U.S. patent application number 15/695093 was filed with the patent office on 2018-01-11 for thin film transistor substrates, methods of manufacturing the same and display devices including the same.
The applicant listed for this patent is Samsung Display Co., Ltd.. Invention is credited to Yi-Joon AHN, Jong-Mo YEO, Yong-Suk YEO.
Application Number | 20180012968 15/695093 |
Document ID | / |
Family ID | 52994381 |
Filed Date | 2018-01-11 |
United States Patent
Application |
20180012968 |
Kind Code |
A1 |
YEO; Yong-Suk ; et
al. |
January 11, 2018 |
THIN FILM TRANSISTOR SUBSTRATES, METHODS OF MANUFACTURING THE SAME
AND DISPLAY DEVICES INCLUDING THE SAME
Abstract
A thin film transistor substrate includes a data line, a gate
line, a gate electrode, a source electrode, a first drain
electrode, a semiconductor layer and a second drain electrode. The
data line and the gate line cross each other on a base substrate.
The gate electrode is electrically connected to the gate line. The
source electrode is electrically connected to the data line. The
first drain electrode and the source electrode face each other. The
semiconductor layer serves as a channel between the source
electrode and the first drain electrode. The second drain electrode
is disposed on the first drain electrode. The second drain
electrode is electrically connected to the first drain
electrode.
Inventors: |
YEO; Yong-Suk; (Seongnam-si,
KR) ; AHN; Yi-Joon; (Seoul, KR) ; YEO;
Jong-Mo; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Display Co., Ltd. |
Yongin-City |
|
KR |
|
|
Family ID: |
52994381 |
Appl. No.: |
15/695093 |
Filed: |
September 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14510284 |
Oct 9, 2014 |
9786750 |
|
|
15695093 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 29/41733 20130101;
H01L 27/124 20130101; H01L 27/3248 20130101; H01L 29/66969
20130101; H01L 29/66757 20130101; H01L 27/3262 20130101 |
International
Class: |
H01L 29/417 20060101
H01L029/417; H01L 27/12 20060101 H01L027/12; H01L 27/32 20060101
H01L027/32; H01L 29/66 20060101 H01L029/66 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 25, 2013 |
KR |
10-2013-0127581 |
Claims
1. A method of manufacturing a thin film transistor substrate,
comprising: forming a semiconductor layer which serves as a channel
of a thin film transistor, on a base substrate; forming a gate
insulation layer which covers the semiconductor layer; forming a
gate electrode of the thin film transistor, overlapping the
semiconductor layer and on the gate insulation layer; forming a
source electrode and a first drain electrode of the thin film
transistor, respectively contacting with ends of the semiconductor
layer; and forming a second drain electrode of the thin film
transistor, on the first drain electrode, wherein the second drain
electrode is electrically connected to the first drain
electrode.
2. The method of claim 1, further comprising: forming an insulating
interlayer which covers the source electrode, the first drain
electrode and the gate electrode; and forming a first contact which
extends through the insulating interlayer and contacts the first
drain electrode.
3. The method of claim 2, wherein the forming the second drain
electrode forms the second drain electrode on the insulating
interlayer, in contact with the first contact and in a different
layer than that of the first drain electrode.
4. The method of claim 1, further comprising forming a gate line
and a data line which cross each other on the base substrate,
wherein the forming the gate line simultaneously forms the gate
electrode, and the forming the data line simultaneously forms the
source electrode and the first drain electrode.
Description
[0001] This application is a divisional application of U.S.
application Ser. No. 14/510,284 filed Oct. 9, 2014, which claims
priority to Korean Patent Application No. 10-2013-0127581 filed on
Oct. 25, 2013, and all the benefits accruing therefrom under 35 USC
.sctn.119, the entire disclosure of which is incorporated by
reference herein.
BACKGROUND
1. Field
[0002] Exemplary embodiments relate to thin film transistor
substrates, methods of manufacturing the same and display devices
including the same. More particularly, exemplary embodiments relate
to thin film transistor substrates capable of realizing high
resolution, methods of manufacturing the same and display devices
including the same.
2. Description of the Related Art
[0003] A thin film transistor ("TFT") is widely used as a switching
device of a display device including, e.g., an organic light
emitting display ("OLED") device, a liquid crystal display ("LCD")
device, etc. The TFT may include a gate electrode electrically
connected to a gate line, a semiconductor layer insulated from the
gate electrode, and source and drain electrodes electrically
connected to the semiconductor layer.
[0004] When an area for the TFT is increased, an aperture ratio and
a resolution of the display device may be decreased.
SUMMARY
[0005] One or more exemplary embodiment provides a thin film
transistor ("TFT") substrate having a high degree of
integration.
[0006] One or more exemplary embodiment provides a method of
manufacturing a TFT substrate having a high degree of
integration.
[0007] One or more exemplary embodiment provides a display device
including a TFT substrate with a high degree of integration.
[0008] According to an exemplary embodiment, there is provided a
TFT substrate. The TFT substrate includes a data line, a gate line,
a gate electrode, a source electrode, a first drain electrode, a
semiconductor layer and a second drain electrode. The data line and
the gate line cross each other on a base substrate. The gate
electrode is electrically connected to the gate line. The source
electrode is electrically connected to the data line. The first
drain electrode and the source electrode face each other. The
semiconductor layer serves as a channel between the source
electrode and the first drain electrode. The second drain electrode
is disposed on the first drain electrode. The second drain
electrode is electrically connected to the first drain
electrode.
[0009] In exemplary embodiments, the second drain electrode may
serve as a land for a pixel electrode contact of a display
device.
[0010] In exemplary embodiments, the second drain electrode may be
in a different layer from that of the first drain electrode.
[0011] In exemplary embodiments, the TFT substrate may include a
first contact which electrically connects the first drain electrode
and the second drain electrode to each other.
[0012] In exemplary embodiments, the channel may extend in a
direction parallel to an extending direction of the gate line.
[0013] In exemplary embodiments, the channel may extend in a
direction vertical to an extending direction of the gate line.
[0014] In exemplary embodiments, the source electrode may be
connected to the data line via a connecting portion which protrudes
from the data line.
[0015] In exemplary embodiments, the second drain electrode may
fully cover a top surface of the first drain electrode.
[0016] In exemplary embodiments, the TFT substrate may include a
first contact which electrically connects the first drain electrode
and the second drain electrode to each other. The first contact and
the first drain electrode may be arranged along the same line
extending vertically with respect to a top surface of the base
substrate.
[0017] In exemplary embodiments, the TFT substrate may include a
gate insulation layer which covers the semiconductor layer on the
base substrate. The gate electrode may be disposed on the gate
insulation layer.
[0018] In exemplary embodiments, the TFT substrate may include a
gate insulation layer which covers the gate electrode on the base
substrate. The semiconductor layer may be disposed on the gate
insulation layer.
[0019] According to another exemplary embodiment, there is provided
a method of manufacturing a TFT substrate. In the method, a
semiconductor layer which serves as a channel is formed on a base
substrate. A gate insulation layer which covers the semiconductor
layer is formed. A gate electrode which is superimposed over the
semiconductor layer is formed on the gate insulation layer. A
source electrode and a first drain electrode which are respectively
in contact with ends of the semiconductor layer are formed. A
second drain electrode is formed on the first drain electrode. The
second drain electrode is electrically connected to the first drain
electrode.
[0020] In exemplary embodiments, an insulating interlayer which
covers the source electrode, the first drain electrode and the gate
electrode may be formed. A first contact which makes contact with
the first drain electrode may be formed extended through the
insulating interlayer.
[0021] In exemplary embodiments, the second drain electrode may be
formed on the insulating interlayer and in contact with the first
contact.
[0022] In exemplary embodiments, a gate line and a data line which
cross each other may be formed on the base substrate. The forming
the gate line may simultaneously form the gate electrode, and the
forming the data line may simultaneously form the source electrode
and the first drain electrode.
[0023] According to an exemplary embodiment, there is provided a
display device. The display device includes a base substrate, a TFT
on the base substrate, a second drain electrode, a first electrode,
an organic light emitting layer on the first electrode and a second
electrode on the organic light emitting layer. The TFT includes a
gate electrode, a gate insulation layer, a semiconductor layer, a
source electrode and a first drain electrode. The second drain
electrode is disposed on the first drain electrode to be
electrically connected to the first drain electrode. The first
electrode is electrically connected to the second drain
electrode.
[0024] In exemplary embodiments, the display device may include a
first contact and a second contact. The first contact may make
contact with the first drain electrode and the second drain
electrode. The second contact may make contact with the second
drain electrode and the first electrode.
[0025] In exemplary embodiments, the second contact may have a top
plan view dimension or a cross-section dimension larger than that
of the first contact.
[0026] In exemplary embodiments, the display device may include an
insulating interlayer which covers the TFT.
[0027] In exemplary embodiments, the first contact may extend
through the insulating interlayer, and the second drain electrode
may be disposed on the insulating interlayer.
[0028] According to one or more exemplary embodiment, a second
drain electrode of a TFT in contact with a pixel electrode contact
of a display device may be in and/or on a different layer or a
different level from that of a first drain electrode of the TFT.
Thus, a space for forming the second drain electrode may be
additionally obtained. Further, the second drain electrode may be
closer to a date line or a gate line, so that an area of the TFT
may be minimized in a pixel region of the display device.
Therefore, a display device having an increased aperture ratio and
a relatively high resolution may be manufactured using the TFT
substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Exemplary embodiments will be more clearly understood from
the following detailed description taken in conjunction with the
accompanying drawings. FIGS. 1 to 24 represent non-limiting,
exemplary embodiments as described herein:
[0030] FIG. 1 is a top plan view illustrating an exemplary
embodiment of a thin film transistor ("TFT") substrate in
accordance with the invention;
[0031] FIGS. 2A and 2B are cross-sectional views taken along line
I-I' and II-II' of FIG. 1, respectively;
[0032] FIG. 3 is a cross-sectional view illustrating a comparative
example of a TFT substrate.
[0033] FIGS. 4A and 4B are cross-sectional views taken along line
I-I' and II-II' of FIG. 3, respectively;
[0034] FIGS. 5 to 9 are cross-sectional views illustrating an
exemplary embodiment of a method of manufacturing the TFT substrate
of FIGS. 1, 2A and 2B;
[0035] FIG. 10 is a top plan view illustrating another exemplary
embodiment of a TFT substrate in accordance with the invention;
[0036] FIG. 11 is a cross-sectional view taken along line of FIG.
10;
[0037] FIG. 12 is a top plan view illustrating still another
exemplary embodiment of a TFT substrate in accordance with the
invention;
[0038] FIG. 13 is a cross-sectional view taken along line of FIG.
12;
[0039] FIG. 14 is a top plan view illustrating yet another
exemplary embodiment of a TFT substrate in accordance with the
invention;
[0040] FIGS. 15A to 15B are cross-sectional views taken along line
IV-IV' and V-V' of FIG. 14, respectively;
[0041] FIGS. 16 to 19 are cross-sectional views illustrating an
exemplary embodiment of a method of manufacturing the TFT substrate
of FIGS. 14, 15A and 15B;
[0042] FIG. 20 is a top plan view illustrating an exemplary
embodiment of a display device in accordance with the
invention;
[0043] FIG. 21 is a cross-sectional view taken along line VI-VI' of
FIG. 20; and
[0044] FIGS. 22 to 24 are cross-sectional views illustrating an
exemplary embodiment of a method of manufacturing the display
device of FIGS. 20 and 21.
DETAILED DESCRIPTION
[0045] Various exemplary embodiments will be described more fully
hereinafter with reference to the accompanying drawings, in which
exemplary embodiments are shown. The invention may, however, be
embodied in many different forms and should not be construed as
limited to the exemplary embodiments set forth herein. Rather,
these exemplary embodiments are provided so that this disclosure
will be thorough and complete, and will fully convey the scope of
the invention to those skilled in the art. In the drawings, the
sizes and relative sizes of layers and regions may be exaggerated
for clarity. Like numerals refer to like elements throughout.
[0046] It will be understood that, although the terms first,
second, third etc. may be used herein to describe various elements,
these elements should not be limited by these terms.
[0047] These terms are used to distinguish one element from
another. Thus, a first element discussed below could be termed a
second element without departing from the teachings of the
invention. As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0048] It will be understood that when an element is referred to as
being "connected" or "coupled" to another element, it can be
directly connected or coupled to the other element or intervening
elements may be present. In contrast, when an element is referred
to as being "directly connected" or "directly coupled" to another
element, there are no intervening elements present. Other words
used to describe the relationship between elements should be
interpreted in a like fashion (e.g., "between" versus "directly
between," "adjacent" versus "directly adjacent," etc.). As used
herein, connected may refer to elements being physically, and/or
electrically connected to each other.
[0049] Spatially relative terms, such as "under," "above," and the
like, may be used herein for ease of description to describe the
relationship of one element or feature to another element(s) or
feature(s) as illustrated in the figures. It will be understood
that the spatially relative terms are intended to encompass
different orientations of the device in use or operation, in
addition to the orientation depicted in the figures. For example,
if the device in the figures is turned over, elements described as
"under" relative to other elements or features would then be
oriented "above" relative to the other elements or features. Thus,
the exemplary term "under" can encompass both an orientation of
above and below. The device may be otherwise oriented (rotated 90
degrees or at other orientations) and the spatially relative
descriptors used herein interpreted accordingly.
[0050] The terminology used herein is for the purpose of describing
particular exemplary embodiments only and is not intended to be
limiting of the invention. As used herein, the singular forms "a,"
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprises" and/or "comprising," when
used in this specification, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof.
[0051] Embodiments of the invention are described herein with
reference to cross-section illustrations that are schematic
illustrations of idealized embodiments (and intermediate
structures) of the invention. As such, variations from the shapes
of the illustrations as a result, for example, of manufacturing
techniques and/or tolerances, are to be expected. Thus, embodiments
of the invention should not be construed as limited to the
particular shapes of regions illustrated herein but are to include
deviations in shapes that result, for example, from
manufacturing.
[0052] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0053] All methods described herein can be performed in a suitable
order unless otherwise indicated herein or otherwise clearly
contradicted by context. The use of any and all examples, or
exemplary language (e.g., "such as"), is intended merely to better
illustrate the invention and does not pose a limitation on the
scope of the invention unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the invention as used
herein.
[0054] Hereinafter, the invention will be described in detail with
reference to the accompanying drawings.
[0055] FIG. 1 is a top plan view illustrating an exemplary
embodiment of a thin film transistor ("TFT") substrate in
accordance with the invention. FIGS. 2A and 2B are cross-sectional
views taken along line I-I' and II-IF of FIG. 1, respectively.
[0056] For convenience of explanation, some elements of the TFT
substrate may be omitted in FIG. 1. For example, FIG. 1 illustrates
a semiconductor layer, a data line, a gate line, a gate electrode,
a source electrode and a drain electrode. In FIG. 1, two directions
substantially parallel to a top surface of a base substrate and
substantially perpendicular to each other are referred to as a
first direction and a second direction. The definition of the
directions is commonly applied substantially throughout all the
descriptions.
[0057] Referring to FIG. 1, the TFT substrate may include a data
line DL, a gate line GL, a semiconductor layer 110, a gate
electrode 130, a source electrode 150, a first drain electrode 155,
a second drain electrode 175 and a first contact 170.
[0058] The gate line GL may extend in the first direction. A
plurality of the gate lines GL may be disposed along the second
direction. The data line DL may extend in the second direction. A
plurality of the data lines DL may be disposed along the first
direction.
[0059] In the illustrated exemplary embodiment, for example, the
data lines DL may cross over the gate lines GL. In one exemplary
embodiment, a pixel region of a display device may be defined by an
intersection region of the data lines DL and the gate lines GL, but
the invention is not limited thereto or thereby.
[0060] The gate electrode 130 may protrude from the gate line GL in
the second direction. The gate electrode 130 may be integral with
the gate line GL, such that the gate line GL including the gate
electrode 130 is a single, unitary, indivisible member.
[0061] The source electrode 150 may protrude from the data line DL
in the first direction. The source electrode 150 may be integral
with the data line DL, such that the data line DL including the
source electrode 150 is a single, unitary, indivisible member.
[0062] The first drain electrode 155 may be spaced apart from the
source electrode 150 along the first direction, such that the
source electrode 150 and the first drain electrode 155 may face
each other with respect to the gate electrode 130. In an exemplary
embodiment of manufacturing the TFT substrate, the first drain
electrode 155 may be patterned simultaneously with the source
electrode 150, such that the first drain electrode 155 and the data
line DL including the source electrode 150 are in a same layer
and/or include a same material.
[0063] The semiconductor layer 110 indicated by dotted lines in
FIG. 1 may substantially overlap with the source electrode 150, the
first drain electrode 155 and the gate electrode 130.
[0064] A TFT may be defined by the semiconductor layer 110, the
gate electrode 130, the source electrode 150 and the first drain
electrode 155.
[0065] The second drain electrode 175 may be disposed on the first
drain electrode 155. The first and second electrodes 155 and 175
may be electrically connected to each other through the first
contact 170. The first and second electrodes 155 and 175 are in
different layers of the TFT substrate, such as being in different
single layers of the TFT substrate.
[0066] Hereinafter, a structure and/or a construction of the TFT
substrate are described in more detail with reference to FIGS. 2A
and 2B. FIGS. 2A and 2B illustrate a top gate type TFT in which the
gate electrode 130 is disposed on the semiconductor layer 110.
[0067] Referring to FIG. 2A, the semiconductor layer 110 and the
gate electrode 130 may be disposed on a base substrate 100, and the
source electrode 150 and the first drain electrode 155 may be
disposed over the gate electrode 130 to be in contact with the
semiconductor layer 110.
[0068] The base substrate 100 may include an insulation substrate
such as a glass substrate or a transparent plastic substrate. In
one exemplary embodiment, a buffer layer 105 may be disposed on the
base substrate 100. The buffer layer 105 may include, for example,
silicon oxide (SiOx), silicon nitride (SiNx) or silicon oxynitride
(SiOxNy).
[0069] The semiconductor layer 110 may include, for example,
amorphous silicon, polysilicon or an oxide semiconductor. The oxide
semiconductor may include, for example, indium gallium zinc oxide
("IGZO"), zinc tin oxide ("ZTO") or indium tin zinc oxide ("ITZO").
The semiconductor layer 110 may serve as a channel of the TFT
through which charges or electrons are transferred between the
source electrode 150 and the first drain electrode 155.
[0070] A gate insulation layer 120 may be disposed on the base
substrate 100 to cover the semiconductor layer 110. The gate
insulation layer 120 may include silicon oxide or silicon nitride.
The gate insulation layer 120 may include a single-layered
structure, but the invention is not limited thereto. In one
exemplary embodiment, the gate insulation layer 120 may have a
multi-layered structure including silicon oxide and silicon
nitride.
[0071] The gate line GL and the gate electrode 130 may be disposed
on the gate insulation layer 120. The gate electrode 130 may have a
substantially rectangular cross section as illustrated in FIG. 2A.
Alternatively, the gate electrode 130 may have a substantially
trapezoidal cross section. The gate electrode 130 may have a
single-layered structure, or a multi-layered structure including a
plurality of conductive layers.
[0072] As described with reference to FIG. 1, the gate line GL and
the gate electrode 130 may be integral with each other and may
include substantially the same material. In one exemplary
embodiment, for example, the gate electrode 130 may include a metal
such as aluminum (Al), copper (Cu), molybdenum (Mo), titanium (Ti)
or silver (Ag), or an alloy thereof. Alternatively, the gate
electrode 130 may include a transparent conductive material such as
indium tin oxide ("ITO"), indium zinc oxide ("IZO") or aluminum
doped zinc oxide ("AZO").
[0073] A first insulating interlayer 140 may be disposed on the
gate insulation layer 120 to cover the gate line GL and the gate
electrode 130. The source electrode 150 and the first drain
electrode 155 may extend through cross-sectional thicknesses of the
first insulating interlayer 140 and the gate insulation layer 120
to be in contact with the semiconductor layer 110.
[0074] The first insulating interlayer 140 may include an
insulation material such as silicon oxide or silicon nitride. The
first insulating interlayer 140 may protrude from the gate
insulation layer 120 according to a shape of the gate electrode
130, in a cross-sectional view. Alternatively, when the first
insulating interlayer 140 has a sufficient cross-sectional
thickness, the first insulating interlayer 140 may have a
substantially even or leveled upper surface (e.g., not
protruded).
[0075] The source electrode 150 and the first drain electrode 155
may be in contact with the semiconductor layer 110 via contact
holes defined through the first insulating interlayer 140 and the
gate insulation layer 120.
[0076] As described with reference to FIG. 1, the source electrode
150 and the first drain electrode 155 may include the same material
as that of the data line DL. In one exemplary embodiment, for
example, the source electrode 150 and the first drain electrode 155
may include a metal such as Al, Cu, Mo, Ti or Ag, or an alloy
thereof. Alternatively, the source electrode 150 and the first
drain electrode 155 may include a transparent conductive material
such as ITO, IZO or AZO.
[0077] In exemplary embodiments, ohmic contact layers (not
illustrated) may be disposed at both of opposing ends of the
semiconductor layer 110 which are in contact with the source
electrode 150 and the first drain electrode 155, respectively. The
ohmic contact layer may include n-type or p-type impurities.
[0078] A second insulating interlayer 160 may be disposed on the
first insulating interlayer 140 to cover the source electrode 150
and the first drain electrode 155. The second insulating interlayer
160 may include an insulation material such as silicon oxide or
silicon nitride.
[0079] As illustrated in FIGS. 1 and 2B, the second drain electrode
175 may be disposed on the second insulating interlayer 160 to be
electrically connected to the first drain electrode 155 via the
first contact 170 that may extend through a cross-sectional
thickness of the second insulating interlayer 160. In exemplary
embodiments, the second drain electrode 175 and the first contact
170 may be integral with each other, such that the second drain
electrode 175 and the first contact 170 form a single, unitary,
indivisible member.
[0080] The second drain electrode 175 and the first contact 170 may
include a metal such as Al, Cu, Mo, Ti or Ag, or an alloy thereof.
Alternatively, the second drain electrode 175 and the first contact
170 may include a transparent conductive material such as ITO, IZO
or AZO. In one exemplary embodiment, the second drain electrode
175, the first contact 170 and the first drain electrode 155 may
include substantially the same conductive material so that contact
resistances therebetween may be reduced.
[0081] In exemplary embodiments, the second drain electrode 175 may
serve as a land for a conductive via or a pixel electrode contact
when the TFT substrate is employed in a display device.
[0082] FIG. 3 is a cross-sectional view illustrating a comparative
example of a TFT substrate. FIGS. 4A and 4B are cross-sectional
views taken along line I-I' and II-II' of FIG. 3, respectively. The
TFT substrate according to the comparative example may have a
construction substantially the same as or similar to that
illustrated with reference to the exemplary embodiment of FIGS. 1
and 2A and 2B except for a shape and/or an arrangement of a second
drain electrode. Thus, detailed descriptions on elements and/or
structures substantially the same as or similar to those
illustrated with reference to FIGS. 1 and 2A and 2B are omitted.
Like reference numerals are used to refer to like elements.
[0083] Referring to FIGS. 3, 4A and 4B, a first drain electrode
155a and a second drain electrode 175a may be disposed in and/or on
a same layer or at same level within the TFT substrate according to
the comparative example. As described with reference to FIG. 2B,
the second drain electrode 175 may be disposed on the second
insulating interlayer 160 and in a different layer than first drain
electrode 155, to be electrically connected to the first drain
electrode 155 via the first contact 170. However, according to the
comparative example, the drain electrode 175a may be integral with
the first drain electrode 155a to be disposed on the first
insulating interlayer 140 and in a same layer as the first drain
electrode 155a.
[0084] In the comparative example, the data line DL, the first
drain electrode 155a and the second drain electrode 175a may be in
and/or on a same level or in a same plane so that a formation of a
TFT having a compact size may be limited. In one exemplary
embodiment, for example, a predetermined distance referred to as
"D2" between the data line DL and the second drain electrode 175a
may be required in consideration of an alignment tolerance when the
data line DL and the second drain electrode 175a are formed using
one patterning mask in a method of manufacturing the TFT
substrate.
[0085] However, according to one or more exemplary embodiment in
accordance with the invention, a distance between the data line DL
and the second drain electrode 175 (referred to as "D1") may be
minimized without a consideration of the alignment tolerance
because the second drain electrode 175 is disposed in and/or on a
different level or a different layer from those of the data line DL
and the first drain electrode 155. Therefore, an overall area
(e.g., planar area) for the TFT may be minimized in a display
device so that an aperture ratio and a resolution of the display
device may be improved.
[0086] In exemplary embodiments, the drain electrode 175 may be
partially superimposed over the data line DL. In one exemplary
embodiment, the second drain electrode 175 may be spaced apart from
the data line DL with a distance smaller than D2 of FIGS. 3 and 4B
in consideration of a parasitic capacitance that may be generated
between the second drain electrode 175 and the date line DL.
[0087] FIGS. 5 to 9 are cross-sectional views illustrating an
exemplary embodiment of a method of manufacturing the TFT substrate
of FIGS. 1, 2A and 2B. Specifically, FIGS. 5 to 8 are
cross-sectional views taken along a direction of line I-I' of FIG.
1. FIG. 9 is a cross-sectional view taken along a direction of line
II-II' of FIG. 1.
[0088] Referring to FIG. 5, a buffer layer 105 may be formed on a
base substrate 100. A semiconductor layer 110 may be formed on the
buffer layer 105. A gate insulation layer 120 covering the
semiconductor layer 110 may be formed on the buffer layer 105.
[0089] An insulation substrate such as a glass substrate or a
transparent plastic substrate may be used as the base substrate
100. The buffer layer 105 may be formed using an insulation
material such as silicon oxide, silicon nitride or silicon
oxynitride by a chemical vapor deposition ("CVD") process, a plasma
enhanced chemical vapor deposition ("PECVD") process or a high
density plasma-chemical vapor deposition ("HDP-CVD") process,
etc.
[0090] An amorphous silicon layer, a polysilicon layer or an oxide
semiconductor layer may be deposited on the buffer layer 105 by a
sputtering process, a CVD process, a low pressure CVD ("LPCVD")
process, a vacuum evaporation process, etc., and then the
semiconductor layer 110 may be obtained by patterning the amorphous
silicon layer, the polysilicon layer or the oxide semiconductor
layer. A laser crystallization process or a thermal crystallization
process may be further performed on the amorphous silicon layer.
The oxide semiconductor layer may be formed using an oxide
semiconductor material such as IGZO, ZTO or ITZO.
[0091] The gate insulation layer 120 may be formed using, e.g.,
silicon oxide or silicon nitride by a CVD process, a PECVD process,
a vacuum evaporation process, etc. The gate insulation layer 120
may be formed to have a single-layer structured, or a multi-layered
structure including, e.g., a silicon nitride layer and a silicon
oxide layer.
[0092] The gate insulation layer 120 may have a substantially even
or leveled (e.g., planarized) upper surface as illustrated in FIG.
5. Alternatively, the gate insulation layer 120 may be protruded at
a portion overlapping with the semiconductor layer 110.
[0093] Referring to FIG. 6, a gate electrode 130 and a gate line GL
may be formed on the gate insulation layer 120.
[0094] In exemplary embodiments, a first conductive layer may be
formed on the gate insulation layer 120, and then the first
conductive layer may be patterned by, e.g., a photolithography
process to form the gate electrode 130 and the gate line GL. The
first conductive layer may be formed using a metal such as Al, Mo,
Ti, Cu or Ag, or an alloy thereof by a sputtering process, a CVD
process, an atomic layer deposition ("ALD") process, a vacuum
evaporation process, a printing process, etc. Alternatively, the
first conductive layer may be formed using a transparent conductive
material such as ITO, IZO or AZO.
[0095] As described with reference to FIG. 1, the gate line GL and
the gate electrode 130 may be connected to and integral with each
other, and may be formed by the same patterning process.
[0096] In one exemplary embodiment, impurities may be implanted
into the semiconductor layer 110 using the gate electrode 130 as a
mask to form ohmic contact layers (not shown) at both ends of the
semiconductor layer 110. The ohmic contact layers may include
n-type or p-type impurities. The ohmic contact layers may serve as
a source region and a drain region.
[0097] A portion of the semiconductor layer 110 between the ohmic
contact layers may serve as a channel of the TFT, that may
substantially overlap with the gate electrode 130.
[0098] Referring to FIG. 7, a first insulating interlayer 140
covering the gate line GL and the gate electrode 130 may be formed
on the gate insulation layer 120. The first insulating interlayer
140 and the gate insulation layer 120 may be partially etched to
form openings 145 partially exposing the semiconductor layer 110.
In exemplary embodiments, where ohmic contact layers serve as a
source region and a drain region, the ohmic contact layers may be
exposed by the openings 145.
[0099] The first insulating interlayer 140 may be formed using an
insulation material such as silicon oxide or silicon nitride by a
CVD process, a PECVD process, a spin coating process, etc. The
first insulating interlayer 140 may be protruded at a portion
covering the gate electrode 130. Alternatively, when the first
insulating interlayer 140 is formed to have a sufficient thickness,
the first insulating interlayer 140 may have a substantially even
or leveled upper surface.
[0100] Referring to FIG. 8, a source electrode 150, and a first
drain electrode 155 filling the openings 145, may be formed on the
first insulating interlayer 140. The source electrode 150 and the
first drain electrode 155 may be in contact with the semiconductor
layer 110. A second insulating interlayer 160 covering the source
electrode 150 and the first drain electrode 155, may be formed on
the first insulating interlayer 140.
[0101] In exemplary embodiments, a second conductive layer
sufficiently filling the openings 145 may be formed on the first
insulating interlayer 140. The second conductive layer may be
patterned using a photoresist pattern or other mask patterns to
form the source electrode 150 and the first drain electrode 155 in
contact with the semiconductor layer 110. In exemplary embodiments,
the source electrode 150 and the first drain electrode 155 may be
in contact with the source region and the drain region of the
semiconductor layer 110, respectively.
[0102] The second conductive layer may be formed using a metal such
as Al, Mo, Ti, Cu or Ag, or an alloy thereof by a sputtering
process, a CVD process, an ALD process, a vacuum evaporation
process, a printing process, etc. Alternatively, the second
conductive layer may be formed using a transparent conductive
material such as ITO, IZO or AZO.
[0103] As described with reference to FIG. 1, the data line DL and
the source electrode 150 may be connected to and integral with each
other, and may be formed by the same patterning process.
[0104] By forming the source electrode 150 and the first drain
electrode 155, a TFT including the semiconductor layer 110, the
gate insulation layer 120, the gate electrode 130, the source
electrode 150 and the first drain electrode 155 may be defined.
[0105] The second insulating interlayer 160 may be formed using an
insulation material such as silicon oxide or silicon nitride by a
CVD process, a PECVD process, a spin coating process, etc.
[0106] Referring to FIG. 9, a second drain electrode 175
electrically connected to the first drain electrode 155 via a first
contact 170 may be formed on the second insulating interlayer
160.
[0107] In exemplary embodiments, the second insulating interlayer
160 may be partially etched to form a first contact hole 165 at
least partially exposing the first drain electrode 155. A third
conductive layer sufficiently filling the first contact hole 165
may be formed on the second insulating interlayer 160, and then the
third conductive layer may be patterned. Accordingly, the first
contact 170 filling the first contact hole 165 may be formed on the
first drain electrode 155, and the second drain electrode 175
contacting the first contact 170 may be formed on the second
insulating interlayer 160.
[0108] The third conductive layer may be formed using a metal such
as Al, Mo, Ti, Cu or Ag, or an alloy thereof by a sputtering
process, a CVD process, an ALD process, a vacuum evaporation
process, a printing process, etc. Alternatively, the third
conductive layer may be formed using a transparent conductive
material such as ITO, IZO or AZO. In exemplary embodiments, the
first drain electrode 155, the first contact 170 and the second
drain electrode 175 may be formed using the same conductive
material.
[0109] The first contact 170 and the second drain electrode 175 may
be integrally formed with each other. In one exemplary embodiment,
the first contact 170 may be formed, and then the second drain
electrode 175 may be formed by performing additional deposition and
patterning processes.
[0110] As described above, the second drain electrode 175 may be
formed in and/or on a different single layer or a different single
level from that of the first drain electrode 155, so that the
second drain electrode 175 may be spaced apart from the data line
DL in the top plan view with a minimum distance Dl. In one
exemplary embodiment, the second drain electrode 175 may be formed
to be partially superimposed over (e.g., overlapped with) the data
line DL. Therefore, an overall planar area for the TFT may be
minimized in the TFT substrate or a display device including the
TFT substrate.
[0111] FIG. 10 is a top plan view illustrating another exemplary
embodiment of a TFT substrate in accordance with the invention.
FIG. 11 is a cross-sectional view taken along line of FIG. 10.
Detailed descriptions on elements, structures and/or materials
substantially the same as or similar to those illustrated with
reference to FIGS. 1, 2A and 2B are omitted.
[0112] Referring to FIGS. 10 and 11, the TFT substrate may include
a base substrate 200, a buffer layer 205, a semiconductor layer
210, a gate electrode 230, a gate insulation layer 220, a first
insulating interlayer 240, a source electrode 250, a first drain
electrode 255, a first contact 270, a second insulating interlayer
260 and a second drain electrode 275.
[0113] A gate line GL may extend in the first direction, and a
portion of the gate line GL substantially overlapping with the
semiconductor layer 210 may serve as the gate electrode 230.
Accordingly, the gate electrode 230 may also extend in the first
direction and be integral with the gate line GL.
[0114] A date line DL may extend in the second direction. The
source electrode 250 may be integral with the data line DL via a
connecting portion 245. The source electrode 250 may also extend in
the second direction and be spaced apart from a main portion of the
data line DL extending in the second direction. The connecting
portion 245 may protrude from the data line DL in the first
direction to connect the data line DL and the source electrode 250
to each other.
[0115] The first drain electrode 255 may be spaced apart from the
source electrode 250 such that the first drain electrode 255 and
the source electrode 250 may face each other in the second
direction with respect to the gate electrode 230. In an exemplary
embodiment of manufacturing the TFT substrate, the data line DL,
the connecting portion 245, the source electrode 250 and the first
drain electrode 255 may be formed by the same patterning process,
such that data line DL, the connecting portion 245, the source
electrode 250 and the first drain electrode 255 are in a same layer
and/or include a same material.
[0116] A portion of the semiconductor layer 210 between the source
electrode 250 and the first drain electrode 255 may substantially
overlap with the gate electrode 230 to serve as a channel of the
TFT. In the TFT substrate of FIG. 1, the channel may be extended
along the first direction substantially the same as or parallel to
an extending direction of the gate line GL. However, in an
alternative exemplary embodiment of the TFT substrate of FIG. 10,
the channel may be extended along the second direction
substantially perpendicular to an extending direction of the gate
line GL. Where the channel is extended along the second direction,
a sufficient channel length may be achieved in the second
direction, and thus a width of the TFT along the first direction
may be decreased.
[0117] Referring to FIG. 11, the second drain electrode 275 may be
disposed on the second insulating interlayer 260 to be electrically
connected to the first drain electrode 255 via the first contact
270. As described above, the second drain electrode 275 may be
located in and/or on a different layer or a different level from
that of the first drain electrode 255 such that the second drain
electrode 275 may be disposed to be more adjacent to (e.g., closer
to) the data line DL in the plan view.
[0118] In exemplary embodiments, the first drain electrode 255 may
include a contact portion 253 and a land portion 254. The contact
portion 253 may be defined as a portion contacting the
semiconductor layer 210 through the first insulating interlayer 240
and the gate insulation layer 220. The land portion 254 may be
defined as a portion disposed on the first insulating interlayer
240 and continuously extending from the contact portion 253. The
first contact 270 may be disposed on the land portion 254 of the
first drain electrode 255 to be electrically connected to the
second drain electrode 275.
[0119] FIG. 12 is a top plan view illustrating still another
exemplary embodiment of a TFT substrate in accordance with the
invention. FIG. 13 is a cross-sectional view taken along line of
FIG. 12. The TFT substrate may have a construction substantially
the same as or similar to that illustrated with reference to FIGS.
10 and 11 except for an arrangement of a second drain electrode.
Thus, detailed descriptions on elements and/or structures
substantially the same as or similar to those illustrated with
reference to FIGS. 10 and 11 are omitted. Like reference numerals
are used to refer to like elements.
[0120] Referring to FIGS. 12 and 13, a second drain electrode 275a
may be disposed to be more adjacent to (e.g., closer to) a gate
electrode 230. Accordingly, a top surface of a first drain
electrode 255 may be fully covered by the second drain electrode
275a.
[0121] In exemplary embodiments, a first contact 270 may be in
contact with a contact portion 253 of the first drain electrode
255. Where the first contact 270 is in contact with the contact
portion 253 of the first drain electrode 255, the first contact 270
and the contact portion 253 may be arranged along the same line
extending vertically with respect to a top surface of a base
substrate 200.
[0122] In one exemplary embodiment, the first contact 270 may be
disposed on the contact portion 253 of the first drain electrode
255 as illustrated in FIG. 13. Thus, a land portion 254 illustrated
in FIG. 11 of the first drain electrode 255 may be omitted. Where
the land portion 254 of the first drain electrode 255 is omitted, a
length of the first drain electrode 255 along the second direction
may be decreased so that an area for a TFT may be additionally
reduced.
[0123] The exemplary embodiments of the TFT substrates illustrated
with reference to FIGS. 10 to 13 may be obtained by processes
substantially the same as or similar to those illustrated with
reference to FIGS. 5 to 9. Thus, detailed descriptions on methods
of manufacturing the TFT substrates illustrated in FIGS. 10 to 13
are omitted.
[0124] FIG. 14 is a top plan view illustrating yet another
exemplary embodiment of a TFT substrate in accordance with the
invention. FIGS. 15A to 15B are cross-sectional views taken along
line IV-IV' and V-V' of FIG. 14, respectively. FIGS. 14, 15A and
15B illustrate the TFT substrate including a bottom gate type TFT
in which a gate electrode is disposed under a semiconductor layer.
Detailed descriptions on elements and/or structures substantially
the same as or similar to those illustrated with reference to FIGS.
1, 2A and 2B are omitted.
[0125] Referring to FIGS. 14 to 15B, a gate line GL and a gate
electrode 310 may be disposed on a base substrate 300. The gate
line GL and the gate electrode 310 may be integral with each other,
and the gate electrode 310 may protrude from the gate line GL in
the second direction.
[0126] A gate insulation layer 320 may be disposed on the base
substrate 300 to cover the gate line GL and the gate electrode 310.
The gate insulation layer 320 may include a protruded portion
according to shapes of the gate electrode 310 and the gate line GL.
Alternatively, the gate insulation layer 320 may have a sufficient
cross-sectional thickness to have a substantially even or leveled
upper surface.
[0127] A semiconductor layer 330 may be disposed on the gate
insulation layer 320 to cover the gate electrode 310. A source
electrode 340 and a first drain electrode 350 facing each other
with respect to the gate electrode 310 may be disposed on the gate
insulation layer 320 and both of opposing ends of the semiconductor
layer 330. A portion of the semiconductor layer 330 between the
source electrode 340 and the first drain electrode 350 which may be
substantially superimposed over the gate electrode 310 may define a
channel of the TFT.
[0128] An insulating interlayer 360 may be disposed on the gate
insulation layer 320 to cover the source electrode 340, the first
drain electrode 350 and the semiconductor layer 330. The insulating
interlayer 360 may include an insulation material such as silicon
oxide or silicon nitride.
[0129] Referring to FIG. 15B, a second drain electrode 375 may be
electrically connected to the first drain electrode 350 via a first
contact 370 extended through the insulating interlayer 360. In
exemplary embodiments, the second drain electrode 375 may serve as
a land for a pixel electrode contact (not illustrated) when the TFT
substrate is employed in a display device.
[0130] A distance between a data line DL and the second drain
electrode 375 in the plan view, may be minimized without a
consideration of an alignment tolerance because the second drain
electrode 375 may be disposed in and/or on a different level or a
different layer from those of the data line DL and the first drain
electrode 350. Therefore, an overall planar area for the TFT may be
minimized in the display device so that an aperture ratio and a
resolution of the display device may be improved.
[0131] FIGS. 16 to 19 are cross-sectional views illustrating an
exemplary embodiment of a method of manufacturing the TFT substrate
of FIGS. 14, 15A and 15B. Specifically, FIGS. 16 to 18 are
cross-sectional views taken along line IV-IV' of FIG. 14. FIG. 19
is a cross-sectional view taken along line V-V' of FIG. 14.
Detailed descriptions on processes and/or materials substantially
the same as or similar to those illustrated with reference to FIGS.
5 to 9 are omitted.
[0132] Referring to FIG. 16, a gate line GL and a gate electrode
310 may be formed on a base substrate 300. In exemplary
embodiments, a first conductive layer may be formed on the base
substrate 300, and then the first conductive layer may be patterned
by, e.g., a photolithography process to form the gate line GL and
the gate electrode 310. The gate line GL and the gate electrode 310
may be simultaneously formed by a patterning process utilizing a
single mask.
[0133] A gate insulation layer 320 covering the gate line GL and
the gate electrode 310 may be formed on the base substrate 300. The
gate insulation layer 320 may have protruded portions according to
shapes of the gate line GL and the gate electrode 310.
Alternatively, the gate insulation layer 320 may be formed to have
a substantially even or leveled upper surface by controlling
deposition conditions.
[0134] Referring to FIG. 17, a semiconductor layer 330 overlapping
with the gate electrode 310 may be formed on the gate insulation
layer 320. A source electrode 340 and a first drain electrode 350
may be formed on both ends of the semiconductor layer 330. In
exemplary embodiments, a second conductive layer may be formed on
the gate insulation layer 320 and the semiconductor layer 330, and
then the second conductive layer may be patterned using a
photoresist pattern or other mask patterns to form the source
electrode 340 and the first drain electrode 350 to be in contact
with the semiconductor layer 330. A data line DL may be formed
together with the source electrode 340 and the first drain
electrode 350.
[0135] Referring to FIG. 18, an insulating interlayer 360 covering
the source electrode 340, the first drain electrode 350 and the
semiconductor layer 330 may be formed on the gate insulation layer
320. The insulating interlayer 360 may be formed using an
insulation material such as silicon oxide or silicon nitride by a
CVD process, a spin coating process, etc. In exemplary embodiments,
the insulating interlayer may serve as a planarization layer.
[0136] Referring to FIG. 19, a second drain electrode 375
electrically connected to the first drain electrode 350 via a first
contact 370 may be formed on the insulating interlayer 360. In
exemplary embodiments, the insulating interlayer 360 may be
partially etched to form a contact hole exposing the first drain
electrode 350, and then a third conductive layer sufficiently
filling the contact hole may be formed on the insulating interlayer
360. The third conductive layer may be patterned to form the second
drain electrode 375 and the first contact 370.
[0137] In the bottom gate type TFT substrate of FIG. 14, the TFT
channel may be formed elongated in a direction substantially
parallel to an extending direction of the gate line GL. However, as
illustrated in FIG. 10, the TFT channel may be formed elongated in
a direction substantially perpendicular to an extending direction
of the gate line GL.
[0138] FIG. 20 is a top plan view illustrating an exemplary
embodiment of a display device in accordance with the invention.
FIG. 21 is a cross-sectional view taken along line VI-VI' of FIG.
20. In an exemplary embodiment, for example, FIGS. 20 and 21
illustrate an organic light emitting display ("OLED") device
including the TFT substrate in accordance with the invention.
Detailed descriptions on elements and/or structures substantially
the same as or similar to those illustrated with reference to FIGS.
1, 2A and 2B are omitted.
[0139] Referring to FIGS. 20 and 21, the display device may include
one or more of the above-described exemplary embodiments of the TFT
substrate in accordance with the invention, and an organic light
emitting structure formed thereon.
[0140] As described with reference to FIGS. 1, 2A and 2B, the TFT
substrate may include a buffer layer 105, a semiconductor layer
110, a gate insulation layer 120, a gate electrode 130, a first
insulating interlayer 140, a source electrode 150, a first drain
electrode 155, a first contact 170 and a second drain electrode
175. The second drain electrode 175 may be disposed on a second
insulating interlayer 160 to be electrically connected to the first
drain electrode 155 via the first contact 170.
[0141] In exemplary embodiments, the TFT substrate may have a
structure substantially the same as or similar to that illustrated
with reference to FIGS. 10 and 11, or FIGS. 12 and 13. In one
exemplary embodiment, the TFT substrate may have a bottom gate
structure substantially the same as or similar to that illustrated
with reference to FIGS. 14, 15A and 15B.
[0142] The organic light emitting structure may be disposed on the
TFT substrate. The organic light emitting structure may include a
passivation layer 400, a second contact 405, a first electrode 410,
a pixel defining layer ("PDL") 420, an organic light emitting layer
("EML") 430 and a second electrode 440.
[0143] The passivation layer 400 may be disposed on the second
insulating interlayer 160 to cover the second drain electrode 175.
The passivation layer 400 may include a transparent insulation
material having a self-planarization property. In one exemplary
embodiment, for example, the passivation layer 400 may include an
organic material such as an acryl-based resin, a polyimide-based
resin, a siloxane-based resin or benzocyclobutene ("BCB").
[0144] The second contact 405 may extend through the passivation
layer 400 to electrically connect the second drain electrode 175
and the first electrode 410 disposed on the passivation layer 400,
to each other. In exemplary embodiments, the second contact 405 may
be integral with the first electrode 410. The second contact 405
and the first electrode 410 may include a metal such as aluminum
(Al), silver (Ag), tungsten (W), copper (Cu), nickel (Ni), chrome
(Cr), molybdenum (Mo), titanium (Ti), tantalum (Ta) or neodymium
(Nd), an alloy thereof or a nitride thereof. Alternatively, the
second contact 405 and the first electrode 410 may include a
transparent conductive material such as ITO, IZO, AZO, tin oxide or
zinc oxide.
[0145] In exemplary embodiments, the second contact 405 may have a
plan view dimension (e.g., diameter) or a cross-section dimension
larger than those of the first contact 170. Thus, the second drain
electrode 175 serving as a land for the second contact 405 may be
needed in consideration of a size of the second contact 405 and an
alignment tolerance. The second contact 405 may serve as pixel
electrode contact of the display device, and the first electrode
410 may serve as a pixel electrode or an anode of the display
device.
[0146] The PDL 420 may be disposed on the passivation layer 400 to
cover peripheral portions of the first electrode 410. In one
exemplary embodiment, the PDL 420 may define a pixel region of the
display device, and a portion of the first electrode 410 not
covered by the PDL 420 may substantially correspond to an area of
the pixel region. The PDL 420 may include photosensitive material
such as polyimide resin or acryl resin. Alternatively, the PDL 420
may include a non-photosensitive organic material or an inorganic
material such as carbon black.
[0147] The EML 430 may be disposed on the PDL 420 and the first
electrode 410 exposed by the PDL 420. In one exemplary embodiment,
a hole transport layer ("HTL") (not illustrated) may be further
disposed between the first electrode 410 and the EML 430.
[0148] The EML 430 may include at least one of light emitting
materials for generating different colors of light, for example, a
red color of light, a green color of light or a blue color of
light. In one exemplary embodiment, the EML 430 may include a
combination of the light emitting materials for generating a white
color of light.
[0149] The HTL may include a hole transport material, for example,
4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl ("NPB"),
4,4'-bis[N-(3-methylphenyl)-N-phenylamino] biphenyl ("TPD"),
N,N'-di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl)-4,4'-diamine
("NPD"), N-phenylcarbazole, polyvinylcarbazole or a combination
thereof.
[0150] As illustrated in FIG. 21, the EML 430 may be disposed
continuously on surfaces of the PDL 420 and the first electrode
410. Alternatively, the EML 430 may be patterned in each pixel to
be a discrete element confined by sidewalls of the PDL 420.
[0151] The second electrode 440 may be disposed on the EML 430. The
second electrode 440 may include a metal such as lithium (Li),
calcium (Ca), lithium fluoride/calcium (LiF/Ca), LiF/Al, Al, Mg,
Ag, Cr, W, Mo or Ti and an alloy thereof. In one exemplary
embodiment, the second electrode 440 may include a transparent
conductive material such as ITO, IZO, AZO, tin oxide or zinc oxide.
The second electrode 440 may serve as a cathode of the display
device.
[0152] The second electrode 440 may be disposed continuously on a
substantially entire surface of the display device, such as to
serve as a common electrode. Alternatively, the second electrode
440 may be patterned in each pixel, such as to include a plurality
of discrete portions. Where the second electrode 440 includes a
plurality of discrete portions, the portions of the collective
second electrode 440 may be respectively confined by the sidewalls
of the PDL 420 together with the EML 430.
[0153] In one exemplary embodiment, an electron transport layer
("ETL") (not illustrated) may be further disposed between the
second electrode 440 and the EML 430. The ETL may include an
electron transport material, for example,
tris(8-quinolinolato)aluminum ("Alq3"),
2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole ("PBD"),
bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum ("Balq"),
bathocuproine ("BCP") or a combination thereof.
[0154] FIGS. 22 to 24 are cross-sectional views illustrating an
exemplary embodiment of a method of manufacturing the display
device of FIGS. 20 and 21.
[0155] Referring to FIG. 22, processes substantially the same as or
similar to those illustrated with reference to FIGS. 5 to 9 may be
performed to form a TFT substrate in accordance with one or more
exemplary embodiment of the invention. The TFT substrate may have a
structure substantially the same as or similar to that illustrated
with reference to FIG. 1, FIG. 10 or FIG. 12.
[0156] In one exemplary embodiment, processes substantially the
same as or similar to those illustrated with reference to FIGS. 16
to 19 may be performed to form an exemplary embodiment of the TFT
substrate in accordance with the invention. Where the TFT substrate
is formed with reference to FIGS. 16 to 19, the TFT substrate may
have a structure substantially the same as or similar to that
illustrated with reference to FIG. 14.
[0157] Referring to FIG. 23, a passivation layer 400 covering a
second drain electrode 175 may be formed on a second insulating
interlayer 160. A second contact 405 may be formed extended through
the passivation layer 400 to be in contact with the second drain
electrode 175. A first electrode 410 may be formed on the
passivation layer 400 to be electrically connected to the second
drain electrode 175 via the second contact 405.
[0158] The passivation layer 400 may be formed using a transparent
organic material such as an acryl-based resin, a polyimide-based
resin, a siloxane-based resin or BCB. The passivation layer 400 may
be formed by a spin coating process, a slit coating process, etc.
In one exemplary embodiment, a planarization process may be further
performed on an upper surface of the passivation layer 400.
[0159] The passivation layer 400 may be partially etched to form a
second contact hole 407 partially exposing a top surface of the
second drain electrode 175, and then a conductive layer filling the
second contact hole 407 may be formed on the passivation layer 400,
a sidewall and a bottom surface of the second contact hole 407. The
conductive layer may be patterned to obtain the second contact 405
and the first electrode 410. In exemplary embodiments, the second
contact 405 and the first electrode 410 may be integrally formed
with each other.
[0160] The conductive layer may be formed using a metal such as Al,
Ag, W, Cu, Ni, Cr, Mo, Ti, Ta or Nd, an alloy thereof or a nitride
thereof. Alternatively, the conductive layer may be formed using a
transparent conductive material such as ITO, IZO, AZO, tin oxide or
zinc oxide. The conductive layer may be obtained by a sputtering
process, a CVD process, an ALD process, a vacuum evaporation
process, a printing process, etc.
[0161] Referring to FIG. 24, a PDL 420 covering peripheral portions
of the first electrode 410 may be formed on the passivation layer
400 to define a pixel region of the display device. An EML 430 and
a second electrode 440 may be sequentially formed on the PDL 420
and the first electrode 410.
[0162] In one exemplary embodiment, for example, a photosensitive
material layer including, e.g., an acryl-based resin, a
polyimide-based resin or BCB may be formed on the passivation layer
400 and the first electrode 410. The photosensitive material layer
may be patterned by an exposure process and a developing process to
form the PDL 420. Alternatively, non-photosensitive organic or
inorganic layers may be formed on the passivation layer 400 and the
first electrode 410, and then the non-photosensitive organic or
inorganic layers may be partially etched to form the PDL 420.
[0163] The EML 430 may be formed using at least one of light
emitting materials for generating different colors of light, for
example, a red color of light, a green color of light or a blue
color of light. In one exemplary embodiment, the EML 430 may be
formed using a combination of the light emitting materials for
generating a white color of light. The EML 430 may be formed by a
spin coating process, a roll printing process, a nozzle printing
process, an inkjet printing process, a transfer process using a
donor substrate, etc.
[0164] The EML 430 may be formed continuously on surfaces of the
PDL 420 and the first electrode 410 as illustrated in FIG. 24.
Alternatively, the EML 430 may be patterned to form discrete
portions confined by sidewalls of the PDL 420.
[0165] In one exemplary embodiment, an HTL may be further formed
between the EML 430 and the first electrode 410 using the above
mentioned hole transport material. In one exemplary embodiment, an
ETL may be further formed on the EML 430 using the above mentioned
electron transport material. The HTL and the ETL may be formed by a
spin coating process, a roll printing process, a nozzle printing
process, an inkjet printing process, a transfer process using a
donor substrate, etc.
[0166] The second electrode 440 may be formed using a metal such as
Li, Ca, LiF/Ca, LiF/Al, Al, Mg, Ag, Cr, W, Mo or Ti, or an alloy
thereof. In one exemplary embodiment, the second electrode 440 may
be formed using a transparent conductive material such as ITO, IZO,
AZO, tin oxide or zinc oxide. The second electrode 440 may be
obtained by a sputtering process, a CVD process, an ALD process, a
vacuum evaporation process, a printing process, etc.
[0167] The second electrode 440 may be formed continuously on a
substantially entire surface of the display device. Alternatively,
the second electrode 440 may be patterned to form discrete portion
respectively disposed in each pixel.
[0168] Additionally, an optical sheet (not shown), a polarization
film (not shown) and an upper transparent substrate (not shown) may
be optionally formed on the second electrode 440 to manufacture the
display device.
[0169] According to one or more exemplary embodiment of the
invention, an area for the TFT may be minimized in a display device
so that an aperture ratio and a resolution of the display device
may be improved.
[0170] The foregoing is illustrative of exemplary embodiments and
is not to be construed as limiting thereof. Although a few
exemplary embodiments have been described, those skilled in the art
will readily appreciate that many modifications are possible in the
exemplary embodiments without materially departing from the novel
teachings and advantages of the invention. Accordingly, all such
modifications are intended to be included within the scope of the
invention as defined in the claims. Therefore, it is to be
understood that the foregoing is illustrative of various exemplary
embodiments and is not to be construed as limited to the specific
exemplary embodiments disclosed, and that modifications to the
disclosed exemplary embodiments, as well as other exemplary
embodiments, are intended to be included within the scope of the
appended claims.
* * * * *