U.S. patent application number 10/984095 was filed with the patent office on 2006-05-11 for controlling the vaporization of organic material.
This patent application is currently assigned to Eastman Kodak Company. Invention is credited to Michael L. Boroson, Jeremy M. Grace, Bruce E. Koppe, Michael Long, Thomas W. Palone, Neil P. Redden, Jinmei Zhang.
Application Number | 20060099344 10/984095 |
Document ID | / |
Family ID | 35892418 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060099344 |
Kind Code |
A1 |
Boroson; Michael L. ; et
al. |
May 11, 2006 |
Controlling the vaporization of organic material
Abstract
A method for controlling the deposition of vaporized organic
material onto a substrate surface, includes providing a manifold
having at least one aperture through which vaporized organic
material passes for deposition onto the substrate surface; and
providing a volume of organic material and maintaining the
temperature of such organic material in a first condition so that
its vapor pressure is below that needed to effectively form a layer
on the substrate, and in a second condition heating a volume
percentage of the initial volume of such organic material so that
the vapor pressure of the heated organic material is sufficient to
effectively form a layer.
Inventors: |
Boroson; Michael L.;
(Rochester, NY) ; Long; Michael; (Hilton, NY)
; Grace; Jeremy M.; (Penfield, NY) ; Zhang;
Jinmei; (Pittsford, NY) ; Koppe; Bruce E.;
(Caledonia, NY) ; Palone; Thomas W.; (Rochester,
NY) ; Redden; Neil P.; (Sodus Point, NY) |
Correspondence
Address: |
Pamela R. Crocker;Patent Legal Staff
Eastman Kodak Company
343 State Street
Rochester
NY
14650-2201
US
|
Assignee: |
Eastman Kodak Company
|
Family ID: |
35892418 |
Appl. No.: |
10/984095 |
Filed: |
November 9, 2004 |
Current U.S.
Class: |
427/255.6 ;
118/726; 427/66 |
Current CPC
Class: |
C23C 14/12 20130101;
C23C 14/542 20130101; H01L 51/001 20130101; C23C 14/246
20130101 |
Class at
Publication: |
427/255.6 ;
427/066; 118/726 |
International
Class: |
B05D 5/06 20060101
B05D005/06; C23C 16/00 20060101 C23C016/00 |
Claims
1. A method for controlling the deposition of vaporized organic
material onto a substrate surface, comprising: a) providing a
manifold having at least one aperture through which vaporized
organic material passes for deposition onto the substrate surface;
b) providing a volume of organic material and maintaining the
temperature of such organic material in a first condition so that
its vapor pressure is below that needed to effectively vaporize and
form a layer on the substrate, and in a second condition heating a
volume percentage of the initial volume of such organic material so
that the vapor pressure of the heated organic material causes such
material to vaporize and pass through the aperture in the manifold
to form a layer on the substrate surface; and c) providing a
rotatable auger and metering by using such auger the organic
material from the position where such organic material is in the
first condition to the position where it is in the second condition
to control the rate of vaporization.
2. The method of claim 1 wherein heating the volume percentage of
the initial volume of organic material includes applying radiation
onto an exposed surface of the organic material.
3. The method of claim 1 further providing a heating device that
heats organic material to be in the second condition and stopping
the vaporization by separating the heating device from the organic
material.
4. The method of claim 1 further including heating the volume
percentage of the initial volume by providing a permeable heating
element in a temperature-controlled region and using such heated
permeable heating element to vaporize organic material adjacent to
such permeable heating element so that the vaporized organic
material passes through the permeable heating element and into the
manifold and out through the manifold aperture.
5. (canceled)
6. Apparatus for controlling the vaporization of organic materials
in a vaporization source onto a substrate surface, which comprises:
a) first heating means for heating the organic material in a first
temperature-controlled region until it is at a temperature below
the vaporization temperature of the organic material; b) second
heating means for heating the organic material above the
vaporization temperature in a second temperature-controlled region;
c) means for metering the organic material from the first
temperature-controlled region to the second temperature-controlled
region, whereby organic material vaporizes and forms on the
substrate surface; and d) means for controlling the temperature
applied at the second temperature-controlled region.
7. The apparatus of claim 6 wherein the temperature controlling
means includes means for separating the second heating device from
the organic material, or means for decreasing the heat provided by
the second heating device applied to the organic material, or
both.
8. The apparatus of claim 6 wherein the second heating device
includes a permeable heating element.
9. The apparatus of claim 6 wherein the second heating device
includes means for applying radiation onto a surface of the organic
material in the second temperature controlled region.
10. The method of claim 1 wherein during vaporization, less than
10% of the provided volume of organic material is heated to the
second condition.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly assigned U.S. patent
application Ser. No. 10/805,847, filed Mar. 22, 2004, entitled
"High Thickness Uniformity Vaporization Source" by Long et al, U.S.
patent application Ser. No. 10/945,940, filed Sep. 21, 2004,
entitled "Delivering Organic Powder to a Vaporization Zone" by Long
et al and U.S. patent application Ser. No. 10/______ filed
concurrently herewith, entitled "Controlling the Vaporization of
Organic Material" by Boroson et al the disclosures of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of physical vapor
deposition where a source material is heated to a temperature so as
to cause vaporization and create a vapor plume to form a thin film
on a surface of a substrate.
BACKGROUND OF THE INVENTION
[0003] Physical vapor deposition in a vacuum environment is a
commonly used way of depositing thin organic material films, for
example in small molecule OLED devices. Such methods are well
known, for example Barr in U.S. Pat. No. 2,447,789 and Tanabe et
al. in EP 0 982 411. The organic materials are often subject to
degradation when maintained at or near the desired rate-dependent
vaporization temperature for extended periods of time. Exposure of
sensitive organic materials to higher temperatures can cause
changes in the structure of the molecules and associated changes in
material properties.
[0004] The organic materials used in OLED devices have a highly
non-linear dependence of vaporization rate on source temperature. A
small change in source temperature leads to a very large change in
vaporization rate. Despite this, prior art devices employ source
temperature as the only way to control vaporization rate. To
achieve good temperature control, prior art deposition sources
typically utilize heating structures whose solid volume is much
larger than the organic charge volume, composed of high
thermal-conductivity materials that are well insulated. The high
thermal conductivity insures good temperature uniformity through
the structure and the large thermal mass helps to maintain the
temperature within a critically small range by reducing temperature
fluctuations. These measures have the desired effect on
steady-state vaporization rate stability but have a detrimental
effect at start-up. It is common that these devices must operate
for long periods of time (e.g. 2-12 hours) at start-up before
steady state temperature distribution and hence a steady
vaporization rate is achieved. It is also common that these devices
also require long times to cool down, and thus significant amounts
of organic material, some of which can be expensive or difficult to
synthesize, can be lost. Furthermore the steady state slowly drifts
as material is consumed from the sources, and input power must be
changed (in order to alter the temperature distribution) to
maintain a constant vaporization rate.
[0005] The current method to minimize material time at high
temperature and to maximize machine operation time by minimizing
the start-up and cool-down times of the material-containing sources
requires using duplicate sources of the same material sequentially.
For example, rather than using one source continuously for eight
days, two sources can be used for four days each or eight sources
can be used in a serial process for one day each by overlapping the
start-up and cool-down times. Duplicate sources, however, increase
equipment size and cost, especially if the number of duplicate
sources or the number of materials that require duplicate sources
is large.
[0006] Forrest et al. (U.S. Pat. No. 6,337,102 B1) disclose a
method for vaporizing organic materials and organic precursors and
delivering them to a reactor vessel wherein the substrate is
situated, and delivery of the vapors generated from solids or
liquids is accomplished by use of carrier gases. The organic
materials are held at a constant temperature that is high enough to
saturate the incoming carrier gas at all possible flow rates.
Deposition rate is controlled by adjusting the carrier-gas flow
rate. In one embodiment of their invention, Forrest et al. locate
the substrates within a suitably large reactor vessel, and the
vapors carried thereto mix and react or condense on the substrate.
Another embodiment of their invention is directed towards
applications involving coating of large area substrates and putting
several such deposition processes in serial fashion with one
another. For this embodiment, Forrest et al. disclose the use of a
gas curtain fed by a gas manifold (defined in the disclosure as
"hollow tubes having a line of holes") in order to form a
continuous line of depositing material perpendicular to the
direction of substrate travel.
[0007] One major problem in the approach disclosed by Forrest et
al. is that all of the materials are continuously heated in high
thermal mass systems to maintain tight temperature control. This
exposure to high temperatures for extended periods of time
increases the likelihood of degradation of some materials in the
same way as the methods taught by Barr and Tanabe et al. Another
problem in the approach disclosed by Forrest et al. is that
cool-down and start-up times to reload material are long, due to
the high thermal mass of the system and the requirement that all
materials be at a uniform temperature before starting the carrier
gas flow.
[0008] Also known in the art are systems such as taught by Hoffman
et al. of Applied Films GmbH & Co. in their paper from the
Society for Information Display 2002 International Symposium, SID
Digest 02 pp. 891-893. These systems combine large heated remote
sources similar to the type used by Barr and Tanabe et al. with
manifolds to distribute the material vapor. These systems suffer
from the same problems as the methods taught by Barr, Tanabe et
al., and Forrest et al. with respect to material degradation, due
to long term exposure to high temperatures and long cool-down and
start-up times due to the high thermal mass of the heating
system.
[0009] The approaches to vapor delivery as disclosed by Forrest et
al. and Hoffman et al. can be characterized as "remote
vaporization" wherein a material is converted to vapor in an
apparatus external to the deposition zone and more likely external
to the deposition chamber. Organic vapors, alone or in combination
with carrier gases, are conveyed into the deposition chamber and
ultimately to the substrate surface. Great care must be taken using
this approach to avoid unwanted condensation in the delivery lines
by use of appropriate heating methods. This problem becomes even
more critical when contemplating the use of inorganic materials
that vaporize to the desired extent at substantially higher
temperatures. Furthermore, the delivery of the vaporized material
for coating large areas uniformly requires the use of gas
manifolds.
[0010] Current remote-vaporization methods suffer from the problems
of long material exposure to high temperatures and start-up and
cool-down delays due to high thermal mass heating systems; however,
these systems have some advantages over the methods taught by Barr
and Tanabe et al. with respect to coating uniformity and control of
instantaneous deposition rates. Although these remote vaporization
methods can stop deposition fairly quickly by closing valves for
the carrier gases in the method of Forrest et al. or for the
organic vapors in the method of Hoffman et al., the organic vapors
and carrier gases downstream of the valves will continue to exit
the manifold until the manifold pressure drops to the deposition
chamber pressure. Likewise this method can start deposition fairly
quickly but organic vapors and carrier gases will not reach steady
state deposition rates until the manifold has reached steady state
pressure. This is a problem due to remote vaporization combined
with structures, such as valves, to control the flow of organic
vapors that are also remote from and not contiguous to the
manifold. These remote structures do not quickly control the
passage of organic material through the manifold apertures,
resulting in delays in starting and stopping deposition. Remote
vaporization systems with remote valves do not resolve the
significant issue of long start-up and cool-down times for loading
fresh material, due to the high thermal mass of these systems, nor
do they resolve the major issue of material degradation due to
extended exposure to high temperature in these systems.
[0011] Furukawa et al., in Japanese Unexamined Patent Application
9-219289, disclose a method of forming an organic thin-film
electroluminescent element by a flash vapor deposition method.
While this method can start and stop quickly, it cannot be run as a
continuous process as taught by Furukawa et al. The organic
material is dropped onto a heated plate. Furakawa is silent on the
nature of the powder delivery system, and how it assures that the
desired quantity of powder is actually dropped on the heated plate,
and therefore how vaporization rate, the deposited film thickness,
and thickness uniformity are controlled. Also unclear is how the
powder delivery system, with a temperature below the condensation
temperature of the just-created vapor, is prevented from acting as
a cold finger upon which a portion of the just-created vapor
condenses.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the present invention to
achieve physical vapor deposition at a steady state with short
start and stop times. It is a further object that the vapor
deposition can be run continuously and in any orientation. It is a
further object to minimize the heat-promoted degradation of organic
materials without resorting to large numbers of duplicate sources.
It is a further object to minimize the start-up and cool-down times
for reloading materials without resorting to duplicate sources.
[0013] This object is achieved by a method for controlling the
deposition of vaporized organic material onto a substrate surface,
comprising:
[0014] a) providing a manifold having at least one aperture through
which vaporized organic material passes for deposition onto the
substrate surface; and
[0015] b) providing a volume of organic material and maintaining
the temperature of such organic material in a first condition so
that its vapor pressure is below that needed to effectively form a
layer on the substrate, and in a second condition heating a volume
percentage of the initial volume of such organic material so that
the vapor pressure of the heated organic material is sufficient to
effectively form a layer.
[0016] It is an advantage of the present invention that the
deposition of organic material vapors can be started and stopped in
a matter of seconds to achieve a steady vaporization rate quickly.
This feature minimizes contamination of the deposition chamber
walls and conserves the organic materials when a substrate is not
being coated.
[0017] It is another advantage of the present invention that the
device overcomes the heating and volume limitations of prior art
devices in that only a small portion of organic material is heated
to the desired rate-dependent vaporization temperature at a
controlled rate. It is therefore a feature of the present invention
to maintain a steady vaporization rate with a large charge of
organic material and with a steady heater temperature. The device
permits extended operation of the source with substantially reduced
risk of degrading even very temperature-sensitive organic
materials. This feature additionally permits materials having
different vaporization rates and degradation temperature thresholds
to be co-sublimated in the same source. This feature additionally
permits short material-reloading times due to the low thermal mass
of the heated material.
[0018] It is a further advantage of some embodiments of the present
invention that it permits finer rate control and additionally
offers an independent measure of the vaporization rate.
[0019] It is a further advantage of some embodiments that the
present device achieves substantially higher vaporization rates
than in prior art devices without material degradation. Further
still, no heater temperature change is required as the source
material is consumed.
[0020] It is a further advantage of some embodiments of the present
invention that it can provide a vapor source in any orientation,
which is not possible with prior-art devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows a cross-sectional view of an apparatus for
controlling the vaporization of organic material in a vaporization
source onto a substrate surface in accordance with this
invention;
[0022] FIG. 2 shows a cross-sectional view of the above apparatus
in a configuration for controlling the vaporization of organic
material in accordance with this invention;
[0023] FIG. 3 shows a cross-sectional view of another apparatus for
controlling the vaporization of organic material in a vaporization
source onto a substrate surface in accordance with this
invention:
[0024] FIG. 4 shows a cross-sectional view of an apparatus for
controlling the deposition of vaporized organic material onto a
substrate surface from a vaporization source in accordance with
this invention;
[0025] FIG. 5 shows a schematic view of another apparatus for
controlling the deposition of vaporized organic material onto a
substrate surface from a vaporization source in accordance with
this invention;
[0026] FIG. 6 shows a schematic view of another apparatus for
controlling the deposition of vaporized organic material onto a
substrate surface from a vaporization source in accordance with
this invention;
[0027] FIG. 7a shows a cross-sectional view of another apparatus in
a closed configuration for controlling the deposition of vaporized
organic material onto a substrate surface from a vaporization
source in accordance with this invention;
[0028] FIG. 7b shows a cross-sectional view of the above apparatus
in an open configuration; and
[0029] FIG. 8 shows a cross-sectional view of another apparatus in
an open configuration for controlling the deposition of vaporized
organic material onto a substrate surface from a vaporization
source in accordance with this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Turning now to FIG. 1, there is shown a cross-sectional view
of an apparatus for controlling the deposition of vaporized organic
material onto a substrate surface by controlling the vaporization
of organic material in a vaporization source onto a substrate
surface in accordance with this invention. Apparatus 10 is a
vaporization source and includes an initial volume of organic
material 20 and a metering device 60 for advancing organic material
20 in a controlled manner from first temperature-controlled region
30 to second temperature-controlled region 50. Metering device 60
can be e.g. an auger screw or a similar auger structure. Such
metering device, and a way of providing a volume of organic
material to them, have previously been described by Long et al. in
above-cited commonly assigned U.S. patent application Ser. No.
10/945,940, the disclosure of which is incorporated by reference.
First temperature-controlled region 30 can be a region of high
thermal mass, e.g. a large base, and can include such materials as
metals and ceramics to maintain organic material 20 at a desired
temperature below its vaporization temperature. First
temperature-controlled region 30 can be heated or cooled as needed
and includes a first heating device, which can be any well-known
heating device, e.g. heating coil, induction heating,
heating/cooling tubes, and the like. The first heating device is
not shown for clarity. First temperature-controlled region 30 is
heated to and maintained below the vaporization temperature of
organic material 20.
[0031] The vaporization temperature is defined as the lowest
temperature wherein the vapor pressure of organic material 20 is
sufficient to effectively form a layer of organic material on a
substrate. By effectively we mean at a practical manufacturing
rate. Because the vapor pressure of a material is a continuous
function with respect to temperature, at any non-zero absolute
temperature, the material has a non-zero vapor pressure. The above
definition of vaporization temperature is useful for describing
operating conditions and relative temperatures of various regions
within a practical deposition device.
[0032] A related matter is that of the condensation temperature. At
a given partial pressure of material, the material vapor will
condense onto a surface held at or below a measurable temperature.
This temperature is defined as the condensation temperature and
depends on the partial pressure of the material vapor.
[0033] Apparatus 10 also provides a manifold, a portion of which is
shown by manifold walls 80. The manifold includes one or more
apertures through which the vaporized organic material will pass
for deposition onto a substrate surface. Long et al. have discussed
examples of suitable manifolds in above cited, commonly assigned
U.S. patent application Ser. No. 10/805,847, the disclosure of
which is incorporated by reference. The manifold can also consist
of a single-aperture heated-wall structure similar to the type
commonly referred to as point sources.
[0034] Second temperature-controlled region 50 is the region from
the end of first temperature-controlled region 30 to a second
heating device 40. Second heating device 40 can be a heating
element that has a very low thermal mass as seen by organic
material 20. Such heating elements include permeable heating
elements such as wire mesh screens and reticulated porous
structures including fine ligaments, and can be heated by
induction, RF energy, or by conducting a current along its length.
Second heating device 40 heats organic material 20 above its
vaporization temperature in second temperature-controlled region
50, so that the vapor pressure of the heated organic material is
sufficient to effectively form a layer on a substrate and the
organic material adjacent to the permeable heating element
vaporizes and is released into the manifold. Organic material 20 is
metered at a predetermined controlled rate to second
temperature-controlled region 50 so that organic material 20 is
vaporized by heat at a controlled rate and the vaporized organic
material passes through the permeable heating element, that is,
second heating device 40, into the manifold and out through the
manifold apertures. In this embodiment the second heating device 40
is shown inside the manifold, but for embodiments where the second
heating device 40 is contiguous to the manifold, the second heating
device 40 can be outside the manifold as long as the volume of the
connection between the second heating device 40 and the manifold is
small relative to the internal volume of the manifold. For
embodiments where the heating device is distant from the manifold,
the volume of the connection is not important as long as the
connection is maintained above the condensation temperature of the
vaporized organic material.
[0035] In practice, the vaporization of organic material 20 can be
controlled by controlling the metering of organic material 20, or
by controlling the temperature applied to organic material 20 at
second temperature-controlled region 50, or both. A controller for
controlling the temperature at second temperature-controlled region
50 and reduces a potential and thereby applies a current to second
heating device 40, that reduces the RF energy applied to second
heating device 40, and separates second heating device 40 and
organic material 20. In order to separate second heating device 40
and organic material 20 a mechanical structure is provided for
moving second heating device 40 away from organic material 20, and
reversing the metering device that feed organic material 20 to
second heating device 40. In a first condition, the temperature of
organic material 20 is maintained below that needed to effectively
form a layer on the substrate, that is, below the vaporization
temperature. In a second condition, a small volume percentage of
the initial volume of organic material 20 adjacent to second
heating device 40 (that is, the portion between first
temperature-controlled region 30 and second heating device 40) is
heated above the vaporization temperature so that the vapor
pressure of the heated organic material is sufficient to
effectively form a layer on a substrate placed near the apertures
of the manifold. FIG. 1 is in the second condition when second
heating device 40 is heated as described above. Thus, all organic
material is contained in a single source while only a small volume
percentage (less than 10%) of the initial volume of organic
material is heated to the vaporization temperature at any time.
This reduces the likelihood of material degradation.
[0036] To rapidly reduce the vaporization of organic material 20,
apparatus 10 is put into the first condition. This can be achieved
by decreasing the heat from second heating device 40 (e.g. by
reducing a potential applied to it so as to reduce the current
through it), or by separating second heating device 40 from organic
material 20, or both. FIG. 2 shows a cross-sectional view of the
above apparatus 10 where heating device 40 has been moved away from
organic material 20 so that apparatus 10 is in the first condition
and organic material is not being vaporized. Alternatively, heating
device 40 can be stationary and organic material 20 can be moved
away from the heating device, e.g. by reversing metering device 60.
This can change the vaporization rate from greater than 90% of the
maximum rate to less than 10% of the maximum rate in less than 5
minutes, and times less than 3 seconds can be achieved. One can
also cool organic material 20, e.g. by cooling first
temperature-controlled region 30. One can use any combination of
these techniques to quickly reduce the vaporization rate of organic
material 20.
[0037] The ability to reduce the vaporization rate quickly is
attained by several features of this invention that provide a
thermal time constant of the vaporization process on the order of
one second. Heating device 40 is thin and thus has a low thermal
mass in contact with organic material 20. Metering device 60 feeds
organic material 20 in the shape of a thin cylinder, such that
organic material 20 has a small cross-sectional area in second
temperature-controlled region 50, but has a much larger area in
contact with first temperature-controlled region 30, which can act
as a heat sink.
[0038] Turning now to FIG. 3, there is shown a cross-sectional view
of another apparatus for controlling the vaporization of organic
material in a vaporization source onto a substrate surface in
accordance with this invention, showing an alternative way of
applying heat to organic material 20. Focused radiation 70 is
applied onto an exposed surface of organic material 20 and heats a
small volume percentage of the initial volume of organic material
20 to vaporization in the second condition of apparatus 10. Thus,
all organic material is contained in a single source while only a
small volume percentage (less than 10%) of the initial volume of
organic material is heated to the vaporization temperature at any
time. This reduces the likelihood of material degradation.
Radiation 70 can be applied by a microwave device, an infrared
device, or the like. In the first condition, radiation 70 is turned
off. Radiation 70 can be turned off or on in a fraction of a
second, thus stopping or starting vaporization of organic material
20 in a matter of seconds. Thus this method can rapidly control the
application of vaporized organic material onto a substrate surface
by rapidly controlling the vaporization of the organic material 20
in the vaporization source.
[0039] Turning now to FIG. 4, there is shown a cross-sectional view
of an apparatus for controlling the deposition of vaporized organic
material onto a substrate surface from a vaporization source in
accordance with this invention. Apparatus 100 is a vaporization
source that includes manifold 110 for containing a quantity of
vaporized organic material. Manifold 110 includes one or more
apertures 150 through which the vaporized organic material passes
for deposition onto the surface of substrate 160. Substrate 160 can
be moved in direction 170 so as to sequentially coat the entire
substrate surface. Apparatus 100 further includes organic material
120 and heating device 130, for example radiant heaters, to heat a
portion of organic material 120 above its vaporization temperature.
Although apparatus 100 is shown with a charge of organic material
120, it can be constructed instead to meter organic material into
manifold 10 and heat the metered materials, for example by an auger
structure and permeable heating element, as shown in other
embodiments of this invention. Thus, all organic material is
contained in a single source while only a small volume percentage
(less than 10%) of the initial volume of organic material is heated
to the vaporization temperature at any time. This reduces the
likelihood of material degradation.
[0040] Apparatus 100 further provides hollow member 140 positioned
in manifold 110 in the flow path of vaporized organic material.
Hollow member 140 is a structure operating independently of heating
device 130 and is effective in a first condition for limiting the
passage of vaporized organic material through apertures 150, and
effective in a second condition for facilitating the passage of
organic material through aperture 150. The outside surface of
hollow member 140 is a temperature-control surface, by which we
mean that the temperature of the outside surface of hollow member
140 and thereby its immediate surroundings can be controlled by
temperature-controlling material (e.g. refrigerant fluid such as
chlorofluorocarbons) that can be delivered at a controlled
temperature through the interior of hollow member 140 by a
structure for delivering such temperature-controlling material
(e.g. a pump or compressor) so as to absorb heat from or deliver
heat to hollow member 140. In a first condition, hollow member 140
is cooled so as to cause the deposition of vaporized organic
material onto the surface of hollow member 140 and not onto the
surface of substrate 160. Under these conditions, organic material
does not escape apertures 150, and therefore is not deposited on
the surface of substrate 160. In a second condition, hollow member
140 is held at approximately the same temperature as the bulk of
the interior of manifold 110, and hollow member 140 is effective so
as to minimally affect the flow of vaporized organic material to
apertures 150 and thereby to the surface of substrate 160.
Additional control can be attained by decreasing the heat from
heating device 130 when hollow member 140 is effective in its first
condition and increasing the heat from heating device 130 when
hollow member 140 is effective in its second condition.
[0041] Turning now to FIG. 5, there is shown a schematic view of
another apparatus for controlling the deposition of vaporized
organic material onto a substrate surface from a vaporization
source in accordance with this invention. A quantity of organic
material is provided into apparatus 200, which is a vaporization
source. Organic material can be provided by metering device 230,
such as an auger structure as already described. It will be
understood that in other embodiments the organic material can also
be provided in a bulk charge, of which only a portion is heated to
the vaporization temperature at a given time as described above, or
vaporized organic material can be provided from heating device
distant from the vaporization source. In the latter case, the
connection between the vaporization source is maintained above the
condensation temperature of the vaporized organic material. In this
embodiment heat from heating device 240 is applied to the organic
material, for example by using an auger structure to move the
organic material to a permeable heated element. Thus, all organic
material is contained in a single source while only a small volume
percentage (less than 10%) of the initial volume of organic
material is heated to the vaporization temperature at any time.
This reduces the likelihood of material degradation. The organic
material is vaporized by heating device 240 into manifold 210 and
thereby out apertures 220, to be deposited on the surface of
substrate 160 placed close to apertures 220 on the outside of
manifold 210. Apparatus 200 is so constructed that the conductance
of organic vapors in manifold 210 is rapid while the conductance of
organic vapors through apertures 220 is slower. Flow path 260 and
valve 250 represent a structure that can be contiguous to or
distant from the manifold 210, that operates independently of
heating device 240, and that is effective in a first condition for
limiting the passage of vaporized organic material through
apertures 220, and effective in a second condition for facilitating
the passage of organic material through apertures 220. The flow of
vaporized organic material can be rapidly diverted from manifold
210 to a first flow path 260 by opening valve 250. In the first
condition, first flow path 260 is opened by opening valve 250 so
that vaporized organic material is not deposited on the surface of
substrate 160. In the second condition, valve 250 is closed so as
to allow organic material to be deposited on substrate 160. The
deposition of vaporized organic material on the surface of
substrate 160 can be rapidly started and stopped.
[0042] Turning now to FIG. 6, there is shown a schematic view of
another apparatus for controlling the deposition of vaporized
organic material onto a substrate surface from a vaporization
source in accordance with this invention. A quantity of organic
material is provided into apparatus 270, which is a vaporization
source. Apparatus 270 includes manifold 210 with one or more
apertures 220, a device for heating the organic material either
contiguous to or distant from the manifold above the vaporization
temperature of the organic material, a reservoir 310, a structure
for defining a flow path 290 connecting reservoir 310 to manifold
210, and another structure connects flow path 290 to reservoir 310
so that the pressure of vaporized organic material in manifold 210
can be reduced. These will be described in further detail. Organic
material can be provided by metering device 230, such as an auger
structure as already described. It will be understood that the
organic material can also be provided in a bulk charge, of which
only a portion is heated to the vaporization temperature at a given
time, as described above. Heat from heating device 240 is applied
to the organic material, for example by using an auger structure to
move the organic material to a permeable heating element. Thus, all
organic material is contained in a single source while only a small
volume percentage (less than 10%) of the initial volume of organic
material is heated to the vaporization temperature at any time.
This reduces the likelihood of material degradation. The organic
material is vaporized by heating device 240 into manifold 210 and
thereby out apertures 220, to be deposited on the surface of
substrate 160 placed close to apertures 220 on the outside of
manifold 210. Apparatus 270 is so constructed that the conductance
of organic vapors in manifold 210 is rapid while the conductance of
organic vapors through apertures 220 is slower. Flow path 290,
valve 295, reservoir 310, inert gas inlet 280, and valve 285
represent a structure operating independently of heating device 240
and are effective in a first condition for limiting the passage of
vaporized organic material through apertures 220, and effective in
a second condition for facilitating the passage of organic material
through apertures 220. First flow path 290 is provided connected to
manifold 210. Reservoir 310 is provided connectable to first flow
path 290 and can serve to store diverted vaporized organic material
from manifold 210, for example by providing a temperature of
reservoir 310 below the condensation temperature of the diverted
organic material.
[0043] Apparatus 270 also includes an inert gas inlet 280 and a
valve 285 for providing a supply of inert gas, e.g. nitrogen, to
manifold 210. The flow of vaporized organic material can be rapidly
diverted from manifold 210 to a first flow path 290 by opening
valve 295. In the first condition, first flow path 290 is opened by
opening valve 295, and a supply of inert gas is supplied through
inert gas inlet 280 to manifold 210 by opening valve 285, so that
vaporized organic material is delivered to reservoir 310. This can
rapidly sweep the vaporized organic material from the interior of
manifold 210. In the second condition, valves 285 and 295 are
closed, closing first flow path 290 to reservoir 310, so as to
allow organic material to be deposited on substrate 160. The
deposition of vaporized organic material on the surface of
substrate 160 can be rapidly started and stopped. One advantage of
this apparatus is that it is not necessary to turn off heat source
240 to stop the flow of organic material to an external substrate.
Thus, when one is ready to restart coating of an external
substrate, one can simply close valves 285 and 295 and rapidly
refill manifold 210 with organic material vapors.
[0044] Turning now to FIGS. 7a and 7b, there is shown a
cross-sectional view of an apparatus for controlling the deposition
of vaporized organic materials onto a substrate surface from a
vaporization source in accordance with this invention. Apparatus
300 is a vaporization source that includes manifold 110 for
containing a quantity of vaporized organic material. Manifold 110
includes one or more apertures 150 through which the vaporized
organic material passes for deposition onto the surface of
substrate 160. Substrate 160 can be moved in direction 170 so as to
sequentially coat the entire surface of substrate 160. Apparatus
300 further includes organic material 120 and heating device 130,
for example radiant heaters, to heat a portion of organic material
120 above its vaporization temperature. Although apparatus 300 is
shown with a charge of organic material 120, it can be constructed
to meter organic material into manifold 110 and heat the metered
materials, for example by an auger structure and permeable heating
element, as shown in other embodiments of this invention. Thus, all
organic material is contained in a single source while only a small
volume percentage (less than 10%) of the initial volume of organic
material is heated to the vaporization temperature at any time.
This reduces the likelihood of material degradation.
[0045] Vaporization apparatus 300 also includes movable element 330
contiguous to the manifold. Movable element 330 is a structure
operating independently of heating device 130 and is effective in a
first condition for limiting the passage of vaporized organic
material through apertures 150, and effective in a second condition
for facilitating the passage of organic material through apertures
150. In a first position, shown in FIG. 7a, element 330 limits the
flow of vaporized organic material through apertures 150. Under
these conditions, vaporized organic material does not escape
apertures 150, and therefore does not deposit on the surface of
substrate 160. In a second position, shown in FIG. 7b, movable
element 330 permits the flow of vaporized organic material through
apertures 150 when it is desired to coat substrate 310. Additional
control can be attained by decreasing the heat from heating device
130 when movable element 330 is effective in its first condition
and increasing the heat from heating device 130 when movable
element 330 is effective in its second condition.
[0046] Turning now to FIG. 8, there is shown a cross-sectional view
of another apparatus for controlling the deposition of vaporized
organic material onto a substrate surface from a vaporization
source in accordance with this invention. Apparatus 350 is a
vaporization source similar to apparatus 300 above, except that it
includes an internal movable element 340 in manifold 110. Movable
element 340 can be moved via mechanics internal to manifold 110 or
via a baffle manipulator that is partly outside of manifold 110.
Movable element 340 can be moved into a position wherein it
obstructs apertures 150 and thereby blocks the flow of organic
materials through the apertures.
[0047] In addition to a single movable element, one can also use a
multiplicity of movable elements in a micro-electromechanical
system (MEMS), wherein each individual aperture 150 has its own
movable element to limit the flow of vaporized organic material.
Such a MEMS system can include pistons, plungers, bimetallic
ribbons, etc.
[0048] It is to be understood that movable elements as shown in
these embodiments differ from the use of shutters as practiced in
the prior art. Shutters that have been used to prevent the coating
of a substrate are used to provide a block to the flow of vaporized
organic material to the substrate. However, vaporization of the
organic material continues unreduced, material vapor continues to
leave the source region (i.e. effuses) and is deposited on the
shutter and other surfaces not protected by the shutter. In this
invention, the movable elements block the apertures through which
the vaporized organic material is released to deposit onto the
substrate, and thereby reduce the rate of effusion of material from
the source region, while maintaining the operating pressure
therein.
[0049] The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
PARTS LIST
[0050] 10 apparatus [0051] 20 organic material [0052] 30 first
temperature-controlled region [0053] 40 heating device [0054] 50
second temperature-controlled region [0055] 60 metering device
[0056] 70 radiation [0057] 80 manifold wall [0058] 100 apparatus
[0059] 110 manifold [0060] 120 organic material [0061] 130 heating
device [0062] 140 hollow member [0063] 150 aperture [0064] 160
substrate [0065] 170 direction [0066] 200 apparatus [0067] 210
manifold [0068] 220 aperture [0069] 230 metering device [0070] 240
heating device [0071] 250 valve [0072] 260 flow path [0073] 270
apparatus [0074] 280 inert gas inlet [0075] 285 valve [0076] 290
flow path [0077] 295 valve [0078] 300 apparatus [0079] 310
reservoir [0080] 330 element [0081] 340 element [0082] 350
apparatus
* * * * *