U.S. patent application number 13/494510 was filed with the patent office on 2012-10-11 for method for producing a thin film transistor and a device of the same.
This patent application is currently assigned to TAIWAN TFT LCD ASSOCIATION. Invention is credited to Lin-En CHOU, Chia-Hao Tsai, Wen-Tung Wang.
Application Number | 20120256302 13/494510 |
Document ID | / |
Family ID | 40622933 |
Filed Date | 2012-10-11 |
United States Patent
Application |
20120256302 |
Kind Code |
A1 |
CHOU; Lin-En ; et
al. |
October 11, 2012 |
METHOD FOR PRODUCING A THIN FILM TRANSISTOR AND A DEVICE OF THE
SAME
Abstract
A method for producing a thin film transistor and including the
following steps for preparing a glass substrate; having a positive
photosensitive coating on the glass substrate; providing a
transparent mold plate, having a plurality of ladder opaque
protrusions in accordance with a predetermined pattern having
different depth; controlling the transparent mold plate downwardly
to press into the positive photosensitive coating and
non-contacting to the glass substrate; exposing a part of the
positive photosensitive coating via an explosion by a UV light;
remaining the other part of the positive photosensitive coating,
which is shielded by the protrusions and shaped corresponding to
the predetermined pattern; separating the transparent mold plate
from the glass substrate, and removing the other parts of the
photosensitive coating unshielded via a chemical solvent. Thereby,
after the positive photosensitive coating is pressed, cured, and
cleaned the thin film transistor is formed.
Inventors: |
CHOU; Lin-En; (Kao Hsiung
Hsien, TW) ; Tsai; Chia-Hao; (Taipei Hsien, TW)
; Wang; Wen-Tung; (Hsinchu County, TW) |
Assignee: |
TAIWAN TFT LCD ASSOCIATION
Hsinchu
TW
CHUNGHWA PICTURE TUBES, LTD.
Taoyuan
TW
AU OPTRONICS CORP.
HsinChu
TW
TOPPOLY OPTOELECTRONICS CORP.
Miao-Li County
TW
CHI MEI OPTOELECTRONICS CORP.
Tainan County
TW
INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE
Hsinchu
TW
HANNSTAR DISPLAY CORP.
Taipei
TW
|
Family ID: |
40622933 |
Appl. No.: |
13/494510 |
Filed: |
June 12, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12353345 |
Jan 14, 2009 |
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13494510 |
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10995479 |
Nov 24, 2004 |
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12353345 |
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Current U.S.
Class: |
257/623 ;
257/E27.112 |
Current CPC
Class: |
G03F 7/0002 20130101;
H01L 29/66742 20130101; B82Y 10/00 20130101; H01L 51/0022 20130101;
H01L 27/1292 20130101; H01L 27/1288 20130101; B82Y 40/00
20130101 |
Class at
Publication: |
257/623 ;
257/E27.112 |
International
Class: |
H01L 27/12 20060101
H01L027/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2004 |
TW |
93126251 |
Claims
1. A thin film transistor comprising: a glass substrate having a
positive photosensitive coating formed thereon, and a part of the
positive photosensitive coating being exposed; and a transparent
mold plate including a plurality of ladder opaque protrusions
disposed thereon, and the ladder opaque protrusions being arranged
relevant to a predetermined pattern having different depth; wherein
the other part of the positive photosensitive coating shielded
under the ladder opaque protrusions is remained while the part of
the positive photosensitive coating unshielded by the ladder opaque
protrusions is removed via a chemical solvent; whereby the thin
film transistor is formed, after the positive photosensitive
coating is pressed, cured, and cleaned.
2. The thin film transistor as claimed in claim 1, wherein the
positive photosensitive coating is made of semiconductor,
conductive or insulating materials in a selective manner.
3. The thin film transistor as claimed in claim 1, wherein the
transparent mold plate is made of glass materials or quartz; the
ladder opaque protrusions are made of metallic materials.
4. The thin film transistor as claimed in claim 3, further
including an adhesion layer formed between the transparent mold
plate and the ladder opaque protrusions; wherein the adhesion layer
has a coefficient of thermal expansion ranging between those of the
transparent mold plate and the ladder opaque protrusions.
5. The thin film transistor as claimed in claim 4, wherein the
adhesion layer is made of a metallic oxide that is made from a
predetermined metal.
6. The thin film transistor as claimed in claim 5, wherein the
predetermined metal is a transition metal, such as Cr, Mo or W; and
the metallic oxide is a transition-metal oxide corresponding to the
predetermined metal.
7. The thin film transistor as claimed in claim 1, further
including a dewetting layer, which is de-wetted from the positive
photosensitive coating, arranged onto the metallic material.
8. The thin film transistor as claimed in claim 7, wherein the
dewetting layer is made from Teflon.
9. A thin film transistor comprising: a glass substrate having a
positive photosensitive coating formed thereon, and a part of the
positive photosensitive coating being exposed via a UV light; a
transparent mold plate including a plurality of ladder opaque
protrusions disposed thereon, and the ladder opaque protrusions
being arranged relevant to a predetermined pattern having different
depth; and an adhesion layer formed between the transparent mold
plate and the ladder opaque protrusions; and the adhesion layer
having a coefficient of thermal expansion ranging between those of
the transparent mold plate and the ladder opaque protrusions;
wherein the other part of the positive photosensitive coating
shielded under the ladder opaque protrusions is remained while the
part of the positive photosensitive coating unshielded by the
ladder opaque protrusions is removed via a chemical solvent;
whereby the thin film transistor is formed a pattern having
different depth, after the positive photosensitive coating is
pressed, cured, and cleaned.
10. The thin film transistor as claimed in claim 9, wherein the
positive photosensitive coating is made of is semiconductor,
conductive or insulating materials.
11. The thin film transistor as claimed in claim 9, wherein the
transparent mold plate is made of the glass materials or quartz;
the ladder opaque protrusions are made of metallic materials.
12. The thin film transistor as claimed in claim 11, wherein the
adhesion layer is made of a metallic oxide that is made from a
predetermined metal.
13. The thin film transistor as claimed in claim 12, wherein the
predetermined metal is a transition metal, such as Cr, Mo or W; and
the metallic oxide is a transition-metal oxide corresponding to the
predetermined metal.
14. The thin film transistor as claimed in claim 12, further
including a dewetting layer, which is de-wetted from the positive
photosensitive coating, arranged onto the metallic materials.
15. The thin film transistor as claimed in claim 14, wherein the
dewetting layer is made from Teflon.
Description
[0001] This application is a divisional patent application of U.S.
application Ser. No. 12/353,345, filed Jan. 14, 2009, that was a
Continuation-in-part of U.S. application Ser. No. 10/995,479, filed
Nov. 24, 2004 which claims priority under 35 U.S.C. .sctn.119 (a)
of Patent Application number 93126251 filed in Taiwan ROC on Aug.
31, 2004.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for producing a
thin film transistor, and particularly relates to a method, rather
than a semiconductor process, for producing a thin film
transistor.
[0004] 2. Background of the Invention
[0005] A conventional method for producing a conventional thin film
transistor uses semiconductor technology, which includes film
deposition, photolithography technology, etching processes and the
like. The film deposition process includes deposing a film of
dielectric or insulating material by chemical vapor deposition
(CVD) and deposing a film of electric material by physical vapor
deposition (PVD). The photolithography and the etching processes
define a pattern thereof. The equipment used for film deposition,
photolithography and etching processes are all high-priced. As
such, semiconductor technology, which consumes a lot of time and
labor and requires expensive paraphernalia, is often
criticized.
[0006] Referring to FIGS. 1A to 1D, the first prior art, a
conventional photosensitive pressing method, illustrates a
transparent plate 1a having a protrusion projected therefrom. The
protrusion is transparent. A photosensitive material 3a is then
poured between the transparent plate 1a and a glass substrate 2a.
The transparent plate 1a and a glass substrate 2a are separated yet
are close to each other. Next an ultraviolet light is provided to
cure the photosensitive material 3a, which has been shaped between
the transparent plate 1a and the glass substrate 2a. After a dry or
wet etching process, a resident part of the photosensitive material
3a will be removed, to form a pattern of a thin film transistor.
However, by this stage all parts of the photosensitive material 3a
have been cured because of the transparent protrusion, so the
etching process is necessary. Furthermore, the transparent
protrusion still plays another role as a photoresist that controls
the depth of the pattern of the thin film transistor.
[0007] FIG. 2, a perspective view of a second prior art, U.S. Pat.
No. 6,518,189, discloses a first conventional nanoimprint method.
An opaque plate 1b has a protrusion projected therefrom, and
presses onto a layer of thermoplastic polymer materials 3b that is
coated on a substrate 2b in advance. Thermoplastic polymer
materials 3b, only melt at high temperatures (more than 300 degrees
centigrade) and shaping requires large amounts of pressure. As such
any press equipment that is used in the process should be resistant
against the testing environment of these kinds of conditions. In
addition, the layer of thermoplastic polymer materials 3b is cured
after a cooling process and is further shaped by an etching process
to produce a pattern.
[0008] With respect to FIG. 3, a perspective view of the third
prior art, U.S. Pat. No. 5,900,160, discloses a first conventional
microcontact method. A turbine mold lc presses onto a substrate 2c
that has a layer of micro-materials 3c in a rotating manner. This
method however, lacks a precise and stable alignment. Furthermore,
the mold lc is made of Polydimethylsiloxane (PDMS) that wears out
easily, deforms and has a negative effect on the precision of the
pattern thereof.
[0009] The fourth prior art is displayed in FIGS. 4A to 4D which
illustrate sequential perspective views as disclosed in U.S. Pat.
No. 6,060,121, as a second conventional microcontact method. A
plate 1d having a protrusion projected therefrom and an impression
coating 3d formed thereon, presses a substrate 2d coated with a
thin film 4d. Although a pattern is formed, the thickness of the
pattern is much thinner that that of other conventional methods
necessitating an additional process with another material in order
to increase the thickness of the pattern.
[0010] The fifth prior art is displayed in FIGS. 5A to 5D which
illustrate sequential perspective views as disclosed in U.S. Pat.
No. 6,380,101, as a third conventional microcontact method. A plate
1e having a protrusion projected therefrom and an impression
coating 3e formed thereon, presses a substrate 2e coated with a
thin film 4e. Similarly to the first prior art, the impression
coating 3e is further provided as a photoresist for post etching
process.
[0011] The sixth prior art is displayed in FIGS. 6A to 6D which
illustrate sequential perspective views as disclosed in U.S. Pat.
No. 6,413,587, as a fourth conventional microcontact method. A
plate if having a protrusion projected therefrom and an impression
coating 3f formed thereon, presses a substrate 2f coated with a
thin film 4f. Similarly to the fourth prior art, an additional
process is necessary with another material in order to increase the
thickness of the pattern because of the thin impression coating
3f.
[0012] In regards to the conventional microcontact methods
according to the third to the sixth prior arts, the first step is
to produce an impression mold made of polymer materials as the
plate or mold for providing sufficient deformation in the pressing
step. The impression mold should separate easily from the substrate
after the pressing step. The impression mold however, often suffers
from defective patterns due to the resilient property caused by the
pressure that it experiences in the pressing step. So the pattern
is often imprecise. Additionally, the impression mold reacts easily
with non-polar organic solvents, such as toluene or hexane. When
this occurs, the impression mold expands by a volume thereof due to
its chemical property. As such, the peripheral environment should
be controlled and monitored.
[0013] Hence, an improvement over the prior art is required to
overcome the disadvantages thereof.
SUMMARY OF INVENTION
[0014] The primary objective of the invention is therefore to
specify a thin film transistor that can replace the conventional
semiconductor process with simple steps, thereby improving
manufacturing efficiency and saving on production costs.
[0015] The secondary objective of the invention is therefore to
specify a thin film transistor that can adjust the depth of a
desired pattern directly, without additional etching or other
processes.
[0016] According to the invention, these objectives are achieved by
a method for producing a thin film transistor and include the
following steps--preparing a glass substrate; having a positive
photosensitive coating on the glass substrate; providing a
transparent mold plate, which has a plurality of ladder opaque
protrusions arranged in accordance with a predetermined pattern
having different depth; controlling the transparent mold plate
closely to press into the positive photosensitive coating and
non-contacting to the glass substrate; Exposing a part of the
positive photosensitive coating, which is unshielded under the
ladder opaque protrusions, via an explosion by a UV light; and
separating the transparent mold plate from the glass substrate, and
removing the part of the positive photosensitive coating, which is
unshielded under the ladder opaque protrusions and not cured, via a
chemical solvent; whereby the thin film transistor is formed a
pattern having different depth, after the positive photosensitive
coating made from changeable material is pressed, cured, and
cleaned.
[0017] According to the invention, these objectives are achieved by
a thin film transistor that includes a glass substrate having a
positive photosensitive coating formed thereon, and a part of the
positive photosensitive coating being exposed via a UV light; a
transparent mold plate including a plurality of ladder opaque
protrusions disposed thereon, and the ladder opaque protrusions
being arranged relevant to the predetermined pattern having
different depth; and an adhesion layer formed between the
transparent mold plate and the ladder opaque protrusions; and the
adhesion layer having a coefficient of thermal expansion ranging
between those of the transparent mold plate and the ladder opaque
protrusions; wherein the other part of the positive photosensitive
coating shielded under the ladder opaque protrusions is remained
while the part of the positive photosensitive coating unshielded by
the ladder opaque protrusions is removed via a chemical solvent;
whereby the thin film transistor is formed a pattern having
different depth, after the positive photosensitive coating is
pressed, cured, and cleaned.
[0018] According to the invention, these objectives are achieved by
a thin film transistor that include a glass substrate having a
positive photosensitive coating formed thereon, and a part of the
positive photosensitive coating being exposed via a UV light; a
transparent mold plate including a plurality of ladder opaque
protrusions disposed thereon, and the ladder opaque protrusions
being arranged relevant to the predetermined pattern having
different depth; and an adhesion layer formed between the
transparent mold plate and the ladder opaque protrusions; and the
adhesion layer having a coefficient of thermal expansion ranging
between those of the transparent mold plate and the ladder opaque
protrusions; wherein the other part of the positive photosensitive
coating shielded under the ladder opaque protrusions is remained
while the part of the positive photosensitive coating unshielded by
the ladder opaque protrusions is removed via a chemical solvent;
whereby the thin film transistor is formed a pattern having
different depth, after the positive photosensitive coating is
pressed, cured, and cleaned.
[0019] To provide a further understanding of the invention, the
following detailed description illustrates embodiments and examples
of the invention. Examples of the more important features of the
invention thus have been summarized rather broadly in order that
the detailed description thereof that follows may be better
understood, and in order that the contributions to the art may be
appreciated. There are, of course, additional features of the
invention that will be described hereinafter and which will form
the subject of the claims appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings,
where:
[0021] FIGS. 1A to 1D are sequential perspective views according to
a conventional photosensitive pressing method as the first example
of prior art;
[0022] FIG. 2 is a perspective view according to a first
conventional nanoimprint method patented by U.S. Pat. No. 6,518,189
as the second example of prior art;
[0023] FIG. 3 is a perspective view according to a first
microcontact method patented by U.S. Pat. No. 5,900,160 as the
third example of prior art;
[0024] FIGS. 4A to 4D are sequential perspective views according to
a second microcontact method patented by U.S. Pat. No. 6,060,121 as
the fourth example of prior art;
[0025] FIGS. 5A to 5D are sequential perspective views according to
a third microcontact method patented by U.S. Pat. No. 6,380,101 as
the fifth example of prior art;
[0026] FIGS. 6A to 6D are sequential perspective views according to
a fourth microcontact method patented by U.S. Pat. No. 6,413,587 as
the sixth example of prior art;
[0027] FIGS. 7A to 7C are sequential perspective views of thin film
transistor of a preferred embodiment according to the present
invention; and
[0028] FIG. 8 is a side view of a mold plate according to the
present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The present invention produces a plurality of ladder opaque
protrusions on a transparent mold plate, and then presses the
transparent mold plate onto a substrate that has a positive
photosensitive coating formed in advance. a part of the positive
photosensitive coating is exposed via a UV light, thus removing the
unshielded part via a chemical solvent, and the other part of the
positive photosensitive coating shielded under the ladder opaque
protrusion is defined the different depth on the predetermined
pattern, thereby, defining both a predetermined pattern and
different depth of the predetermined pattern simultaneously without
additional etching or other processes.
[0030] The method according to the present invention can be brought
into practice to each layer of a thin film transistor by taking
different photosensitive materials with specific properties; for
example, a semiconductor photosensitive material can be used as a
semiconductor layer and the like, such as active layer or an ohmic
contact layer; a conductive material can be used as a conductive
line or a electrode layer, such as a gate electrode, a source
electrode, a drain electrode, a contact pad, a capacitance
electrode, a circuit line and so on; an insulating material is used
for isolation, such as an insulator layer, a dielectric layer or a
passivation layer. These layers mentioned above need more steps if
produced by a conventional semiconductor process. These additional
steps ensure that the method according to the present invention is
effective and that the expensive equipment that the conventional
semiconductor process needs are not required.
[0031] With respect to FIGS. 7A to 7C, a method for producing a
thin film transistor of sequential perspective views according to
the present invention includes the following steps. Firstly,
preparing a glass substrate 2 prior to providing a positive
photosensitive coating 3 on the glass substrate 2 in a spin-coating
manner as shown in FIG. 7A. Secondly, providing a transparent mold
plate 1, which then has a plurality of ladder opaque protrusions 11
in accordance with a predetermined pattern having the different
depth. Thirdly, in FIG. 7B, the transparent mold plate 1 is
controlled to press closely to the positive photosensitive coating
3 of the glass substrate 2 with uniform pressure, and
non-contacting to the glass substrate 2. The positive
photosensitive coating 3 is a kind of fluid, so that the positive
photosensitive coating 3 is forced with a at least two
predetermined depth by the ladder opaque protrusions 11 and flows
to fill a space between the transparent mold plate 1 and the glass
substrate 2. A part of the positive photosensitive coating 3, which
is not shielded under the opaque protrusions 1, is exposed via a UV
light 4. FIG. 7C shows that the other part of the positive
photosensitive coating 3, which is shielded under the ladder opaque
protrusions 1 and not exposed. thereby, a part of the unshielded
positive photosensitive coating 3 is removed via a chemical
solvent, after the transparent mold plate 1 is separated from the
glass substrate 2. Therefore, the positive photosensitive coating 3
is finally formed with the predetermined pattern having at least
two different depths. The positive photosensitive coating 3 can be
made of semiconductor, conductive or insulating materials. The thin
film transistor is formed after the positive photosensitive coating
3 is pressed, cured, and cleaned in a sequential manner. The
transparent mold plate 1 is made of glass material or quartz; the
ladder opaque protrusions 11 are made of metallic material, such as
Cr, Mo or W. At this stage the height of the ladder opaque
protrusions 11 are a little less than their required height at the
end of the process.
[0032] The transparent mold plate 1 is cleaned by part of the
conventional semiconductor process. Furthermore, the transparent
mold plate 1 can be deposed with an adhesion layer 5 (a kind of a
metallic oxide) prior to being disposed with the protrusions 11 (a
kind of a metallic thin film) wherein the adhesion layer 5 has a
coefficient of thermal expansion ranging between those of the
transparent mold plate 1 and the opaque protrusions 11. The
adhesion layer 5 is made of a metallic oxide that is made from a
predetermined metal. The predetermined metal is one of the
transition metals, which includes Cr, Mo or W; and the metallic
oxide is a transition-metal oxide corresponding to the
predetermined metal. According to a proffered embodiment, the
transparent mold plate 1 is deposed with a chromium oxide, which
has a thickness of less than 500 .ANG. The transparent mold plate 1
with the chromium oxide is then further deposited with a layer of
chromium (Cr). The layer of chromium has a real thickness a little
less than the anticipated predetermined depth of the predetermined
pattern, and a difference, between the real thickness and the
anticipated depth, exists due to the forcing pressure of the
transparent mold plate 1 and properties of viscosity of the opaque
protrusions 11 and the negative photosensitive coating 3. The
difference should be within or no more than 10%. The layer of the
protrusions 11, the metallic thin film, and the layer of adhesion
layer 5, metallic oxide, are further processed by photo and etching
processes (like dry-etching, wet etching, using an E-beam process
or laser writing) simultaneously, so as to form as a plurality of
the protrusions 11 corresponding to the predetermined pattern.
After the protrusions 11 are defined, a transparent material (like
Teflon) will be deposed onto a surface each of the protrusions 11.
Because Teflon is de-wetted from the negative photosensitive
coating 3, Teflon is called a dewetting layer 6.
[0033] An image sensor is provided in order to align with both of
the transparent mold plate 1 and the glass substrate 2. The image
sensor is a charge coupled device (CCD) and complementary
metal-oxide semiconductor (CMOS) selectively.
[0034] Advantages of the present invention are summarized as
follows:
[0035] 1. To replace the conventional semiconductor process with
simple steps, so as to improve efficiency and save on production
costs.
[0036] 2. To adjust the predetermined at least two different depths
of the desired pattern directly with the chemical solvent, without
additional etching or other processes; this will also lower
costs.
[0037] 3. The method can be practiced in each layer of the thin
film transistor.
[0038] 4. The protrusions are made of metal materials with rare
deformation, so they are more precise and accurate.
[0039] It should be apparent to those skilled in the art that the
above description is only illustrative of specific embodiments and
examples of the invention. The invention should therefore cover
various modifications and variations made to the herein-described
structure and operations of the invention, provided they fall
within the scope of the invention as defined in the following
appended claims.
* * * * *