U.S. patent application number 14/287077 was filed with the patent office on 2014-10-23 for semiconductor device and method for manufacturing the same.
This patent application is currently assigned to Industrial Technology Research Institute. The applicant listed for this patent is Industrial Technology Research Institute. Invention is credited to Chih-Ming Lai, Yung-Hui Yeh.
Application Number | 20140312343 14/287077 |
Document ID | / |
Family ID | 48425934 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140312343 |
Kind Code |
A1 |
Yeh; Yung-Hui ; et
al. |
October 23, 2014 |
SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
Abstract
A method for manufacturing a semiconductor device includes
forming a metal oxide semiconductor layer and a first insulating
layer on a substrate. A gate is formed on the first insulating
layer. The first insulating layer is patterned by using the gate as
an etching mask so as to expose the metal oxide semiconductor layer
to serve as a source region and a drain region. A dielectric layer
is formed on the substrate to cover the gate and the oxide
semiconductor layer, where the dielectric layer has at least one of
hydrogen group and hydroxyl group. A heating treatment is performed
so that the at least one of hydrogen group and hydroxyl group
reacts with the source region and the drain region. A source
electrode and a drain electrode electrically connected to the
source region and the drain region respectively are formed on the
dielectric layer.
Inventors: |
Yeh; Yung-Hui; (Hsinchu
City, TW) ; Lai; Chih-Ming; (Changhua County,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Industrial Technology Research Institute |
Hsinchu |
|
TW |
|
|
Assignee: |
Industrial Technology Research
Institute
Hsinchu
TW
|
Family ID: |
48425934 |
Appl. No.: |
14/287077 |
Filed: |
May 26, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13354334 |
Jan 20, 2012 |
8759186 |
|
|
14287077 |
|
|
|
|
Current U.S.
Class: |
257/43 |
Current CPC
Class: |
H01L 29/66969 20130101;
H01L 27/1225 20130101; H01L 29/7869 20130101; H01L 27/1248
20130101 |
Class at
Publication: |
257/43 |
International
Class: |
H01L 29/786 20060101
H01L029/786; H01L 29/66 20060101 H01L029/66 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2011 |
TW |
100142527 |
Claims
1. A semiconductor device, comprising: a metal oxide semiconductor
layer, comprising a source region and a drain region, wherein a
surface of the source region and the drain region composes at least
one of hydrogen group and hydroxyl group; a first insulating layer,
located on the metal oxide semiconductor layer, wherein the first
insulating layer does not cover the source region and the drain
region; a gate, located on the first insulating layer; a dielectric
layer, covering the gate, the source region and the drain region of
the metal oxide semiconductor layer; and a source electrode and a
drain electrode, located on the dielectric layer, and electrically
connected to the source region and the drain region
respectively.
2. The semiconductor device according to claim 1, wherein the
concentration of the at least one of hydrogen group and hydroxyl
group in the dielectric layer is higher than 1E18 cm.sup.-3.
3. The semiconductor device according to claim 1, wherein the
dielectric layer comprises polyvinylpyrrolidone (PVP), polyvinyl
alcohol (PVA), polyacrylates, cinnamate-based polyvinylphenols
(Ci-PVP), silicon nitride (SiN.sub.X), or SiO.sub.2.
4. The semiconductor device according to claim 1, wherein the metal
oxide semiconductor layer comprises zinc oxide (ZnO) doped with
indium (In), aluminum (Al), gallium (Ga), stannum (Sn), zinc (Zn)
or hafnium (Hf), or Ga and In co-doped ZnO (IGZO).
5. The semiconductor device according to claim 1, wherein the first
insulating layer comprises an intermediate layer and a barrier
layer, the intermediate layer is located between the barrier layer
and the metal oxide semiconductor layer, the intermediate layer
comprises silicon oxide, Y.sub.2O.sub.3, Ta.sub.2O.sub.5, or
HfO.sub.2, and the barrier layer comprises SiN.sub.X, or aluminum
oxide.
6. The semiconductor device according to claim 1, further
comprising a second insulating layer, located between the gate and
the first insulating layer, wherein the second insulating layer
comprises silicon oxide, SiN.sub.X, silicon oxynitride, polyvinyl
pyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylates,
cinnamate-based polyvinylphenols (Ci-PVP), parylenes or
photoacryl.
7. The semiconductor device according to claim 1, further
comprising a source top-electrode and a drain top-electrode located
on the dielectric layer, wherein a storage capacitor is formed by
the source top-electrode and the source region and by the drain
top-electrode and the drain region.
8. The semiconductor device according to claim 1, further
comprising: a protection layer, covering the dielectric layer, the
source electrode and the drain electrode; and a pixel electrode,
located on the protection layer, wherein the pixel electrode is
electrically connected to the drain electrode.
9. The semiconductor device according to claim 8, further
comprising: a light-emitting material layer, located on the pixel
electrode; and an electrode film, located on the light-emitting
material layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of and claims priority
benefit of U.S. patent application Ser. No. 13/354,334, filed on
Jan. 20, 2012, now allowed, which claims the priority benefit of
Taiwan application serial no. 100142527, filed on Nov. 21, 2011.
The entirety of each of the above-mentioned patent applications is
hereby incorporated by reference herein and made a part of this
specification.
BACKGROUND
[0002] 1. Technical Field
[0003] The disclosure relates to a semiconductor device and a
method for manufacturing the same, in particular, to a self-aligned
top gate type thin-film transistor and a method for manufacturing
the same.
[0004] 2. Related Art
[0005] In recent years, with the advancement of the semiconductor
manufacturing technology, the manufacturing of an active device has
become easier and faster. The active device has been widely used
as, for example, a computer chip, a cell-phone chip, or an
active-device display. Taking the active-device display as an
example, the active device may be used as a switch for charging or
discharging. In order to ensure the active device with high
reliability and high display quality, the active device is required
to have a high-passing current under an on-state and to have a
low-leakage current under the off-state.
[0006] In addition, current metal oxide semiconductor thin-film
transistors are commonly made by bottom gate type thin-film
transistor. The main reason is that a processing apparatus for
manufacturing the bottom gate type thin-film transistor is
compatible to an apparatus for manufacturing a conventional
amorphous silicon thin-film transistor. However, the bottom gate
type metal oxide semiconductor thin-film transistor has a poor
resistance to water and oxygen species. On the other hand, the
conventional top gate type metal oxide semiconductor thin-film
transistor has a good resistance to water and oxygen species but
without a self-alignment process. Therefore, the conventional top
gate type metal oxide semiconductor thin-film transistor has a
large device parasitic capacitance, requires a large device layout
area which does not help the development of a high-resolution
panel, and has a poor frequency response with the reliability of
the device to be enhanced.
SUMMARY
[0007] The disclosure provides a semiconductor device and a method
for manufacturing the same. The method includes: sequentially
forming a metal oxide semiconductor layer and a first insulating
layer on a substrate; forming a gate on the first insulating layer;
patterning the first insulating layer by using the gate as an
etching mask so as to expose the metal oxide semiconductor layer on
two sides of the gate to serve as a source region and a drain
region; forming a dielectric layer to cover the gate and the metal
oxide semiconductor layer, where the dielectric layer has at least
one of hydrogen group (--H) and hydroxyl group (--OH); performing a
heating treatment so as to make the at least one of hydrogen group
and hydroxyl group in the dielectric layer to react with the source
region and the drain region; and forming a source electrode and a
drain electrode on the dielectric layer, where the source electrode
and the drain electrode are electrically connected to the source
region and the drain region respectively.
[0008] A method for manufacturing a semiconductor device is
introduced herein, which includes: sequentially forming a metal
oxide semiconductor layer and a first insulating layer on a
substrate; forming a gate on the first insulating layer; patterning
the first insulating layer by using the gate as an etching mask so
as to expose the metal oxide semiconductor layer on two sides of
the gate to serve as a source region and a drain region; forming a
doped layer to cover the gate and the metal oxide semiconductor
layer, where the doped layer comprises at least one of hydrogen
group and hydroxyl group, or comprises a dopant comprising indium
(In), aluminum (Al), gallium (Ga), stannum (Sn), zinc (Zn) or
hafnium (Hf); performing a heating treatment so as to make the at
least one of hydrogen group and hydroxyl group in the doped layer
to react with the source region and the drain region, or to make
the dopant of the doped layer diffusing to the source region and
the drain region; removing the doped layer; forming a dielectric
layer to cover the gate, the source region and the drain region;
and forming a source electrode and a drain electrode on the
dielectric layer, where the source electrode and the drain
electrode are electrically connected to the source region and the
drain region respectively.
[0009] A semiconductor device is introduced herein, which includes
a metal oxide semiconductor layer having a source region and a
drain region, where a surface of the source region and the drain
region has at least one of hydrogen group and hydroxyl group; a
first insulating layer, located on the metal oxide semiconductor
layer, where the first insulating layer does not cover the source
region and the drain region; a gate, located on the first
insulating layer; a dielectric layer, covering the gate and the
source region and the drain region of the metal oxide semiconductor
layer; a source electrode and a drain electrode, located on the
dielectric layer and electrically connected to the source region
and the drain region respectively.
[0010] Several exemplary embodiments accompanied with figures are
described in detail below to further describe the disclosure in
details.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings are included to provide further
understanding, and are incorporated in and constitute a part of
this specification. The drawings illustrate exemplary embodiments
and, together with the description, serve to explain the principles
of the disclosure.
[0012] FIG. 1A to FIG. 1E are schematic flowcharts of a method for
manufacturing a thin-film transistor according to an exemplary
embodiment;
[0013] FIG. 2A to FIG. 2C are schematic flowcharts of a method for
manufacturing a thin-film transistor according to another exemplary
embodiment;
[0014] FIG. 3A to FIG. 3G are schematic flowcharts of a method for
manufacturing a thin-film transistor according to still another
exemplary embodiment;
[0015] FIG. 4 is a schematic cross-sectional view of a pixel
structure according to an exemplary embodiment;
[0016] FIG. 5 is a schematic cross-sectional view of a pixel
structure of an organic light emitting display (OLED) according to
an exemplary embodiment; and
[0017] FIG. 6A to FIG. 6B are schematic views of a relation between
a voltage and a current of a thin-film transistor according to a
comparative example and an example.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0018] FIG. 1A to FIG. 1E are schematic flowcharts of a method for
manufacturing a thin-film transistor according to an exemplary
embodiment. Referring to FIG. 1A, in the method of manufacturing a
thin-film transistor provided in an exemplary embodiment, a metal
oxide semiconductor layer 102 and a first insulating layer 104 are
formed sequentially on a substrate 100.
[0019] The substrate 100 may use a flexible base material (such as
an organic polymer base material or a metal base material) or a
rigid base material (such as a glass base material or a quartz base
material). If the thin-film transistor is used in a flexible
apparatus, the substrate 100 usually selects a flexible
material.
[0020] The material of the metal oxide semiconductor layer 102
includes ZnO doped with In, Al, Ga, Sn, or Hf. For example, the
metal oxide semiconductor layer 102 includes Indium-Gallium-Zinc
Oxide (IGZO), ZnO, SnO, Indium-Zinc Oxide (IZO), Gallium-Zinc Oxide
(GZO), Zinc-Tin Oxide (ZTO), Indium-Aluminum-Tin Oxide (InAlZnO),
Indium-Tin-Zinc Oxide (InSnZnO), Indium-Hafnium-Zinc Oxide
(InHfZnO), or Indium-Tin Oxide (ITO).
[0021] In addition, in this exemplary embodiment, the first
insulating layer 104 includes an intermediate layer 104a and a
barrier layer 104b, where the intermediate layer 104a is located
between the barrier layer 104b and the metal oxide semiconductor
layer 102. However, in this exemplary embodiment, the first
insulating layer 104 is not limited herein to be a two-layered
structure (including the intermediate layer 104a and the barrier
layer 104b). In other words, in other embodiments, the first
insulating layer 104 may also be a single-layered structure, for
example, the first insulating layer 104 may be the barrier layer
104b.
[0022] Base on the foregoing description, in this exemplary
embodiment, the first insulating layer 104 includes the
intermediate layer 104a and the barrier layer 104b. The barrier
layer 104b is disposed to block moisture and oxygen in an
environment so as to prevent adverse effects on the metal oxide
semiconductor layer 102 caused by the moisture and the oxygen in
the environment. Here, the material of the barrier layer 104b
includes silicon nitride (SiN.sub.X), aluminium oxide, or other
moisture-resistant and oxidation-resistant materials. In addition,
the intermediate layer 104 is used to serve as a boundary layer or
compatibility layer between the metal oxide semiconductor layer 102
and the barrier layer 104b. So, the material adopted in the
intermediate layer 104a is related to the material of the metal
oxide semiconductor layer 102 and the material of the barrier layer
104b. For example, if SiN.sub.X is adopted in the barrier layer
104b and the ZnO doped with In, Al, Ga, Sn, or Hf is adopted in the
metal oxide semiconductor layer 102, the intermediate layer 104a
may use silicon oxide or metal oxide insulating thin film (such as
Y.sub.2O.sub.3, Ta.sub.2O.sub.5, or HfO.sub.2). However, the
disclosure is not limited hereto.
[0023] According to this embodiment, the method of forming the
metal oxide semiconductor layer 102 and the first insulating layer
104 on the substrate 100 is, for example, forming a metal oxide
semiconductor material (not shown) and an insulating material (not
shown) on the substrate 100 sequentially by using a deposition
process (such as a chemical vapor deposition process, a physical
vapor deposition process, or a sputtering process), a coating
process (such as a spin coating process), or another appropriate
process. And then, the metal oxide semiconductor material and the
insulating material are patterned by using a lithography process
and an etching process, so as to form the platform-shaped metal
oxide semiconductor layer 102 and the first insulating layer
104.
[0024] According to other embodiments, an ink-jet printing process,
a screen printing process or other appropriate processes may also
be adopted in the forming of the metal oxide semiconductor layer
102 and the first insulating layer 104, so as to directly form the
platform-shaped metal oxide semiconductor layer 102 and the first
insulating layer 104.
[0025] Referring to FIG. 1B, a second insulating layer 106 is
formed on the first insulating layer 104. The material of the
second insulating layer 106 comprises, for example, an inorganic
insulating material (such as silicon oxide, SiN.sub.X, silicon
oxynitride or other inorganic materials) or an organic material
(such as PVP, PVA, polyacrylates, Ci-PVP, parylenes, or photoacryl
(PC403 from JSR co.)). Forming the second insulating layer 106 on
the first insulating layer 104 may increase the flexibility of a
device. However, the second insulating layer 106 is not an
integrant layer, so the second insulating layer 106 may be
considered to be omitted in other embodiments of the disclosure.
This exemplary embodiment takes that the second insulating layer
106 is formed on the first insulating layer 104, the metal oxide
semiconductor layer 102 and the substrate 100 as an example for
description.
[0026] Thereafter, a gate G is formed on the second insulating
layer 106. In this exemplary embodiment, the method of forming the
gate G is, for example, forming a conductive layer on the second
insulating layer 106, and then patterning the conductive layer by
using the lithography and etching process, so as to define the gate
G. In another embodiment, the gate G may also be directly formed on
the second insulating layer 106 by using the ink-jet printing or
the screen printing method. Based on the consideration of
conductivity, a metal material is usually used in the gate G.
However, the disclosure is not limited hereto. According to other
embodiments, other conductive materials such as an alloy, a nitride
of a metal material, an oxide of a metal material and a nitrogen
oxide of a metal material may also be used in the gate G.
[0027] Referring to FIG. 1C, the second insulating layer 106 and
the first insulating layer 104 are patterned by using the gate G as
an etching mask, so as to expose the metal oxide semiconductor
layer 102 on two sides of the gate G to serve as a source region S
and a drain region D, where the region between the source region S
and the drain region D is set to be a channel region CH. At this
time, the gate G, the second insulating layer 106, and the first
insulating layer 104 form a stacked structure; and the gate G, the
second insulating layer 106 and the first insulating layer 104 in
the stacked structure have the same pattern. In this exemplary
embodiment, the second insulating layer 106 and the first
insulating layer 104 located below the gate G serve as insulting
layers of the gate.
[0028] Referring to FIG. 1D, a dielectric layer 110 is formed on
the substrate 100 to cover the gate G and the metal oxide
semiconductor layer 102. Especially, the dielectric layer 110
includes at least one of hydrogen group and hydroxyl group. The
aforesaid dielectric layer 110 may include organic insulating
material or inorganic insulating material. The organic insulating
material includes PVP, PVA, polyacrylates, Ci-PVP, or other organic
insulating materials. The inorganic insulating material includes
SiN.sub.X, silicon oxide, or other inorganic insulating materials.
In addition, according to this exemplary embodiment, the
concentration of the at least one of hydrogen group and hydroxyl
group in the dielectric layer 110 is higher than 1E18 cm.sup.-3.
The concentration of the hydrogen group or the hydroxyl group in
the dielectric layer is measured by using a secondary ion mass
spectrometer (SIMS). It should be noted that, the first insulating
layer 104 above the source region S and drain region D is removed
in the patterning process, so the dielectric layer 110 may directly
contact with the source region S and the drain region D.
[0029] Subsequently, a heating treatment is performed, so that the
at least one of hydrogen group and hydroxyl group in the dielectric
layer 110 reacts with the metal oxide semiconductor layer 102 of
the source region S and the drain region D to form a conductive
region 102a. In other words, the conductive region 102a is formed
after the source region S and the drain region D of the metal oxide
semiconductor layer 102 react with the at least one of hydrogen
group and hydroxyl group, which may increase the conductivity of
the source region S and the drain region D. Therefore, the
conductivity of the source region S and the drain region D at this
time is higher than that of the channel region CH. According to
this exemplary embodiment, the temperature of the heating treatment
is, for example, between 100.degree. C. and 500.degree. C.; the
environment of the heating treatment may be an atmospheric
environment, nitrogen gas, oxygen gas, inert gas, or under a low
pressure between 10.sup.-3 torr and 10.sup.-6 ton; and the time of
the heating treatment is set to be between 4 hours and 10 minutes
according to the change of the temperature and the pressure.
However, the disclosure is not limited hereto. According to other
embodiments, the heating treatment may also be other treatment
processes which enable the at least one of hydrogen group and
hydroxyl group in the dielectric layer 110 to react with the metal
oxide semiconductor layer 102 of the source region S and the drain
region D.
[0030] It should be noted that, while performing the aforesaid
heating treatment, the channel region CH of the metal oxide
semiconductor layer 102 is covered by the gate G, the second
insulating layer 106 and the first insulating layer 104, and the
barrier layer 104b in the first insulating layer 104 is capable of
blocking hydrogen group and hydroxyl group to prevent them from
reacting with the channel region CH of the metal oxide
semiconductor layer 102. Therefore, the electrical property of the
channel region CH will not be changed, and the electrical stability
of the thin-film transistor is thus maintained.
[0031] Referring to FIG. 1E, a source electrode SE and a drain
electrode DE are formed on the dielectric layer 110, where the
source electrode SE and the drain electrode DE are electrically
connected to the source region S and the drain region D
respectively. According to this exemplary embodiment, the source
electrode SE and a drain electrode DE are electrically connected to
the source region S and the drain region D respectively through a
contact window in the dielectric layer 110.
[0032] FIG. 2A to FIG. 2C are schematic flowcharts of a method for
manufacturing a thin-film transistor according to another exemplary
embodiment. The exemplary embodiment shown in FIG. 2A to FIG. 2C is
similar to that of FIG. 1A to FIG. 1E, therefore, the same element
are indicated with the same symbols, and are not be redescribed
here. Referring to FIG. 2A, in this exemplary embodiment, after
forming a metal oxide semiconductor layer 102 and a first
insulating layer 104 on the substrate 100, a gate G is directly
formed on the first insulating layer 104. In other words, the
manufacturing of a second insulating layer is omitted in this
exemplary embodiment. The method of forming the metal oxide
semiconductor layer 102, the first insulating layer 104 and the
gate G is the same as or similar to the previous exemplary
embodiment.
[0033] Referring to FIG. 2B, the first insulating layer 104 is
patterned by using the gate G as an etching mask, so as to expose
the metal oxide semiconductor layer 102 on two sides of the gate G
to serve as a source region S and a drain region D. At this time,
the gate G and the first insulating layer 104 form a stacked
structure; and the gate G and the first insulating layer 104 in the
stacked structure have the same pattern. In this exemplary
embodiment, the first insulating layer 104 (a barrier layer 104b
and an intermediate layer 104a) located below the gate G serves as
an insulting layer of the gate.
[0034] Referring to FIG. 2C, a dielectric layer 110 is formed on
the substrate 100 to cover the gate G and the metal oxide
semiconductor layer 102. Especially, the dielectric layer 110 has
at least one of hydrogen group and hydroxyl group. Subsequently, a
heating treatment is performed, so that the at least one of
hydrogen group and hydroxyl group in the dielectric layer 110
reacts with the metal oxide semiconductor layer 102 of the source
region S and the drain region D to make the source region S and the
drain region D of the metal oxide semiconductor layer have a
conductive region 102a. In other words, the conductive region 102a
is formed after the source region S and the drain region D of the
metal oxide semiconductor layer 102 react with the at least one of
hydrogen group and hydroxyl group, which may increase the
conductivity of the source region S and the drain region D.
Therefore, the conductivity of the source region S and the drain
region D at this time is higher than that of a channel region CH.
After then, a source electrode SE and a drain electrode DE are
formed on the dielectric layer 110, where the source electrode SE
and the drain electrode DE are electrically connected to the source
region S and the drain region D respectively.
[0035] FIG. 3A to FIG. 3G are schematic flowcharts of a method for
manufacturing a thin-film transistor according to still another
exemplary embodiment. Referring to FIG. 3A, a metal oxide
semiconductor layer 102 and a first insulating layer 104 are
sequentially formed on a substrate 100. The method of forming the
metal oxide semiconductor layer 102 and the first insulating layer
104 on the substrate 100 is the same as or similar to that of FIG.
1A.
[0036] Referring to FIG. 3B, a second insulating layer 106 is
formed on the first insulating layer 104, and then a gate G is
formed on the second insulating layer 106. The method of forming
the second insulating layer 106 and the gate G is the same as or
similar to that of FIG. 1B.
[0037] Referring to FIG. 3C, the second insulating layer 106 and
the first insulating layer 104 are patterned by using the gate G as
an etching mask, so as to expose the metal oxide semiconductor
layer 102 on two sides of the gate G to serve as a source region S
and a drain region D. At this time, the gate G, the second
insulating layer 106, and the first insulating layer 104 form a
stacked structure; and the gate G, the second insulating layer 106
and the first insulating layer 104 in the stacked structure have
the same pattern. This exemplary embodiment takes that the second
insulating layer 106 is formed on the first insulating layer 104,
the metal oxide semiconductor layer 102 and the substrate 100 as an
example for description.
[0038] Likewise, according to another exemplary embodiment, in the
steps of FIG. 3B and FIG. 3C, the manufacturing of the second
insulating layer 106 may also be omitted, that is, the gate G is
directed formed on the first insulating layer 104. So, after
patterning the first insulating layer 104 by using the gate G as
the etching mask, the formed stacked structure includes the gate G
and the first insulating layer 104.
[0039] Referring to FIG. 3D, a doped layer 202 is formed to cover
the gate G and the metal oxide semiconductor layer 102, where the
doped layer 202 includes at least one of hydrogen group and
hydroxyl group, or includes a dopant comprising In, Al, Ga, Sn, Zn
or Hf. More specifically, the main material of the doped layer 202
is a dielectric material (such as silicon oxide, SiN.sub.X and
PVP). The dielectric material includes at least one of the hydrogen
groups or the hydroxyl groups, or includes In, Al, Ga, Sn, Zn or
Hf. According to this exemplary embodiment, the concentration of
the at least one of hydrogen group and hydroxyl group in the doped
layer 202 is higher than 1E18 cm.sup.-3 or the concentration of the
In, Al, Ga, Sn, Zn or Hf in the doped layer 202 is higher than 1E18
cm.sup.-3. The concentration of the hydrogen group or the hydroxyl
group in the doped layer 202 or the concentration of the In, Al,
Ga, Sn, Zn or Hf is measured by using a SIMS. It should be noted
that, the first insulating layer 104 above the source region S and
drain region D is removed in the patterning process, so the doped
layer 202 may directly contact with the source region S and the
drain region D.
[0040] Subsequently, a heating treatment is performed, so that the
at least one of hydrogen group and hydroxyl group in the doped
layer 202 reacts with the metal oxide semiconductor layer 102 of
the source region S and the drain region D, or the In, Al, Ga, Sn,
Zn or Hf is diffused to the source region S and the drain region D.
After the at least one of hydrogen group and hydroxyl group reacts
with the source region S and the drain region D of the metal oxide
semiconductor layer 102, or after the In, Al, Ga, Sn, Zn or Hf is
diffused to the source region S and the drain region D of the metal
oxide semiconductor layer 102, or the hydroxyl group in the metal
oxide semiconductor layer 102 are diffused to the doped layer 202
and combined with a doped metal to make a surface of the metal
oxide semiconductor layer in an oxygen deficit condition, the
source region S and the drain region D of the metal oxide
semiconductor layer 102 are enabled to have a conductive region
102a, which increases the conductivity of the source region S and
the drain region D. Therefore, the conductivity of the source
region S and the drain region D at this time is higher than that of
the channel region CH, which is shown in FIG. 3E. For the heating
treatment, for example, the temperature is between 100.degree. C.
and 500.degree. C., the gas environment may be an atmospheric
environment, nitrogen gas, oxygen gas, inert gas, or under a low
pressure between 10.sup.-3 torr and 10.sup.-6 torr. The
temperature, pressure, and time may be set by persons of ordinary
skills in the art according to actual requirements. However, the
disclosure is not limited hereto.
[0041] It should be noted that, while performing the aforesaid
heating treatment, the channel region CH of the metal oxide
semiconductor layer 102 is covered by the gate G and the first
insulating layer 104, and the barrier layer 104b in the first
insulating layer 104 is capable of blocking hydrogen group and
hydroxyl group to prevent them from reacting with the channel
region CH of the metal oxide semiconductor layer 102. So, the
property of the channel region CH will not be changed, and
therefore the electrical stability of the thin-film transistor is
maintained.
[0042] After performing the treatment process, the doped layer 202
is removed. The method of removing the doped layer 202 may be, for
example, a wet-etching removing method or another appropriate
method.
[0043] Referring to FIG. 3F, a dielectric layer 112 is formed on
the substrate 100. According to this exemplary embodiment, the
material of the dielectric layer 112 may be an inorganic insulating
material (such as silicon oxide, SiN.sub.X or aluminium oxide), or
an organic insulating material (such as PVP). In addition, the
dielectric layer 112 may also include a small amount of hydrogen
group (--H) or hydroxyl group (--OH).
[0044] Referring to FIG. 3F, a source electrode SE and a drain
electrode DE are formed on the dielectric layer 112, where the
source electrode SE and the drain electrode DE are electrically
connected to the source region S and the drain region D
respectively. According to this exemplary embodiment, the source
electrode SE and a drain electrode DE are electrically connected to
the source region S and the drain region D respectively through a
contact window in the dielectric layer 112.
[0045] Based on the foregoing description, the thin-film transistor
formed in each of the aforesaid exemplary embodiments (referring to
FIG. 1E, FIG. 2C, or FIG. 3G) includes a metal oxide semiconductor
layer 102, a gate G, a second insulating layer 106, a first
insulating layer 104, a dielectric layer 110 or 112, a source
electrode SE, and a drain electrode DE. The metal oxide
semiconductor layer 102 includes a channel region CH, a source
region S, and a drain region D. A surface of the source region S
and the drain region D of the metal oxide semiconductor layer 102
includes at least one of hydrogen group and hydroxyl group (i.e., a
conductive region 102a). The gate G is located above the metal
oxide semiconductor layer 102. The second insulating layer 106 and
the first insulating layer 104 are located between the metal oxide
semiconductor layer 102 and the gate G. The dielectric layer 110 or
112 covers the gate G, the source region S and the drain region D
of the metal oxide semiconductor layer 102. The source electrode SE
and the drain electrode DE are located on the dielectric layer 110
or 112. The source electrode SE and the drain electrode DE are
electrically connected to the source region S and the drain region
D respectively.
[0046] The thin-film transistor may be used in a pixel structure of
a display. For example, if the thin-film transistor is used in a
pixel structure of a liquid crystal display, a cross-sectional view
of the pixel structure is shown in FIG. 4. The structure includes a
thin-film transistor T, a storage capacitor CS, and a pixel
electrode PE.
[0047] The thin-film transistor T includes a metal oxide
semiconductor layer 102 (including a source region S, a drain
region D and a channel region CH), a gate G, a source electrode SE
and a drain electrode DE. The metal oxide semiconductor layer 102
(including the source region S, the drain region D and the channel
region CH) is located on the substrate 100. Especially, the source
region S and the drain region D of the metal oxide semiconductor
layer 102 have a conductive region 102a. The conductive region 102a
is formed by a reaction of a metal oxide semiconductor layer and at
least one of hydrogen group and hydroxyl group, or includes In, Al,
Ga, Sn, Zn, or Hf. The gate G is located above the channel region
CH of the metal oxide semiconductor layer 102. A first insulating
layer 104 and a second insulating layer 106 are included between
the gate G and the metal oxide semiconductor layer 102. According
to this exemplary embodiment, the second insulating layer 106 is
located below the gate G, so the second insulating layer 106 serves
as an insulting layer of the gate. According to another exemplary
embodiment, the second insulating layer 106 may be omitted. At this
time, the first insulating layer 104 located below the gate G
(including a barrier layer 104b and an intermediate layer 104a)
serves as an insulting layer of the gate. The dielectric layer 110
covers the gate G. The source electrode SE and the drain electrode
DE are located above the dielectric layer 110, and are electrically
connected to the source region S and the drain region D
respectively. In addition, a protection layer 120 further covers
the dielectric layer 110. The material of the protection layer 120
may be an inorganic insulating material, an organic material, or a
double-layer of the two.
[0048] The storage capacitor CS is formed by a drain
bottom-electrode BE and a drain top-electrode TE. According to this
exemplary embodiment, one part of the metal oxide semiconductor
layer 102 serves as the drain bottom-electrode BE of the storage
capacitor. The gate G serves as a self-alignment mask when the
source region S and the drain region D of the metal oxide
semiconductor layer 102 form the conductive region 102a, so the
conductive region 102a may also be form in the drain
bottom-electrode BE of the metal oxide semiconductor layer 102. In
addition, the drain top-electrode TE of the storage capacitor CS is
defined at the same time with the forming of the source electrode
SE and the drain electrode DE, so the drain top-electrode TE, the
source electrode SE and the drain electrode DE have the same
material and belong to the same layer. The dielectric layer 110
between the drain top-electrode TE and the drain bottom-electrode
BE serves as a capacitance dielectric layer of the storage
capacitor CS. Similarly, by using the above method, a source
top-electrode (not shown) may also be selectively manufactured on a
source region, or simultaneously forming source and drain
top-electrodes (not shown) on both the source and drain regions, so
as to form the storage capacitor CS.
[0049] The pixel electrode PE is located on the protection layer
120. The pixel electrode PE is electrically connected to the drain
electrode DE. According to this exemplary embodiment, the pixel
electrode PE is electrically connected to the drain electrode DE
through a contact window in the protection layer 120. The pixel
electrode PE may be of a transparent electrode material or
reflective electrode material. The transparent electrode material
includes indium tin oxide (ITO), indium zinc oxide (IZO), aluminum
tin oxide (ATO), aluminum zinc oxide (AZO), indium-gallium-zinc
oxide (IGZO) or any other suitable metal oxide material. The
reflective electrode materials include metal with high
reflectivity.
[0050] In addition, the thin-film transistor described in FIG. 1E,
FIG. 2C and FIG. 3G may be used in a pixel structure of an organic
electroluminescent display. Referring to FIG. 5, the pixel
structure includes thin-film transistors T and T', a storage
capacitor CS, a pixel electrode PE, a light-emitting material layer
OM, and an electrode film CA.
[0051] The thin-film transistor T includes a metal oxide
semiconductor layer 102 (including a source region S, a drain
region D and a channel region CH), a gate G, a source electrode SE
and a drain electrode DE. The thin-film transistor T' includes a
metal oxide semiconductor layer 102 (including a source region S',
a drain region D' and a channel region CH'), a gate G', a source
electrode SE' and a drain electrode DE'. The thin-film transistor T
serves as a switch device of the pixel structure. The thin-film
transistor T' serves as a driving device of the pixel structure. In
addition, the thin-film transistors T and T' may be manufactured by
using the method described in FIG. 1A to FIG. 1E, or FIG. 2A to
FIG. 2C or the method described in FIG. 3A to FIG. 3G. It should be
noted that, the source region S, the drain region D, the source
region S', and the drain region D' of the metal oxide semiconductor
layer 102 have a conductive region 102a. The conductive region 102a
is formed by a reaction of a metal oxide semiconductor layer and
the at least one of hydrogen group and hydroxyl group, or includes
In, Al, Ga, Sn, Zn, or Hf.
[0052] The capacitor CS includes a bottom-electrode BE and a
top-electrode TE. According to this exemplary embodiment, one part
of the metal oxide semiconductor layer 102 serves as the
bottom-electrode BE of the capacitor. The gate G serves as a
self-alignment mask when forming the conductive region 102a in the
source region S and the drain region D of the metal oxide
semiconductor layer 102, so the conductive region 102a may also be
formed in the bottom-electrode BE of the metal oxide semiconductor
layer 102. In addition, the top-electrode TE of the storage
capacitance CS is defined at the same time with the forming of the
source electrode SE and the drain electrode DE, so the
top-electrode TE, the source electrode SE and the drain electrode
DE have the same material and belong to the same layer. The
dielectric layer 110 between the top-electrode TE and the
bottom-electrode BE serves as a capacitance dielectric layer of the
storage capacitor.
[0053] The pixel electrode PE is located on the protection layer
120. The pixel electrode PE is electrically connected to the source
electrode SE' of the thin-film transistor T'. According to this
exemplary embodiment, the pixel electrode PE is electrically
connected to the source electrode SE' through a contact window in
the protection layer 120. A third insulating layer 130 is disposed
above the pixel electrode PE. The third insulating layer 130 covers
the protection layer 120, and patterns and exposes the pixel
electrode PE. The third insulating layer 130 may be an organic
insulating layer or an inorganic insulating layer.
[0054] The light-emitting material layer OM is located at the pixel
electrode PE exposed by the third insulating layer 130. The
electrode film CA covers the third insulating layer 130 and the
light-emitting material layer OM. The light-emitting material layer
OM may be an organic light-emitting material, which may be a
light-emitting material with a red light-emitting material, a green
light-emitting material, a blue light-emitting material, a white
light-emitting material cooperated with a color filter, or another
material with other colors. The electrode film CA may fully cover
the third insulating layer 130 and the light-emitting material
layer OM. The material of the electrode film CA may be a metal
material or a transparent conductive material.
[0055] In order to prove that the insulating layer disposed below
the gate may block moisture and oxygen gas (i.e., the hydrogen
group and hydroxyl group) to ensure the stability of the channel
region of the thin-film transistor, the following will be described
with an example and a comparative example.
[0056] In the comparative example, the thin-film transistor is a
top gate type oxide thin-film transistor. The metal oxide
semiconductor layer is InGaZnO with the thickness of 50 nm. A
SiO.sub.2 layer and a PVP layer are disposed between the gate and
the metal oxide semiconductor layer. The PVP layer serves as a gate
insulating layer. The relation between a voltage and a current of a
thin-film transistor of the comparative example is shown in FIG.
6A. In FIG. 6A, the curve N is a relation curve of the voltage and
the current of a thin-film transistor when the thin-film transistor
is just manufactured. The curve M is a relation curve of the
voltage and the current of the thin-film transistor one day later.
It can be seen from FIG. 6A that the thin-film transistor, after
one day, may have a short-circuit state. The main reason is that
the PVP layer absorbs water molecules or oxygen molecules, and that
hydroxyl group may be diffused to the channel region of the metal
oxide semiconductor layer, so that a short-circuit phenomenon
occurs.
[0057] In an example, the thin-film transistor is a top gate type
oxide thin-film transistor. The metal oxide semiconductor layer is
InGaZnO with the thickness of 50 nm. A SiO.sub.2 layer and a
SiN.sub.X layer are disposed between the gate and the metal oxide
semiconductor layer. The SiN.sub.X layer serves as a gate
insulating layer. The relation between the voltage and the current
of the thin-film transistor of the example is shown in FIG. 6B. In
FIG. 6B, the curve P is a relation curve of the voltage and the
current of a thin-film transistor when the thin-film transistor is
just manufactured. The curve Q is a relation curve of the voltage
and the current of the thin-film transistor 21 days later. It can
be seen from FIG. 6B that the thin-film transistor, after 21 days,
does not have an obvious electrical property change. The main
reason is that the SiN.sub.X barrier layer may prevent hydrogen
group and hydroxyl group from being diffused to the channel of the
metal oxide semiconductor layer, and therefore the thin-film
transistor is enabled to have a certain electrical stability.
[0058] It should be noted that, as can be seen from FIG. 6A, the
hydrogen group and/or hydroxyl group in the PVP layer may be
diffused to the channel of the metal oxide semiconductor layer to
trigger a short-circuit in the device, so it an be further proved
that the adopted PVP layer having hydrogen group and/or hydroxyl
group described in the previous exemplary embodiments is capable of
making the hydrogen group and/or hydroxyl group be diffused to the
source region and the source region so as to increase the
conductivity of the source region and the drain region.
[0059] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
disclosed embodiments without departing from the scope or spirit of
the disclosure. In view of the foregoing, it is intended that the
disclosure cover modifications and variations of this disclosure
provided they fall within the scope of the following claims and
their equivalents.
* * * * *