U.S. patent application number 10/624311 was filed with the patent office on 2005-01-27 for thermal physical vapor deposition source using pellets of organic material for making oled displays.
This patent application is currently assigned to Eastman Kodak Company. Invention is credited to Carlton, Donn B., Ghosh, Syamal K., Klug, Justin H..
Application Number | 20050016461 10/624311 |
Document ID | / |
Family ID | 33541437 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016461 |
Kind Code |
A1 |
Klug, Justin H. ; et
al. |
January 27, 2005 |
THERMAL PHYSICAL VAPOR DEPOSITION SOURCE USING PELLETS OF ORGANIC
MATERIAL FOR MAKING OLED DISPLAYS
Abstract
A thermal physical vapor deposition source for vaporizing
compacted pellets of organic materials onto a surface of a
substrate in forming a display, including a housing defining a
plurality of spaced passages each for receiving compacted pellets,
a cover plate over the housing, with a first plurality of openings
corresponding to the spaced passages of the housing and an
electrical heater structure disposed over the cover plate. The
thermal physical vapor deposition source further including an
aperture plate, disposed over the electrical heater structure, an
electrically insulating spacer member located between the
electrical heater structure and an aperture plate, and circuitry
for applying current to the electrical heater structure to produce
heat sufficient to vaporize the pellets and permit vapor efflux of
materials to pass through the cover plate, the heater structure,
the electrically insulating spacer member and the aperture plate,
onto the substrate.
Inventors: |
Klug, Justin H.; (Rochester,
NY) ; Ghosh, Syamal K.; (Rochester, NY) ;
Carlton, Donn B.; (Hamlin, NY) |
Correspondence
Address: |
Thomas H. Close
Patent Legal Staff
Eastman Kodak Company
343 State Street
Rochester
NY
14650-2201
US
|
Assignee: |
Eastman Kodak Company
|
Family ID: |
33541437 |
Appl. No.: |
10/624311 |
Filed: |
July 22, 2003 |
Current U.S.
Class: |
118/726 ;
118/723VE |
Current CPC
Class: |
H01L 51/001 20130101;
C23C 14/12 20130101; C23C 14/243 20130101; C23C 14/246 20130101;
C23C 14/26 20130101 |
Class at
Publication: |
118/726 ;
118/723.0VE |
International
Class: |
C23C 016/00 |
Claims
What is claimed is:
1. A thermal physical vapor deposition source for vaporizing
pellets containing organic materials onto a surface of a substrate
in forming a display, comprising: (a) a housing defining a
plurality of spaced passages each for receiving compacted pellets
of organic materials; (b) a cover plate over the housing, with a
first plurality of openings corresponding to the spaced passages of
the housing; (c) an electrical heater structure disposed over the
cover plate; (d) an aperture plate, disposed over the electrical
heater structure and having at least one aperture; (e) an
electrically insulating spacer member located between the
electrical heater structure and engaging the aperture plate, such
electrically insulating spacer member having at least one opening,
corresponding to the first plurality of openings of the cover plate
and the spaced passages of the housing; and (f) means for applying
current to the electrical heater structure to produce heat
sufficient to vaporize the pellets and permit vapor efflux of
materials to pass through the first plurality of openings of the
cover plate, the heater structure, the electrically insulating
spacer member and the apertures of the aperture plate, onto the
substrate.
2. The thermal physical vapor deposition source of claim 1, wherein
the housing includes thermally insulating material.
3. The thermal physical vapor deposition source of claim 1, wherein
the electrical heater structure includes an electrically conductive
heater plate over the cover plate, such heater plate having a
second plurality of openings, each opening of the heater plate
corresponding to a first plurality opening of the cover plate and
corresponding to a spaced passage of the housing.
4. The thermal physical vapor deposition source of claim 1, wherein
the cover plate includes electrically insulating material.
5. The thermal physical vapor deposition source of claim 1, wherein
the electrically insulating spacer member includes electrically
insulating material.
6. The thermal physical vapor deposition source of claim 1, wherein
the aperture plate includes electrically insulated material and is
electrically insulated from the conductive heater plate by the
electrically insulating spacer member.
7. The thermal physical vapor deposition source of claim 1, wherein
different cross-sectional areas of the apertures of the aperture
plate are selected to form different flow rates and patterns of
vapor efflux.
8. The thermal physical vapor deposition source of claim 1, wherein
the heater structure includes one or more heating elements.
9. The thermal physical vapor deposition source of claim 1, further
includes a mixing zone defined between the electrical heater
structure and the aperture plate.
10. The thermal physical vapor deposition source of claim 1,
wherein the electrical heater structure includes a heating array
with a plurality of heating elements.
11. The thermal physical vapor deposition source of claim 1 further
including means engageable with pellets in the spaced passages for
adjusting the position of the pellets to compensate for material
loss during vaporization.
12. A thermal physical vapor deposition source for vaporizing
pellets containing organic materials onto a surface of a substrate
in forming a display, comprising: (a) a housing, defining a
plurality of spaced passages, each such passage having an open
first end and an open second end and being adapted to receive a
pellet; (b) a cover plate, over the housing, with a first plurality
of openings, corresponding to the spaced passages of the housing;
(c) an electrical heater structure over the cover plate; (d) a
vaporization zone defined between the housing and the electrical
heater structure; (e) push rods, each being insertable into the
open first end of one of the spaced passages for engaging a pellet
in the passage and moving the pellet into the vaporization zone;
(f) means for moving the push rods for engaging the pellets, to
move the top portion of each pellet into the vaporization zone; (g)
an aperture plate, having at least one aperture; (h) an
electrically insulating spacer member located between the
electrical heater structure and engaging the aperture plate, such
electrically insulating spacer member having at least one opening,
corresponding to the first plurality of openings in the cover plate
and the spaced passages of the housing; and (i) means for applying
current to the electrical heater structure sufficient to vaporize
the pellets and permit vapor efflux of the materials to pass
through the first plurality of openings in the cover plate, the
electrical heater structure, the electrically insulating spacer
member and the apertures of the aperture plate, onto the
substrate;
13. The thermal physical vapor deposition source of claim 12,
wherein the housing includes thermally insulating material.
14. The thermal physical vapor deposition source of claim 12,
wherein the cover plate includes electrically insulating
material.
15. The thermal physical vapor deposition source of claim 12,
wherein the electrical heater structure includes an electrically
conductive heater plate, over the cover plate, having a second
plurality of openings, each of the openings corresponding to each
of the first plurality of openings of the cover plate and the
spaced passages of the housing.
16. The thermal physical vapor deposition source of claim 12,
wherein the spacer member includes electrically insulating
material.
17. The thermal physical vapor deposition source of claim 12,
wherein the aperture plate includes electrically insulated material
and is electrically insulated from the conducting plate by the
spacer member.
18. The thermal physical vapor deposition source of claim 12,
wherein the apertures of the aperture plate are selected to have
different cross-sectional areas to produce different flow rates and
patterns of vapor efflux.
19. The thermal physical vapor deposition source of claim 12,
wherein the electrical heater structure includes a heating array
with a plurality of heating elements.
20. The thermal physical vapor deposition source of claim 12,
further includes a mixing zone defined between the electrical
heater structure and the aperture plate.
21. The thermal physical vapor deposition source of claim 12
wherein the means for moving the push rods for engaging the pellets
includes barreled screws, a common base connected to all the push
rods driven by a single screw, a hydraulic or pneumatic jack
engaging the push rods at the same time, or an automatic or
computer controlled system for operating the movement of the push
rods.
22. A thermal physical vapor deposition source for vaporizing
pellets containing organic materials onto a surface of a substrate
in forming a display, comprising: (a) a housing, defining a
plurality of spaced passages, each such spaced passage having an
open first end and an open second end and being adapted to receive
a pellet; (b) a cover plate, over the housing, with a first
plurality of openings, corresponding to the spaced passages of the
housing; (c) an electrical heater structure including an
electrically conductive heater plate, disposed over the cover
plate, with a second plurality of openings corresponding to the
first plurality of openings of the cover plate and a heating array
including a plurality of heating elements, each such heating
element corresponding to each opening in the conductive heater
plate; (d) a vaporization zone defined between the housing and the
electrical heater structure; (e) push rods, each being insertable
into the open first end of one of the spaced passages for engaging
a pellet and moving the pellet into the vaporization zone; (f) an
electrically insulating spacer member over the electrical heater
structure with at least one opening, corresponding to the first
plurality of openings in the cover plate and the spaced passages of
the housing; (g) an aperture plate, over the insulating plate,
having at least one aperture; (h) a mixing zone defined between the
electrical heater structure and the aperture plate; and (i) means
for applying current to the heating array including the plurality
of heating elements, thereby controlling temperature gradients in
the electrical heater structure to vaporize the pellets and permit
vapor efflux of materials to pass through the first plurality of
openings in the cover plate, the second plurality of openings in
the electrical heater structure, the electrically insulating spacer
member and the apertures of the aperture plate, onto the
substrate.
23. A thermal physical vapor deposition source for vaporizing a
plurality of pellets containing organic materials onto a surface of
a substrate in forming a display, comprising: (a) a housing,
defining a plurality of spaced passages wherein certain passages
receive compacted pellets of host organic material and others
receive dopant organic material; (b) a cover plate over the
housing, with a first plurality of openings corresponding to the
spaced passages of the housing; (c) an electrical heater structure,
disposed over the cover plate; (d) an aperture plate, disposed over
the electrical heater structure and having at least one aperture;
(e) an electrically insulating spacer member located between the
electrical heater structure and engaging the aperture plate, such
electrically insulating spacer member having at least one opening,
corresponding to the first plurality of openings of the cover plate
and the spaced passages of the housing; and (f) means for applying
current to the electrical heater structure to produce heat
sufficient to vaporize the pellets and permit vapor efflux of
materials to pass through the first plurality of openings of the
cover plate, the heater structure, the electrically insulating
spacer member and the apertures of the aperture plate, onto the
substrate.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly assigned U.S. patent
application Ser. No. 10/352,558 filed Jan. 28, 2003, entitled
"Method of Designing a Thermal Physical Vapor Deposition System" By
Grace et al.; U.S. patent application Ser. No. 10/093,739 filed
Mar. 8, 2002 entitled "Elongating Thermal Physical Vapor Deposition
Source with Plural Apertures for Making an Organic Light-Emitting
Device" by Freeman et al.; U.S. patent application Ser. No.
09/898,369 filed Jul. 3, 2001, entitled "Method of Handling Organic
Material in Making An Organic Light-Emitting Device" by VanSlyke et
al.; and U.S. patent application Ser. No. 10/073,690 filed Feb. 11,
2002, entitled "Using Organic Materials in Making An Organic
Light-Emitting Device" by Ghosh et al., the teachings of which are
incorporated herein.
FIELD OF THE INVENTION
[0002] The present invention relates to physical vapor deposition
of organic material to form an organic layer, which will form part
of an organic light-emitting display (OLED). More particularly, the
present invention relates to using an improved vapor deposition
physical vapor deposition source wherein pellets of compacted
organic materials are used.
BACKGROUND OF THE INVENTION
[0003] An organic light-emitting device, also referred to as an
organic electroluminescent device, can be constructed by
sandwiching two or more organic layers between first and second
electrodes.
[0004] In a passive matrix organic light-emitting device (OLED) of
conventional construction, a plurality of laterally spaced
light-transmissive anodes, for example indium-tin-oxide (ITO)
anodes, are formed as first electrodes on a light-transmissive
substrate such as, for example, a glass substrate. Two or more
organic layers are then formed successively by vapor deposition of
respective organic materials from respective sources, within a
chamber held at reduced pressure, typically less than 10.sup.-3
torr (1.33.times.10.sup.-1 pascal). In addition to doped or undoped
organic light-emitting material, typical organic layers used in
making OLED displays are doped or undoped organic hole-injecting
material, doped or undoped organic hole-transporting material, and
doped or undoped organic electron-transporting material, where
doping refers to adding a minor constituent to enhance the
electrical performance, optical performance, stability, or life
time of a given material or device constructed thereof. A plurality
of laterally spaced cathodes is deposited as second electrodes over
an uppermost one of the organic layers. The cathodes are oriented
at an angle, typically at a right angle, with respect to the
anodes.
[0005] Applying an electrical potential (also referred to as a
drive voltage) operates such conventional passive matrix organic
light-emitting devices between appropriate columns (anodes) and,
sequentially, each row (cathode). When a cathode is biased
negatively with respect to an anode, light is emitted from a pixel
defined by an overlap area of the cathode and the anode, and
emitted light reaches an observer through the anode and the
substrate.
[0006] In an active matrix organic light-emitting device (OLED), an
array of anodes are provided as first electrodes by thin-film
transistors (TFTs) which are connected to a respective
light-transmissive portion. Two or more organic layers are formed
successively by vapor deposition in a manner substantially
equivalent to the construction of the aforementioned passive matrix
device. A common cathode is deposited as a second electrode over an
uppermost one of the organic layers. The construction and function
of an active matrix organic light-emitting device is described in
commonly-assigned U.S. Pat. No. 5,550,066, the disclosure of which
is herein incorporated by reference.
[0007] Organic materials, thicknesses of vapor-deposited organic
layers, and layer configurations, useful in constructing an organic
light-emitting device, are described, for example, in
commonly-assigned U.S. Pat. Nos. 4,356,429; 4,539,507; 4,720,432,
and 4,769,292, the disclosures of which are herein incorporated by
reference.
[0008] Other kinds of imaging devices, such as imaging phosphors
for computed radiography and x-ray photoconductive devices for
digital radiography, depend on the ability to coat the active
materials uniformly over large areas. While the following
discussion pertains to OLED displays, it should be readily apparent
that the same invention can be applied to the deposition of
alkalihalide phosphors, amorphous semiconductors, and other
luminescent or photoactive layers, as well as a variety of other
materials used in devices based on such luminescence or photoactive
layers.
[0009] For sufficiently small substrates, a point source approach
can be implemented wherein the material to be deposited emanates
from a localized heated crucible and the substrate is placed
sufficiently far from the localized region of vaporization that the
coating is sufficiently far from the localized region of
vaporization that the coating is sufficiently uniform along the
substrate. As substrate size increases or working distance
increases, rotary or planetary motion of the substrate relative to
the localized source is often required to produce the desired
uniformity.
[0010] By elongating the vaporization source and providing for
translation of source and substrate relative to one another, the
desired uniformity can be attained at considerably smaller working
distances and thus considerably higher rates and better materials
utilization, if desired. Scaling of such a process to large areas
(i.e. substrates greater than 15 cm in at least one dimension) is
considerably easier than for point sources.
[0011] An elongated source for thermal physical vapor deposition of
organic layers onto a structure for making an organic
light-emitting device has been disclosed by Spahn in commonly
assigned U.S. Pat. No. 6,237,529. The source disclosed by Spahn
includes a housing, which defines an enclosure for receiving solid
organic material, which can be vaporized. The housing is further
defined by a top plate which defines a vapor efflux slit-aperture
for permitting organic vapors to pass through the slit onto a
surface of a structure spaced apart from the elongated source. The
housing defining the enclosure is connected to the top plate. The
source disclosed by Spahn further includes a conductive baffle
member attached to the top plate. This baffle member provides
line-of-sight covering of the slit in the top plate so that organic
vapors can pass around the baffle member and through the slit onto
the substrate or structure while particles of organic materials are
prevented from passing through the slit by the baffle member when
an electrical potential is applied to the housing to cause heat to
be applied to the solid organic material in the enclosure causing
the solid organic material to vaporize.
[0012] In using the thermal physical vapor deposition source
disclosed by Spahn to form an organic layer of a selected organic
material on a substrate or structure, it has been found that the
vapor efflux slit-aperture causes non-uniform vapor flux of organic
material to emanate along a length dimension of the slit. There is
a problem when the width dimension of the slit is reduced, for
example, to a width dimension less than 0.5 mm. Such spatially
non-uniform orientation of opposing slit edges can be thought of as
a deviation of planarity of opposing edges which, in turn, can
promote a greater fraction of organic vapors to exit the vapor
deposition source through a central portion of the slit, with a
correspondingly lower fraction of organic vapors exiting the source
through remaining portions of the slit along its length dimension.
Such non-uniform vapor flux, directed at a substrate or structure,
will cause the formation of an organic layer thereon which will
have a non-uniform layer thickness in correspondence with the
non-uniform vapor flux.
[0013] In addition, any nonuniformities in heat generation from the
heater or heat absorption by the material to be deposited or
distribution of the material within the source can give rise to
nonuniformity in deposition along the length of the source. Yet
another source of nonuniformity is unintended leaks in the source
enclosure other than the apertures used to deliver the organic
vapor. If such leak exists at the ends of the source, the flow of
vapor from center to end of the source can cause pressure gradients
within the source, thereby causing nonuniformity in the resultant
deposition.
[0014] Forrest et al (U.S. Pat. No. 6,337,102B1) disclosed a method
of 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. In one embodiment
of their invention, Forrest et al located 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 disclosed the use of a gas curtain fed by a gas manifold
(defined 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.
[0015] The approach to vapor delivery as disclosed by Forrest et al
can be characterized as "remote vaporization" wherein a material is
converted to vapor in an thermal physical deposition source
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 organic vapor for
coating large areas uniformly requires the use of gas
manifolds.
[0016] Each one, or a combination, of the aforementioned aspects of
organic powders, flakes, or granules can lead to nonuniform heating
of such organic materials in physical vapor deposition sources with
attendant spatially non-uniform sublimation or vaporization of
organic material and can, therefore, result in potentially
non-uniform vapor-deposited organic layers formed on a
structure.
SUMMARY OF THE INVENTION
[0017] It is an object of the present invention to provide a
thermal physical vapor deposition source which is capable of
coating thin uniform layer of organic material.
[0018] It is another object of the present invention to provide a
thermal physical vapor source that is particularly suited for
coating large areas.
[0019] It is another object of the present invention to make
effective use of pellets of organic material that can be vaporized
by the thermal physical vapor deposition source.
[0020] The above objects are achieved by a thermal physical vapor
deposition source for vaporizing pellets containing organic
materials onto a surface of a substrate in forming a display,
comprising:
[0021] (a) a housing defining a plurality of spaced passages each
for receiving compacted pellets of organic materials;
[0022] (b) a cover plate over the housing, with a first plurality
of openings corresponding to the spaced passages of the
housing;
[0023] (c) an electrical heater structure disposed over the cover
plate;
[0024] (d) an aperture plate, disposed over the electrical heater
structure and having at least one aperture;
[0025] (e) an electrically insulating spacer member located between
the electrical heater structure and engaging the aperture plate,
such electrically insulating spacer member having at least one
opening, corresponding to the first plurality of openings of the
cover plate and the spaced passages of the housing; and
[0026] (f) means for applying current to the electrical heater
structure to produce heat sufficient to vaporize the pellets and
permit vapor efflux of materials to pass through the first
plurality of openings of the cover plate, the heater structure, the
electrically insulating spacer member and the apertures of the
aperture plate, onto the substrate.
[0027] A feature of the present invention is the provision of the
thermal physical vapor deposition source, which is designed to make
use of compacted pellets of organic material that is capable of
depositing thin layers to form a part of an OLED display.
[0028] Another feature of the present invention is that the thermal
physical vapor deposition source is capable of depositing uniform
organic layers which include at least one host component and at
least one dopant component on a relatively large structure.
[0029] Yet, another beneficial feature of the present invention is
that the compacted pellet of mixed organic materials can be
evaporated for a longer time from a single thermal physical vapor
deposition source rather than co-evaporation from a multiple
deposition sources as in single component powders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is an exploded view of a thermal physical vapor
deposition source in accordance with the present invention;
[0031] FIG. 2 is a cross-sectional view of the thermal physical
vapor deposition source of FIG. 1;
[0032] FIG. 3 is cross-sectional view of another embodiment of a
thermal physical vapor deposition source; and
[0033] FIG. 4 is an exploded view of a thermal physical vapor
deposition source having a different electrical heater
structure.
DETAILED DESCRIPTION OF THE INVENTION
[0034] The term "substrate" denotes at least a portion of an OLED
display, which includes one or more layers onto which another
organic layer is to be formed.
[0035] Turning to FIG. 1, a thermal physical deposition source 100
is illustrated, wherein a housing 110, defining a plurality of
spaced passages 120, each spaced passage 120 having a closed first
end 112 and an open second end 114 is shown. The spaced passages
120 can be of any shape and size and are fabricated such that
compacted pellets 215 (see FIG. 2) of organic materials can be
inserted through the open second end 114.
[0036] The housing 110 can be formed from thermally insulating
materials such as high temperature glasses like quartz,
alumino-boro-silicate glass and ceramics like alumina, zirconia,
boron nitride, or magnesia. The purpose of using thermally
insulating materials is to manage the thermal characteristics of
the housing 110 when compacted pellets 215 used have more than one
organic component, the details of which will be described
hereinafter. Alternatively, if the thermal physical vapor
deposition source 100 is used primarily for depositing organic
layers from the compacted pellet 215 including a single component,
the housing 110 can be made using thermally conductive materials
such as stainless steel, tantalum, tungsten, or molybdenum.
Further, the temperature of the housing 110 can be controlled using
a variety of different methods, including controlling the
temperature source (not shown), using integrated cooling or heating
lines (not shown) to pass liquid or gaseous fluids through the
housing 110 or integrating one or more heating elements (not shown)
in the housing 110.
[0037] The thermal physical vapor deposition source 100 further
includes a cover plate 130 disposed over the housing 110. The cover
plate 130 defines a first plurality of openings 134, each opening
134 corresponding to one of the spaced passages 120 of the housing
110. The cover plate 130 can be made of electrically insulating
materials such as alumina, high temperature glass like Pyrex.RTM.,
silicon carbide or silicon nitride.
[0038] The thermal physical vapor deposition source 100 further
includes an electrical heater structure 140. In this embodiment,
the electrical heater structure 140 includes an electrically
conductive heater plate 141 disposed over the cover plate 130. The
electrical heater structure 140 can be either a single unit as
shown in FIG. 1 or it can be a heating array 442 (see FIG. 4) of
heating elements 443 (see FIG. 4). The heating elements 443 are
driven by a DC power supply 148. The heater plate 141 includes a
second plurality of openings 144, each one of the second plurality
of openings 144 corresponds to each one of the first plurality of
openings 134 of the cover plate 130.
[0039] The DC power supply 148 provides drive current through the
heater plate 141. As current passes through the heater plate 141,
thermal radiation is produced which is absorbed by the upper
portions of the compacted pellets 215 causing vaporization of
portions of the compacted pellets 215 in a vaporization zone 235
(see FIG. 2). Vaporization occurs in the vaporization zone 235,
which is disposed between the heater plate 141 and the housing 110.
The heater plate 141 can be made from electrically conductive
materials, such as a metal or a conductive alloy. The conductive
materials included in the heater plate 141 are selected to prevent
condensation of the vaporized materials during operation of the
thermal physical deposition source 100.
[0040] The thermal physical vapor deposition source 100 further
includes an electrically insulating spacer member 150 disposed
between the heater plate 141 and an aperture plate 160. The
electrically insulating spacer member 150 has at least one opening
154, corresponding to the second plurality of openings 144 of the
heater plate 141. The electrically insulating spacer member 150 is
located between the aperture plate 160 and the heater plate 141 to
electrically insulate the aperture plate 160 from the current
passing through the heater plate 141. The electrically insulating
spacer member 150 can be made from electrically insulating
materials such as ceramic, glass and mica.
[0041] A mixing zone 255 (see FIG. 2) is disposed between the
heater plate 141 and the aperture plate 160. The electrically
insulating spacer member 150 can also include materials selected to
remove any potential for internal vaporized material condensing on
the spacer member 150.
[0042] The aperture plate 160 having at least one aperture 164 to
permit vapors of organic materials to pass through the aperture
plate 160 and deposit on a substrate 270 (see FIG. 2). The shape
and number of the apertures 164 is selected to control the rate and
pattern of vapor efflux and to promote sufficient deposition
thickness uniformity on the substrate 270. The aperture plate 160
can include refractory metals like W, Ta or Mo or ceramics like
alumina, zirconia, magnesia, or high temperature glass like quartz
or Pyrex.RTM..
[0043] When the power supply 148 drives current through the heater
plate 141 sufficient heat is generated in the vaporization zone 235
to cause a portion of the compacted pellet 215 to vaporize. The
vapor of organic material produced in the vaporization zone 235
sequentially passes through the first plurality of openings 134 in
the cover plate 130, the second plurality of openings 144 in the
heater plate 141, the electrically insulating spacer member 150 and
the apertures 164 of the aperture plate 160. Further, additional
heating elements may be placed on or near the cover plate 130,
spacer member 150, and aperture plate 160 to prevent vaporous
material from condensing on the cover plate 130, the spacer member
150, or the aperture plate 160.
[0044] Turning to FIG. 2, a cross-sectional view of another
embodiment of a thermal physical deposition source 200 is shown.
The compacted pellets 215 are placed in a plurality of spaced
passages 220 of a housing 210 the details of which have been
described hereinbefore (see FIG. 1). The spaced passages 220 can
include multiple shapes, having an open first end 212 and an open
second end 214 and each spaced passage 220 is adapted to receive
the compacted pellet 215.
[0045] The spaced passages 220 are formed so that compacted pellets
215 can be inserted through the open second end 214 of the spaced
passages 220. In this embodiment, a way of advancing the compacted
pellets 215 so that the top portion of the compacted pellets 215
are in the vaporization zone 235 includes a plurality of push rods
225. The push rods 225 are insertable into the open first ends 212
of the spaced passages 220 and engage the compacted pellets 215 in
the spaced passages 220 in order to adjust the position of the
compacted pellets 215 to compensate for material loss during
vaporization in the vaporization zone 235. The vaporization zone
235 is defined as the region between the housing 210 and the
electrical heater structure 240.
[0046] The compacted pellets 215 are inserted into the spaced
passages 220 and the push rods 225 are inserted into the open first
ends 212 of the spaced passages 220 until the push rods 225 engage
the compacted pellets 215. During vaporization of the compacted
pellets 215 the top portion of the compacted pellet 215 is
vaporized in the vaporization zone 235. The push rods 225 move the
compacted pellets 215 through the spaced passages 220 and expose
the compacted pellets 215 to the vaporization zone 235 until the
pellets 215 are completely vaporized. To this end, the push rods
225 are engaged by a thumb screw assembly 227 which can be manually
adjusted to change the position of the push rods.
[0047] Alternative embodiments can be used to position the push
rods 225 including barreled screws, a common base connected to each
of the push rods 225 being driven by a single screw, a hydraulic or
pneumatic jack pushing all the push rods 225 at the same time, or
an automatic or computer controlled system for operating the
movement of the push rods 225.
[0048] The thermal physical vapor deposition source 200 further
includes a cover plate 230 over the housing 210. The cover plate
230 defines a first plurality of openings 234, each opening 234
corresponding to each one of the spaced passages 220 of the housing
210. The cover plate 230 can be made of thermally conducting and
electrically insulating materials such as alumina, high temperature
glass like Pyrex.RTM., silicon carbide or silicon nitride.
[0049] The thermal physical vapor deposition source 200 further
includes an electrical heater structure 240. In this embodiment,
the electrical heater structure 240 includes an electrically
conductive heater plate 241 disposed over the cover plate 230. The
heater plate 241 includes a second plurality of openings 244,
wherein each one of the second plurality of openings 244
corresponding to each one of the first plurality of openings 234 of
the cover plate 230.
[0050] A DC power supply 148 (see FIG. 1) provides a drive current
through the heater plate 241. As current passes through the heater
plate 241, thermal radiation is produced from the heater plate 241.
The thermal radiation is absorbed by the upper portion of the
compacted pellets 215 causing vaporization of the compacted pellets
215. The heater plate 241 can include electrically conductive
materials, such as quartz bulbs, strip tantalum, cartridge heaters,
and other metals. The materials of the heater plate 241 can be
selected to prevent condensation of the vaporized materials during
operation of the thermal physical deposition source 200.
[0051] The thermal physical vapor deposition source 200 further
includes an electrically insulating spacer member 250 located over
the heater plate 241 and an aperture plate 260 located over the
electrically insulating spacer member 250. The electrically
insulating spacer member 250 has at least one opening 254,
corresponding to the second plurality of openings 244 of the heater
plate 241 first plurality of openings 234 of the cover plate 230
and the spaced passages 220 of the housing 210. The electrically
insulating spacer member 250 is located between the aperture plate
260 and the heater plate 241 to electrically insulate the aperture
plate 260 from the current passing through the heater plate 241.
The electrically insulating spacer member 250 can be made of
electrically insulating materials such as ceramic, glass and
mica.
[0052] The mixing zone 255 is disposed between the heater plate 241
and the aperture plate 260. The electrically insulating spacer
member 250 can include materials selected to remove any potential
for internal vaporized material condensing on the spacer member
250.
[0053] The aperture plate 260 having at least one aperture 264 to
permit vapors of organic materials to pass through the aperture
plate 260 and deposit on the substrate 270. The shape and number of
the apertures 264 is selected to control the rate and pattern of
vapor efflux and promote sufficient deposition thickness uniformity
on the substrate 270.
[0054] In this embodiment, the compacted pellets 215 made of
organic material are vaporized in the vaporization zone 235. The
vapor of organic material passes sequentially through the first
plurality of openings 234 in the cover plate 230, the second
plurality of openings 244 in the heater plate 241, the electrically
insulating spacer member 250 and the apertures 264 of the aperture
plate 260. The aperture plate 260 can include refractory metals
like W, Ta or Mo or ceramics like alumina, zirconia, magnesia, or
high temperature glass like quartz or Pyrex.RTM.. The materials of
the aperture plate 260 can be selected to prevent condensation of
vaporized material during vaporization of the compacted pellets
215. Further, additional heating elements may be placed on or near
the cover plate 230, electrically insulating spacer member 250, and
aperture plate 260 to prevent vaporous material from condensing on
the cover plate 230, the spacer member 250, or the aperture plate
260.
[0055] Turning to FIG. 3, another embodiment of a thermal physical
deposition source 300 is illustrated, wherein compacted pellets 315
are placed in a plurality of spaced passages 320 of a housing 310.
The spaced passages 320 can include multiple shapes and have an
open first end 312 and an open second end 314 and are adapted to
receive the compacted pellets 315.
[0056] In this embodiment, the spaced passages 320 include both
large cross-sectional area spaced passages 321 and small
cross-sectional area spaced passages 322 to receive the compacted
pellets 315 of different sizes and different compositions. For
example, pellets including a host organic material can be contained
in the large cross-sectional area spaced passages 321 and pellets
including a dopant organic material can be contained in the small
cross-sectional area spaced passages 322 to support the deposition
of multi-component thin films. Such host and dopant organic
materials will mix upon vaporization and be deposited on a
substrate in the proportions controlled by the cross-sectional area
of the spaced passages 320 and the rate of vaporization.
[0057] The housing 310 can be made of thermally and electrically
insulating or conductive materials such as graphite, quartz,
tantalum, ceramics, and metals. Further, the temperature of the
housing 310 can be controlled using a variety of different methods,
including controlling the temperature source (not shown), using
integrated cooling or heating lines (not shown) to pass liquid or
gaseous fluids through the housing 310 or integrating one or more
heating elements (not shown) in the housing 310.
[0058] The spaced passages 320 are formed so that compacted pellets
315 can be inserted into the open second ends 314 of the spaced
passages 320. In this embodiment, a way of advancing the pellets so
that the top portion of the compacted pellets 315 are in the
vaporization zone 335 includes a plurality of push rods 325. The
push rods 325 are insertable into the open first ends 312 of the
spaced passages 320 and engage the pellets 315 in the spaced
passages 320 in order to adjust the position of the pellets 315 to
compensate for material loss during vaporization in the
vaporization zone 335. The vaporization zone 335 is defined as the
region between the housing 310 and the electrical heater structure
340.
[0059] The compacted pellets 315 are inserted into the spaced
passages 320 and the push rods 325 are inserted into the open first
ends 312 of the spaced passages 320 until the push rods 325 engage
the compacted pellets 315. During vaporization of the compacted
pellets 315 the top portion of the pellets 315 are vaporized in the
vaporization zone 335. The push rods 325 move the compacted pellets
315 through the spaced passages 320 and expose the compacted
pellets 315 to the vaporization zone 335 until the pellets 315 are
completely vaporized. To this end, the push rods 325 are engaged by
a thumb screw assembly 327, which can be manually adjusted to
change the position of the push rods 325.
[0060] Alternative embodiments can be used to position the push
rods 325 including barreled screws, a common base connected to each
of the push rods 325 being driven by a single screw, a hydraulic or
pneumatic jack pushing all the push rods 325 at the same time, or
an automatic or computer controlled system for operating the
movement of the push rods 325.
[0061] The thermal physical vapor deposition source 300 further
includes a cover plate 330 over the housing 320. The cover plate
330 includes a first plurality of openings 334, each one of the
first plurality of openings 334, corresponding to each one of the
spaced passages 320 of the housing 310. The cover plate 330 can
include thermally conducting and electrically insulating materials
such as alumina, high temperature glass like Pyrex.RTM., silicon
carbide or silicon nitride.
[0062] The thermal physical vapor deposition source 300 further
includes an electrical heater structure 340. In this embodiment,
the electrical heater structure 340 includes an electrically
conductive heater plate 341 disposed over the cover plate 330. The
heater plate 341 includes a second plurality of openings 344, each
one of the second plurality of openings 344 corresponding to the
first plurality of openings 334 of the cover plate 330.
[0063] A DC power supply 148 (see FIG. 1) provides drive current
through the heater plate 341. As current passes through the heater
plate 341, thermal radiation is produced from the heater plate 341.
The thermal radiation is absorbed by the upper portion of the
compacted pellets 315 causing vaporization of the compacted pellets
315. The heater plate 341 can include electrically conductive
materials, such as quartz bulbs, strip tantalum, cartridge heaters,
and other metals. The materials of the heater plate 341 can be
selected to prevent condensation of the vaporized materials during
operation of the thermal physical deposition source 300.
[0064] The thermal physical vapor deposition source 300 further
includes an electrically insulating spacer member 350 located over
the heater plate 341 and an aperture plate 360 located over the
electrically insulating spacer member 350. The electrically
insulating spacer member 350 has at least one opening 354,
corresponding to the second plurality of openings 344 of the heater
plate 341, first plurality of openings 334 of the cover plate 330
and the spaced passages 320 of the housing 310. The electrically
insulating spacer member 350 is located between the aperture plate
360 and the electrical heater structure 340 to electrically
insulate the aperture plate 360 from the current passing through
the heater plate 341. The electrically insulating spacer member 350
can be made from electrically insulating materials such as ceramic,
glass and mica.
[0065] The mixing zone 355 is disposed between the heater plate 341
and the aperture plate 360. The electrically insulating spacer
member 350 can also include materials selected to remove any
potential for internal vaporized material condensing on the spacer
member 350.
[0066] The aperture plate 360 includes at least one aperture 364 to
permit vapors of organic materials to pass through the aperture
plate 360 and deposit on the substrate 270 (see FIG. 2). The shape
and number of the apertures 364 is selected to control the rate and
pattern of vapor efflux and promote sufficient deposition thickness
uniformity on the substrate 270.
[0067] In this embodiment, compacted pellets 315 made of organic
material are vaporized in the vaporization zone 335. The vapor of
organic material passes sequentially through the first plurality of
openings 334 in the cover plate 330, the second plurality of
openings 344 in the heater plate 341, the electrically insulating
spacer member 350 and the apertures 364 of the aperture plate 360.
The aperture plate 360 can include refractory metals like W, Ta or
Mo or ceramics like alumina, zirconia, magnesia, or high
temperature glass like quartz or Pyrex.RTM.. The materials of the
aperture plate 360 can be selected to prevent condensation of
vaporized materials during the vaporization of the compacted
pellets 315. Further, additional heating elements may be placed on
or near the cover plate 330, spacer member 350, and aperture plate
360 to prevent vaporous material from condensing on the cover plate
330, the electrically insulating spacer member 350, or the aperture
plate 360.
[0068] Turning to FIG. 4, another embodiment of a thermal physical
vapor deposition source 400 is illustrated, wherein the compacted
pellets 215 (FIG. 2) are placed in a plurality of spaced passages
420 of a housing 410. The spaced passages 420 can include multiple
shapes and sizes and have an open first end 412 and an open second
end 414 and are adapted to receive the compacted pellet 215. The
housing 410 can include thermally and electrically insulating
materials such as quartz, tantalum, ceramics, and
glass-ceramics.
[0069] The spaced passages 420 are formed so that compacted pellets
215 can be inserted into the open second ends 414 of the spaced
passages 420. In this embodiment, a way of advancing the compacted
pellets 215 so that the top portion of the compacted pellets 215
are in the vaporization zone 235 includes the push rods 225 as
described hereinbefore. The push rods 225 are insertable into the
open first ends 412 of the spaced passages 420 and engage the
compacted pellets 215 in the spaced passages 420 in order to adjust
the position of the compacted pellets 215 to compensate for
material loss during vaporization in the vaporization zone 235. The
vaporization zone 235 is defined as the region between the housing
410 and the electrical heater structure 440.
[0070] The compacted pellets 215 are inserted into the spaced
passages 420 and the push rods 225 are inserted into the open first
end 412 of the spaced passages 420 until the push rods 225 engage
the compacted pellets 215. During vaporization of the compacted
pellets 215 the top portion of the pellet 215 is vaporized in the
vaporization zone 235. The push rods 225 move the compacted pellets
215 through the spaced passages 420 and expose the compacted
pellets 215 to the vaporization zone 235 until the pellets 215 are
completely vaporized. To this end, the push rods 225 are engaged by
a thumb screw assembly 227, which can be manually adjusted to
change the position of the push rod.
[0071] Alternative embodiments can be used to position the push
rods 225 including barreled screws, a common base connected to all
the push rods 225 being driven by a single screw, a hydraulic or
pneumatic jack pushing all the push rods 225 at the same time, or
an automatic or computer controlled system for operating the
movement of the push rods 225.
[0072] The thermal physical vapor deposition source 400 further
includes a cover plate 430 over the housing 410. The cover plate
430 includes a first plurality of openings 434, each one of the
first plurality of openings 434 corresponding to the each one of
the spaced passages 420 of the housing 410. The cover plate 430 can
include thermally conducting and electrically insulating materials
such as alumina, high temperature glass like Pyrex.RTM., silicon
carbide or silicon nitride. The materials of the cover plate 430
can be selected to prevent condensation of vaporized materials onto
the surface of the cover plate 430 during vaporization of the
compacted pellets 215.
[0073] The thermal physical vapor deposition source 400 further
includes an electrical heater structure 440. In this embodiment,
the electrical heater structure 440 includes a heater plate 441
disposed over the cover plate, having a second plurality of
openings 444 corresponding to the first plurality of openings 434
of the cover plate 430 and the spaced passages 420 of the housing
410. The electrical heater structure 440 further includes a heating
array 442, which includes a plurality of heating elements 443 over
the heater plate 441, each such heating element 443 corresponding
to each opening in the heater plate 441.
[0074] A DC power supply 148 (see FIG. 1) provides a drive current
through the heating elements 443. As current passes through the
heating elements 443, thermal radiation is produced from the
heating elements 443 proportional to the current applied to the
individual heating element 443. The thermal radiation is absorbed
by the portion of the compacted pellets 215 in the vaporization
zone causing vaporization of the compacted pellets 215. The heating
elements 443 in the heating array 442 and the heater plate 441
include quartz bulbs, strip tantalum, cartridge heaters, and other
metals. The materials of the electrical heater structure 440 can be
selected to prevent condensation of the vaporized materials during
operation of the thermal physical deposition source 400.
[0075] The advantages of using the individually-controlled heating
elements 443, include producing varying radiation profiles thereby
controlling temperature gradients in the heater structure and
resulting in better control in the rate of vaporization of
individual compacted pellets 215. Combining the embodiment of FIG.
4 with the embodiment of FIG. 3 can produce improved controlled
deposition by improved control of internal mixing behavior and
improved control of the vapor composition deposited on the
substrate 270.
[0076] The thermal physical vapor deposition source 400 further
includes an electrically insulating spacer member 450 located over
the electrical heater structure 440 and an aperture plate 460
located over the electrically insulating spacer member 450. The
electrically insulating spacer member 450 has at least one opening
454, corresponding to the second plurality of openings 444 of the
electrical heater structure 440, first plurality of openings 434 of
the cover plate 430 and the spaced passages 420 of the housing 410.
The electrically insulating spacer member 450 is located between
the aperture plate 460 and the electrical heater structure 440 to
electrically insulate the aperture plate 460 from the electrical
potential and resulting current passed through the electrical
heater structure 440. The electrically insulating spacer member 450
can be made from electrically insulating materials such as ceramic,
glass and mica.
[0077] The mixing zone 255 is disposed between the heater plate 441
and the aperture plate 460. The electrically insulating spacer
member 450 can also include materials selected to remove any
potential for internal vaporized material condensing on the spacer
member 450.
[0078] The aperture plate 460 includes at least one aperture 464 to
permit vapors of organic materials to pass through the aperture
plate 460 and deposit on a substrate 270. The shape and number of
the apertures 464 is selected to control the rate and pattern of
vapor efflux and promote deposition thickness uniformity on the
substrate 270.
[0079] In this embodiment, the compacted pellets 215 made of
organic material are vaporized in the vaporization zone 235. The
vapor of organic material passes sequentially through the first
plurality of openings 434 in the cover plate 430, the second
plurality of openings 444 in the heater plate 441, the electrically
insulating spacer member 450 and the apertures 464 of the aperture
plate 460. The aperture plate 460 can include refractory metals
like W, Ta or Mo or ceramics like alumina, zirconia, magnesia, or
high temperature glass like quartz or Pyrex.RTM.. The materials of
the aperture plate 460 can be selected to prevent condensation of
vaporized materials during the vaporization of the compacted
pellets 215. Further, additional heating elements may be placed on
or near the cover plate 430, spacer member 450, and aperture plate
460 to prevent vaporous material from condensing on the cover plate
430, the spacer member 450, or the aperture plate 460.
[0080] 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
[0081] 100 thermal physical vapor deposition source
[0082] 110 housing
[0083] 112 closed first end
[0084] 114 open second end
[0085] 120 spaced passages
[0086] 130 cover plate
[0087] 134 first plurality of openings
[0088] 140 electrical heater structure
[0089] 141 heater plate
[0090] 144 second plurality of openings
[0091] 148 power supply
[0092] 150 electrically insulating spacer member
[0093] 154 opening
[0094] 160 aperture plate
[0095] 164 aperture(s)
[0096] 200 thermal physical vapor deposition source
[0097] 210 housing
[0098] 212 open first end
[0099] 214 open second end
[0100] 215 compacted pellets
[0101] 220 spaced passages
[0102] 225 push rods
[0103] 227 thumb screw assembly
[0104] 230 cover plate
[0105] 234 first plurality of openings
[0106] 235 vaporization zone
[0107] 240 electrical heater structure
[0108] 241 heater plate
[0109] 244 second plurality of openings
[0110] List Cont'd
[0111] 250 electrically insulating spacer member
[0112] 254 opening
[0113] 255 mixing zone
[0114] 260 aperture plate
[0115] 264 aperture(s)
[0116] 270 substrate
[0117] 300 thermal physical vapor deposition source
[0118] 310 housing
[0119] 312 open first end
[0120] 314 open second end
[0121] 315 compacted pellets
[0122] 320 spaced passages
[0123] 321 large cross-sectional area spaced passages
[0124] 322 small cross-sectional area spaced passages
[0125] 325 push rods
[0126] 327 thumb screw assembly
[0127] 330 cover plate
[0128] 334 first plurality of openings
[0129] 335 vaporization zone
[0130] 340 electrical heater structure
[0131] 341 heater plate
[0132] 344 second plurality of openings
[0133] 350 electrically insulating spacer member
[0134] 354 opening
[0135] 355 mixing zone
[0136] 360 aperture plate
[0137] 364 aperture(s)
[0138] 400 thermal physical vapor deposition source
[0139] 410 housing
[0140] List Cont'd
[0141] 412 open first end
[0142] 414 open second end
[0143] 420 spaced passages
[0144] 430 cover plate
[0145] 434 first plurality of openings
[0146] 440 electrical heater structure
[0147] 441 heater plate
[0148] 442 heating array
[0149] 443 heating elements
[0150] 444 second plurality of openings
[0151] 450 electrically insulating spacer member
[0152] 454 opening
[0153] 460 aperture plate
[0154] 464 aperture(s)
* * * * *