DEVICES
Abstract
The present invention provides methods and apparatus for
melt-based patterning for electronic devices. It employs and
provides processes and apparatus for fabricating an electronic
device having a pattern formed on a surface by a deposition
material. Further, the invention a process for fabricating
semiconductors, organic light-emitting devices (OLEDs),
field-effect transistors, and in particular high-resolution
patterning for RGB displays. A process for fabricating an organic
electronic device includes the steps of heating and applying a
pressure to the deposition material to form a melt, and depositing
the melted deposition material on the surface with a phase-change
printing technique or a spray technique. The melted deposition
material solidifies on the surface.
Inventors: |
Karg; Siegfried F.;
(Adliswil, CH) ; Riel; Heike E.; (Rueschlikon,
CH) ; Riess; Walter H.; (Thalwil, CH) |
Correspondence
Address: |
LOUIS PAUL HERZBERG
3 CLOVERDALE LANE
MONSEY
NY
10952
US
|
Family ID: |
33566319 |
Appl. No.: |
11/871135 |
Filed: |
October 11, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10852714 |
May 24, 2004 |
7282430 |
|
|
11871135 |
|
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Current U.S.
Class: |
438/99 ; 118/300;
257/E51.006; 427/58 |
Current CPC
Class: |
H01L 51/0541 20130101;
H01L 51/56 20130101; H01L 51/0004 20130101 |
Class at
Publication: |
438/99 ; 427/58;
118/300; 257/E51.006 |
International
Class: |
H01L 51/40 20060101
H01L051/40; B05D 5/12 20060101 B05D005/12; B05C 5/00 20060101
B05C005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2003 |
EP |
03405403.1 |
Aug 29, 2003 |
EP |
03019744.6 |
Claims
1. A process comprising fabricating an electronic device having a
pattern formed on a surface by a deposition material, the step of
fabricating comprising the steps of: heating and applying a
pressure to the deposition material without requiring a solvent to
be present to form a melt; depositing the melted deposition
material on the surface with one of a phase-change printing
technique and a spray technique, wherein the melted deposition
material solidifies on the surface in a single phase transition
from the melt to a solid.
2. The process according to claim 1, wherein the deposition
material is selected to comprise one of: an organic material an
OLED material, biological molecules, nanoparticles, and any
combination of these materials, wherein in the step of heating and
applying a pressure is performed in a pressure chamber, and further
comprising repeating the steps of heating and depositing to deposit
multiple layers of the deposition material, wherein the multiple
layers are formed by depositing different deposition materials.
3. The process according to claim 1, further comprising repeating
the steps of heating and depositing to deposit multiple layers of
the deposition material.
4. The process according to claim 3, wherein the multiple layers
are formed by depositing different deposition materials.
5. The process according to claim 1, wherein the deposition
material is selected to comprise one of: an organic material; an
OLED material; biological molecules; nanoparticles; and any
combination of these materials.
6. The process according to claim 1, wherein the deposition
material is selected to comprise a composition in form of a
powder.
7. The process according to claim 1, wherein the deposition
material is provided as a pellet.
8. The process according to claim 1, used to fabricate one of: an
organic light-emitting device; a monochrome and/or color display; a
biological pattern; a biochip; a sensor; a semiconductor device;
and a circuit.
9. A process for fabricating a field-effect transistor comprising
the steps of: forming source and drain contacts on a substrate;
heating and applying a pressure to a deposition material without
requiring a solvent to be present to form a melt, the deposition
material comprising an organic semiconducting material; depositing
the melted deposition material onto the substrate with the source
and drain contacts by one of: a phase-change printing technique;
and a spray technique, wherein the melted deposition material
solidifies on the substrate and forms an organic semiconducting
layer in a single phase transition from the melt to a solid;
forming an insulating layer on the organic semiconducting layer;
and forming a gate contact on the insulating layer.
10. An apparatus to fabricate an electronic device having a pattern
formed on a surface by a deposition material, the process
comprising: means for heating and applying a pressure to the
deposition material without requiring a solvent to be present to
form a melt; and means for depositing the melted deposition
material on the surface with one of: a phase-change printing
technique; and a spray technique, wherein the melted deposition
material solidifies on the surface in a single phase transition
from the melt to a solid.
11. The process according to claim 1, wherein the means for heating
and applying a pressure is performed in a pressure chamber, and
further comprising repeating the steps of heating and depositing to
deposit multiple layers of the deposition material, wherein the
multiple layers are formed by depositing different deposition
materials.
12. An apparatus to fabricate a field-effect transistor comprising:
means for forming source and drain contacts on a substrate; means
for heating and applying a pressure to a deposition material
without requiring a solvent to be present to form a melt, the
deposition material comprising an organic semiconducting material;
means for depositing the melted deposition material onto the
substrate with the source and drain contacts by one of a
phase-change printing technique, and a spray technique, wherein the
melted deposition material solidifies on the substrate and forms an
organic semiconducting layer; means for forming an insulating layer
on the organic semiconducting layer; and means for forming a gate
contact on the insulating layer.
13. The process according to claim 12, further comprising repeating
the steps of heating and depositing to deposit multiple layers of
the deposition material.
14. The process according to claim 9, wherein the step of heating
and applying a pressure is performed in a pressure chamber.
15. The process according to claim 14, further comprising repeating
the steps of heating and depositing to deposit multiple layers of
the deposition material.
16. The process according to claim 15, wherein the multiple layers
are formed by depositing different deposition materials.
17. The process according to claim 9, wherein the deposition
material is selected to comprise one of: an organic material; an
OLED material; biological molecules; nanoparticles; and any
combination of these materials.
18. The process according to claim 9, wherein the deposition
material is selected to comprise a composition in form of a
powder.
19. The apparatus according to claim 10, wherein the device is one
of: an organic light-emitting device, a monochrome and/or color
display, a biological pattern, a biochip, a sensor, a semiconductor
device, and a circuit.
20. The apparatus according to claim 10, wherein multiple layers
are formed by the means for depositing depositing different
deposition materials.
Description
TECHNICAL FIELD
[0001] The present invention is related to a process for
fabricating an electronic device having a pattern formed on a
surface by a deposition material. Further, the invention is related
to a process for fabricating a field-effect transistor and in
particular to high-resolution patterning for RGB displays.
BACKGROUND OF THE INVENTION
[0002] Organic electronic devices and in particular organic
light-emitting devices (OLEDs) are commonly manufactured as a
sequence of layers deposited on top of each other such as a first
electrode on a supporting substrate, several organic and inorganic
layers, and a second electrode. So far, OLED technology is lacking
a high-resolution patterning method for RGB displays for small
molecules. The deposition technologies developed for small
molecules so far show limitations for mass production of
large-sized displays.
[0003] Conventionally, vacuum evaporation is employed as the
physical vapor deposition method in forming the organic layers. A
common method for patterning of the organic layers e.g. for red,
green, and blue emitting sub-pixels in a full-color display, is the
shadow mask technique. However, this technique is limited in size,
resolution of the panel, and the individual fill-factor of the
pixel. For example, shadow mask technology becomes extremely
complicated in particular for small feature sizes. The material
deposition during the process requires regular mask cleaning steps
which delay the manufacturing. Thermal expansion of the mask during
the deposition limits the precision and aperture ratio. Moreover,
repeatedly necessary mask alignment is time consuming and reduces
yield.
[0004] A method used for patterning polymer light-emitting devices
is ink-jet printing of dissolved polymers as described in U.S. Pat.
No. 6,087,196. This method of dispensing a liquid solution is not
suitable for multi-layer OLEDs based on small molecules because
previously deposited layers are re-dissolved and intermixed by the
sequential deposition of multiple layers from different solutions.
When small molecules are heated some of the small molecules sublime
directly, while others first melt and then evaporate. Therefore a
new way of depositing such molecules is needed. It follows that
there is still a need in the art for improved patterning of
structures for the fabrication of semiconductor devices, sensors,
biochips, and displays using organic and/or inorganic active or
biological layers.
SUMMARY AND ADVANTAGES OF THE INVENTION
[0005] An aspect of the present invention is to provide methods and
apparatus for the fabrication of semiconductor devices, circuits,
sensors, biological patterns, biochips, and monochrome and/or color
displays using organic and/or inorganic active or biological
layers. It involves the deposition of molecules, oligomers or
nanoparticles by a phase-change printing or spray technique and the
fabrication of organic light-emitting devices (OLEDs), color
displays and other semiconductor devices.
[0006] In an example embodiment of the present invention, there is
provided a process for fabricating an electronic device having a
pattern formed on a surface by a deposition material. The process
comprises the steps of heating and applying a pressure to the
deposition material to form a melt, and depositing the melted
deposition material on the surface with a phase-change printing
technique or a spray technique. Thereby the melted deposition
material solidifies on the surface, i.e. when it reaches the
surface.
[0007] In an other example embodiment of the present invention, a
field-effect transistor, also referred to as a thin-film
field-effect transistor, is made by a process comprising the steps
of forming source and drain contacts on a substrate; heating and
applying a pressure to a deposition material to form a melt, the
deposition material comprising an organic semiconducting material;
depositing the melted deposition material onto the substrate with
the source and drain contacts by one of a phase-change printing
technique, and a spray technique, wherein the melted deposition
material solidifies on the substrate and forms an organic
semiconducting layer; forming an insulating layer on the organic
semiconducting layer; and forming a gate contact on the insulating
layer.
[0008] It is also possible to form the source, drain, and gate
contacts as well as the insulating layer by the phase-change
printing or spray technique. This has the advantage that the whole
device can be fabricated by the disclosed process.
DESCRIPTION OF THE DRAWINGS
[0009] Embodiments of the invention are described in detail below,
by way of example only, with reference to the following schematic
drawings, in which:
[0010] FIG. 1 illustrates a phase diagram of a one-component
system;
[0011] FIGS. 2 a-c illustrate steps for forming a pattern on a
surface by deposition of a deposition material using a pressure
chamber in accordance with the present invention;
[0012] FIGS. 3a, b show schematic illustrations of a formation of
organic light-emitting devices;
[0013] FIG. 3c shows a schematic illustration of a formation of an
RGB display;
[0014] FIG. 5 shows a schematic illustration of a formation of a
field-effect transistor; and
[0015] FIG. 6 illustrates a printing principle.
[0016] The drawings are provided for illustrative purpose only and
do not necessarily represent examples of the present invention to
scale.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention enables methods and apparatus for the
fabrication of semiconductor devices, circuits, sensors, biological
patterns, biochips, and monochrome and/or color displays using
organic and/or inorganic active or biological layers. It includes
the deposition of molecules, oligomers or nanoparticles by a
phase-change printing or spray technique and the fabrication of
organic light-emitting devices (OLEDs), color displays and other
semiconductor devices.
[0018] In accordance with the present invention, there is provided
an example of a process for fabricating an electronic device having
a pattern formed on a surface by a deposition material. The process
comprises the steps of heating and applying a pressure to the
deposition material to form a melt, and depositing the melted
deposition material on the surface with a phase-change printing
technique or a spray technique. Thereby the melted deposition
material solidifies on the surface, i.e. when it reaches the
surface.
[0019] In general, the present invention relates to a way of
high-resolution patterning of layers, for example with organic
molecules, by a phase-change printing technique, also referred to
as wax or fusion printing technique, for the use in semiconductor
devices, sensors, or color displays. Also a spray technique
utilizing a gas can be applied. Prior to deposition, the deposition
material or a part thereof is heated to the melting temperature in
a pressure chamber utilizing the p-V (T) diagram and deposited onto
a substrate or surface, e.g. a thin film transistor array for a
full-color display. The deposition of the melted deposition
material can be performed by a thermal phase-change printing
technique or a spray technique. The material solidifies immediately
when it hits the substrate. The deposition can be repeated to cast
multiple layers on top of each other. The steps of the process can
be repeated to deposit multiple layers, i.e. more than three layers
can be formed easily. In a further example, the multiple layers can
be formed by depositing different deposition materials. The process
allows a controlled deposition of the materials and tailoring of
the characteristics, e.g. by substrate heating/cooling, deposition
in hot environment (gas), changing pressure etc. Further, the
process is also ideally suited for doped systems (mixing of
liquids).
[0020] As indicated, the heating and applying of pressure can be
performed in a pressure chamber exploiting the pressure
(P)/temperature (T) phase diagram according to the
Clausius-Clapeyron equation. This allows a controlled melting of
the deposition material. By using the pressure chamber, basically
every material, can be used for phase-change or thermal printing
and spray technique. There is no need for a mask, the pattern is
determined by the printing process, i.e. droplets emerging as a jet
from nozzles towards the surface or substrate. The nozzles can be
piezo-controlled and moved over the substrate. It is also possible
to move the substrate while the nozzles are fixed. Additionally,
even higher precision can be achieved by using an integrated shadow
mask, e.g. a photo resist, which can be used to determine the
patterns. Ultrahigh precision can thus be achieved.
[0021] The deposition material can be selected to comprise one of
an organic material, an OLED material, biological molecules,
nanoparticles, and a combination thereof. Further, the deposition
material can be a composition in form of a powder. This has the
advantage that it can be easily mixed with further components.
Moreover, the deposition material can be provided as a pellet. This
allows a comfortable way of packaging, storing, handling, and
processing.
[0022] In another embodiment of the present invention, a
field-effect transistor, also referred to as a thin-film
field-effect transistor, is made by a process comprising the steps
of forming source and drain contacts on a substrate; heating and
applying a pressure to a deposition material to form a melt, the
deposition material comprising an organic semiconducting material;
depositing the melted deposition material onto the substrate with
the source and drain contacts by one of a phase-change printing
technique, and a spray technique, wherein the melted deposition
material solidifies on the substrate and forms an organic
semiconducting layer; forming an insulating layer on the organic
semiconducting layer; and forming a gate contact on the insulating
layer. It is also possible to form the source, drain, and/or gate
contacts as well as the insulating layer by the phase-change
printing or spray technique. This has the advantage that the whole
device can be fabricated by the presently disclosed process.
[0023] Although the present invention is applicable in a broad
variety of applications it will be described with the focus put on
an application to an organic electroluminescent device, i.e. an
organic light-emitting device (OLED) and a field-effect transistor,
but first general issues and the process is addressed. Within the
description, the same reference numbers are used to denote the same
parts or the like.
[0024] FIG. 1 illustrates a phase diagram of a one-component
system. In a conventional physical vapor deposition process the
solid material is usually heated at a reduced pressure to a
temperature above the respective sublimation temperature to
vaporize the material (arrow labeled with a). When the solid
material is heated at a pressure above the triple point then the
solid changes into liquid phase at the respective fusion point
(arrow labeled with b). In the depicted example for Anthracene the
triple point temperature is 489K, the fusion temperature at normal
pressure is 490K. The phase diagram of two and more-component
systems is by far more complex. The principle of changing from
solid to liquid phase is still applicable.
[0025] FIGS. 2a-c illustrate steps for forming a pattern on a
surface 10 by deposition of a deposition material 20. For the sake
of simplicity, the figure is simplified to a droplet. Two or more
thereof are contemplated to form a pattern and multiple a layer.
FIG. 2a illustrates the deposition material 20. As indicated by the
arrow and the letters T, P, the deposition material 20 is heated
and a pressure is applied within a pressure chamber (not shown) to
form a melt. The melted deposition material 21 is illustrated in
FIG. 2b. Then, as indicated in FIG. 2c, the melted deposition
material 21 is deposited on the surface 10 by a phase-change
printing or spraying technique. Thereby the melted deposition
material 21 solidifies instantaneously when it reaches the surface
10. The melted deposition material 21 can be deposited via piezo
elements (not shown). Finally, as indicated in FIG. 2c, the
solidified deposition material 20 remains on the surface 10. In
order to deposit multiple or various layers of the deposition
material 20 or different deposition materials, the process steps
are repeated. The deposition material 20 can also be mixed with
other materials or may 16 comprise of two or more components. In
the FIGS. 2a-c, the symbols "o" illustrate the components of the
deposition material 20 in solid form whilst the symbols "-"
illustrate the components of the deposition material 20 in melted
form.
[0026] The FIGS. 3a to 3c show a schematic illustration of the
formation of an organic light-emitting device (OLED). In at least
some instance the OLED includes a thin layer, or layers, of
suitable organic materials sandwiched between a cathode and an
anode. One suitable example of the OLED is illustrated in FIG. 3a.
On a suitable surface of a substrate 100, a first electrode (anode)
102 (metal, ITO, conductive polymer) is provided either by
conventional methods, like PVD, CVD, spin coating or sputtering, or
by the phase-change printing technique. The substrate 100 can be
made of glass, silicon, polymer, or a combination thereof or might
even be a pre-patterned thin-film transistor array. The OLED
further comprises a hole transport layer 106 and an electron
transport/emitter layer 110' and a second electrode (cathode) 112
(metal).
[0027] Other OLED multi-layer devices may include further layers as
depicted in FIG. 3b. Besides the hole transport layer 106 a hole
injection layer 104 may be included. The combined electron
transport/recombination layer could be separated into an electron
transport layer 110 and an emission layer 108. All of those layers
can be blends of several materials in particular the emission layer
could be a blend of one or several host and dye materials. Thus,
such multi-layer OLEDs can be formed on the suitable surface by
consecutive casting of individual layers by the phase-change
printing or spraying technique described with reference to the
FIGS. 2a-c and FIG. 5.
[0028] A display can be formed as illustrated in FIG. 3c. Red 302,
green 304, and blue 306 OLED pixels may be printed on a receptor
substrate 300 by phase-change printing or spraying technique.
Alternatively, the red, green and blue OLEDs could be printed on
top of each other to create a multicolor stacked OLED device.
[0029] One example of the formation of a field-effect transistor is
illustrated in FIG. 4. Two electrical contacts named source and
drain 402 are formed on the surface of an insulating substrate 400
that can comprise glass, silicon, polymer, or a combination
thereof. The source and drain 402 can be formed by conventional
techniques, e.g. PVD, CVD, sputtering, etc., but source and drain
402 can also be formed by phase-change printing or spraying.
Further, an organic semiconducting layer 404 is applied by
phase-change printing or spraying between source and drain contacts
and overlapping these contacts 402. Pentacene or
alpha-sexithiophene can here be used as organic molecules for the
deposition material. An insulating layer 406 is then formed over
the semiconducting layer 404, thereby the insulating layer 406 can
comprise highly insulating materials such as tetrafluorethylen or
vinylidenedifluoride derivatives. The polymers thereof are known as
Teflon or PVDF (Teflon is a trademark of E.I. Du Pont de Nemours
& Company). Finally, a third electrode 408, the gate electrode,
is formed on top of the insulating layer 406. The third electrode
408 can be formed like the source and drain 402 and also may
comprise nanoparticles of gold. The phase-change printing or
spraying technique can be applied to all or several layers of the
field-effect transistor. In fact, one printer with various
containers each filled with the respective application or
deposition materials can be used to produce a complete device, like
the above-described OLED or thin-film transistor.
[0030] FIG. 5 illustrates the phase-change printing principle with
its units. The simplified illustration shows a print-head 40 that
comprises a pressure chamber 42 with the deposition material 20
filled in. Further, the print-head 40 comprises material jets 46
which work, for example, with piezo elements or nozzles (not shown
in detail) to eject the melted deposition material 21. The
print-head 40 can be brought close to the surface 10 of a device or
substrate 11. For applying the deposition material 20 to the
surface, either the print-head 40 is moved over the surface 10 or
the print-head 40 is fixed and the substrate 11 with the surface 10
is moved in a way to pattern the surface 10 accordingly. In
operation, via the material jets 46, the melted deposition material
21 is brought to the surface 10 where the melt 21 solidifies
immediately and the solidified deposition material 20 remains. In a
further embodiment, a material loader (not shown) containing the
deposition material 20 is positioned close to the print-head 40 or
even form together a single unit. In another embodiment, multiple
of the material loader, each filled with a different deposition
material 20, can be used to support the pressure chamber 42 and the
print-head 40.
[0031] Any disclosed embodiment may be combined with one or several
of the other embodiments shown and/or described. This is also
possible for one or more features of the embodiments. Thus, the
invention includes apparatus providing the steps of any process
described above employing means known to those familiar with the
art.
* * * * *