U.S. patent application number 14/261181 was filed with the patent office on 2015-04-23 for liquid crystal display and manufacturing method thereof.
This patent application is currently assigned to Samsung Display Co., Ltd.. The applicant listed for this patent is Samsung Display Co., Ltd.. Invention is credited to Byeong-Hee WON, Hae Ju YUN.
Application Number | 20150109566 14/261181 |
Document ID | / |
Family ID | 52825907 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150109566 |
Kind Code |
A1 |
YUN; Hae Ju ; et
al. |
April 23, 2015 |
LIQUID CRYSTAL DISPLAY AND MANUFACTURING METHOD THEREOF
Abstract
A liquid crystal display is provided. The liquid crystal display
includes a substrate including a reflective area and a transmissive
area, a thin film transistor disposed on the substrate, a pixel
electrode disposed on the thin film transistor, and a roof layer
disposed facing the pixel electrode. The liquid crystal display
further includes a plurality of microcavities formed between the
pixel electrode and the roof layer, and a liquid crystal material
disposed in the plurality of microcavities. The reflective area
includes a first cell gap, and the transmissive area includes a
second cell gap that is different from the first cell gap.
Inventors: |
YUN; Hae Ju; (Hwaseong-si,
KR) ; WON; Byeong-Hee; (Hwaseong-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Display Co., Ltd. |
Yongin-City |
|
KR |
|
|
Assignee: |
Samsung Display Co., Ltd.
Yongin-City
KR
|
Family ID: |
52825907 |
Appl. No.: |
14/261181 |
Filed: |
April 24, 2014 |
Current U.S.
Class: |
349/113 ;
438/30 |
Current CPC
Class: |
G02F 1/133345 20130101;
G02F 1/133377 20130101; G02F 1/13439 20130101; G02F 2001/133368
20130101; G02F 1/1341 20130101; G02F 1/1368 20130101; G02F 1/133371
20130101; G02F 1/133555 20130101; G02F 2201/123 20130101; G02F
2201/121 20130101 |
Class at
Publication: |
349/113 ;
438/30 |
International
Class: |
G02F 1/1335 20060101
G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2013 |
KR |
10-2013-0126048 |
Claims
1. A liquid crystal display, comprising: a substrate including a
reflective area and a transmissive area; a thin film transistor
disposed on the substrate; a pixel electrode disposed on the thin
film transistor; and a roof layer disposed facing the pixel
electrode, wherein a plurality of microcavities are formed between
the pixel electrode and the roof layer, and a liquid crystal
material is disposed in the plurality of microcavities, and wherein
the reflective area includes a first cell gap, and the transmissive
area includes a second cell gap that is different from the first
cell gap.
2. The liquid crystal display of claim 1, wherein: the first cell
gap corresponds to a height of the microcavities in the reflective
area, and the second cell gap corresponds to a height of the
microcavities in the transmissive area.
3. The liquid crystal display of claim 2, wherein the first cell
gap is smaller than the second cell gap.
4. The liquid crystal display of claim 3, wherein a thickness of
the roof layer in the reflective area is different from a thickness
of the roof layer in the transmissive area.
5. The liquid crystal display of claim 4, wherein: the pixel
electrode includes a transparent electrode and a reflective
electrode disposed on a first portion of the transparent electrode,
and the first portion of the transparent electrode and the
reflective electrode are disposed in the reflective area, and a
second portion of the transparent electrode is disposed in the
transmissive area.
6. The liquid crystal display of claim 4, wherein each of the
reflective area and the transmissive area corresponds to one unit
pixel area.
7. The liquid crystal display of claim 6, wherein the reflective
area includes one of a pixel area adjacent in a horizontal
direction and a pixel area adjacent in a vertical direction, and
the transmissive area includes the other one of the pixel area
adjacent in the horizontal direction and the pixel area adjacent in
the vertical direction.
8. The liquid crystal display of claim 4, further comprising: a
common electrode and a lower insulating layer disposed between the
microcavity and the roof layer, wherein the lower insulating layer
is disposed on the common electrode.
9. The liquid crystal display of claim 8, further comprising: a
capping layer disposed on the roof layer, wherein a liquid crystal
injection hole formation region is disposed between the plurality
of microcavities, and the capping layer is disposed covering the
liquid crystal injection hole formation region.
10. The liquid crystal display of claim 9, wherein the liquid
crystal injection hole formation region extends in a direction
parallel to a gate line connected to the thin film transistor.
11. A method of manufacturing a liquid crystal display, comprising:
forming a thin film transistor on a substrate; forming a pixel
electrode, wherein the pixel electrode is connected to a terminal
of the thin film transistor; forming a sacrificial layer on the
pixel electrode, wherein the sacrificial layer includes a first
portion having a first thickness and a second portion having a
second thickness; forming a roof layer on the sacrificial layer;
forming, by removing the sacrificial layer, a plurality of
microcavities having a liquid crystal injection hole; and injecting
an alignment material and a liquid crystal material into the
plurality of microcavities through the liquid crystal injection
hole, wherein the first portion of the sacrificial layer
corresponds to a reflective area, and the second portion of the
sacrificial layer corresponds to a transmissive area.
12. The method of claim 11, wherein the first thickness corresponds
to a cell gap of the reflective area, and the second thickness
corresponds to a cell gap of the transmissive area.
13. The method of claim 12, wherein a thickness of the roof layer
in the reflective area is greater than a thickness of the roof
layer in the transmissive area.
14. The method of claim 13, wherein forming the sacrificial layer
on the pixel electrode further comprises: forming the first portion
and the second portion alternately in a direction of a gate line
connected to the thin film transistor.
15. The method of claim 13, wherein forming the sacrificial layer
on the pixel electrode further comprises: forming the first portion
and the second portion alternately in a direction of a data line
connected to the thin film transistor.
16. The method of claim 13, further comprising: forming a common
electrode and a lower insulating layer on the sacrificial layer
before forming the roof layer.
17. The method of claim 16, further comprising: forming a capping
layer on the roof layer to cover the liquid crystal injection
hole.
18. The method of claim 17, wherein: a liquid crystal injection
hole formation region is formed between the plurality of
microcavities, and the capping layer is formed covering the liquid
crystal injection hole formation region.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2013-0126048 filed in the Korean
Intellectual Property Office on Oct. 22, 2013, the entire contents
of which are incorporated herein by reference.
BACKGROUND
[0002] (a) Field
[0003] The present disclosure relates to a liquid crystal display
and a manufacturing method thereof.
[0004] (b) Description of the Related Art
[0005] A liquid crystal display, which is one of the most common
types of flat panel displays currently in use, typically includes
two sheets of display panels with field generating electrodes (such
as a pixel electrode and a common electrode) and a liquid crystal
layer interposed therebetween.
[0006] The liquid crystal display generates an electric field in
the liquid crystal layer by applying a voltage to the field
generating electrodes. The electric field determines the alignment
of liquid crystal molecules in the liquid crystal layer, which
controls polarization of incident light, thereby enabling images to
be displayed.
[0007] The liquid crystal display can be manufactured using
different methods. For example, a method of forming a pixel unit
having a cavity and filling a liquid crystal therein has been
developed. Specifically, the method may include forming a
sacrificial layer (comprising an organic material and the like) on
a lower plate, removing the sacrificial layer after forming a
support member thereon, and filling a liquid crystal in the empty
space (formed by the removal of the sacrificial layer) through a
liquid crystal injection hole.
[0008] Different types of liquid crystal display devices may
possess different display characteristics. For example, a
transmissive liquid crystal display including a backlight may have
high luminance and high contrast ratio indoors (e.g. inside a
building), but low luminance and low contrast ratio outdoors. On
the other hand, a reflective liquid crystal display may have good
electro-optical characteristics outdoors (by using natural light
from the surroundings as a light source), but poor electro-optical
characteristic indoors.
[0009] Accordingly, there is a need for a liquid crystal display
combining the above-described advantages of both the transmissive
and reflective liquid crystal displays without having their
inherent deficiencies.
SUMMARY
[0010] The present disclosure is directed to address at least the
above need, by providing a double cell gap structure in a
transflective liquid crystal display using sacrificial layers of
different thicknesses.
[0011] According to some embodiments of the inventive concept, a
liquid crystal display is provided. The liquid crystal display
includes a substrate including a reflective area and a transmissive
area; a thin film transistor disposed on the substrate; a pixel
electrode disposed on the thin film transistor; and a roof layer
disposed facing the pixel electrode, wherein a plurality of
microcavities are formed between the pixel electrode and the roof
layer, and a liquid crystal material is disposed in the plurality
of microcavities, and wherein the reflective area includes a first
cell gap, and the transmissive area includes a second cell gap that
is different from the first cell gap.
[0012] In some embodiments, the first cell gap may correspond to a
height of the microcavities in the reflective area, and the second
cell gap may correspond to a height of the microcavities in the
transmissive area.
[0013] In some embodiments, the first cell gap may be smaller than
the second cell gap.
[0014] In some embodiments, a thickness of the roof layer in the
reflective area may be different from a thickness of the roof layer
in the transmissive area.
[0015] In some embodiments, the pixel electrode may include a
transparent electrode and a reflective electrode disposed on a
first portion of the transparent electrode, and the first portion
of the transparent electrode and the reflective electrode may be
disposed in the reflective area, and a second portion of the
transparent electrode may be disposed in the transmissive area.
[0016] In some embodiments, each of the reflective area and the
transmissive area may correspond to one unit pixel area.
[0017] In some embodiments, the reflective area may include one of
a pixel area adjacent in a horizontal direction and a pixel area
adjacent in a vertical direction, and the transmissive area may
include the other one of the pixel area adjacent in the horizontal
direction and the pixel area adjacent in the vertical
direction.
[0018] In some embodiments, the liquid crystal display may further
include a common electrode and a lower insulating layer disposed
between the microcavity and the roof layer, wherein the lower
insulating layer may be disposed on the common electrode. In some
embodiments, the liquid crystal display may further include a
capping layer disposed on the roof layer, wherein a liquid crystal
injection hole formation region may be disposed between the
plurality of microcavities, and the capping layer may be disposed
covering the liquid crystal injection hole formation region.
[0019] In some embodiments, the liquid crystal injection hole
formation region may extend in a direction parallel to a gate line
connected to the thin film transistor.
[0020] According to some other embodiments of the inventive
concept, a method of manufacturing a liquid crystal display is
provided. The method includes forming a thin film transistor on a
substrate; forming a pixel electrode, wherein the pixel electrode
is connected to a terminal of the thin film transistor; forming a
sacrificial layer on the pixel electrode, wherein the sacrificial
layer includes a first portion having a first thickness and a
second portion having a second thickness; forming a roof layer on
the sacrificial layer; forming, by removing the sacrificial layer,
a plurality of microcavities having a liquid crystal injection
hole; and injecting an alignment material and a liquid crystal
material into the plurality of microcavities through the liquid
crystal injection hole, wherein the first portion of the
sacrificial layer corresponds to a reflective area, and the second
portion of the sacrificial layer corresponds to a transmissive
area.
[0021] In some embodiments, the first thickness may correspond to a
cell gap of the reflective area, and the second thickness may
correspond to a cell gap of the transmissive area.
[0022] In some embodiments, a thickness of the roof layer in the
reflective area may be greater than a thickness of the roof layer
in the transmissive area. In some embodiments, forming the
sacrificial layer on the pixel electrode may further include
forming the first portion and the second portion alternately in a
direction of a gate line connected to the thin film transistor.
[0023] In some embodiments, forming the sacrificial layer on the
pixel electrode may further include forming the first portion and
the second portion alternately in a direction of a data line
connected to the thin film transistor.
[0024] In some embodiments, the method may further include forming
a common electrode and a lower insulating layer on the sacrificial
layer before forming the roof layer.
[0025] In some embodiments, the method may further include forming
a capping layer on the roof layer to cover the liquid crystal
injection hole.
[0026] In some embodiments, a liquid crystal injection hole
formation region may be formed between the plurality of
microcavities, and the capping layer may be formed covering the
liquid crystal injection hole formation region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a plan view illustrating a liquid crystal display
according to an exemplary embodiment of the inventive concept.
[0028] FIG. 2 is a cross-sectional view of the liquid crystal
display of FIG. 1 taken along line II-II.
[0029] FIG. 3 is a cross-sectional view of the liquid crystal
display of FIG. 1 taken along line III-III.
[0030] FIG. 4 is a plan view schematically illustrating a
reflective area and a transmissive area in the liquid crystal
display of FIG. 1.
[0031] FIG. 5 is a plan view illustrating an exemplary embodiment
in which the layout of the reflective area and the transmissive
area in FIG. 4 is modified.
[0032] FIG. 6 is a plan view illustrating another exemplary
embodiment in which the layout of the reflective area and the
transmissive area in FIG. 4 is modified.
[0033] FIGS. 7 to 17 are cross-sectional views illustrating a
method of manufacturing a liquid crystal display according to an
exemplary embodiment of the inventive concept.
DETAILED DESCRIPTION
[0034] Exemplary embodiments of the inventive concept will be
described in detail herein with reference to the accompanying
drawings. As those skilled in the art would realize, the described
embodiments may be modified in various ways without departing from
the spirit or scope of the inventive concept.
[0035] In the drawings, the thickness of layers, films, panels,
regions, etc., may be exaggerated for clarity. It will be
understood that when a layer is referred to as being "on" another
layer or substrate, it can be disposed directly on the other layer
or substrate, or with one or more intervening layers or substrates
being present. Like reference numerals designate like elements
throughout the specification.
[0036] FIG. 1 is a plan view illustrating a liquid crystal display
according to an exemplary embodiment of the inventive concept. FIG.
2 is a cross-sectional view of the liquid crystal display of FIG. 1
taken along line II-II. FIG. 3 is a cross-sectional view of the
liquid crystal display of FIG. 1 taken along line III-III. FIG. 4
is a plan view schematically illustrating a reflective area and a
transmissive area in the liquid crystal display of FIG. 1.
[0037] The liquid crystal display includes a plurality of pixels PX
disposed in a display area DA, which will be described in detail
with reference to FIGS. 1 to 3.
[0038] Referring to FIGS. 1 to 3, a gate line 121 and a storage
electrode line 131 are formed on a substrate 110. The substrate 110
may be formed of transparent glass, plastic, or the like. The gate
line 121 includes a gate electrode 124. The storage electrode line
131 transfers a predetermined voltage (such as a common voltage
Vcom), and extends in a substantially horizontal direction. The
storage electrode line 131 also includes a pair of vertical
portions 135a extending substantially perpendicular to the gate
line 121, and a pair of horizontal portions 135b connecting the
ends of the vertical portions 135a. The vertical and horizontal
portions 135a and 135b of the storage electrode line 131 are formed
surrounding a pixel electrode 191.
[0039] A gate insulating layer 140 is formed on the gate line 121
and the storage electrode line 131. Semiconductor layers (151 and
154) and data conductors (171, 173, and 175) are formed on the gate
insulating layer 140. Referring to FIG. 3, a semiconductor layer
151 is formed on the gate insulating layer 140, and a data line 171
is formed on the semiconductor layer 151. Referring to FIG. 2, a
semiconductor layer 154 is formed on the gate insulating layer 140,
and a source electrode 173 and a drain electrode 175 are formed on
the semiconductor layer 154. The data line 171 is connected to the
source electrode 173.
[0040] In some embodiments, a plurality of ohmic contacts (not
shown) may be formed on the respective semiconductor layers 151 and
154, and between the data line 171 and the source/drain electrodes
173 and 175.
[0041] The gate electrode 124, the source electrode 173, and the
drain electrode 175, together with the semiconductor layer 154,
collectively constitute a thin film transistor Q. A channel of the
thin film transistor Q is formed in a portion of the semiconductor
layer 154 between the source electrode 173 and the drain electrode
175.
[0042] A first interlayer insulating layer 180a is formed on the
data conductors 171, 173, and 175, and on an exposed portion of the
semiconductor layer 154. The first interlayer insulating layer 180a
may include an inorganic insulator (such as silicon nitride (SiNx)
or silicon oxide (SiOx)) or an organic insulator.
[0043] A color filter 230 and a plurality of light blocking members
are formed on the first interlayer insulating layer 180a. The
plurality of light blocking members include a horizontal light
blocking member 220a and a vertical light blocking member 220b.
[0044] The light blocking members 220a and 220b are formed in a
lattice structure of the color filter 230. The lattice structure
includes openings corresponding to an area for displaying images.
The light blocking members 220a and 220b are formed of an opaque
material (that does not transmit light). The light blocking members
220a and 220b are formed in the openings of the color filter 230.
In particular, the horizontal light blocking member 220a is formed
in a direction parallel to the gate line 121, and the vertical
light blocking member 220b is formed in a direction parallel to the
data line 171.
[0045] The color filter 230 may display one of the primary colors
(such as the three primary colors red, green, and blue). However,
the color filter 230 need not be limited to the three primary
colors red, green, and blue. In some embodiments, the color filter
230 may display one of cyan, magenta, yellow, and white-based
colors. The color filter 230 may be formed of a material capable of
displaying a different color for every adjacent pixel.
[0046] A second interlayer insulating layer 180b is formed on the
color filter 230 and the light blocking members 220a and 220b,
covering the color filter 230 and the light blocking members 220a
and 220b. The second interlayer insulating layer 180b may include
an inorganic insulator (such as silicon nitride (SiNx) or silicon
oxide (SiOx)) or an organic insulator. As shown in FIG. 2, a step
is created due to a thickness difference between the color filter
230 and the light blocking members 220a and 220b. Nevertheless, the
effect of the step on surface planarity can be mitigated by forming
the second interlayer insulating layer 180b over the step.
[0047] A contact hole 185 exposing the drain electrode 175 is
formed in the color filter 230, the light blocking members 220a,
and the interlayer insulating layers 180a and 180b.
[0048] The pixel electrode 191 is formed on the second interlayer
insulating layer 180b.
[0049] The pixel electrode 191 may be formed having a quadrangle
shape. The pixel electrode 191 includes a plurality of horizontal
stems 192a and 194a, and a plurality of vertical stems 192b and
194b crossing the horizontal stems 192a and 194a. Further, the
pixel electrode 192 is divided into four subregions by the
horizontal stems 192a and 194a and the vertical stems 192b and
194b, and each subregion includes a plurality of minute branches
192c and 194c. In some embodiments, the pixel electrode 191 may
further include an outer stem surrounding the pixel electrode
191.
[0050] The minute branches 192c of the pixel electrode 191 form an
angle of approximately 40.degree. to 45.degree. with the gate line
121 or the horizontal stem 192a. Also, the minute branches of two
adjacent subregions may be perpendicular to each other.
Furthermore, a distance between the minute branches 192c and 194c
may vary with an increase in a linewidth of the minute
branches.
[0051] The pixel electrode 191 includes an extension 197 connected
at lower ends of the vertical stems 192b and 194b. The extension
197 has a larger area than the vertical stems 192b and 194b. The
pixel electrode 191 is physically and electrically connected with
the drain electrode 175 through the contact hole 185 at the
extension 197, so as to receive a data voltage from the drain
electrode 175.
[0052] In some embodiments, the pixel electrode 191 includes a
transparent electrode 192 and a reflective electrode 194 disposed
on a portion of the transparent electrode 192. Accordingly, a
transflective liquid crystal display is formed, comprising a
reflective area RA and a transmissive area TA formed on the
substrate 110.
[0053] In the reflective area RA, the pixel electrode 191 includes
the transparent electrode 192 and the reflective electrode 194
disposed on the portion of the transparent electrode 192. In the
transmissive area TA, the transparent electrode 192 may be formed
as the pixel electrode 191. The transparent electrode 192 may be
formed of a transparent conductive material (such as ITO or IZO),
and the reflective electrode 194 may be formed of a reflective
metal (such as aluminum, silver, chromium, or an alloy thereof). In
some embodiments (not illustrated), the reflective electrode 194
may have a dual-layer structure including a low-resistive
reflective upper layer and a lower layer. The low-resistive
reflective upper layer may be formed of aluminum, silver, or an
alloy thereof. The lower layer may be formed of a material having
excellent contact characteristics with ITO or IZO (such as
molybdenum-based metals, chromium, tantalum, or titanium).
[0054] Although not illustrated in the figures, an upper surface of
the second interlayer insulating layer 180b disposed at the portion
corresponding to the reflective area RA may have a curved surface.
Also, the transparent electrode 192 and the reflective electrode
194 disposed on the second interlayer insulating layer 180b may be
curved along the upper surface of the second interlayer insulating
layer 180b.
[0055] In the transmissive area TA, light that is incident from a
rear side of the substrate 110 passes through liquid crystal
molecules 310 of a microcavity 305, and is then emitted to a front
side (towards a capping layer 390), thereby displaying an
image.
[0056] In the reflective area RA, external light that is input from
the front side enters into the microcavity 305 and is reflected by
the reflective electrode 194. The reflected light then passes
through the liquid crystal molecules 310 of the microcavity 305
again and is emitted to the front side, thereby displaying the
image. In this case, the curved surface of the reflective electrode
194 induces diffused reflection of light, so as to prevent a
phenomenon in which an object is reflected on the screen.
[0057] In some embodiments, the reflective area RA and the
transmissive area TA may each include one or more unit pixel areas.
Referring to FIGS. 1 and 4, the transmissive area TA may include a
unit pixel area disposed on an upper left quadrant and a unit pixel
area disposed on a lower right quadrant diagonal to the upper left
quadrant. The reflective area RA may include a unit pixel area
disposed on a lower left quadrant and a unit pixel area disposed on
an upper right quadrant diagonal to the lower left quadrant.
Although FIGS. 1 and 4 illustrate 2.times.2 pixel areas, it should
be understood that the layout of the reflective area RA and the
transmissive area TA described above (i.e. the 2.times.2 pixel
areas) may be repeated across the entire pixel areas.
[0058] Furthermore, the thin film transistor Q and the pixel
electrode 191 described above are merely exemplary. In some
embodiments, a structure of the thin film transistor Q and a design
of the pixel electrode 191 may be modified to improve side
visibility.
[0059] A lower alignment layer 11 is formed on the pixel electrode
191. The lower alignment layer 11 may correspond to a vertical
alignment layer. The lower alignment layer 11 serves as a liquid
crystal alignment layer, and may be formed of materials such as
polyamic acid, polysiloxane, polyimide, or the like.
[0060] An upper alignment layer 21 is disposed at a portion facing
the lower alignment layer 11, and the microcavity 305 is formed
between the lower alignment layer 11 and the upper alignment layer
21. A liquid crystal material including the liquid crystal
molecules 310 is injected into the microcavity 305 through a liquid
crystal injection hole 307. The microcavity 305 may be formed in a
column direction, that is, a vertical direction of the pixel
electrode 191. In some embodiments, the alignment material (for
forming the alignment layers 11 and 21) and the liquid crystal
material (including the liquid crystal molecules 310) may be
injected into the microcavity 305 via capillary force.
[0061] In some embodiments, a height of a first cell gap in the
reflective area RA may be different from a height of a second cell
gap in the transmissive area TA. For example, the first cell gap
may correspond to a first height d1 of the microcavity 305 in the
reflective area RA, the second cell gap may correspond to a second
height d2 of the microcavity 305 in the transmissive area TA, and
the first cell gap may be smaller than the second cell gap such
that d1 is less than d2.
[0062] In some embodiments, the reflective area RA may be designed
for .lamda./4 wavelengths and the transmissive area TA may be
designed for .lamda./2 wavelengths, so as to equalize the
polarization states of light reaching a last polarizer in the
reflective area RA and the transmissive area TA. Specifically, the
reflective area RA and the transmissive area TA may be designed for
.lamda./4 and .lamda./2 wavelengths, respectively, by setting the
height of the first cell gap of the reflective area RA (d1) to be
1/2 of the height of the second cell gap of the transmissive area
TA (d2).
[0063] The microcavity 305 is divided in a vertical direction by a
plurality of liquid crystal injection hole formation regions 307FP
disposed at the portion overlapping with the gate line 121. As
such, a plurality of microcavities 305 are formed in a direction in
which the gate line 121 extends. Each of the microcavities 305 may
correspond to one or two or more pixel areas, and the pixel areas
may correspond to the area for displaying an image.
[0064] A common electrode 270 and a lower insulating layer 350 are
disposed on the upper alignment layer 21. The common electrode 270
receives a common voltage and generates an electric field together
with the pixel electrode 191 (to which the data voltage is
applied). The electric field determines the tilt directions of the
liquid crystal molecules 310 disposed in the microcavity 305
between the two electrodes 270 and 191. The common electrode 270
and the pixel electrode 191 collectively form a capacitor to
maintain the applied voltage even after the thin film transistor is
turned off. The lower insulating layer 350 may be formed of silicon
nitride (SiNx) or silicon oxide (SiO2).
[0065] In some embodiments, the common electrode 270 is formed on
the microcavity 305. In some other embodiments, the common
electrode 270 may be formed below the microcavity 305 and thus the
liquid crystal may be driven according to an in-plane switching
mode.
[0066] A roof layer 360 is disposed on the lower insulating layer
350. The roof layer 360 serves to support the microcavity 305. As
previously described, the microcavity 305 is formed as a space
between the pixel electrode 191 and the common electrode 270. The
roof layer 360 may be formed of a photoresist or other organic
materials. In some embodiments, a thickness of the roof layer 360
may vary according to the cell gaps of the reflective area RA and
the transmissive area TA. For example, a thickness of a portion of
the roof layer 360 corresponding to the reflective area RA (having
a small cell gap) may be greater than a thickness of another
portion of the roof layer 360 corresponding to the transmissive
area TA (having a large cell gap).
[0067] An upper insulating layer 370 is disposed on the roof layer
360. The upper insulating layer 370 may contact an upper surface of
the roof layer 360. The upper insulating layer 370 may be formed of
silicon nitride (SiNx) or silicon oxide (SiO2).
[0068] In some embodiments, the capping layer 390 is disposed in
the liquid crystal injection hole formation region 307FP covering
the liquid crystal injection hole 307 of the microcavity 305. The
capping layer 390 may include an organic material or an inorganic
material.
[0069] In some embodiments (for example, as illustrated in FIG. 3),
a partition wall formation portion PWP is disposed between
microcavities 305 adjacent to each other in a horizontal direction.
The partition wall formation portion PWP may extend in a same
direction as the data line 171, and may be covered by the roof
layer 360. The lower insulating layer 350, the common electrode
270, the upper insulating layer 370, and the roof layer 360 are
disposed in the partition wall formation portion PWP. The partition
wall formation portion PWP serves as a partition wall structure to
partition or define the microcavity 305. In some embodiments, a
partition wall structure (such as the partition wall formation
portion PWP) between the microcavities 305 may allow the liquid
crystal display to be more flexible. Accordingly, in those
embodiments, the heights of the cell gaps can be more uniformly
maintained, and the stress generated in the display is small even
when the substrate 110 is bent.
[0070] FIG. 5 is a plan view illustrating an exemplary embodiment
in which the layout of the reflective area and the transmissive
area in FIG. 4 is modified.
[0071] Referring to FIG. 5, the reflective area RA or transmissive
area TA may be disposed along a direction in which the gate line
121 extends, and the reflective area RA and the transmissive area
TA may be alternately disposed along a direction in which the data
line 171 extends.
[0072] FIG. 6 is a plan view illustrating another exemplary
embodiment in which the layout of the reflective area and the
transmissive area in FIG. 4 is modified.
[0073] Referring to FIG. 6, the reflective area RA or transmissive
area TA may be disposed along a direction in which the data line
171 extends, and the reflective area RA and the transmissive area
TA may be alternately disposed along a direction in which the gate
line 121 extends.
[0074] Next, a method of manufacturing a liquid crystal display
according to an exemplary embodiment of the inventive concept will
be described with reference to FIGS. 7 to 17. Specifically, FIGS.
7, 9, 11, 13, 14, and 16 depict cross-sectional views of the liquid
crystal display of FIG. 1 taken along line II-II, and FIGS. 8, 10,
12, 15, and 17 depict cross-sectional views of the liquid crystal
display of FIG. 1 taken along line III-III, at different stages of
manufacturing.
[0075] Referring to FIGS. 1, 7, and 8, the gate line 121 is formed
extending in a horizontal direction on the substrate 110, the gate
insulating layer 140 is formed on the gate line 121, the
semiconductor layers 151 and 154 are formed on the gate insulating
layer 140, and the source electrode 173 and the drain electrode 175
are formed on the semiconductor layer 154. The data line 171 is
formed on the semiconductor layer 151, and is connected to the
source electrode 173. Also, the data line 171 may be formed
crossing the gate line 121 and extending in a vertical
direction.
[0076] Next, the first interlayer insulating layer 180a is formed
on the data conductors (source electrode 173, drain electrode 175,
and data line 171) and on the exposed portion of the semiconductor
layer 154.
[0077] Next, the color filter 230 is formed on the first interlayer
insulating layer 180a at a position corresponding to the pixel
area. The light blocking members 220a and 220b are formed in the
openings between the color filters 230.
[0078] Next, the second interlayer insulating layer 180b is formed
on the color filter 230 and the light blocking members 220a and
220b, covering the color filter 230 and the light blocking members
220a and 220b. The contact hole 185 is formed in the second
interlayer insulating layer 180b, and allows the pixel electrode
191 to be electrically and physically connected to the drain
electrode 175. The upper surface of the second interlayer
insulating layer 180b disposed at a portion of the reflective area
RA may be formed having a curved surface (not shown).
[0079] Next, the pixel electrode 191 is formed on the second
interlayer insulating layer 180b.
[0080] In the reflective area RA, the pixel electrode 191 includes
the transparent electrode 192 and the reflective electrode 194
disposed on a portion of the transparent electrode 192. In the
transmissive area TA, the pixel electrode 191 is formed as the
transparent electrode 192.
[0081] Next, a sacrificial layer 300 is formed on the pixel
electrode 191. As illustrated in FIG. 8, an open portion OPN is
formed in the sacrificial layer 300. The open portion OPN is formed
in a direction parallel to the data line 171. Next, as illustrated
in FIG. 10, the common electrode 270, the lower insulating layer
350, the roof layer 360, and the upper insulating layer 370 are
formed in the open portion OPN so as to form the partition wall
formation portion PWP.
[0082] In some embodiments, the sacrificial layer 300 is formed
having different thicknesses in the reflective area RA and the
transmissive area TA. To form the sacrificial layer 300 having
different thicknesses, a slit mask or a halftone mask may be
used.
[0083] Referring to FIGS. 9 and 10, the common electrode 270, the
lower insulating layer 350, and the roof layer 360 are sequentially
formed on the sacrificial layer 300. The roof layer 360 may be
removed in a region corresponding to the horizontal light blocking
member 220a disposed between adjacent pixel areas in the vertical
direction using a photolithography process. As a result, a portion
of the lower insulating layer 350 corresponding to the horizontal
light blocking member 220a is exposed by the opening in the roof
layer 360. As previously described, the common electrode 270, the
lower insulating layer 350, and the roof layer 360 are formed in
the open portion OPN of the vertical light blocking member 220b, so
as to form the partition wall formation portion PWP.
[0084] The roof layer 360 has a substantially greater thickness
than the common electrode 270 or the lower insulating layer 350. An
interlayer step is thus created between the reflective area RA and
the transmissive area TA due to the sacrificial layer 300 having
different thicknesses. As a result, the thickness of the roof layer
360 in the reflective area RA may be greater than the thickness of
the roof layer 360 in the transmissive area TA (as illustrated in
FIG. 9).
[0085] Referring to FIGS. 11 and 12, the upper insulating layer 370
is formed covering the roof layer 360 and the exposed portion of
the lower insulating layer 350.
[0086] Referring to FIG. 13, the upper insulating layer 370, the
lower insulating layer 350, and the common electrode 270 are
partially removed by dry-etching the upper insulating layer 370,
the lower insulating layer 350, and the common electrode 270 to
form the liquid crystal injection hole formation region 307FP. In
this case, the upper insulating layer 370 may have a structure
covering the side of the roof layer 360, but is not limited
thereto. For example, in some other embodiments, the upper
insulating layer 370 covering the side of the roof layer 360 may be
removed to expose the side of the roof layer 360.
[0087] Referring to FIGS. 14 and 15, the sacrificial layer 300 is
removed from the liquid crystal injection hole formation region
307FP by an oxygen (O2) ashing process or a wet-etching method,
thereby forming the microcavity 305 with the liquid crystal
injection hole 307. The microcavity 305 is an empty space that is
formed when the sacrificial layer 300 is removed.
[0088] Referring to FIGS. 16 and 17, the alignment layers 11 and 21
are formed on the pixel electrode 191 and the common electrode 270
by injecting the aligning material through the liquid crystal
injection hole 307. The aligning material includes a solid and a
solvent. Thereafter, a bake process is performed so as to drive the
solvent from the aligning material.
[0089] Next, the liquid crystal material including the liquid
crystal molecules 310 is injected into the microcavity 305 through
the liquid crystal injection hole 307 using an inkjet method and
the like.
[0090] Thereafter, the capping layer 390 is formed on the upper
insulating layer 370 to cover the liquid crystal injection hole 307
and the liquid crystal injection hole formation region 307FP, thus
forming the liquid crystal display illustrated in FIGS. 2 and
3.
[0091] While this inventive concept has been described in
connection with what is presently considered to be practical
exemplary embodiments, it is to be understood that the inventive
concept is not limited to the disclosed embodiments, but, on the
contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended
claims.
* * * * *