U.S. patent application number 15/116980 was filed with the patent office on 2018-11-22 for polysilicon thin film and manufacturing method thereof, tft and manufacturing method thereof, and disply panel.
The applicant listed for this patent is BOE TECHNOLOGY GROUP CO., LTD.. Invention is credited to Dong LI, Xiaolong LI, Zheng LIU, Chunping LONG, Xiaoyong LU.
Application Number | 20180337262 15/116980 |
Document ID | / |
Family ID | 54577623 |
Filed Date | 2018-11-22 |
United States Patent
Application |
20180337262 |
Kind Code |
A9 |
LI; Xiaolong ; et
al. |
November 22, 2018 |
POLYSILICON THIN FILM AND MANUFACTURING METHOD THEREOF, TFT AND
MANUFACTURING METHOD THEREOF, AND DISPLY PANEL
Abstract
A manufacturing method for a polysilicon thin film is provided.
The manufacturing method for a polysilicon thin film includes
forming a polysilicon layer, treating a surface of the polysilicon
layer so that the surface of the polysilicon layer is
electronegative, and supplying polar gas into a process chamber so
that polar molecules of the polar gas are adsorbed on the surface
of the polysilicon layer which is electronegative so as to form the
polysilicon thin film, a surface of which has a hole density higher
than an electron density.
Inventors: |
LI; Xiaolong; (Beijing,
CN) ; LIU; Zheng; (Beijing, CN) ; LU;
Xiaoyong; (Beijing, CN) ; LI; Dong; (Beijing,
CN) ; LONG; Chunping; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BOE TECHNOLOGY GROUP CO., LTD. |
Beijing |
|
CN |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20180108757 A1 |
April 19, 2018 |
|
|
Family ID: |
54577623 |
Appl. No.: |
15/116980 |
Filed: |
October 16, 2015 |
PCT Filed: |
October 16, 2015 |
PCT NO: |
PCT/CN2015/092080 PCKC 00 |
371 Date: |
August 5, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/2026 20130101;
H01L 29/78696 20130101; H01L 21/265 20130101; H01L 21/28 20130101;
H01L 29/66757 20130101; H01L 29/06 20130101; H01L 27/1281 20130101;
H01L 27/1296 20130101 |
International
Class: |
H01L 29/66 20060101
H01L029/66; H01L 21/20 20060101 H01L021/20; H01L 27/12 20060101
H01L027/12; H01L 21/265 20060101 H01L021/265; H01L 29/06 20060101
H01L029/06; H01L 21/28 20060101 H01L021/28 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2015 |
CN |
201510350269.7 |
Claims
1. A manufacturing method of a polysilicon thin film, the method
comprising: forming a polysilicon layer; treating a surface of the
polysilicon layer so that the surface of the polysilicon layer is
electronegative; and supplying polar gas into a process chamber so
that polar molecules of the polar gas are adsorbed on the surface
of the polysilicon layer which is electronegative so as to form the
polysilicon thin film, a surface of which has a hole density higher
than an electron density.
2. The manufacturing method of a polysilicon thin film according to
claim 1, wherein treating a surface of the polysilicon layer
comprises supplying oxygen gas into the process chamber and
performing oxygen plasma treatment on the surface of the
polysilicon layer.
3. The manufacturing method of a polysilicon thin film according to
claim 2, wherein performing oxygen plasma treatment on the surface
of the polysilicon layer includes maintaining a gas pressure in the
process chamber in a range of 1100 to 1300 mTorr and a treatment
time in a range of 250 to 350 seconds.
4. The manufacturing method of a polysilicon thin film according to
claim 1, further comprising vacuumizing the process chamber before
supplying the polar gas into the process chamber.
5. The manufacturing method of a polysilicon thin film according to
claim 1, wherein supplying the polar gas into the process chamber
includes maintaining a gas pressure in the process chamber in a
range of 50 to 150 mTorr and supplying the polar gas over a time
period in a range of 30 to 50 minutes.
6. The manufacturing method of a polysilicon thin film according to
claim 1, wherein the polar gas includes any one or more kinds of
N2, SiH4, NO2 and NH3.
7. The manufacturing method of a polysilicon thin film according to
claim 1, wherein treating a surface of the polysilicon layer
comprises supplying hydrogen gas into the process chamber and
performing hydrogen plasma treatment on the surface of the
polysilicon layer.
8. The manufacturing method of a polysilicon thin film according to
claim 1, wherein forming a polysilicon layer comprises: forming an
amorphous silicon layer on a base substrate; and performing an
excimer laser annealing treatment on the amorphous silicon layer to
form the polysilicon layer.
9. The manufacturing method of a polysilicon thin film according to
claim 8, wherein a buffer layer is provided between the base
substrate and the polysilicon layer, and includes a silicon nitride
layer in contact with the base substrate and a silicon oxide layer
in contact with the polysilicon layer.
10. A manufacturing method of a TFT comprising using the
manufacturing method of a polysilicon thin film according to claim
1 to form a polysilicon thin film in a channel region of the
TFT.
11. The manufacturing of a TFT according to claim 10, further
comprising, after forming the polysilicon thin film, the steps of
sequentially forming a first insulating layer and a patterned gate
on the polysilicon thin film; forming a second insulting layer on
the gate; forming a first via-hole penetrating through the second
insulating layer and the first insulating layer on a first lateral
side of the gate, and a second via-hole penetrating through the
second insulating layer and the first insulating layer on a second
lateral side opposite the first lateral side of the gate,
respectively; and forming a source contact, on the second
insulating layer and in the first via-hole and a drain contact, on
the second insulating layer and in the second via-hole,
respectively, wherein the source contact is connected to a source
of the TFT, and wherein the drain contact is connected a drain of
the TFT.
12. A polysilicon thin film, a surface of which has a hole density
higher than an electron density.
13. The polysilicon thin film according to claim 12, wherein the
surface of the polysilicon thin film is formed to have Si--O
dipoles, with polar molecules adsorbed by a part of the Si--O
dipoles on the outside of the polysilicon thin film.
14. The polysilicon thin film according to claim 12, wherein the
surface of the polysilicon thin film is formed to have Si--H
dipoles, with polar molecules adsorbed by a part of the Si--H
dipoles on the outside of the polysilicon thin film.
15. A TFT, comprising, a polysilicon thin film formed by the
manufacturing method according to claim 1.
16. A display panel comprising a TFT formed by the manufacturing
method according to claim 10.
17. The manufacturing method of a polysilicon thin film according
to claim 4, wherein treating a surface of the polysilicon layer
comprises supplying hydrogen gas into the process chamber and
performing hydrogen plasma treatment on the surface of the
polysilicon layer.
18. The manufacturing method of a polysilicon thin film according
to claim 2, wherein forming a polysilicon layer comprises: forming
an amorphous silicon layer on a base substrate; and performing an
excimer laser annealing treatment on the amorphous silicon layer to
form the polysilicon layer.
19. A TFT, comprising the polysilicon thin film according to claim
12.
20. A display panel comprising the TFT according to claim 15.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a National Stage Entry of
PCT/CN2015/092080 filed Oct. 16, 2015, which claims the benefit and
priority of Chinese Patent Application No. 201510350269.7, filed on
Jun. 23, 2015, the entire content of each of which is incorporated
by reference herein as a part of this application.
BACKGROUND
[0002] The embodiments of the disclosure relate to a polysilicon
thin film and a manufacturing method thereof, a TFT including the
polysilicon thin film and a manufacturing method thereof, and a
display panel including the TFT.
[0003] Low-temperature polysilicon (LTPS) thin film transistor
(TFT) are widely used in liquid crystal display panels (LCDs) and
organic light-emitting diode display panels (OLEDs) due to its
advantages of high mobility, low power consumption, being light and
thin, and so on. However, when illumination, high temperature,
stress or the like is applied to the LTPS TFT, leakage current
significantly increases. This problem impedes the development of
low-temperature polysilicon display panels to some extent.
[0004] In the prior art, the leakage current of low temperature
polysilicon devices is reduced mainly by a method of providing a
lightly doped drain region (LDD). As shown in FIG. 1, a lightly
doped drain region 2 is provided at positions of a channel region 1
close to a source and a drain of a thin film transistor device and
bears partial voltage to reduce the leakage current. However, a
mask process would be added in such a method, which increases
production cost. In addition, the accuracy of a photoresist mask is
about 2 .mu.m, which is difficult to meet the requirements of
small-sized channel.
SUMMARY OF THE INVENTION
[0005] The embodiments of the present invention disclosure provide
a polysilicon thin film and a manufacturing method thereof, a TFT
and a manufacturing method thereof, and a display panel so as to
reduce the leakage current.
[0006] As a first aspect of the embodiments of the present
disclosure, a manufacturing method of a polysilicon thin film is
provided, the manufacturing method including steps of forming a
polysilicon layer, treating a surface of the polysilicon layer so
that the surface of the polysilicon layer is electronegative, and
supplying polar gas into a process chamber so that polar molecules
of the polar gas are adsorbed on the surface of the polysilicon
layer which is electronegative so as to form the polysilicon thin
film, a surface of which has a hole density higher than an electron
density.
[0007] In an exemplary embodiment of the present disclosure, the
step of treating a surface of the polysilicon layer includes
supplying oxygen gas into the process chamber and performing oxygen
plasma treatment on the surface of the polysilicon layer.
[0008] In an exemplary embodiment of the present disclosure, in the
step of performing oxygen plasma treatment on the surface of the
polysilicon layer, gas pressure in the process chamber is
maintained in a range of 1100 to 1300 mTorr and treatment time is
in a range of 250 to 350 seconds.
[0009] In an exemplary embodiment of the present disclosure, the
manufacturing method further includes a step of vacuumizing the
process chamber before supplying the polar gas into the process
chamber.
[0010] In an exemplary embodiment of the present disclosure, in the
step of supplying the polar gas into the process chamber, gas
pressure in the process chamber is maintained in a range of 50 to
150 mTorr and supplying time of the polar gas is in a range of 30
to 50 minutes.
[0011] In an exemplary embodiment of the present disclosure, the
polar gas includes any one or more kinds of N2, SiH4, NO2 and
NH3.
[0012] In an exemplary embodiment of the present disclosure, the
step of treating a surface of the polysilicon layer includes
supplying hydrogen gas into the process chamber and performing
hydrogen plasma treatment on the surface of the polysilicon
layer.
[0013] In an exemplary embodiment of the present disclosure, the
step of forming a polysilicon layer includes forming an amorphous
silicon layer on a base substrate, and performing an excimer laser
annealing treatment on the amorphous silicon layer to form the
polysilicon layer.
[0014] As a second aspect of the embodiments of the present
disclosure, a manufacturing method of a TFT is provided, the
manufacturing method of the TFT including a step of using above
manufacturing method provided in the first aspect of the
embodiments of the present disclosure to form a polysilicon thin
film in a channel region of the TFT.
[0015] In an exemplary embodiment of the present disclosure, the
manufacturing method of a TFT further includes, after forming the
polysilicon thin film, the steps of sequentially forming a first
insulating layer and a patterned gate on the polysilicon thin film,
forming a second insulting layer on the gate, forming via-holes
penetrating through the second insulating layer and the first
insulating layer on opposite sides of the gate respectively, and
forming a source contact and a drain contact on the second
insulating layer and in the via-holes, the source contact and the
drain contact being connected to a source and a drain on opposite
sides of the polysilicon thin film respectively.
[0016] As a third aspect of the embodiments of the present
disclosure, a polysilicon thin film, a surface of which has a hole
density higher than an electron density, is provided.
[0017] In an exemplary embodiment of the present disclosure, the
surface of the polysilicon thin film is formed to have Si--O
dipoles, with polar molecules adsorbed by a part of the Si--O
dipoles on the outside of the polysilicon thin film.
[0018] In an exemplary embodiment of the present disclosure, the
surface of the polysilicon thin film is formed to have Si--H
dipoles, with polar molecules adsorbed by a part of the Si--H
dipoles on the outside of the polysilicon thin film.
[0019] As a fourth aspect of the embodiments of the present
disclosure, a TFT is provided, the TFT including, in a channel
region, a polysilicon thin film formed by the manufacturing method
provided in the first aspect of the embodiments of the present
disclosure or the polysilicon thin film provided in the third
aspect of the embodiments of the present disclosure.
[0020] As a fifth aspect of the embodiments of the present
disclosure, a display panel is provided, the display panel
including a TFT formed by the manufacturing method provided in the
second aspect of the embodiments of the present disclosure or the
TFT provided in the fourth aspect of the embodiments of the present
disclosure.
[0021] The surface of the polysilicon thin film manufactured in
accordance with the embodiments of the present disclosure has
accumulated a lot of holes thereon so that a stable hole conductive
channel is formed. Since holes have a low migration rate, leakage
effect due to the illumination, high temperature, stress or the
like can be effectively alleviated, and thereby leakage current of
the TFT device is effectively reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] For the sake of describing the technical solutions of the
embodiments of the present disclosure more clearly, the accompany
drawings of the embodiments will be briefly introduced below, and
obviously, the accompany drawings described below merely relate to
some embodiments of the present disclosure and are not a limitation
to the present invention.
[0023] FIG. 1 is a channel region structure for reducing leakage
current in the prior art;
[0024] FIGS. 2a-2b are schematic diagrams of a flow chart of
manufacturing a polysilicon thin film in embodiments of the present
invention; and
[0025] FIGS. 3a-3d are schematic diagrams of a flow chart of
manufacturing a TFT in embodiments of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The technical solutions of the embodiments of the present
invention will be described clearly and thoroughly hereinafter in
conjunction with the drawings in respective embodiments in order to
make the objects, the solutions and the advantages of the
embodiments of the present invention more clear. Obviously, the
embodiments described are only some rather than all of the
embodiments of the present invention. Other embodiments may be
obtained by one ordinary person skilled in the art based on the
embodiments in the present invention without any creative work, and
such other embodiments are within the scope of the present
invention.
[0027] In the description of the present invention, it should be
noted that the oriental or positional relationship indicated by the
terms "upper", "lower", "top" , "bottom" or the like is the
oriental or positional relationship shown in the drawings, and such
terms are used only for the purpose of description and simplifying
the description rather than indicating or suggesting that the
device or element indicated must be in a specific orientation, be
structured and operated in a specific orientation. Such terms shall
not be deemed to limit the scope of the present invention.
[0028] Furthermore, in the description of the present invention,
the expression "multiple" means two or more unless otherwise
specified.
[0029] A first aspect of embodiments of present disclosure provides
a manufacturing method of a polysilicon thin film, the
manufacturing method including steps of forming a polysilicon
layer, treating a surface of the polysilicon layer so that the
surface of the polysilicon layer is electronegative, and supplying
polar gas into a process chamber so that polar molecules of the
polar gas are adsorbed on the surface of the polysilicon layer
which is electronegative so as to form the polysilicon thin film, a
surface of which has a hole density higher than an electron
density.
[0030] The surface of the existing polysilicon thin film is
electrically neutral, i.e., has a hole density the same as an
electron density. Since electrons have a faster migration rate, it
is likely to form a surface leakage current. The polysilicon layer
before the surface treatment in the present disclosure is
equivalent to the existing polysilicon thin film, the surface of
which is electrically neutral. After the surface treatment
performed on the surface of the polysilicon layer, the surface of
the polysilicon layer is electronegative so that it can adsorb
polar molecules. After the adsorption of the polar molecules,
electrons migrate toward terminals of polar molecules because of
the low chemical potential of the terminals of polar molecules, so
that holes accumulate massively on the surface of the polysilicon
thin film, which shows macroscopically that a stable hole
conductive channel is formed on the surface of the polysilicon thin
film. Due to the low migration rate of the holes, the leakage
effect caused by illumination, high temperature, stress or the like
can be effectively alleviated, and thereby the leakage current of
the TFT device can be effectively reduced.
[0031] According to an exemplary embodiment of the present
disclosure, as shown in FIG. 2a, the step of treating a surface of
the polysilicon layer 3 includes supplying oxygen gas into the
process chamber and performing oxygen plasma treatment on the
surface of the polysilicon layer 3. Thus Si--O dipoles are formed
on the surface of the polysilicon layer 3. That is, stable oxygen
terminal groups are formed on the treated surface of the
polysilicon layer 3, and thereby the surface of the polysilicon
layer 3 is electronegative.
[0032] In above treatment step, gas pressure in the process chamber
is controlled to be 1100 to 1300 mTorr, for example, 1200 mTorr;
treatment time is controlled to be 250 to 350 seconds, for example,
300 seconds; the flow rate for supplying the oxygen gas is about
2000 sccm.
[0033] In an exemplary embodiment of the present disclosure, the
step of treating the surface of the polysilicon layer 3 may be
carried out by supplying hydrogen gas into the process chamber and
performing hydrogen plasma treatment on the surface of the
polysilicon layer 3. Thus Si--H dipoles are formed on the surface
of the polysilicon layer 3, and thereby the surface of the
polysilicon layer 3 is electronegative.
[0034] In an exemplary embodiment of the present disclosure, the
manufacturing method further includes, before supplying the polar
gas into the process chamber, a step of vacuumizing the process
chamber so as to remove pre-existing gas in the process chamber.
After the vacuumizing step, the polar gas is supplied into the
process chamber so as to secure the adsorption efficiency and
adsorption stability of the polar molecules in the polar gas.
[0035] FIG. 2b is a schematic diagram illustrating the surface of
the polysilicon layer 3 after supplying the polar gas into the
process chamber in an exemplary embodiment in which the surface
treatment is performed using oxygen gas. When the surface of the
polysilicon layer 3 having the oxygen terminal group is exposed to
the polar gas, the surface of the polysilicon layer 3 will adsorb
the polar molecules 4 in the polar gas so that an electrochemical
system is formed. In this electrochemical system, the energy
valence band of the Si--O dipoles is higher than the chemical
potential of the polar molecules 4, which causes the electrons to
migrate to the polar molecules and thereby holes 5 are accumulated
on the surface of the polysilicon layer 3, as a result of which a
stable hole conductive channel is formed.
[0036] According to an exemplary embodiment of the present
disclosure, in the step of supplying the polar gas into the process
chamber, gas pressure in the process chamber is controlled to be in
a range of 50 to 150 mTorr, for example, 100 mTorr, and the
supplying time of the polar gas is controlled to be in a range of
30 to 50 minutes, for example, 40 minutes, so as to achieve
desirable adsorption efficiency.
[0037] In an exemplary embodiment of the present disclosure, the
polar gas includes any one or more kinds of N2, SiH4, NO2, NH3, or
the like. Accordingly, the polar molecules 4 may be any one or more
kinds of N2 molecules, SiH4 molecules, NO2 molecules, NH3
molecules, or the like.
[0038] In an exemplary embodiment of the present disclosure, as
shown in FIG. 3a, the step of forming a polysilicon layer includes,
forming an amorphous silicon layer (a-silicon layer) on a base
substrate 6, and performing an excimer laser annealing treatment on
the amorphous silicon layer to form the polysilicon layer 3.
[0039] According to an exemplary embodiment of the present
disclosure, as shown in FIGS. 3a-3c, a buffer layer 7 is provided
between the base substrate 6 and the polysilicon layer 3, and
includes a silicon nitride layer in contact with the base substrate
6 and a silicon oxide layer in contact with the polysilicon layer
3. The silicon nitride layer functions to separate the base
substrate 6 from the polysilicon layer 3, and the silicon oxide
layer functions to match the lattice with the polysilicon layer
3.
[0040] A second aspect of the embodiments of the present disclosure
provide a manufacturing method of a thin film transistor (TFT)
including a step of using above manufacturing method provided in
the first aspect of the embodiments of the present disclosure to
form a polysilicon thin film in a channel region of the thin film
transistor.
[0041] As described above, the TFT formed by the method of the
second aspect of the embodiments of the present disclosure is
capable of reducing leakage current effectively.
[0042] According to an exemplary embodiment of the present
disclosure, as shown in FIG. 3d, the manufacturing method of a TFT
in the second aspect further includes, after forming the
polysilicon thin film, the steps of sequentially forming a first
insulating layer 8 and a patterned gate 9 on the polysilicon thin
film, forming a second insulting layer 10 on the gate 9, forming
via-holes penetrating through the second insulating layer 10 and
the first insulating layer 8 on opposite sides of the gate 9
respectively, and forming a source contact 11 and a drain contact
12 on the second insulating layer 10 and in the via-holes, the
source contact 11 and the drain contact 12 being connected to a
source and a drain on opposite sides of the polysilicon thin film
respectively.
[0043] A third aspect of the embodiments of the present disclosure
provide a polysilicon thin film, a surface of which has a hole
density higher than an electron density. As shown in FIGS. 2b, 3c,
and 3d, the surface of the polysilicon thin film has accumulated a
lot of holes 5 thereon. Since holes have a low migration rate, the
photo-induced leakage effect and the leakage effect due to high
temperature, stress or the like can be effectively alleviated, and
thereby leakage current of a TFT which uses this polysilicon thin
film as a channel region is reduced.
[0044] According to an exemplary embodiment of the present
disclosure, the surface of the polysilicon thin film is formed to
have Si--O dipoles, with polar molecules adsorbed by a part of the
Si--O dipoles on the outside of the polysilicon thin film. The
energy valence band of the Si--O dipoles is higher than the
chemical potential of the polar molecules, which causes the
electrons to migrate to the polar molecules and thereby a lot of
holes are accumulated on the surface of the polysilicon thin film,
making the surface of the polysilicon thin film have a hole density
larger than the electron density.
[0045] According to an exemplary embodiment of the present
invention, the surface of the polysilicon thin film is formed to
have Si--H dipoles, with polar molecules adsorbed by a part of the
Si--H dipoles on the outside of the polysilicon thin film. The
energy valence band of the Si--H dipoles is higher than the
chemical potential of the polar molecules, which causes the
electrons to migrate to the polar molecules and thereby a lot of
holes are accumulated on the surface of the polysilicon thin film,
making the surface of the polysilicon thin film have a hole density
larger than the electron density.
[0046] A fourth aspect of the embodiments of the present disclosure
provide a thin film transistor (TFT) including, in a channel
region, a polysilicon thin film formed by the manufacturing method
provided in the first aspect of the embodiments of the present
disclosure or the polysilicon thin film provided in the third
aspect of the embodiments of the present invention. The TFT can be
used in a display panel (for example, in an array substrate of the
display panel), can effectively reduce the leakage current in the
display panel, and can promote the display quality.
[0047] A fifth aspect of the embodiments of the present disclosure
provides a display panel including a TFT formed by the
manufacturing method provided in the second aspect of the
embodiments of the present disclosure or the TFT provided in the
fourth aspect of the embodiments of the present invention. As
described above, the display panel provided in the fifth aspect of
the embodiments of the present disclosure has good display quality
because of the improvement in the leakage current.
[0048] Above described are merely exemplary embodiments of the
present invention, which is not intended to limit the protection
scope of present disclosure defined by the appended claims.
* * * * *