U.S. patent application number 17/306724 was filed with the patent office on 2021-09-02 for method for producing an output coupling element for an optoelectronic component and optoelectronic component.
The applicant listed for this patent is OSRAM OLED GmbH. Invention is credited to Christian Eichinger, Maja Hackenberger.
Application Number | 20210273129 17/306724 |
Document ID | / |
Family ID | 1000005599014 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210273129 |
Kind Code |
A1 |
Eichinger; Christian ; et
al. |
September 2, 2021 |
Method for Producing an Output Coupling Element for an
Optoelectronic Component and Optoelectronic Component
Abstract
A method for producing an output coupling element and an
optoelectronic component are disclosed. In an embodiment, a method
includes providing an inorganic dielectric element with a surface
in a chamber, wherein the inorganic dielectric element is rotatable
in the chamber, providing a structuring agent comprising water and
ozone and introducing the structuring agent into the chamber so
that the structuring agent contacts the surface of the inorganic
dielectric element thereby producing a roughening in the
surface.
Inventors: |
Eichinger; Christian;
(Wenzenbach, DE) ; Hackenberger; Maja;
(Nittendorf, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OSRAM OLED GmbH |
Regensburg |
|
DE |
|
|
Family ID: |
1000005599014 |
Appl. No.: |
17/306724 |
Filed: |
May 3, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16498966 |
Sep 27, 2019 |
11024764 |
|
|
PCT/EP2018/057785 |
Mar 27, 2018 |
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17306724 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 33/0075 20130101;
H01L 33/22 20130101 |
International
Class: |
H01L 33/00 20060101
H01L033/00; H01L 33/22 20060101 H01L033/22 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 6, 2017 |
DE |
102017107432.5 |
Claims
1. A method for producing an output coupling element for an
optoelectronic component, the method comprising: providing an
inorganic dielectric element with a surface in a chamber, wherein
the inorganic dielectric element is rotatable in the chamber;
providing a structuring agent comprising water and ozone; and
introducing the structuring agent into the chamber so that the
structuring agent contacts the surface of the inorganic dielectric
element thereby producing a roughening in the surface.
2. The method according to claim 1, wherein the inorganic
dielectric element is formed of an oxide or a nitride of a
metal.
3. The method according to claim 1, wherein a mean roughness (Rq)
after roughening is between 20 and 30 nm, inclusive.
4. The method according to claim 1, wherein the structuring agent
further comprises a base.
5. The method according to claim 4, wherein the base is
ammonia.
6. The method according to claim 5, wherein a concentration of the
ammonia is less than or equal to 0.05%.
7. The method according to claim 1, wherein the ozone is introduced
into the chamber in gaseous form.
8. The method according to claim 1, wherein a concentration of the
ozone is between 180 g/m3 to 250 g/m3.
9. The method according to claim 1, wherein the water is
deionized.
10. The method according to claim 1, wherein the structuring agent
comprises a temperature between room temperature and 90.degree. C.,
inclusive.
11. The method according to claim 1, wherein the chamber and/or the
inorganic dielectric element has a rotational speed of 5 rpm to
1200 rpm, inclusive.
12. The method according to claim 1, wherein the inorganic
dielectric element is formed as a layer with a layer thickness
between 20 nm and 150 nm, inclusive.
13. The method according to claim 1, wherein the inorganic
dielectric element is treated with the structuring agent between 5
minutes and 20 minutes, inclusive.
14. An optoelectronic component comprising: a semiconductor layer
sequence configured to emit radiation; and an output coupling
element comprising at least one inorganic dielectric element with a
surface, wherein the inorganic dielectric element comprises a mean
roughness (Rq) between 20 nm and 30 nm, including, and wherein the
output coupling element comprises the roughness on the surface of
the inorganic dielectric element facing away from the semiconductor
layer sequence.
15. The optoelectronic component according to claim 14, wherein the
optoelectronic component is an organic light-emitting diode
(OLED).
16. The optoelectronic component according to claim 14, wherein the
output coupling element is arranged directly at the semiconductor
layer sequence.
17. The optoelectronic component according to claim 16, further
comprising: a carrier; and a second output coupling element,
wherein the semiconductor layer sequence is arranged on the
carrier, and wherein a second output coupling element is arranged
at a side of the carrier opposite the semiconductor layer sequence.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of U.S. application Ser.
No. 16/498,966 entitled "Method for Producing an Output Coupling
Element for an Optoelectronic Component and Optoelectronic
Component," which was filed on Sep. 27, 2019, which is a national
phase filing under section 371 of PCT/EP2018/057785, filed Mar. 27,
2018, which claims the priority of German patent application
102017107432.5, filed Apr. 6, 2017, all of which are incorporated
herein by reference in its entirety.
TECHNICAL FIELD
[0002] The invention relates to a method for producing an output
coupling element for an optoelectronic component. Furthermore, the
invention relates to an optoelectronic component, which in
particular comprises an output coupling element.
BACKGROUND
[0003] So far, inorganic semiconductor layers, if applicable
dielectric layers or semiconductor layers, have been roughened
using wet chemistry. Potassium hydroxide solution, for example, can
serve this purpose. In this way, a statistical distribution of the
roughening structure sizes can be achieved. Alternatively, the
roughening can also be produced by plasma structuring. In this way,
defined structures can be produced.
SUMMARY OF THE INVENTION
[0004] Embodiments provide a method for producing an output
coupling element for an optoelectronic component that efficiently
and simply produces an output coupling element. Further embodiments
provide an optoelectronic component with an output coupling
element.
[0005] In at least one embodiment, the method for producing an
output coupling element for an optoelectronic component comprises
the following method steps: A) providing an inorganic dielectric
element. The dielectric element comprises a surface. The dielectric
element is introduced into a chamber. The dielectric element and/or
a carrier are configured to rotate during operation. Alternatively
or additionally, the chamber can also rotate during operation.
[0006] The method comprises step B), which contains providing a
structuring agent and introducing the structuring agent into the
chamber. The structuring agent comprises ozone and water or
consists thereof. The structuring agent can contact the surface of
the inorganic dielectric element, in particular contact it
directly, and thus produce a roughening in the surface.
[0007] Direct contact here means direct mechanical contact of the
structuring agent with the surface of the inorganic dielectric
element.
[0008] Inorganic dielectric element here means that the element,
which is formed in particular as a layer, comprises dielectric
properties. In addition, the dielectric element is formed
exclusively of inorganic materials.
[0009] The inventors have recognized that with the method described
here a roughening in the inorganic dielectric element can be
produced, so that the output coupling element comprises a very good
light extraction. In addition, the method described here is easy to
apply.
[0010] According to at least one embodiment, the method comprises a
step A), providing an inorganic dielectric element. The inorganic
dielectric element can be formed as a layer. In particular, the
inorganic dielectric element comprises a homogeneous layer
thickness of, for example, between 20 nm and 150 nm. In principle,
thicker layers with layer thicknesses greater than 150 nm can also
be used. The inorganic dielectric element comprises a surface. In
particular, the surface is accessible for the structuring agent. In
step A), the inorganic dielectric element is arranged in a chamber.
The dielectric element and/or the carrier with the wafers rotate
during operation, in particular around their axis of rotation. The
inorganic dielectric element can be introduced into the
chamber.
[0011] According to at least one embodiment, the inorganic
dielectric element comprises an oxide or nitride of a metal or
consists thereof. The metal can be aluminum, for example.
[0012] According to at least one embodiment, the inorganic
dielectric element comprises aluminum oxide (Al.sub.2O.sub.3).
Alternatively, the inorganic dielectric element consists of
aluminum oxide.
[0013] According to at least one embodiment, the method comprises a
step B). In method step B), the structuring agent is provided. The
structuring agent comprises water and ozone. The structuring agent
is introduced into the chamber. Thus, the structuring agent can
contact the surface of the inorganic dielectric element, in
particular contact it directly, and produce a roughening in the
surface.
[0014] According to at least one embodiment, the mean roughness Rq
during or after step B) is between including 20 nm and including 50
nm, in particular between including 22 nm and including 40 nm, in
particular between including 25 nm and including 35 nm, in
particular between including 25 nm and including 32 nm, for
example, 30 nm.
[0015] Preferably, the mean roughness Rq after step B) is between
20 nm and 30 nm. The mean roughness Rq can be determined by white
light interferometry (WLI). WLI is a non-contact optical
measurement method which exploits the interference of broadband
light (white light) and allows so-called three-dimensional profile
measurements of structures with dimensions between a few
centimeters and a few micrometers. White light interferometry is
sufficiently well known to a person skilled in the art and is
therefore not further explained at this point.
[0016] In particular, the mean roughness Rq is given here for layer
thicknesses between including 20 nm and including 150 nm, in
particular between including 35 nm and including 85 nm, for
example, between including 40 nm and including 80 nm of the organic
dielectric element.
[0017] The term mean roughness Rq is known to a person skilled in
the art and is therefore not explained in more detail at this
point. The mean square roughness Rq can be the mean square value of
the profile deviation.
[0018] According to at least one embodiment, the structuring agent
comprises water and ozone. In particular, the water is deionized.
Deionized water here means that the water has been freed from its
ions by different methods. This water is characterized by its low
conductivity.
[0019] The structuring agent comprises ozone. By using the
structuring agent, i.e., a mixture of ozone and water, a
structuring or roughening can be produced in the surface of the
inorganic dielectric element.
[0020] According to at least one embodiment, ozone is introduced
into the chamber in gaseous form. In addition, water in particular
is introduced in liquid form. During the rotation of the inorganic
dielectric element in the chamber, the water forms a thin film of
water on the surface of the inorganic dielectric element, wherein
the ozone is cleaved into radicals, is easily accessible to the
dielectric element and thus causes a roughening of the surface of
the inorganic dielectric element.
[0021] According to at least one embodiment, the structuring agent
additionally comprises a base or an acid, wherein the base acts
catalysing and the acid inhibiting. A base is a chemical compound
with a pH value greater than 7. The base can be dissolved in water,
i.e., an aqueous base can be present. Ammonia, for example, can be
used as a base. Ammonia can be used here as a catalyst which
contributes to the dissociation of the ozone.
[0022] According to at least one embodiment, the concentration of
ammonia is less than or equal to 0.05%. The term % here refers to
volume percent.
[0023] According to at least one embodiment, the ozone, in
particular the gaseous ozone, is introduced into the chamber with a
concentration between 180 g/m3 and 250 g/m3, for example, 240
g/m3.
[0024] According to at least one embodiment, the structuring agent
in step B) comprises a temperature between including room
temperature and including 90.degree. C., in particular 40.degree.
C., for example. The reaction temperature should not be below
40.degree. C. in order to produce an optimal roughening on the
surface of the inorganic dielectric element. It has been shown that
in particular an optimal result in relation to the reaction rate at
a reaction temperature of about 40.degree. C. could be
observed.
[0025] The carrier in or on which the wafers are arranged can have
a rotational speed between 5 rpm or 25 rpm and 1200 rpm. The
thinner the water film contacting the surface of the inorganic
dielectric element is, the greater is the amount of ozone that can
reach the surface. This results in an optimal roughening of the
surface of the inorganic dielectric element.
[0026] According to at least one embodiment, the method comprises a
further step after step B), drying of the inorganic dielectric
element. In other words, after the roughening of the surface of the
inorganic dielectric element, the structuring agent can be removed
again.
[0027] In the subsequent method step, the inorganic dielectric
element can be purged with a gas, such as nitrogen, or compressed
air (CDA). Inert gas and/or compressed air can be used.
[0028] According to at least one embodiment, the carrier in the
chamber comprises a rotation speed of 25 RPM to 1200 RPM during
operation, typically 1000 RPM.
[0029] According to at least one embodiment, the inorganic
dielectric element is formed as a layer with a layer thickness
between including 20 nm and including 150 nm.
[0030] According to at least one embodiment, the inorganic
dielectric element is treated with the structuring agent between
including 5 minutes and including 20 minutes.
[0031] The inventors have recognized that, by the method described
here, a micro-roughness can be produced in the inorganic dielectric
element, which is in particular an aluminum oxide layer. The method
preferably uses a wet chemical etching with a structuring agent of
at least deionized water and ozone. In addition, ammonia can be
added.
[0032] The adjustment of the roughness dimension of the layer
thickness change of the inorganic dielectric element is possible.
The conventional methods cannot cover the complete dimensional
spectrum up to smaller structure sizes.
[0033] Embodiments of the invention further relate to an
optoelectronic component. Preferably, the optoelectronic component
comprises an output coupling element. The optoelectronic component
is preferably produced with the method described here. All
definitions and embodiments of the method also apply to the
optoelectronic component and vice versa.
[0034] According to at least one embodiment, the optoelectronic
component comprises a semiconductor layer sequence. The
semiconductor layer sequence is configured for radiation emission.
Alternatively, the optoelectronic component can also comprise an
organic layer sequence. The optoelectronic component comprises an
output coupling element. The output coupling element comprises at
least an inorganic dielectric element with a surface. The inorganic
dielectric element can comprise a mean roughness, here also
referred to as Rq, between including 20 nm and including 30 nm.
[0035] According to at least one embodiment, the optoelectronic
component comprises a semiconductor layer sequence. The
semiconductor layer sequence is preferably based on a III-V
compound semiconductor material. The semiconductor material is, for
example, a nitride compound semiconductor material such as
Al.sub.nIn.sub.1-n-mGa.sub.mN or a phosphide compound semiconductor
material such as Al.sub.nIn.sub.1-n-mGa.sub.mP or also an arsenide
compound semiconductor material such as
Al.sub.nIn.sub.1-n-mGa.sub.mAs, wherein 0.ltoreq.n.ltoreq.1,
0.ltoreq.m.ltoreq.1 and n+m.ltoreq.1 respectively. The
semiconductor layer sequence can comprise dopants as well as
additional components. For the sake of simplicity, however, only
the essential components of the crystal lattice of the
semiconductor layer sequence are indicated, i.e., Al, As, Ga, In, N
or P, even if these may be partially replaced and/or supplemented
by small quantities of other substances.
[0036] The semiconductor layer sequence comprises one or more
active layers. The at least one active layer is configured for
generating electromagnetic radiation. For example, the active layer
contains at least one pn junction or at least one quantum well. In
particular, ultraviolet, visible and/or near infrared light or
radiation is generated in the active layer during operation of the
optoelectronic component. The radiation generated in the active
layer comprises a peak wavelength. The peak wavelength is the
wavelength at which the highest radiation intensity is generated
during intended operation.
[0037] According to at least one embodiment, the optoelectronic
component is a light-emitting diode, LED for short.
[0038] According to at least one embodiment, the optoelectronic
component is formed as an organic light-emitting diode (OLED).
[0039] According to at least one embodiment, the component
comprises a substrate. For example, the substrate can comprise one
or more materials in form of a layer, a plate, a foil or a laminate
selected from gas, quartz, plastic, metal, silicon wafer, ceramic
coated paper. The substrate preferably comprises glass, for
example, in form of a glass layer, glass foil or glass plate or
consists thereof.
[0040] According to at least one embodiment, the optoelectronic
component comprises a first and a second electrode. At least one of
these electrodes is formed transparent. Here and in the following,
transparent refers to a layer that is permeable for visible light.
Alternatively, both electrodes can also be transparent, so that the
component is designed as a so-called double-sided emitting
OLED.
[0041] For example, a transparent conductive oxide (TCO) such as
ITO can be used as the material for a transparent electrode.
[0042] Furthermore, a transparent electrode can also comprise a
metal layer with a metal or alloy, for example, with one or more of
the following materials: silver, platinum, gold, magnesium or an
alloy of silver and magnesium.
[0043] In particular, one electrode forms the anode while the other
electrode forms the cathode.
[0044] According to at least one embodiment, the component as an
OLED comprises an organic functional layer stack. During operation
of the optoelectronic component, radiation is generated in the
organic functional layer stack. A wavelength of the radiation or
the maximum wavelength is preferably in the infrared and/or
ultraviolet and/or visible spectral range, in particular at
wavelengths between including 420 nm and including 680 nm.
[0045] The organic functional layer stack can comprise layers with
organic polymers, organic oligomers, organic monomers, organic
small light polymeric molecules (small molecules) or combinations
thereof. The organic functional layer stack can comprise additional
functional layers which are designed as hole transport layers in
order to enable an effective hole injection into the at least one
functional layer stack. The organic functional layer stack can
further comprise at least one functional layer which is designed as
an electron transport layer. In general, the organic functional
layer stack can comprise additional layers selected from hole
injection layers, hole transport layers, electron injection layers,
electron transport layers, hole blocking layers and electron
blocking layers. In particular, the layers of the organic
functional layer stack can be completely or at least predominantly
organic functional layers. In addition, it can also be possible
that individual layers of the organic functional layer stack
comprise inorganic materials or are formed thereof.
[0046] The optoelectronic component can also comprise current
expansion structures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Further advantages, advantageous embodiments and further
developments result from the exemplary embodiments described in
connection in the following.
[0048] FIGS. 1A to 1C show an optoelectronic component according to
an embodiment,
[0049] FIGS. 2A to 2B show a semiconductor layer sequence or an
organic layer sequence according to an embodiment,
[0050] FIGS. 3A to 3E show a method for producing an optoelectronic
component according to an embodiment,
[0051] FIGS. 4A to 4C each show an electro-microscope image (SEM)
according to one embodiment each,
[0052] FIGS. 5A and 5C show a three-dimensional profile measurement
by white light interferometry according to an embodiment,
[0053] FIGS. 5B and 5D show the corresponding measured values of
the 3D profile measurement of FIGS. 5B and 5C, respectively,
and
[0054] FIGS. 6A and 6B show AFM measurements according to one
embodiment.
[0055] In the exemplary embodiments and in the figures, identical,
similar and similarly acting elements can each be provided with the
same reference signs. The elements shown and their proportions
among each other are not to be regarded as true to scale. Rather,
individual elements, such as layers, components, devices and areas,
can be displayed exaggeratedly large for better representability
and/or better understanding.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0056] FIGS. 1A to 1C each show a schematic side view of an
optoelectronic component according to an embodiment. The
optoelectronic component comprises a substrate 11, also known as a
carrier. A semiconductor layer sequence 1 or an organic layer
sequence 1 is arranged on the carrier 11. In the case of a
semiconductor layer sequence 1, this semiconductor layer sequence
is grown epitaxially on a sapphire substrate, for example. In the
case of an OLED, an organic layer sequence 1 is applied to a glass
substrate 11, for example.
[0057] FIG. 1A shows that the output coupling element 2 is arranged
on the semiconductor layer sequence 1, in particular directly. The
output coupling element 2 comprises a structuring on the surface 4.
The structuring is produced as a result of the roughening with the
method described here. The structuring or roughening comprises a
mean roughness in particular between including 10 nm and including
50 nm, for example, between including 20 nm and including 30 nm.
The light generated in semiconductor layer sequence 1 can be
decoupled 12 from component 100 via the output coupling element
2.
[0058] In contrast, FIG. 1B shows that the output coupling element
2 is arranged directly on the back of carrier 11. In particular, as
shown in FIG. 1A, the radiation generated in semiconductor layer
sequence 1 can be decoupled upwards, i.e., in the opposite
direction of carrier 11. In the case of FIG. 1B, the radiation is
decoupled from component 100 via the carrier 11 and the output
coupling element 2.
[0059] FIG. 1C shows a combination of the arrangement of the output
coupling element 2 of FIGS. 1A and 1B. Two output coupling elements
2 are present in the component of FIG. 1C. One output coupling
element 2-1 is applied directly to the semiconductor layer sequence
1. The second output coupling element 2-2 is applied to a side of
carrier 11 opposite the semiconductor layer sequence 1, in
particular directly.
[0060] Preferably, aluminum oxide is used as the material for the
inorganic dielectric element 3 in the output coupling element 2-1,
2-2 or in the output coupling elements 2-1, 2-2 described here.
[0061] FIGS. 2A and 2B show a schematic side view of a
semiconductor layer sequence 1 or an organic layer sequence 1
according to an embodiment.
[0062] FIG. 2A shows an n-doped semiconductor layer 101, an active
layer 102 arranged thereon, and a p-doped semiconductor layer 103
arranged thereon. These layers can form the epitaxially grown
semiconductor layer sequence 1 of an inorganic light emitting diode
(LED).
[0063] In comparison, as shown in FIG. 2B, the layer sequence is
formed organically. The layer sequence here is in particular a
layer sequence 1 of an OLED. The layer sequence comprises a hole
transport layer 104, a light injection layer 105, an emission layer
106, an electron transport layer 107 and an electron injection
layer 108. These organic layers can be arranged between two
electrodes 109 and 110.
[0064] FIGS. 3A to 3E show a method for producing an output
coupling element 2 for an optoelectronic component 100.
[0065] FIG. 3A shows providing an inorganic dielectric element 3
with a surface 4. The inorganic dielectric element 3 is introduced
into a chamber 10 as shown in FIG. 3B. The carrier 11 and/or the
inorganic dielectric element 3 are configured to rotate during
operation. In this way, a uniform application of the structuring
agent 6 to the inorganic dielectric element 3, which can be
arranged on a wafer, can be produced in chamber 10, wherein a
uniform roughening is produced in surface 4.
[0066] The structuring agent 10 can be added via separate inlets.
The structuring agent can comprise water 7 and ozone 8. In
addition, ammonia can also be added as a catalyst (not shown
here).
[0067] FIG. 3C shows the inorganic dielectric element 3, which
comprises a roughening in surface 4. The roughening can have any
possible structure, such as pyramidal or truncated cone-like.
[0068] The FIG. 3D shows that not only the surface 4 has been
structured, but also the side opposite the surface 4 of the
inorganic dielectric element 3 is structured.
[0069] FIG. 3E shows that the roughening of the inorganic
dielectric element 3 here was performed area by area. For example,
before introducing the inorganic dielectric element 3, certain
areas on the surface 4, which should not be roughened, can be
masked. After the treatment of the inorganic dielectric element 3
in the chamber 10 and after step B), this mask can be removed
again, so that areas are produced on the surface which are
roughened and areas are produced which comprise no roughening.
[0070] FIGS. 4A to 4C each show an electron microscope image (SEM)
according to one embodiment.
[0071] FIGS. 4A to 4C each show an inorganic dielectric element 2
with a surface 4 comprising the roughening. In the center of the
respective section of the electron microscope images, a circular
arrangement is applied. For example, this can be an additional
element arranged on the inorganic dielectric element 3.
[0072] FIGS. 5A and 5C show a three-dimensional profile structure
of a white light interferometry measurement according to one
embodiment each.
[0073] FIGS. 5B and 5D each show the corresponding measured values
from the 3D profile measurements. The table in FIG. 5B shows the
results of the measurement in FIG. 5A. The table in FIG. 5D shows
the results of the measurements in FIG. 5C. Tables 5B and 5D
respectively show Ra values, Rp values, Rq values, Rt values and Rv
values (mean square roughness value Rq, mean arithmetic roughness
value Ra, roughness depth Rt, mean smoothing depth Rp and mean
groove depth Rv).
[0074] The tables in FIGS. 5B and 5D indicate that the measurements
here comprise an Rq value of 31.05 nm or 22.35 nm, respectively. In
other words, a mean roughness Rq of between including 20 nm and
including 35 nm, in particular between including 22 nm and
including 30 nm, can be produced by the method described here. The
layer thicknesses of the dielectric element 3 determined here are,
for example, between 40 nm and 80 nm. Thicker or thinner layers are
also possible.
[0075] FIGS. 6A and 6B show atomic force microscope images (AFM)
according to one embodiment. The inorganic dielectric element 3 is
here formed from aluminum oxide. The layer thickness of the
inorganic dielectric element 3 is 190 nm. The mean roughness Rq has
a value of about 27.9 nm.
[0076] The exemplary embodiments described in connection with the
figures and their features can also be combined with each other
according to further exemplary embodiments, even if such
combinations are not explicitly shown in the figures. Furthermore,
the exemplary embodiments described in connection with the figures
can comprise additional or alternative features according to the
description in the general part.
[0077] The invention is not limited to the exemplary embodiments by
the description of the exemplary embodiments. Rather, the invention
includes each feature as well as each combination of features
which, in particular, includes each combination of features in the
patent claims, even if that feature or combination itself is not
explicitly stated in the patent claims or exemplary
embodiments.
* * * * *