U.S. patent application number 14/664696 was filed with the patent office on 2016-09-29 for laser annealing method and laser annealing apparatus.
The applicant listed for this patent is V Technology Co., Ltd.. Invention is credited to Koichi Kajiyama, Michinobu Mizumura.
Application Number | 20160279736 14/664696 |
Document ID | / |
Family ID | 43297641 |
Filed Date | 2016-09-29 |
United States Patent
Application |
20160279736 |
Kind Code |
A9 |
Kajiyama; Koichi ; et
al. |
September 29, 2016 |
Laser annealing method and laser annealing apparatus
Abstract
In the present invention, At least one row of lens arrays, in
which a plurality of lenses are arranged in a direction
intersecting with the conveying direction of a substrate to
correspond to the plurality of TFT forming areas set in a matrix on
the substrate, is shifted in the direction intersecting with the
conveying direction of the substrate, to thereby align the lenses
in the lens array with the TFT forming areas on the substrate based
on the alignment reference position. The laser beams are irradiated
onto the lens array when the substrate moves and the TFT forming
areas reach the underneath of the corresponding lenses of the lens
array, and the laser beams are focused by the plurality of lenses
to anneal the amorphous silicon film in each TFT forming area.
Inventors: |
Kajiyama; Koichi;
(Yokohama-Shi, JP) ; Mizumura; Michinobu;
(Yokahama-shi, JP) |
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Applicant: |
Name |
City |
State |
Country |
Type |
V Technology Co., Ltd. |
Kanagawa |
|
JP |
|
|
Prior
Publication: |
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Document Identifier |
Publication Date |
|
US 20150258630 A1 |
September 17, 2015 |
|
|
Family ID: |
43297641 |
Appl. No.: |
14/664696 |
Filed: |
March 20, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13310024 |
Dec 2, 2011 |
9012338 |
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14664696 |
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PCT/JP2010/058787 |
May 25, 2010 |
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13310024 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/02422 20130101;
H01L 21/02532 20130101; H01L 21/02686 20130101; B23K 26/0006
20130101; B23K 26/352 20151001; H01L 21/02675 20130101; B23K 26/083
20130101; H01L 21/02691 20130101; H01L 21/67259 20130101; H01L
21/02488 20130101; B23K 2103/56 20180801; H01L 21/268 20130101;
B23K 26/354 20151001; H01L 27/1285 20130101; H01L 21/67115
20130101; H01L 29/66765 20130101 |
International
Class: |
B23K 26/00 20060101
B23K026/00; B23K 26/08 20060101 B23K026/08; H01L 27/12 20060101
H01L027/12; H01L 21/67 20060101 H01L021/67; H01L 21/268 20060101
H01L021/268; H01L 21/02 20060101 H01L021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2009 |
JP |
2009-134181 |
Claims
1-3. (canceled)
4. A laser annealing apparatus that focuses laser beams onto a
plurality of TFT forming areas set in a matrix on a substrate with
a predetermined array pitch by a plurality of lenses in a lens
array, and anneals an amorphous silicon film in each of the TFT
forming areas, the laser annealing apparatus comprising: a
conveying device that conveys the substrate at a certain speed in
either one array direction of horizontal and vertical directions of
the TFT forming areas set in the matrix; a laser source that emits
the laser beams; a lens array including at least one row of a
plurality of condenser lenses, arranged in parallel in a direction
intersecting with a conveying direction of the substrate in a plane
parallel to a surface of the substrate to correspond to the
plurality of TFT forming areas in the same direction; an imaging
device that captures an image on the surface of the substrate,
designating a position away from a condensing position of laser
beams by the lens array by a certain distance in a direction
opposite to the conveying direction of the substrate, as an image
capturing position; an alignment device that aligns the lenses in
the lens array with the TFT forming areas on the substrate by
shifting the lens array in the direction intersecting with the
conveying direction of the substrate; and a control device that
controls drive of the respective components, wherein the control
device processes mages sequentially input from the imaging device
that captures the image on the surface of the substrate being
conveyed, to detect an alignment reference position preset on the
surface of the substrate, causes the lenses in the lens array to be
aligned with the TFT forming areas on the substrate based on the
alignment reference position, and controls the laser source to
irradiate laser beams toward the lens array when the substrate
moves and the TFT forming areas reach the underneath of the
corresponding lenses in the lens array.
5. A laser annealing apparatus according to claim 4, wherein the
lens array has such a configuration that the lens array includes a
plurality of rows of lens arrays in which lenses are arranged in
parallel in the direction intersecting with the conveying direction
of the substrate with a pitch of an integral multiple of two or
more of an array pitch of the TFT forming areas in the same
direction, and a subsequent lens array is shifted by a
predetermined dimension in a parallel arrangement direction of the
plurality of lenses so as to fill a gap between respective lenses
in the lens array positioned at the head in the conveying direction
of the substrate.
6. A laser annealing apparatus according to claim 4, wherein the
substrate is a TFT substrate on which a plurality of wiring lines
is formed horizontally and vertically, and the TFT forming area is
set at a crossing of the plurality of wiring lines, and the
alignment reference position is set at one edge of the wiring line
parallel to the conveying direction of the TFT substrate.
Description
[0001] This application is a division of application Ser. No.
13/310,024, filed Dec. 2, 2011, which is a continuation of
PCT/JP2010/058787, filed on May 25, 2010, each of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a laser annealing method
for condensing laser beams by a microlens array to anneal only a
thin-film transistor forming area of an amorphous silicon film. In
particular, the present invention relates to a laser annealing
method and a laser annealing apparatus for enhancing the
irradiation position accuracy of laser beams by moving the
microlens array following the movement of a substrate to be
conveyed.
[0004] 2. Description of Related Art
[0005] In a conventional laser annealing method, a plurality of
laser beams is formed by a microlens array, and a focal point is
formed for each beam, and each focal point of the beam is
transferred to and imaged on an amorphous silicon film surface
side, and laser processing is performed by irradiating the beams
onto the amorphous silicon film surface, thereby recrystallization
the amorphous silicon film in the thin-film transistor
(hereinafter, referred to as "TFT") forming area (for example,
refer to Japanese Laid-open Patent Publication No.
2004-311906).
[0006] However, in such a conventional laser annealing method,
laser beams are focused by the microlens array and only the
amorphous silicon film in a plurality of TFT forming areas is
annealed, and hence, there is an advantage in that the use
efficiency of the laser beams increases. However, there is no
disclosure about; moving the microlens array following the movement
of a substrate to be conveyed while meandering, positioning each
lens in the microlens array at each TFT forming area, and
irradiating the laser beams. Consequently, at the time of conveying
and annealing a large substrate having a size of one meter or more
on one side, when the substrate is conveyed while meandering, it
can be difficult to anneal only each TFT forming area reliably due
to the mechanical accuracy of a conveying mechanism.
SUMMARY OF THE INVENTION
[0007] In view of the above problems, it is an object of the
present invention to provide a laser annealing method and a laser
annealing apparatus that enhances the irradiation position accuracy
of laser beams by shifting the microlens array following the
movement of a substrate to be conveyed.
[0008] In order to achieve the above object, the laser annealing
method of the present invention is a laser annealing method for
annealing an amorphous silicon film in each of a plurality of
thin-film transistor (hereinafter, referred to as "TFT") forming
areas set in a matrix on a substrate with a predetermined array
pitch, by focusing laser beams onto the TFT forming areas by a
plurality of lenses in a lens array. According to the laser
annealing method, an image on a surface of the substrate is
captured by an imaging device while the substrate is being conveyed
in either one array direction of horizontal and vertical directions
of the TFT forming areas set in the matrix, and an alignment
reference position preset on the surface of the substrate is
detected based on the captured image. Then at least one row of lens
arrays, in which a plurality of lenses are arranged in a direction
intersecting with a conveying direction of the substrate to
correspond to the plurality of TFT forming areas, is shifted in the
direction intersecting with the conveying direction of the
substrate, to align the lenses in the lens array with the TFT
forming areas on the substrate based on the alignment reference
position. The laser beams are then irradiated onto the lens array
when the substrate moves and the TFT forming area reaches the
underneath of a corresponding lens of the lens array.
[0009] According to this configuration, the image on the surface of
the substrate is captured by the imaging device while the substrate
is being conveyed in either one array direction of horizontal and
vertical directions of the TFT forming areas set in the matrix, and
the alignment reference position preset on the surface of the
substrate is detected based on the captured image. Then at least
one row of lens arrays, in which the plurality of lenses are
arranged in the direction intersecting with the conveying direction
of the substrate to correspond to the plurality of TFT forming
areas, is shifted in the direction intersecting with the conveying
direction of the substrate, to align the lenses in the lens array
with the TFT forming areas on the substrate based on the alignment
reference position. The laser beams are then irradiated onto the
lens array when the substrate moves and the TFT forming areas reach
the underneath of the corresponding lenses of the lens array, and
the laser beams are focused by the plurality of lenses to anneal
the amorphous silicon film in each TFT forming area.
[0010] Moreover, the lens array has such a configuration that the
lens array includes a plurality of rows of lens arrays in which
lenses are arranged in parallel in the direction intersecting with
the conveying direction of the substrate with a pitch of an
integral multiple of two or more of an array pitch of the TFT
forming areas in the same direction, and a subsequent lens array is
shifted by a predetermined dimension in a parallel arrangement
direction of the plurality of lenses so as to fill a gap between
the respective lenses in the lens array positioned at the head in
the conveying direction of the substrate. Consequently, laser beams
are focused onto the amorphous silicon film in each TFT forming
area by the lens array having such a configuration that the lens
array includes a plurality of rows of lens arrays in which lenses
are arranged in parallel in the direction intersecting with the
conveying direction of the substrate with a pitch of an integral
multiple of two or more of the array pitch of the TFT forming areas
in the same direction, and a subsequent lens array is shifted by a
predetermined dimension in the parallel arrangement direction of
the plurality of lenses so as to fill the gap between the
respective lenses in the lens array positioned at the head in the
conveying direction of the substrate.
[0011] Moreover, the substrate is a TFT substrate on which wiring
lines are formed horizontally and vertically, and the TFT forming
area is set at a crossing of the horizontal and vertical wiring
lines, and the alignment reference position is set at an edge of
the wiring line parallel to the conveying direction of the TFT
substrate. Accordingly, alignment of the lenses in the lens array
with the TFT forming areas on the TFT substrate is performed based
on the alignment reference position set at the edge of the wiring
line parallel to the conveying direction of the TFT substrate, on
which the TFT forming area is set at the crossing of the horizontal
and vertical wiring lines.
[0012] A laser annealing apparatus according to the present
invention focuses laser beams onto a plurality of TFT forming areas
set in a matrix on a substrate with a predetermined array pitch by
a plurality of lenses in a lens array, and anneals an amorphous
silicon film in each of the TFT forming areas. The laser annealing
apparatus includes; a conveying device that conveys the substrate
at a certain speed in either one array direction of horizontal and
vertical directions of the TFT forming areas set in the matrix; a
laser source that irradiates the laser beams; a lens array
including at least one row of a plurality of condenser lenses,
arranged in parallel in a direction intersecting with a conveying
direction of the substrate in a plane parallel to a surface of the
substrate to correspond to the plurality of TFT forming areas in
the same direction; an imaging device that captures an image on the
surface of the substrate, designating a position away from a
focusing position of laser beams by the lens array by a certain
distance in a direction opposite to the conveying direction of the
substrate, as an image capturing position; an alignment device that
aligns the lenses in the lens array with the TFT forming areas on
the substrate by shifting the lens array in the direction
intersecting with the conveying direction of the substrate; and a
control device that controls drive of the respective components.
The control device processes images sequentially input from the
imaging device that captures the image on the surface of the
substrate being conveyed, to detect an alignment reference position
preset on the surface of the substrate, causes the lenses in the
lens array to be aligned with the TFT forming areas on the
substrate based on the alignment reference position, and controls
the laser source to irradiate laser beams toward the lens array
when the substrate moves and the TFT forming areas reach the
underneath of the corresponding lenses in the lens array.
[0013] According to this configuration, the control device
processes images sequentially input from the imaging device that
captures the image on the surface of the substrate being conveyed,
to detect the alignment reference position preset on the surface of
the substrate, controls the drive of the alignment device to shift
the lens array in the direction intersecting with the conveying
direction of the substrate, causes the lenses in the lens array to
be aligned with the TFT forming areas on the substrate based on the
alignment reference position, and controls the laser source to
irradiate laser beams toward the lens array when the substrate is
moved by the conveying device and the TFT forming areas reach the
underneath of the corresponding lenses in the lens array. The laser
beam is then focused onto the plurality of TFT forming areas set in
the matrix on the substrate with the predetermined array pitch by
the plurality of lenses in the lens array, and the amorphous
silicon film in each TFT forming area is annealed.
[0014] Moreover, the lens array has such a configuration that it
includes a plurality of rows of lens arrays in which lenses are
arranged in parallel in a direction intersecting with the conveying
direction of the substrate with a pitch of an integral multiple of
two or more of the array pitch of the TFT forming areas in the same
direction, and a subsequent lens array is shifted by a
predetermined dimension in a parallel arrangement direction of the
plurality of lenses so as to fill a gap between respective lenses
in the lens array positioned at the head in the conveying direction
of the substrate. As a result, laser beams are focused onto the
plurality of TFT forming areas by the lens array having such a
configuration that the lens array includes a plurality of rows of
lens arrays in which lenses are arranged in parallel in the
direction intersecting with the conveying direction of the
substrate with the pitch of the integral multiple of two or more of
the array pitch of the TFT forming areas in the same direction, and
the subsequent lens array is shifted by the predetermined dimension
in the parallel arrangement direction of the plurality of lenses so
as to fill the gap between respective lenses in the lens array
positioned at the head in the conveying direction of the
substrate.
[0015] Moreover the substrate is a TFT substrate on which a
plurality of wiring lines are formed horizontally and vertically
and the TFT forming area is set at a crossing of the plurality of
wiring lines, and the alignment reference position is set at one
edge of the wiring line parallel to the conveying direction of the
TFT substrate. As a result, alignment of the lenses in the lens
array with the TFT forming areas on the TFT substrate is performed
based on the alignment reference position set at the edge of the
wiring line parallel to the conveying direction of the TFT
substrate on which each TFT forming area is set at the crossing of
the horizontal and vertical wiring lines.
Advantageous Effects of the Invention
[0016] According to the invention of a first or fourth aspect, the
microlens array can be moved following the movement of the
substrate being conveyed, and hence, the irradiation position
accuracy of the laser beams can be enhanced. Consequently, at the
time of conveying and annealing a large substrate having a size of
one meter or more on one side, even if the substrate is conveyed
while meandering, only each TFT forming area can be annealed
reliably with the mechanical accuracy of the conveying
mechanism.
[0017] Moreover, according to the invention of a second or fifth
aspect, the shape of each lens in the lens array can be made large
to increase an intake of laser beams, thereby enabling to increase
the irradiation energy of laser beams onto the amorphous silicon
film. Consequently, the load on the laser source that irradiates
the laser beams can be reduced, thereby enabling to enhance
reliability of the apparatus.
[0018] Furthermore, according to the invention of a fourth or sixth
aspect, while conveying the substrate, alignment of the lens with
the TFT forming area can be constantly performed based on the edge
of the wiring provided on the TFT substrate of a liquid crystal
display panel or an organic EL display panel and extending
continuously in the conveying direction of the substrate, thereby
enabling to enhance the alignment accuracy of the lens with the TFT
forming area.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic diagram showing an embodiment of a
laser annealing apparatus according to the present invention;
[0020] FIG. 2 is a plan view showing a TFT substrate to be used in
the laser annealing apparatus according to the present
invention;
[0021] FIGS. 3A-3B is an explanatory diagram showing one
configuration example of a microlens array constituting the laser
annealing apparatus according to the present invention, showing the
position in relation to an imaging device;
[0022] FIG. 4 is a block diagram showing one configuration example
of a control device constituting the laser annealing apparatus
according to the present invention;
[0023] FIG. 5 is an explanatory diagram illustrating detection of
an edge of a gate line on the TFT substrate;
[0024] FIG. 6 is a flowchart illustrating a laser annealing method
according to the present invention;
[0025] FIGS. 7A-7B is an explanatory diagram illustrating a
situation in which the whole TFT forming areas on the TFT substrate
are sequentially laser-annealed by the microlens array;
[0026] FIGS. 8A-8B is a sectional view for explaining an annealing
process of the TFT forming area on the TFT substrate by the
microlens array; and
[0027] FIGS. 9A-9C is a sectional view for explaining a process for
etching an annealed polysilicon film according to the laser
annealing method of the present invention, to a certain shape.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] An embodiment of the present invention is explained
hereunder with reference to the accompanying drawings. FIG. 1 is a
schematic diagram showing an embodiment of a laser annealing
apparatus according to the present invention. The laser annealing
apparatus is for focusing laser beams by a microlens array to
anneal only a TFT forming area of an amorphous silicon film formed
on a substrate, and includes a conveying device 1, a laser source
2, a microlens array 3, an imaging device 4, an alignment device 5,
and a control device 6.
[0029] Here, as shown in FIG. 2, the substrate is a TFT substrate
10 on which a plurality of data lines 7 and gate lines 8 are formed
horizontally and vertically, and a TFT forming area 9 is set on a
gate electrode 30 (refer to FIGS. 8A and 8B) at a crossing of the
data line 7 and the gate line 8. A plurality of TFT forming areas 9
are set in a matrix with an array pitch (width W and length L in
direction of arrow A) the same as that of pixels 11. On the TFT
substrate 10, an alignment reference position is set, which becomes
a reference for alignment of the TFT forming areas 9 with
microlenses 15 in the microlens array 3 described later, for
example, at an edge of the data line 7 parallel to the substrate
conveying direction (direction of arrow A). Specifically, in the
present embodiment, the alignment reference position is set at a
right edge of the data line 7 located at a left end toward the
substrate conveying direction (direction of arrow A). At this time,
a horizontal distance between the right edge of the data line 7 and
the center of the TFT forming area 9 is determined by a design
value.
[0030] The conveying device 1 is for mounting the TFT substrate 10
on an upper surface thereof and conveying the TFT substrate 10 at a
certain speed in either one array direction of horizontal and
vertical directions of the TFT forming areas 9, for example, in the
direction of arrow A in FIG. 2. A plurality of unit stages 12
having a plurality of ejection holes for ejecting gas and a
plurality of suction holes for sucking gas in an upper surface
thereof, is arranged parallel to the conveying direction of the TFT
substrate 10 (hereinafter, referred to as the "substrate conveying
direction"). The TFT substrate 10 is conveyed with both edges
thereof being supported by conveyer rollers 13, in a state with the
TFT substrate 10 being floated on the plurality of unit stages 12
by a certain amount due to a balance between ejection and suction
of the gas.
[0031] The laser source 2 is provided above the conveying device 1.
The laser source 2 is an excimer laser that irradiates laser beams
14 having a wavelength of, for example, 308 nm or 353 nm with a
recurrence period of, for example, 50 Hz.
[0032] The microlens array 3 is provided on an optical path of the
laser beams 14 irradiated from the laser source 2. The microlens
array 3 is for focusing the laser beams 14 onto the plurality of
TFT forming areas 9 set on the TFT substrate 10. The microlens
array 3 has such a configuration that for example, six lens arrays,
as shown in FIG. 3A, in which the microlenses 15 are arranged in
parallel with a pitch of an integral multiple of two or more (shown
by 2W in FIG. 3A) of an array pitch W of the severally set TFT
forming areas 9, are arranged in parallel away from each other by a
distance L, intersecting with the substrate conveying direction
(direction of arrow A in FIG. 2) in a plane parallel to the TFT
substrate 10. Moreover, the microlens array 3 has such a
configuration that the subsequent three lens arrays (hereinafter,
referred to as the "second lens group 17") are shifted by a
predetermined dimension (shown by W in FIG. 3A) in a parallel
arrangement direction of the microlenses 15 so as to fill the gap
between respective lenses in the three lens arrays (hereinafter,
referred to as the "first lens group 16") positioned at the head in
the substrate conveying direction.
[0033] A specific configuration example of the microlens array 3 is
such that, as shown in FIG. 3B, a plurality of microlens arrays 3
is formed on one surface of a transparent substrate 34, and an
opaque shading film 35 having openings corresponding to the
microlenses 15, is formed on the other surface thereof. Moreover, a
long and thin aperture window 36 parallel to the lens array, is
formed on the shading film 35 away from the second lens group 17 by
a certain distance in a direction opposite to the substrate
conveying direction. An N-shaped alignment mark 37 is provided in
the aperture window 36. The alignment mark 37 is for position
alignment with the TFT substrate 10, and a centerline of a diagonal
fine line 37a parallel to the substrate conveying direction is
matched with the center of the microlenses 15 in the first lens
group 16 or the second lens group 17, and horizontally parallel
fine lines 37b are arranged parallel to the substrate conveying
direction. As a result, respective microlenses 15 in the microlens
array 3 have a certain position relation with respect to the center
of the alignment mark 37. That is to say, the respective
microlenses 15 have such a relation that a horizontal distance with
respect to the center of the alignment mark 37 in a direction
orthogonal to the substrate conveying direction is nW (n is an
integer equal to or larger than 1).
[0034] The imaging device 4 is provided between adjacent unit
stages 12 of the conveying device 1 corresponding to the aperture
window 36 of the microlens array 3. The imaging device 4 is for
capturing an image of a wiring pattern formed on the surface of the
TFT substrate 10 and an image of the alignment mark 37 of the
microlens array 3 simultaneously, through the substrate from an
underside of the TFT substrate 10, designating a position away from
a focusing position of the laser beams 14 by the microlens array 3
by a certain distance in a direction opposite to the substrate
conveying direction, as an image capturing position. The imaging
device 4 is a line camera (line CCD) having a plurality of light
receiving elements arranged linearly intersecting with the
substrate conveying direction shown by arrow A in FIG. 3A. The
imaging device 4 is provided, for example, away by a distance D
from a lens array 17a of the second lens group 17 in the microlens
array 3, which is positioned at the head in the substrate conveying
direction, such that a centerline of a major axis of a linear light
receiving surface is matched with the centerline of the alignment
mark 37 of the microlens array 3 intersecting with the substrate
conveying direction.
[0035] The alignment device 5 is provided so that the microlens
array 3 can be moved in a direction intersecting with the substrate
conveying direction. The alignment device 5 is for moving the
microlens array 3 such that a distance between the alignment
reference position preset on the data line 7 on the TFT substrate
10 (hereinafter, referred to as a "substrate-side alignment
reference position") and a central position of the diagonal fine
line 37a of the alignment mark 37 of the microlens array 3
(hereinafter, referred to as a lens-side alignment reference
position) becomes a predetermined value, to align each microlens 15
in the microlens array 3 with the TFT forming area 9 on the TFT
substrate 10. For example, the alignment device 5 includes a stage
and a motor for moving the microlens array 3 in a direction
intersecting with the substrate conveying direction (direction of
arrow A). Moreover, another motor for rotating the microlens array
3 within a certain angular range centering on an optical axis
thereof may be provided.
[0036] Reference symbol 18 in FIG. 1 denotes a homogenizer that
homogenizes the intensity distribution in the cross-section of
laser beams 14 irradiated from the laser source 2, and reference
symbol 19 denotes a condenser lens that turns the laser beams 14
into parallel beams to be irradiated onto the microlens array 3.
Moreover reference symbol 20 denotes an illuminating light source
for illuminating an image capturing position of the imaging device
4.
[0037] The control device 6 is provided connected to; the conveying
device 1, the laser source 2, the imaging device 4, and the
alignment device 5. The control device 6 processes on a real time
basis, the substrate surface and a one-dimensional image of the
alignment mark 37 of the microlens array 3 simultaneously imaged by
the imaging device 4, to detect the substrate-side alignment
reference position set on the data line 7 on the TFT substrate 10
and the lens-side alignment reference position of the microlens
array 3. The control device 6 then drives the alignment device 5 so
that the distance between these alignment reference positions
becomes the predetermined value, to move the microlens array 3 in
the direction intersecting with the substrate conveying direction,
and aligns each microlens 15 in the microlens array 3 with the TFT
forming area 9 on the TFT substrate 10. After the TFT substrate 10
has moved a certain distance or a certain period of time has passed
since it was detected that the edge of the gate line 8 on the TFT
substrate 10 matched with the center of the alignment mark 37 based
on the image captured by the imaging device 4, when the TFT forming
areas 9 reach the underneath of the corresponding lenses in the
microlens array 3, the control device 6 controls the laser source 2
to light up for a certain period of time and irradiate laser beams
14 onto the microlens array 3. As shown in FIG. 4, the control
device 6 includes an image processing section 21, a memory 22, an
arithmetic section 23, a conveying-device drive controller 24, an
alignment-device drive controller 25, a laser-source drive
controller 26, and a control section 27.
[0038] Here, the image processing section 21 detects a luminance
change in the alignment direction (major axis direction) of a
plurality of light-receiving elements in the imaging device 4 by
processing the one-dimensional image captured by the imaging device
4 on a real time basis, to detect the substrate-side alignment
reference position set on the data line 7 on the TFT substrate 10
and the lens-side alignment reference position of the microlens
array 3, and detects that the edge of the gate line 8 on the TFT
substrate 10 has matched with the center of the alignment mark 37
based on the image captured by the imaging device 4.
[0039] The memory 22 stores; a distance D between the imaging
device 4 and the lens array 17a of the second lens group 17 in the
microlens array 3, which is positioned at the head in the substrate
conveying direction, a distance between the lens arrays 16a and 17a
positioned respectively at the head in the substrate conveying
direction of the first lens group 16 and the second lens group 17
in the microlens array 3 (for example, 3L in FIG. 3A), an alignment
reference value for aligning the TFT substrate 10 with the
microlens array 3, and a moving distance of the TFT substrate 10 or
elapsed time since detection of the edge of the gate line 8 on the
TFT substrate 10 until lighting of the laser source 2.
[0040] The arithmetic section 23 calculates a misregistration
amount between the substrate-side alignment reference position of
the TFT substrate 10 and the lens-side alignment reference position
of the microlens array 3 detected by the image processing section
21.
[0041] The conveying-device drive controller 24 controls drive of
the conveying device by a constant frequency pulse so that the TFT
substrate 10 is conveyed at a certain speed.
[0042] The alignment-device drive controller 25 compares the
misregistration amount between the substrate-side alignment
reference position of the TFT substrate 10 and the lens-side
alignment reference position of the microlens array 3 calculated by
the arithmetic section 23 with the alignment reference value read
from the memory 22, and drives the alignment device 5 so that these
match with each other to shift the microlens array 3 in the
direction intersecting with the substrate conveying direction.
[0043] The laser-source drive controller 26 controls lighting and
extinction of the laser source 2. The control section 27 integrates
and controls the whole components to operate appropriately.
[0044] An operation of the laser annealing apparatus configured in
such a manner will be explained next.
[0045] At first, an input device such as a ten key is operated to
store in the memory 22; the distance D between the imaging device 4
and the lens array 17a of the second lens group 17 in the microlens
array 3, which is positioned at the head in the substrate conveying
direction, the distance between the lens arrays 16a and 17a
positioned respectively at the head in the substrate conveying
direction of the first lens group 16 and the second lens group 17
in the microlens array 3, the alignment reference value for
aligning the TFT substrate 10 with the microlens array 3, and the
moving distance of the TFT substrate 10 or elapsed time since
detection of the edge of the gate line 8 on the TFT substrate 10
until lighting of the laser source 2.
[0046] Next the TFT substrate 10 on which an amorphous silicon film
is formed to cover the whole surface thereof, is mounted on an
upper surface of the conveying device 1, so that the amorphous
silicon film is upside and the data line 7 is positioned to become
parallel to the conveying direction.
[0047] Then when a start switch is turned on, the conveying device
1 is pulse-controlled by the conveying-device drive controller 24
to convey the TFT substrate 10 in the direction of arrow A shown in
FIG. 1 at a certain speed, in a state with the TFT substrate 10
being floated on the upper surface of the conveying device 1 by a
certain amount.
[0048] Subsequently, when the TFT substrate 10 reaches a position
above the imaging device 4, the imaging device 4 simultaneously
captures images of the data lines 7 and the gate lines 8 formed on
the surface of the TFT substrate 10 and the alignment mark 37 of
the microlens array 3 through the TFT substrate 10. The
one-dimensional images sequentially captured and input by the
imaging device 4 are processed on a real time basis by the image
processing section 21. As shown in FIG. 5, when it is detected that
an edge 8a of the gate line 8 on the TFT substrate 10 matches with
the center of the alignment mark 37 of the microlens array 3, the
laser annealing apparatus counts the pulses of the conveying-device
drive controller 24 based on the detection time, to start
measurement of the moving distance of the TFT substrate 10, or
starts to clock the elapsed time based on the detection time.
[0049] Here, matching of the edge 8a of the gate line 8 on the TFT
substrate 10 with the center of the alignment mark 37 of the
microlens array 3 can be detected, as shown in FIG. 5, by capturing
the moment when the dimensions 8b and 8c on the right and left in
the substrate conveying direction of the edge 8a of the gate line 8
between the opposite parallel fine lines 37b of the alignment mark
37 divided by the diagonal fine line 37a, become equal.
[0050] Hereunder, the laser annealing method of the present
invention will be explained with reference to the flowchart in FIG.
6.
[0051] At first, in step S1, a one-dimensional image captured by
the imaging device 4 is processed on a real time basis by the image
processing section 21, to detect positions of the right edges of a
plurality of data lines 7 in the substrate conveying direction and
a central position of the diagonal fine line 37a of the alignment
mark 37 of the microlens array 3 (the lens-side alignment reference
position) by a luminance change in the alignment direction (major
axis direction) of a plurality of light-receiving elements in the
imaging device 4. Then, a position of the right edge of the data
line 7, for example, at the left end in the substrate conveying
direction, is specified as the substrate-side alignment reference
position, from the detected right edges of the plurality of data
lines 7.
[0052] In step S2, a misregistration amount between the specified
substrate-side alignment reference position and the lens-side
alignment reference position is calculated by the arithmetic
section 23, and the misregistration amount is compared with the
alignment reference value stored in the memory 22. Then the
alignment device 5 is driven by the alignment-device drive
controller 25 so that these match with each other, and the
microlens array 3 is shifted in the direction intersecting with the
substrate conveying direction to align the microlenses 15 with the
TFT forming areas 9.
[0053] In step S3, after the TFT substrate 10 has moved a certain
distance or a certain period of time has passed since it was
detected that the edge 8a of the gate line 8 on the TFT substrate
10 positioned at the head in the conveying direction matched with
the center of the alignment mark 37, then as shown in FIG. 7A, when
one row of the TFT forming areas 9 positioned at the head in the
conveying direction reaches the underneath of the lens array 17a at
the head in the conveying direction of the second lens group 17 in
the microlens array 3, the laser-source drive controller 26 is
driven to light up the laser source 2 for a certain period of time
to irradiate the laser beams onto the microlens array 3, and the
amorphous silicon film in the TFT forming areas 9 corresponding to
the second lens group 17 is annealed. Specifically, as shown in
FIG. 8A, the laser beams 14 are focused onto the TFT forming areas
9 on the gate electrodes 30 by the microlenses 15, to anneal the
amorphous silicon film 28 in the TFT forming areas 9. That is, due
to the irradiation of the laser beams 14, the amorphous silicon
film 28 in the TFT forming area 9 melts as shown in FIG. 8B, and
thereafter the molten amorphous silicon film 28a is rapidly cooled
and recrystallized simultaneously with extinction of the laser
source 2, thereby forming a polysilicon film. At this time, the
irradiation position of the laser beams 14 by the first lens group
16 is outside a forming area of the pixels 11, which becomes a
so-called blind print. In FIGS. 8A and 8B, reference symbol 29
denotes a glass substrate, and 31 denotes a SiN insulating
film.
[0054] In step S4, the laser source 2 is driven to light up for a
certain period of time by the laser-source drive controller 26,
every time the conveying device 1 is pulse-controlled by the
conveying-device drive controller 24 to move the TFT substrate 10
by a distance equal to the distance 3L between the lens arrays 16a
and 17a positioned respectively at the head in the substrate
conveying direction of the first lens group 16 and the second lens
group 17 in the microlens array 3. As a result, the whole TFT
forming areas 9 set on the TFT substrate 10 are sequentially
annealed and polysiliconized, thereby forming a polysilicon film 32
(refer to FIGS. 9A-9C). FIG. 7B shows a state in which the TFT
substrate 10 is moved by the distance 3L from the state in FIG. 7A,
and the TFT forming areas 9 between the TFT forming areas 9
corresponding to the second lens group 17 are annealed by the first
lens group 16.
[0055] In the present embodiment, alignment of the microlenses 15
in the microlens array 3 with the TFT forming areas 9 on the TFT
substrate 10 in step S3 is executed constantly even while the TFT
substrate 10 is being conveyed. Consequently, even if the TFT
substrate 10 is conveyed while oscillating from side to side, the
microlenses 15 can be positioned on the TFT forming areas 9
following the movement of the substrate. As a result, only the
amorphous silicon film 28 in the TFT forming area 9 can be annealed
reliably, to form the polysilicon film 32.
[0056] When annealing of the TFT substrate 10 is finished, then
after a resist mask 33 having a certain shape is formed on the
polysilicon film 32 on the gate electrode 30 as shown in FIG. 9A,
the amorphous silicon film 28 and the polysilicon film 32 around
the resist mask 33, and the SiN insulating film 31 formed
underneath thereof are etched and removed, as shown in FIG. 9B, by
a known etching technique. By removing the resist mask 33, as shown
in FIG. 9 (c), the TFT substrate 10 on which the polysilicon film
32 having a certain shape is formed on the gate electrode 30 can be
obtained. Thereafter, by forming a source electrode and a drain
electrode on the polysilicon film 32, a low-temperature polysilicon
thin-film transistor substrate is complete.
[0057] In the above-described embodiment, there is explained a case
in which after the TFT forming areas 9 on the TFT substrate 10, on
which the amorphous silicon film 28 is formed over the whole
surface thereof, are annealed and polysiliconized, an unnecessary
film around the polysilicon film 32 in the TFT forming area 9 is
etched so that the polysilicon film 32 having the predetermined
shape is left. However, the present invention is not limited
thereto, and after the unnecessary film around the polysilicon film
32 in the TFT forming area 9 is removed so that the polysilicon
film 32 having the predetermined shape is left, the remaining
amorphous silicon film 28 can be annealed and polysiliconized.
[0058] In the above-described embodiment, there is explained a case
in which the imaging device 4 is provided on the conveying device
side, and images of the data lines 7 and the gate lines 8 on the
substrate surface and the alignment mark 37 of the microlens array
3 are captured from the underside of the TFT substrate 10 through
the substrate. However, the present invention is not limited
thereto, and the imaging device 4 may be provided above the
conveying device 1, so that the images of the data lines 7 and the
gate lines 8 on the substrate surface and the alignment mark 37 of
the microlens array 3 are captured from above.
[0059] Moreover, in the above-described embodiment, there is
explained a case in which the microlens array 3 includes a
plurality of rows of lens arrays in which the microlenses 15 are
arranged in parallel in the direction intersecting with the
substrate conveying direction with a pitch (2W) twice the array
pitch W of the TFT forming areas in the same direction, and a
subsequent lens array is shifted by W in the parallel arrangement
direction of the plurality of microlenses 15 so as to fill the gap
between the respective microlenses 15 in the lens array positioned
at the head in the substrate conveying direction. However, the
present invention is not limited thereto, and the microlens array 3
may include at least one lens array in which a plurality of
microlenses 15 are arranged in parallel in the direction
intersecting with the substrate conveying direction with the same
pitch W as the array pitch W of the TFT forming areas in the same
direction.
[0060] Furthermore, in the above-described embodiment, there is
explained a case in which the alignment device 5 shifts the
microlens array 3 in the direction intersecting with the substrate
conveying direction. However, the present invention is not limited
thereto, and the microlens array 3 and the imaging device 4 may be
integrally moved.
[0061] Furthermore, in the above-described embodiment, there is
explained a case in which the microlens array 3 is formed by one
lens array having approximately the same length as the whole width
of the TFT substrate 10 intersecting with the substrate conveying
direction. However, the present invention is not limited thereto,
and the microlens array 3 may be formed approximately in the same
length as the above-described width by alternately arranging a
plurality of unit lens arrays having a shorter length than the
above-described width of the TFT substrate 10. In this case, one
imaging device 4 may be provided, respectively, corresponding to
each unit lens array.
[0062] In the above explanation, there is explained a case in which
the substrate is the TFT substrate 10. However, the present
invention is not limited thereto, and the substrate may be a
semiconductor substrate.
[0063] It should be noted that the entire contents of Japanese
Patent Application No. 2009-134181, filed on Jun. 3, 2009, on which
the convention priority is claimed is incorporated herein by
reference.
[0064] It should also be understood that many modifications and
variations of the described embodiments of the invention will occur
to a person having an ordinary skill in the art without departing
from the spirit and scope of the present invention as claimed in
the appended claims.
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